[PATCH v11 00/14] Git filter protocol

[PATCH v11 00/14] Git filter protocol

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

The goal of this series is to avoid launching a new clean/smudge filter
process for each file that is filtered.

A short summary about v1 to v5 can be found here:
https://git.github.io/rev_news/2016/08/17/edition-18/

This series is also published on web:
https://github.com/larsxschneider/git/pull/15

Patches 1 and 2 are cleanups and not strictly necessary for the series.
Patches 3 to 12 are required preparation. Patch 13 is the main patch.
Patch 14 adds an example how to use the Git filter protocol in contrib.

Thanks a lot to
 Jakub, Junio, Ramsay, Dscho, Torsten and Peff
for very helpful reviews,
Lars

## Changes since v10
  * clarify documentation (Jakub)
  * change "<capability>=true" to "capability=<capability>" in protocol (Jakub)
  * make stop_multi_file_filter() static (Ramsay)
  * add flush packet after version negotiation for consistency (Jakub)
  * fix pid_t translation error on Windows (Dscho)
  * fix Unquoted references in tests (Junio)
  * remove smudge invocation count in tests (Junio)


Lars Schneider (14):
  convert: quote filter names in error messages
  convert: modernize tests
  run-command: move check_pipe() from write_or_die to run_command
  run-command: add clean_on_exit_handler
  pkt-line: rename packet_write() to packet_write_fmt()
  pkt-line: extract set_packet_header()
  pkt-line: add packet_write_fmt_gently()
  pkt-line: add packet_flush_gently()
  pkt-line: add packet_write_gently()
  pkt-line: add functions to read/write flush terminated packet streams
  convert: make apply_filter() adhere to standard Git error handling
  convert: prepare filter.<driver>.process option
  convert: add filter.<driver>.process option
  contrib/long-running-filter: add long running filter example

 Documentation/gitattributes.txt        | 157 ++++++++++-
 builtin/archive.c                      |   4 +-
 builtin/receive-pack.c                 |   4 +-
 builtin/remote-ext.c                   |   4 +-
 builtin/upload-archive.c               |   4 +-
 connect.c                              |   2 +-
 contrib/long-running-filter/example.pl | 128 +++++++++
 convert.c                              | 375 +++++++++++++++++++++---
 daemon.c                               |   2 +-
 http-backend.c                         |   2 +-
 pkt-line.c                             | 152 +++++++++-
 pkt-line.h                             |  12 +-
 run-command.c                          |  39 ++-
 run-command.h                          |   4 +-
 shallow.c                              |   2 +-
 t/t0021-conversion.sh                  | 502 ++++++++++++++++++++++++++++++---
 t/t0021/rot13-filter.pl                | 192 +++++++++++++
 upload-pack.c                          |  30 +-
 write_or_die.c                         |  13 -
 19 files changed, 1495 insertions(+), 133 deletions(-)
 create mode 100755 contrib/long-running-filter/example.pl
 create mode 100755 t/t0021/rot13-filter.pl



## Interdiff (v10..v11)

diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index a182ef2..976243a 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -297,9 +297,11 @@ upon checkin. By default these commands process only a single
 blob and terminate. If a long running `process` filter is used
 in place of `clean` and/or `smudge` filters, then Git can process
 all blobs with a single filter command invocation for the entire
-life of a single Git command, for example `git add --all`.  See
-section below for the description of the protocol used to
-communicate with a `process` filter.
+life of a single Git command, for example `git add --all`. If a
+long running `process` filter is configured then it always takes
+precedence over a configured single blob filter. See section
+below for the description of the protocol used to communicate with
+a `process` filter.

 One use of the content filtering is to massage the content into a shape
 that is more convenient for the platform, filesystem, and the user to use.
@@ -393,10 +395,10 @@ text and therefore are terminated by a LF.

 Git starts the filter when it encounters the first file
 that needs to be cleaned or smudged. After the filter started
-Git sends a welcome message ("git-filter-client"), a list of
-supported protocol version numbers, and a flush packet. Git expects
-to read a welcome response message ("git-filter-server") and exactly
-one protocol version number from the previously sent list. All further
+Git sends a welcome message ("git-filter-client"), a list of supported
+protocol version numbers, and a flush packet. Git expects to read a welcome
+response message ("git-filter-server"), exactly one protocol version number
+from the previously sent list, and a flush packet. All further
 communication will be based on the selected version. The remaining
 protocol description below documents "version=2". Please note that
 "version=42" in the example below does not exist and is only there
@@ -414,12 +416,13 @@ packet:          git> version=42
 packet:          git> 0000
 packet:          git< git-filter-server
 packet:          git< version=2
-packet:          git> clean=true
-packet:          git> smudge=true
-packet:          git> not-yet-invented=true
+packet:          git< 0000
+packet:          git> capability=clean
+packet:          git> capability=smudge
+packet:          git> capability=not-yet-invented
 packet:          git> 0000
-packet:          git< clean=true
-packet:          git< smudge=true
+packet:          git< capability=clean
+packet:          git< capability=smudge
 packet:          git< 0000
 ------------------------
 Supported filter capabilities in version 2 are "clean" and
@@ -428,7 +431,7 @@ Supported filter capabilities in version 2 are "clean" and
 Afterwards Git sends a list of "key=value" pairs terminated with
 a flush packet. The list will contain at least the filter command
 (based on the supported capabilities) and the pathname of the file
-to filter relative to the repository root. Right after these packets
+to filter relative to the repository root. Right after the flush packet
 Git sends the content split in zero or more pkt-line packets and a
 flush packet to terminate content. Please note, that the filter
 must not send any response before it received the content and the
@@ -447,7 +450,10 @@ problems then the list must contain a "success" status. Right after
 these packets the filter is expected to send the content in zero
 or more pkt-line packets and a flush packet at the end. Finally, a
 second list of "key=value" pairs terminated with a flush packet
-is expected. The filter can change the status in the second list.
+is expected. The filter can change the status in the second list
+or keep the status as is with an empty list. Please note that the
+empty list must be terminated with a flush packet regardless.
+
 ------------------------
 packet:          git< status=success
 packet:          git< 0000
@@ -457,7 +463,7 @@ packet:          git< 0000  # empty list, keep "status=success" unchanged!
 ------------------------

 If the result content is empty then the filter is expected to respond
-with a "success" status and an empty list.
+with a "success" status and a flush packet to signal the empty content.
 ------------------------
 packet:          git< status=success
 packet:          git< 0000
@@ -466,9 +472,7 @@ packet:          git< 0000  # empty list, keep "status=success" unchanged!
 ------------------------

 In case the filter cannot or does not want to process the content,
-it is expected to respond with an "error" status. Depending on the
-`filter.<driver>.required` flag Git will interpret that as error
-but it will not stop or restart the filter process.
+it is expected to respond with an "error" status.
 ------------------------
 packet:          git< status=error
 packet:          git< 0000
@@ -476,9 +480,7 @@ packet:          git< 0000

 If the filter experiences an error during processing, then it can
 send the status "error" after the content was (partially or
-completely) sent. Depending on the `filter.<driver>.required` flag
-Git will interpret that as error but it will not stop or restart the
-filter process.
+completely) sent.
 ------------------------
 packet:          git< status=success
 packet:          git< 0000
@@ -488,31 +490,31 @@ packet:          git< status=error
 packet:          git< 0000
 ------------------------

-If the filter dies during the communication or does not adhere to
-the protocol then Git will stop the filter process and restart it
-with the next file that needs to be processed. Depending on the
-`filter.<driver>.required` flag Git will interpret that as error.
-
-The error handling for all cases above mimic the behavior of
-the `filter.<driver>.clean` / `filter.<driver>.smudge` error
-handling.
-
 In case the filter cannot or does not want to process the content
 as well as any future content for the lifetime of the Git process,
-it is expected to respond with an "abort" status at any point in
-the protocol. Depending on the `filter.<driver>.required` flag Git
-will interpret that as error for the content as well as any future
-content for the lifetime of the Git process but it will not stop or
-restart the filter process.
+then it is expected to respond with an "abort" status at any point
+in the protocol.
 ------------------------
 packet:          git< status=abort
 packet:          git< 0000
 ------------------------

+Git neither stops nor restarts the filter process in case the
+"error"/"abort" status is set. However, Git sets its exit code
+according to the `filter.<driver>.required` flag, mimicking the
+behavior of the `filter.<driver>.clean` / `filter.<driver>.smudge`
+mechanism.
+
+If the filter dies during the communication or does not adhere to
+the protocol then Git will stop the filter process and restart it
+with the next file that needs to be processed. Depending on the
+`filter.<driver>.required` flag Git will interpret that as error.
+
 After the filter has processed a blob it is expected to wait for
 the next "key=value" list containing a command. Git will close
 the command pipe on exit. The filter is expected to detect EOF
-and exit gracefully on its own.
+and exit gracefully on its own. Git will wait until the filter
+process has stopped.

 A long running filter demo implementation can be found in
 `contrib/long-running-filter/example.pl` located in the Git
@@ -520,10 +522,6 @@ core repository. If you develop your own long running filter
 process then the `GIT_TRACE_PACKET` environment variables can be
 very helpful for debugging (see linkgit:git[1]).

-If a `filter.<driver>.process` command is configured then it
-always takes precedence over a configured `filter.<driver>.clean`
-or `filter.<driver>.smudge` command.
-
 Please note that you cannot use an existing `filter.<driver>.clean`
 or `filter.<driver>.smudge` command with `filter.<driver>.process`
 because the former two use a different inter process communication
diff --git a/contrib/long-running-filter/example.pl b/contrib/long-running-filter/example.pl
index f4102d2..3945705 100755
--- a/contrib/long-running-filter/example.pl
+++ b/contrib/long-running-filter/example.pl
@@ -70,13 +70,14 @@ sub packet_flush {

 packet_txt_write("git-filter-server");
 packet_txt_write("version=2");
+packet_flush();

-( packet_txt_read() eq ( 0, "clean=true" ) )  || die "bad capability";
-( packet_txt_read() eq ( 0, "smudge=true" ) ) || die "bad capability";
+( packet_txt_read() eq ( 0, "capability=clean" ) )  || die "bad capability";
+( packet_txt_read() eq ( 0, "capability=smudge" ) ) || die "bad capability";
 ( packet_bin_read() eq ( 1, "" ) )                  || die "bad capability end";

-packet_txt_write("clean=true");
-packet_txt_write("smudge=true");
+packet_txt_write("capability=clean");
+packet_txt_write("capability=smudge");
 packet_flush();

 while (1) {
diff --git a/convert.c b/convert.c
index 1d89632..9d2aa68 100644
--- a/convert.c
+++ b/convert.c
@@ -567,7 +567,7 @@ static void kill_multi_file_filter(struct hashmap *hashmap, struct cmd2process *
 	free(entry);
 }

-void stop_multi_file_filter(struct child_process *process)
+static void stop_multi_file_filter(struct child_process *process)
 {
 	sigchain_push(SIGPIPE, SIG_IGN);
 	/* Closing the pipe signals the filter to initiate a shutdown. */
@@ -622,8 +622,11 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
 	err = strcmp(packet_read_line(process->out, NULL), "version=2");
 	if (err)
 		goto done;
+	err = packet_read_line(process->out, NULL) != NULL;
+	if (err)
+		goto done;

-	err = packet_write_list(process->in, "clean=true", "smudge=true", NULL);
+	err = packet_write_list(process->in, "capability=clean", "capability=smudge", NULL);

 	for (;;) {
 		cap_buf = packet_read_line(process->out, NULL);
@@ -631,10 +634,10 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
 			break;
 		string_list_split_in_place(&cap_list, cap_buf, '=', 1);

-		if (cap_list.nr != 2 || strcmp(cap_list.items[1].string, "true"))
+		if (cap_list.nr != 2 || strcmp(cap_list.items[0].string, "capability"))
 			continue;

-		cap_name = cap_list.items[0].string;
+		cap_name = cap_list.items[1].string;
 		if (!strcmp(cap_name, "clean")) {
 			entry->supported_capabilities |= CAP_CLEAN;
 		} else if (!strcmp(cap_name, "smudge")) {
diff --git a/run-command.c b/run-command.c
index e5fd6ff..ca905a9 100644
--- a/run-command.c
+++ b/run-command.c
@@ -36,7 +36,10 @@ static void cleanup_children(int sig, int in_signal)
 		if (p->process && !in_signal) {
 			struct child_process *process = p->process;
 			if (process->clean_on_exit_handler) {
-				trace_printf("trace: run_command: running exit handler for pid %d", p->pid);
+				trace_printf(
+					"trace: run_command: running exit handler for pid %"
+					PRIuMAX, (uintmax_t)p->pid
+				);
 				process->clean_on_exit_handler(process);
 			}
 		}
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index 9f892c0..a20b9f5 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -31,38 +31,35 @@ filter_git () {
 	rm -f git-stderr.log
 }

-# Count unique lines in two files and compare them.
-test_cmp_count () {
-	for FILE in $@
-	do
-		sort $FILE | uniq -c | sed "s/^[ ]*//" >$FILE.tmp
-		cat $FILE.tmp >$FILE
-	done &&
-	test_cmp $@
-}
-
-# Count unique lines except clean invocations in two files and compare
-# them. Clean invocations are not counted because their number can vary.
+# Compare two files and ensure that `clean` and `smudge` respectively are
+# called at least once if specified in the `expect` file. The actual
+# invocation count is not relevant because their number can vary.
 # c.f. http://public-inbox.org/git/xmqqshv18i8i.fsf@gitster.mtv.corp.google.com/
-test_cmp_count_except_clean () {
-	for FILE in $@
+test_cmp_count () {
+	expect=$1
+	actual=$2
+	for FILE in "$expect" "$actual"
 	do
-		sort $FILE | uniq -c | sed "s/^[ ]*//" |
-			sed "s/^\([0-9]\) IN: clean/x IN: clean/" >$FILE.tmp
-		cat $FILE.tmp >$FILE
+		sort "$FILE" | uniq -c | sed "s/^[ ]*//" |
+			sed "s/^\([0-9]\) IN: clean/x IN: clean/" |
+			sed "s/^\([0-9]\) IN: smudge/x IN: smudge/" >"$FILE.tmp" &&
+		mv "$FILE.tmp" "$FILE"
 	done &&
-	test_cmp $@
+	test_cmp "$expect" "$actual"
 }

-# Compare two files but exclude clean invocations because they can vary.
+# Compare two files but exclude all `clean` invocations because Git can
+# call `clean` zero or more times.
 # c.f. http://public-inbox.org/git/xmqqshv18i8i.fsf@gitster.mtv.corp.google.com/
 test_cmp_exclude_clean () {
-	for FILE in $@
+	expect=$1
+	actual=$2
+	for FILE in "$expect" "$actual"
 	do
-		grep -v "IN: clean" $FILE >$FILE.tmp
-		cat $FILE.tmp >$FILE
+		grep -v "IN: clean" "$FILE" >"$FILE.tmp" &&
+		mv "$FILE.tmp" "$FILE"
 	done &&
-	test_cmp $@
+	test_cmp "$expect" "$actual"
 }

 # Check that the contents of two files are equal and that their rot13 version
@@ -395,7 +392,7 @@ test_expect_success PERL 'required process filter should filter data' '
 			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
 			STOP
 		EOF
-		test_cmp_count_except_clean expected.log rot13-filter.log &&
+		test_cmp_count expected.log rot13-filter.log &&

 		rm -f test2.r "testsubdir/test3 '\''sq'\'',\$x.r" &&

diff --git a/t/t0021/rot13-filter.pl b/t/t0021/rot13-filter.pl
index 1a6959c..ae4c50f 100755
--- a/t/t0021/rot13-filter.pl
+++ b/t/t0021/rot13-filter.pl
@@ -95,13 +95,14 @@ $debug->flush();

 packet_txt_write("git-filter-server");
 packet_txt_write("version=2");
+packet_flush();

-( packet_txt_read() eq ( 0, "clean=true" ) )  || die "bad capability";
-( packet_txt_read() eq ( 0, "smudge=true" ) ) || die "bad capability";
+( packet_txt_read() eq ( 0, "capability=clean" ) )  || die "bad capability";
+( packet_txt_read() eq ( 0, "capability=smudge" ) ) || die "bad capability";
 ( packet_bin_read() eq ( 1, "" ) )                  || die "bad capability end";

 foreach (@capabilities) {
-	packet_txt_write( $_ . "=true" );
+	packet_txt_write( "capability=" . $_ );
 }
 packet_flush();
 print $debug "init handshake complete\n";

--
2.10.0

[PATCH v11 01/14] convert: quote filter names in error messages

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

Git filter driver commands with spaces (e.g. `filter.sh foo`) are hard
to read in error messages. Quote them to improve the readability.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 convert.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/convert.c b/convert.c
index 077f5e6..986c239 100644
--- a/convert.c
+++ b/convert.c
@@ -412,7 +412,7 @@ static int filter_buffer_or_fd(int in, int out, void *data)
 	child_process.out = out;
 
 	if (start_command(&child_process))
-		return error("cannot fork to run external filter %s", params->cmd);
+		return error("cannot fork to run external filter '%s'", params->cmd);
 
 	sigchain_push(SIGPIPE, SIG_IGN);
 
@@ -430,13 +430,13 @@ static int filter_buffer_or_fd(int in, int out, void *data)
 	if (close(child_process.in))
 		write_err = 1;
 	if (write_err)
-		error("cannot feed the input to external filter %s", params->cmd);
+		error("cannot feed the input to external filter '%s'", params->cmd);
 
 	sigchain_pop(SIGPIPE);
 
 	status = finish_command(&child_process);
 	if (status)
-		error("external filter %s failed %d", params->cmd, status);
+		error("external filter '%s' failed %d", params->cmd, status);
 
 	strbuf_release(&cmd);
 	return (write_err || status);
@@ -477,15 +477,15 @@ static int apply_filter(const char *path, const char *src, size_t len, int fd,
 		return 0;	/* error was already reported */
 
 	if (strbuf_read(&nbuf, async.out, len) < 0) {
-		error("read from external filter %s failed", cmd);
+		error("read from external filter '%s' failed", cmd);
 		ret = 0;
 	}
 	if (close(async.out)) {
-		error("read from external filter %s failed", cmd);
+		error("read from external filter '%s' failed", cmd);
 		ret = 0;
 	}
 	if (finish_async(&async)) {
-		error("external filter %s failed", cmd);
+		error("external filter '%s' failed", cmd);
 		ret = 0;
 	}
 
-- 
2.10.0

[PATCH v11 02/14] convert: modernize tests

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

Use `test_config` to set the config, check that files are empty with
`test_must_be_empty`, compare files with `test_cmp`, and remove spaces
after ">" and "<".

Please note that the "rot13" filter configured in "setup" keeps using
`git config` instead of `test_config` because subsequent tests might
depend on it.

Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 t/t0021-conversion.sh | 58 +++++++++++++++++++++++++--------------------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index e799e59..dc50938 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -38,8 +38,8 @@ script='s/^\$Id: \([0-9a-f]*\) \$/\1/p'
 
 test_expect_success check '
 
-	cmp test.o test &&
-	cmp test.o test.t &&
+	test_cmp test.o test &&
+	test_cmp test.o test.t &&
 
 	# ident should be stripped in the repository
 	git diff --raw --exit-code :test :test.i &&
@@ -47,10 +47,10 @@ test_expect_success check '
 	embedded=$(sed -ne "$script" test.i) &&
 	test "z$id" = "z$embedded" &&
 
-	git cat-file blob :test.t > test.r &&
+	git cat-file blob :test.t >test.r &&
 
-	./rot13.sh < test.o > test.t &&
-	cmp test.r test.t
+	./rot13.sh <test.o >test.t &&
+	test_cmp test.r test.t
 '
 
 # If an expanded ident ever gets into the repository, we want to make sure that
@@ -130,7 +130,7 @@ test_expect_success 'filter shell-escaped filenames' '
 
 	# delete the files and check them out again, using a smudge filter
 	# that will count the args and echo the command-line back to us
-	git config filter.argc.smudge "sh ./argc.sh %f" &&
+	test_config filter.argc.smudge "sh ./argc.sh %f" &&
 	rm "$normal" "$special" &&
 	git checkout -- "$normal" "$special" &&
 
@@ -141,7 +141,7 @@ test_expect_success 'filter shell-escaped filenames' '
 	test_cmp expect "$special" &&
 
 	# do the same thing, but with more args in the filter expression
-	git config filter.argc.smudge "sh ./argc.sh %f --my-extra-arg" &&
+	test_config filter.argc.smudge "sh ./argc.sh %f --my-extra-arg" &&
 	rm "$normal" "$special" &&
 	git checkout -- "$normal" "$special" &&
 
@@ -154,9 +154,9 @@ test_expect_success 'filter shell-escaped filenames' '
 '
 
 test_expect_success 'required filter should filter data' '
-	git config filter.required.smudge ./rot13.sh &&
-	git config filter.required.clean ./rot13.sh &&
-	git config filter.required.required true &&
+	test_config filter.required.smudge ./rot13.sh &&
+	test_config filter.required.clean ./rot13.sh &&
+	test_config filter.required.required true &&
 
 	echo "*.r filter=required" >.gitattributes &&
 
@@ -165,17 +165,17 @@ test_expect_success 'required filter should filter data' '
 
 	rm -f test.r &&
 	git checkout -- test.r &&
-	cmp test.o test.r &&
+	test_cmp test.o test.r &&
 
 	./rot13.sh <test.o >expected &&
 	git cat-file blob :test.r >actual &&
-	cmp expected actual
+	test_cmp expected actual
 '
 
 test_expect_success 'required filter smudge failure' '
-	git config filter.failsmudge.smudge false &&
-	git config filter.failsmudge.clean cat &&
-	git config filter.failsmudge.required true &&
+	test_config filter.failsmudge.smudge false &&
+	test_config filter.failsmudge.clean cat &&
+	test_config filter.failsmudge.required true &&
 
 	echo "*.fs filter=failsmudge" >.gitattributes &&
 
@@ -186,9 +186,9 @@ test_expect_success 'required filter smudge failure' '
 '
 
 test_expect_success 'required filter clean failure' '
-	git config filter.failclean.smudge cat &&
-	git config filter.failclean.clean false &&
-	git config filter.failclean.required true &&
+	test_config filter.failclean.smudge cat &&
+	test_config filter.failclean.clean false &&
+	test_config filter.failclean.required true &&
 
 	echo "*.fc filter=failclean" >.gitattributes &&
 
@@ -197,8 +197,8 @@ test_expect_success 'required filter clean failure' '
 '
 
 test_expect_success 'filtering large input to small output should use little memory' '
-	git config filter.devnull.clean "cat >/dev/null" &&
-	git config filter.devnull.required true &&
+	test_config filter.devnull.clean "cat >/dev/null" &&
+	test_config filter.devnull.required true &&
 	for i in $(test_seq 1 30); do printf "%1048576d" 1; done >30MB &&
 	echo "30MB filter=devnull" >.gitattributes &&
 	GIT_MMAP_LIMIT=1m GIT_ALLOC_LIMIT=1m git add 30MB
@@ -207,7 +207,7 @@ test_expect_success 'filtering large input to small output should use little mem
 test_expect_success 'filter that does not read is fine' '
 	test-genrandom foo $((128 * 1024 + 1)) >big &&
 	echo "big filter=epipe" >.gitattributes &&
-	git config filter.epipe.clean "echo xyzzy" &&
+	test_config filter.epipe.clean "echo xyzzy" &&
 	git add big &&
 	git cat-file blob :big >actual &&
 	echo xyzzy >expect &&
@@ -215,20 +215,20 @@ test_expect_success 'filter that does not read is fine' '
 '
 
 test_expect_success EXPENSIVE 'filter large file' '
-	git config filter.largefile.smudge cat &&
-	git config filter.largefile.clean cat &&
+	test_config filter.largefile.smudge cat &&
+	test_config filter.largefile.clean cat &&
 	for i in $(test_seq 1 2048); do printf "%1048576d" 1; done >2GB &&
 	echo "2GB filter=largefile" >.gitattributes &&
 	git add 2GB 2>err &&
-	! test -s err &&
+	test_must_be_empty err &&
 	rm -f 2GB &&
 	git checkout -- 2GB 2>err &&
-	! test -s err
+	test_must_be_empty err
 '
 
 test_expect_success "filter: clean empty file" '
-	git config filter.in-repo-header.clean  "echo cleaned && cat" &&
-	git config filter.in-repo-header.smudge "sed 1d" &&
+	test_config filter.in-repo-header.clean  "echo cleaned && cat" &&
+	test_config filter.in-repo-header.smudge "sed 1d" &&
 
 	echo "empty-in-worktree    filter=in-repo-header" >>.gitattributes &&
 	>empty-in-worktree &&
@@ -240,8 +240,8 @@ test_expect_success "filter: clean empty file" '
 '
 
 test_expect_success "filter: smudge empty file" '
-	git config filter.empty-in-repo.clean "cat >/dev/null" &&
-	git config filter.empty-in-repo.smudge "echo smudged && cat" &&
+	test_config filter.empty-in-repo.clean "cat >/dev/null" &&
+	test_config filter.empty-in-repo.smudge "echo smudged && cat" &&
 
 	echo "empty-in-repo filter=empty-in-repo" >>.gitattributes &&
 	echo dead data walking >empty-in-repo &&
-- 
2.10.0

[PATCH v11 03/14] run-command: move check_pipe() from write_or_die to run_command

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

Move check_pipe() to run_command and make it public. This is necessary
to call the function from pkt-line in a subsequent patch.

While at it, make async_exit() static to run_command.c as it is no
longer used from outside.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 run-command.c  | 17 +++++++++++++++--
 run-command.h  |  2 +-
 write_or_die.c | 13 -------------
 3 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/run-command.c b/run-command.c
index 5a4dbb6..3269362 100644
--- a/run-command.c
+++ b/run-command.c
@@ -634,7 +634,7 @@ int in_async(void)
 	return !pthread_equal(main_thread, pthread_self());
 }
 
-void NORETURN async_exit(int code)
+static void NORETURN async_exit(int code)
 {
 	pthread_exit((void *)(intptr_t)code);
 }
@@ -684,13 +684,26 @@ int in_async(void)
 	return process_is_async;
 }
 
-void NORETURN async_exit(int code)
+static void NORETURN async_exit(int code)
 {
 	exit(code);
 }
 
 #endif
 
+void check_pipe(int err)
+{
+	if (err == EPIPE) {
+		if (in_async())
+			async_exit(141);
+
+		signal(SIGPIPE, SIG_DFL);
+		raise(SIGPIPE);
+		/* Should never happen, but just in case... */
+		exit(141);
+	}
+}
+
 int start_async(struct async *async)
 {
 	int need_in, need_out;
diff --git a/run-command.h b/run-command.h
index 5066649..cf29a31 100644
--- a/run-command.h
+++ b/run-command.h
@@ -139,7 +139,7 @@ struct async {
 int start_async(struct async *async);
 int finish_async(struct async *async);
 int in_async(void);
-void NORETURN async_exit(int code);
+void check_pipe(int err);
 
 /**
  * This callback should initialize the child process and preload the
diff --git a/write_or_die.c b/write_or_die.c
index 0734432..eab8c8d 100644
--- a/write_or_die.c
+++ b/write_or_die.c
@@ -1,19 +1,6 @@
 #include "cache.h"
 #include "run-command.h"
 
-static void check_pipe(int err)
-{
-	if (err == EPIPE) {
-		if (in_async())
-			async_exit(141);
-
-		signal(SIGPIPE, SIG_DFL);
-		raise(SIGPIPE);
-		/* Should never happen, but just in case... */
-		exit(141);
-	}
-}
-
 /*
  * Some cases use stdio, but want to flush after the write
  * to get error handling (and to get better interactive
-- 
2.10.0

[PATCH v11 04/14] run-command: add clean_on_exit_handler

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

Some processes might want to perform cleanup tasks before Git kills them
due to the 'clean_on_exit' flag. Let's give them an interface for doing
this. The feature is used in a subsequent patch.

Please note, that the cleanup callback is not executed if Git dies of a
signal. The reason is that only "async-signal-safe" functions would be
allowed to be call in that case. Since we cannot control what functions
the callback will use, we will not support the case. See 507d7804 for
more details.

Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
---
 run-command.c | 22 ++++++++++++++++++----
 run-command.h |  2 ++
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/run-command.c b/run-command.c
index 3269362..ca905a9 100644
--- a/run-command.c
+++ b/run-command.c
@@ -21,6 +21,7 @@ void child_process_clear(struct child_process *child)
 
 struct child_to_clean {
 	pid_t pid;
+	struct child_process *process;
 	struct child_to_clean *next;
 };
 static struct child_to_clean *children_to_clean;
@@ -31,6 +32,18 @@ static void cleanup_children(int sig, int in_signal)
 	while (children_to_clean) {
 		struct child_to_clean *p = children_to_clean;
 		children_to_clean = p->next;
+
+		if (p->process && !in_signal) {
+			struct child_process *process = p->process;
+			if (process->clean_on_exit_handler) {
+				trace_printf(
+					"trace: run_command: running exit handler for pid %"
+					PRIuMAX, (uintmax_t)p->pid
+				);
+				process->clean_on_exit_handler(process);
+			}
+		}
+
 		kill(p->pid, sig);
 		if (!in_signal)
 			free(p);
@@ -49,10 +62,11 @@ static void cleanup_children_on_exit(void)
 	cleanup_children(SIGTERM, 0);
 }
 
-static void mark_child_for_cleanup(pid_t pid)
+static void mark_child_for_cleanup(pid_t pid, struct child_process *process)
 {
 	struct child_to_clean *p = xmalloc(sizeof(*p));
 	p->pid = pid;
+	p->process = process;
 	p->next = children_to_clean;
 	children_to_clean = p;
 
@@ -422,7 +436,7 @@ int start_command(struct child_process *cmd)
 	if (cmd->pid < 0)
 		error_errno("cannot fork() for %s", cmd->argv[0]);
 	else if (cmd->clean_on_exit)
-		mark_child_for_cleanup(cmd->pid);
+		mark_child_for_cleanup(cmd->pid, cmd);
 
 	/*
 	 * Wait for child's execvp. If the execvp succeeds (or if fork()
@@ -483,7 +497,7 @@ int start_command(struct child_process *cmd)
 	if (cmd->pid < 0 && (!cmd->silent_exec_failure || errno != ENOENT))
 		error_errno("cannot spawn %s", cmd->argv[0]);
 	if (cmd->clean_on_exit && cmd->pid >= 0)
-		mark_child_for_cleanup(cmd->pid);
+		mark_child_for_cleanup(cmd->pid, cmd);
 
 	argv_array_clear(&nargv);
 	cmd->argv = sargv;
@@ -765,7 +779,7 @@ int start_async(struct async *async)
 		exit(!!async->proc(proc_in, proc_out, async->data));
 	}
 
-	mark_child_for_cleanup(async->pid);
+	mark_child_for_cleanup(async->pid, NULL);
 
 	if (need_in)
 		close(fdin[0]);
diff --git a/run-command.h b/run-command.h
index cf29a31..dd1c78c 100644
--- a/run-command.h
+++ b/run-command.h
@@ -43,6 +43,8 @@ struct child_process {
 	unsigned stdout_to_stderr:1;
 	unsigned use_shell:1;
 	unsigned clean_on_exit:1;
+	void (*clean_on_exit_handler)(struct child_process *process);
+	void *clean_on_exit_handler_cbdata;
 };
 
 #define CHILD_PROCESS_INIT { NULL, ARGV_ARRAY_INIT, ARGV_ARRAY_INIT }
-- 
2.10.0

[PATCH v11 05/14] pkt-line: rename packet_write() to packet_write_fmt()

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

packet_write() should be called packet_write_fmt() because it is a
printf-like function that takes a format string as first parameter.

packet_write_fmt() should be used for text strings only. Arbitrary
binary data should use a new packet_write() function that is introduced
in a subsequent patch.

Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/archive.c        |  4 ++--
 builtin/receive-pack.c   |  4 ++--
 builtin/remote-ext.c     |  4 ++--
 builtin/upload-archive.c |  4 ++--
 connect.c                |  2 +-
 daemon.c                 |  2 +-
 http-backend.c           |  2 +-
 pkt-line.c               |  2 +-
 pkt-line.h               |  2 +-
 shallow.c                |  2 +-
 upload-pack.c            | 30 +++++++++++++++---------------
 11 files changed, 29 insertions(+), 29 deletions(-)

diff --git a/builtin/archive.c b/builtin/archive.c
index a1e3b94..49f4914 100644
--- a/builtin/archive.c
+++ b/builtin/archive.c
@@ -47,10 +47,10 @@ static int run_remote_archiver(int argc, const char **argv,
 	if (name_hint) {
 		const char *format = archive_format_from_filename(name_hint);
 		if (format)
-			packet_write(fd[1], "argument --format=%s\n", format);
+			packet_write_fmt(fd[1], "argument --format=%s\n", format);
 	}
 	for (i = 1; i < argc; i++)
-		packet_write(fd[1], "argument %s\n", argv[i]);
+		packet_write_fmt(fd[1], "argument %s\n", argv[i]);
 	packet_flush(fd[1]);
 
 	buf = packet_read_line(fd[0], NULL);
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 011db00..1ce7682 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -218,7 +218,7 @@ static int receive_pack_config(const char *var, const char *value, void *cb)
 static void show_ref(const char *path, const unsigned char *sha1)
 {
 	if (sent_capabilities) {
-		packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
+		packet_write_fmt(1, "%s %s\n", sha1_to_hex(sha1), path);
 	} else {
 		struct strbuf cap = STRBUF_INIT;
 
@@ -233,7 +233,7 @@ static void show_ref(const char *path, const unsigned char *sha1)
 		if (advertise_push_options)
 			strbuf_addstr(&cap, " push-options");
 		strbuf_addf(&cap, " agent=%s", git_user_agent_sanitized());
-		packet_write(1, "%s %s%c%s\n",
+		packet_write_fmt(1, "%s %s%c%s\n",
 			     sha1_to_hex(sha1), path, 0, cap.buf);
 		strbuf_release(&cap);
 		sent_capabilities = 1;
diff --git a/builtin/remote-ext.c b/builtin/remote-ext.c
index 88eb8f9..11b48bf 100644
--- a/builtin/remote-ext.c
+++ b/builtin/remote-ext.c
@@ -128,9 +128,9 @@ static void send_git_request(int stdin_fd, const char *serv, const char *repo,
 	const char *vhost)
 {
 	if (!vhost)
-		packet_write(stdin_fd, "%s %s%c", serv, repo, 0);
+		packet_write_fmt(stdin_fd, "%s %s%c", serv, repo, 0);
 	else
-		packet_write(stdin_fd, "%s %s%chost=%s%c", serv, repo, 0,
+		packet_write_fmt(stdin_fd, "%s %s%chost=%s%c", serv, repo, 0,
 			     vhost, 0);
 }
 
diff --git a/builtin/upload-archive.c b/builtin/upload-archive.c
index 2caedf1..dc872f6 100644
--- a/builtin/upload-archive.c
+++ b/builtin/upload-archive.c
@@ -88,11 +88,11 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 	writer.git_cmd = 1;
 	if (start_command(&writer)) {
 		int err = errno;
-		packet_write(1, "NACK unable to spawn subprocess\n");
+		packet_write_fmt(1, "NACK unable to spawn subprocess\n");
 		die("upload-archive: %s", strerror(err));
 	}
 
-	packet_write(1, "ACK\n");
+	packet_write_fmt(1, "ACK\n");
 	packet_flush(1);
 
 	while (1) {
diff --git a/connect.c b/connect.c
index 722dc3f..5330d9c 100644
--- a/connect.c
+++ b/connect.c
@@ -730,7 +730,7 @@ struct child_process *git_connect(int fd[2], const char *url,
 		 * Note: Do not add any other headers here!  Doing so
 		 * will cause older git-daemon servers to crash.
 		 */
-		packet_write(fd[1],
+		packet_write_fmt(fd[1],
 			     "%s %s%chost=%s%c",
 			     prog, path, 0,
 			     target_host, 0);
diff --git a/daemon.c b/daemon.c
index 425aad0..afce1b9 100644
--- a/daemon.c
+++ b/daemon.c
@@ -281,7 +281,7 @@ static int daemon_error(const char *dir, const char *msg)
 {
 	if (!informative_errors)
 		msg = "access denied or repository not exported";
-	packet_write(1, "ERR %s: %s", msg, dir);
+	packet_write_fmt(1, "ERR %s: %s", msg, dir);
 	return -1;
 }
 
diff --git a/http-backend.c b/http-backend.c
index adc8c8c..eef0a36 100644
--- a/http-backend.c
+++ b/http-backend.c
@@ -464,7 +464,7 @@ static void get_info_refs(struct strbuf *hdr, char *arg)
 		hdr_str(hdr, content_type, buf.buf);
 		end_headers(hdr);
 
-		packet_write(1, "# service=git-%s\n", svc->name);
+		packet_write_fmt(1, "# service=git-%s\n", svc->name);
 		packet_flush(1);
 
 		argv[0] = svc->name;
diff --git a/pkt-line.c b/pkt-line.c
index 62fdb37..0a9b61c 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -118,7 +118,7 @@ static void format_packet(struct strbuf *out, const char *fmt, va_list args)
 	packet_trace(out->buf + orig_len + 4, n - 4, 1);
 }
 
-void packet_write(int fd, const char *fmt, ...)
+void packet_write_fmt(int fd, const char *fmt, ...)
 {
 	static struct strbuf buf = STRBUF_INIT;
 	va_list args;
diff --git a/pkt-line.h b/pkt-line.h
index 3cb9d91..1902fb3 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -20,7 +20,7 @@
  * side can't, we stay with pure read/write interfaces.
  */
 void packet_flush(int fd);
-void packet_write(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
+void packet_write_fmt(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 void packet_buf_flush(struct strbuf *buf);
 void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 
diff --git a/shallow.c b/shallow.c
index 54e2db7..d666e24 100644
--- a/shallow.c
+++ b/shallow.c
@@ -260,7 +260,7 @@ static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *c
 {
 	int fd = *(int *)cb;
 	if (graft->nr_parent == -1)
-		packet_write(fd, "shallow %s\n", oid_to_hex(&graft->oid));
+		packet_write_fmt(fd, "shallow %s\n", oid_to_hex(&graft->oid));
 	return 0;
 }
 
diff --git a/upload-pack.c b/upload-pack.c
index ca7f941..cd47de6 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -393,13 +393,13 @@ static int get_common_commits(void)
 			if (multi_ack == 2 && got_common
 			    && !got_other && ok_to_give_up()) {
 				sent_ready = 1;
-				packet_write(1, "ACK %s ready\n", last_hex);
+				packet_write_fmt(1, "ACK %s ready\n", last_hex);
 			}
 			if (have_obj.nr == 0 || multi_ack)
-				packet_write(1, "NAK\n");
+				packet_write_fmt(1, "NAK\n");
 
 			if (no_done && sent_ready) {
-				packet_write(1, "ACK %s\n", last_hex);
+				packet_write_fmt(1, "ACK %s\n", last_hex);
 				return 0;
 			}
 			if (stateless_rpc)
@@ -416,20 +416,20 @@ static int get_common_commits(void)
 					const char *hex = sha1_to_hex(sha1);
 					if (multi_ack == 2) {
 						sent_ready = 1;
-						packet_write(1, "ACK %s ready\n", hex);
+						packet_write_fmt(1, "ACK %s ready\n", hex);
 					} else
-						packet_write(1, "ACK %s continue\n", hex);
+						packet_write_fmt(1, "ACK %s continue\n", hex);
 				}
 				break;
 			default:
 				got_common = 1;
 				memcpy(last_hex, sha1_to_hex(sha1), 41);
 				if (multi_ack == 2)
-					packet_write(1, "ACK %s common\n", last_hex);
+					packet_write_fmt(1, "ACK %s common\n", last_hex);
 				else if (multi_ack)
-					packet_write(1, "ACK %s continue\n", last_hex);
+					packet_write_fmt(1, "ACK %s continue\n", last_hex);
 				else if (have_obj.nr == 1)
-					packet_write(1, "ACK %s\n", last_hex);
+					packet_write_fmt(1, "ACK %s\n", last_hex);
 				break;
 			}
 			continue;
@@ -437,10 +437,10 @@ static int get_common_commits(void)
 		if (!strcmp(line, "done")) {
 			if (have_obj.nr > 0) {
 				if (multi_ack)
-					packet_write(1, "ACK %s\n", last_hex);
+					packet_write_fmt(1, "ACK %s\n", last_hex);
 				return 0;
 			}
-			packet_write(1, "NAK\n");
+			packet_write_fmt(1, "NAK\n");
 			return -1;
 		}
 		die("git upload-pack: expected SHA1 list, got '%s'", line);
@@ -650,7 +650,7 @@ static void receive_needs(void)
 		while (result) {
 			struct object *object = &result->item->object;
 			if (!(object->flags & (CLIENT_SHALLOW|NOT_SHALLOW))) {
-				packet_write(1, "shallow %s",
+				packet_write_fmt(1, "shallow %s",
 						oid_to_hex(&object->oid));
 				register_shallow(object->oid.hash);
 				shallow_nr++;
@@ -662,7 +662,7 @@ static void receive_needs(void)
 			struct object *object = shallows.objects[i].item;
 			if (object->flags & NOT_SHALLOW) {
 				struct commit_list *parents;
-				packet_write(1, "unshallow %s",
+				packet_write_fmt(1, "unshallow %s",
 					oid_to_hex(&object->oid));
 				object->flags &= ~CLIENT_SHALLOW;
 				/* make sure the real parents are parsed */
@@ -741,7 +741,7 @@ static int send_ref(const char *refname, const struct object_id *oid,
 		struct strbuf symref_info = STRBUF_INIT;
 
 		format_symref_info(&symref_info, cb_data);
-		packet_write(1, "%s %s%c%s%s%s%s%s agent=%s\n",
+		packet_write_fmt(1, "%s %s%c%s%s%s%s%s agent=%s\n",
 			     oid_to_hex(oid), refname_nons,
 			     0, capabilities,
 			     (allow_unadvertised_object_request & ALLOW_TIP_SHA1) ?
@@ -753,11 +753,11 @@ static int send_ref(const char *refname, const struct object_id *oid,
 			     git_user_agent_sanitized());
 		strbuf_release(&symref_info);
 	} else {
-		packet_write(1, "%s %s\n", oid_to_hex(oid), refname_nons);
+		packet_write_fmt(1, "%s %s\n", oid_to_hex(oid), refname_nons);
 	}
 	capabilities = NULL;
 	if (!peel_ref(refname, peeled.hash))
-		packet_write(1, "%s %s^{}\n", oid_to_hex(&peeled), refname_nons);
+		packet_write_fmt(1, "%s %s^{}\n", oid_to_hex(&peeled), refname_nons);
 	return 0;
 }
 
-- 
2.10.0

[PATCH v11 06/14] pkt-line: extract set_packet_header()

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

Extracted set_packet_header() function converts an integer to a 4 byte
hex string. Make this function locally available so that other pkt-line
functions could use it.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 pkt-line.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/pkt-line.c b/pkt-line.c
index 0a9b61c..e8adc0f 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -97,10 +97,20 @@ void packet_buf_flush(struct strbuf *buf)
 	strbuf_add(buf, "0000", 4);
 }
 
-#define hex(a) (hexchar[(a) & 15])
-static void format_packet(struct strbuf *out, const char *fmt, va_list args)
+static void set_packet_header(char *buf, const int size)
 {
 	static char hexchar[] = "0123456789abcdef";
+
+	#define hex(a) (hexchar[(a) & 15])
+	buf[0] = hex(size >> 12);
+	buf[1] = hex(size >> 8);
+	buf[2] = hex(size >> 4);
+	buf[3] = hex(size);
+	#undef hex
+}
+
+static void format_packet(struct strbuf *out, const char *fmt, va_list args)
+{
 	size_t orig_len, n;
 
 	orig_len = out->len;
@@ -111,10 +121,7 @@ static void format_packet(struct strbuf *out, const char *fmt, va_list args)
 	if (n > LARGE_PACKET_MAX)
 		die("protocol error: impossibly long line");
 
-	out->buf[orig_len + 0] = hex(n >> 12);
-	out->buf[orig_len + 1] = hex(n >> 8);
-	out->buf[orig_len + 2] = hex(n >> 4);
-	out->buf[orig_len + 3] = hex(n);
+	set_packet_header(&out->buf[orig_len], n);
 	packet_trace(out->buf + orig_len + 4, n - 4, 1);
 }
 
-- 
2.10.0

[PATCH v11 07/14] pkt-line: add packet_write_fmt_gently()

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

packet_write_fmt() would die in case of a write error even though for
some callers an error would be acceptable. Add packet_write_fmt_gently()
which writes a formatted pkt-line like packet_write_fmt() but does not
die in case of an error. The function is used in a subsequent patch.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 pkt-line.c | 34 ++++++++++++++++++++++++++++++----
 pkt-line.h |  1 +
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/pkt-line.c b/pkt-line.c
index e8adc0f..56915f0 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -125,16 +125,42 @@ static void format_packet(struct strbuf *out, const char *fmt, va_list args)
 	packet_trace(out->buf + orig_len + 4, n - 4, 1);
 }
 
+static int packet_write_fmt_1(int fd, int gently,
+			      const char *fmt, va_list args)
+{
+	struct strbuf buf = STRBUF_INIT;
+	ssize_t count;
+
+	format_packet(&buf, fmt, args);
+	count = write_in_full(fd, buf.buf, buf.len);
+	if (count == buf.len)
+		return 0;
+
+	if (!gently) {
+		check_pipe(errno);
+		die_errno("packet write with format failed");
+	}
+	return error("packet write with format failed");
+}
+
 void packet_write_fmt(int fd, const char *fmt, ...)
 {
-	static struct strbuf buf = STRBUF_INIT;
 	va_list args;
 
-	strbuf_reset(&buf);
 	va_start(args, fmt);
-	format_packet(&buf, fmt, args);
+	packet_write_fmt_1(fd, 0, fmt, args);
+	va_end(args);
+}
+
+int packet_write_fmt_gently(int fd, const char *fmt, ...)
+{
+	int status;
+	va_list args;
+
+	va_start(args, fmt);
+	status = packet_write_fmt_1(fd, 1, fmt, args);
 	va_end(args);
-	write_or_die(fd, buf.buf, buf.len);
+	return status;
 }
 
 void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
diff --git a/pkt-line.h b/pkt-line.h
index 1902fb3..3caea77 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -23,6 +23,7 @@ void packet_flush(int fd);
 void packet_write_fmt(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 void packet_buf_flush(struct strbuf *buf);
 void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
+int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 
 /*
  * Read a packetized line into the buffer, which must be at least size bytes
-- 
2.10.0

[PATCH v11 08/14] pkt-line: add packet_flush_gently()

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

packet_flush() would die in case of a write error even though for some
callers an error would be acceptable. Add packet_flush_gently() which
writes a pkt-line flush packet like packet_flush() but does not die in
case of an error. The function is used in a subsequent patch.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 pkt-line.c | 8 ++++++++
 pkt-line.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/pkt-line.c b/pkt-line.c
index 56915f0..286eb09 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -91,6 +91,14 @@ void packet_flush(int fd)
 	write_or_die(fd, "0000", 4);
 }
 
+int packet_flush_gently(int fd)
+{
+	packet_trace("0000", 4, 1);
+	if (write_in_full(fd, "0000", 4) == 4)
+		return 0;
+	return error("flush packet write failed");
+}
+
 void packet_buf_flush(struct strbuf *buf)
 {
 	packet_trace("0000", 4, 1);
diff --git a/pkt-line.h b/pkt-line.h
index 3caea77..3fa0899 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -23,6 +23,7 @@ void packet_flush(int fd);
 void packet_write_fmt(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 void packet_buf_flush(struct strbuf *buf);
 void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
+int packet_flush_gently(int fd);
 int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 
 /*
-- 
2.10.0

[PATCH v11 09/14] pkt-line: add packet_write_gently()

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

packet_write_fmt_gently() uses format_packet() which lets the caller
only send string data via "%s". That means it cannot be used for
arbitrary data that may contain NULs.

Add packet_write_gently() which writes arbitrary data and does not die
in case of an error. The function is used by other pkt-line functions in
a subsequent patch.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 pkt-line.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/pkt-line.c b/pkt-line.c
index 286eb09..dca5a64 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -171,6 +171,23 @@ int packet_write_fmt_gently(int fd, const char *fmt, ...)
 	return status;
 }
 
+static int packet_write_gently(const int fd_out, const char *buf, size_t size)
+{
+	static char packet_write_buffer[LARGE_PACKET_MAX];
+	size_t packet_size;
+
+	if (size > sizeof(packet_write_buffer) - 4)
+		return error("packet write failed - data exceeds max packet size");
+
+	packet_trace(buf, size, 1);
+	packet_size = size + 4;
+	set_packet_header(packet_write_buffer, packet_size);
+	memcpy(packet_write_buffer + 4, buf, size);
+	if (write_in_full(fd_out, packet_write_buffer, packet_size) == packet_size)
+		return 0;
+	return error("packet write failed");
+}
+
 void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
 {
 	va_list args;
-- 
2.10.0

[PATCH v11 10/14] pkt-line: add functions to read/write flush terminated packet streams

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

write_packetized_from_fd() and write_packetized_from_buf() write a
stream of packets. All content packets use the maximal packet size
except for the last one. After the last content packet a `flush` control
packet is written.

read_packetized_to_strbuf() reads arbitrary sized packets until it
detects a `flush` packet.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 pkt-line.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 pkt-line.h |  8 +++++++
 2 files changed, 80 insertions(+)

diff --git a/pkt-line.c b/pkt-line.c
index dca5a64..0b5125f 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -197,6 +197,46 @@ void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
 	va_end(args);
 }
 
+int write_packetized_from_fd(int fd_in, int fd_out)
+{
+	static char buf[LARGE_PACKET_DATA_MAX];
+	int err = 0;
+	ssize_t bytes_to_write;
+
+	while (!err) {
+		bytes_to_write = xread(fd_in, buf, sizeof(buf));
+		if (bytes_to_write < 0)
+			return COPY_READ_ERROR;
+		if (bytes_to_write == 0)
+			break;
+		err = packet_write_gently(fd_out, buf, bytes_to_write);
+	}
+	if (!err)
+		err = packet_flush_gently(fd_out);
+	return err;
+}
+
+int write_packetized_from_buf(const char *src_in, size_t len, int fd_out)
+{
+	int err = 0;
+	size_t bytes_written = 0;
+	size_t bytes_to_write;
+
+	while (!err) {
+		if ((len - bytes_written) > LARGE_PACKET_DATA_MAX)
+			bytes_to_write = LARGE_PACKET_DATA_MAX;
+		else
+			bytes_to_write = len - bytes_written;
+		if (bytes_to_write == 0)
+			break;
+		err = packet_write_gently(fd_out, src_in + bytes_written, bytes_to_write);
+		bytes_written += bytes_to_write;
+	}
+	if (!err)
+		err = packet_flush_gently(fd_out);
+	return err;
+}
+
 static int get_packet_data(int fd, char **src_buf, size_t *src_size,
 			   void *dst, unsigned size, int options)
 {
@@ -306,3 +346,35 @@ char *packet_read_line_buf(char **src, size_t *src_len, int *dst_len)
 {
 	return packet_read_line_generic(-1, src, src_len, dst_len);
 }
+
+ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out)
+{
+	int packet_len;
+
+	size_t orig_len = sb_out->len;
+	size_t orig_alloc = sb_out->alloc;
+
+	for (;;) {
+		strbuf_grow(sb_out, LARGE_PACKET_DATA_MAX);
+		packet_len = packet_read(fd_in, NULL, NULL,
+			/* strbuf_grow() above always allocates one extra byte to
+			 * store a '\0' at the end of the string. packet_read()
+			 * writes a '\0' extra byte at the end, too. Let it know
+			 * that there is already room for the extra byte.
+			 */
+			sb_out->buf + sb_out->len, LARGE_PACKET_DATA_MAX+1,
+			PACKET_READ_GENTLE_ON_EOF);
+		if (packet_len <= 0)
+			break;
+		sb_out->len += packet_len;
+	}
+
+	if (packet_len < 0) {
+		if (orig_alloc == 0)
+			strbuf_release(sb_out);
+		else
+			strbuf_setlen(sb_out, orig_len);
+		return packet_len;
+	}
+	return sb_out->len - orig_len;
+}
diff --git a/pkt-line.h b/pkt-line.h
index 3fa0899..18eac64 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -25,6 +25,8 @@ void packet_buf_flush(struct strbuf *buf);
 void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 int packet_flush_gently(int fd);
 int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
+int write_packetized_from_fd(int fd_in, int fd_out);
+int write_packetized_from_buf(const char *src_in, size_t len, int fd_out);
 
 /*
  * Read a packetized line into the buffer, which must be at least size bytes
@@ -77,8 +79,14 @@ char *packet_read_line(int fd, int *size);
  */
 char *packet_read_line_buf(char **src_buf, size_t *src_len, int *size);
 
+/*
+ * Reads a stream of variable sized packets until a flush packet is detected.
+ */
+ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out);
+
 #define DEFAULT_PACKET_MAX 1000
 #define LARGE_PACKET_MAX 65520
+#define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
 extern char packet_buffer[LARGE_PACKET_MAX];
 
 #endif
-- 
2.10.0

[PATCH v11 11/14] convert: make apply_filter() adhere to standard Git error handling

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

apply_filter() returns a boolean that tells the caller if it
"did convert or did not convert". The variable `ret` was used throughout
the function to track errors whereas `1` denoted success and `0`
failure. This is unusual for the Git source where `0` denotes success.

Rename the variable and flip its value to make the function easier
readable for Git developers.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 convert.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/convert.c b/convert.c
index 986c239..597f561 100644
--- a/convert.c
+++ b/convert.c
@@ -451,7 +451,7 @@ static int apply_filter(const char *path, const char *src, size_t len, int fd,
 	 *
 	 * (child --> cmd) --> us
 	 */
-	int ret = 1;
+	int err = 0;
 	struct strbuf nbuf = STRBUF_INIT;
 	struct async async;
 	struct filter_params params;
@@ -477,23 +477,20 @@ static int apply_filter(const char *path, const char *src, size_t len, int fd,
 		return 0;	/* error was already reported */
 
 	if (strbuf_read(&nbuf, async.out, len) < 0) {
-		error("read from external filter '%s' failed", cmd);
-		ret = 0;
+		err = error("read from external filter '%s' failed", cmd);
 	}
 	if (close(async.out)) {
-		error("read from external filter '%s' failed", cmd);
-		ret = 0;
+		err = error("read from external filter '%s' failed", cmd);
 	}
 	if (finish_async(&async)) {
-		error("external filter '%s' failed", cmd);
-		ret = 0;
+		err = error("external filter '%s' failed", cmd);
 	}
 
-	if (ret) {
+	if (!err) {
 		strbuf_swap(dst, &nbuf);
 	}
 	strbuf_release(&nbuf);
-	return ret;
+	return !err;
 }
 
 static struct convert_driver {
-- 
2.10.0

[PATCH v11 12/14] convert: prepare filter.<driver>.process option

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

Refactor the existing 'single shot filter mechanism' and prepare the
new 'long running filter mechanism'.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
---
 convert.c | 60 ++++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 34 insertions(+), 26 deletions(-)

diff --git a/convert.c b/convert.c
index 597f561..71e11ff 100644
--- a/convert.c
+++ b/convert.c
@@ -442,7 +442,7 @@ static int filter_buffer_or_fd(int in, int out, void *data)
 	return (write_err || status);
 }
 
-static int apply_filter(const char *path, const char *src, size_t len, int fd,
+static int apply_single_file_filter(const char *path, const char *src, size_t len, int fd,
                         struct strbuf *dst, const char *cmd)
 {
 	/*
@@ -456,12 +456,6 @@ static int apply_filter(const char *path, const char *src, size_t len, int fd,
 	struct async async;
 	struct filter_params params;
 
-	if (!cmd || !*cmd)
-		return 0;
-
-	if (!dst)
-		return 1;
-
 	memset(&async, 0, sizeof(async));
 	async.proc = filter_buffer_or_fd;
 	async.data = &params;
@@ -493,6 +487,9 @@ static int apply_filter(const char *path, const char *src, size_t len, int fd,
 	return !err;
 }
 
+#define CAP_CLEAN    (1u<<0)
+#define CAP_SMUDGE   (1u<<1)
+
 static struct convert_driver {
 	const char *name;
 	struct convert_driver *next;
@@ -501,6 +498,29 @@ static struct convert_driver {
 	int required;
 } *user_convert, **user_convert_tail;
 
+static int apply_filter(const char *path, const char *src, size_t len,
+			int fd, struct strbuf *dst, struct convert_driver *drv,
+			const unsigned int wanted_capability)
+{
+	const char *cmd = NULL;
+
+	if (!drv)
+		return 0;
+
+	if (!dst)
+		return 1;
+
+	if ((CAP_CLEAN & wanted_capability) && drv->clean)
+		cmd = drv->clean;
+	else if ((CAP_SMUDGE & wanted_capability) && drv->smudge)
+		cmd = drv->smudge;
+
+	if (cmd && *cmd)
+		return apply_single_file_filter(path, src, len, fd, dst, cmd);
+
+	return 0;
+}
+
 static int read_convert_config(const char *var, const char *value, void *cb)
 {
 	const char *key, *name;
@@ -839,7 +859,7 @@ int would_convert_to_git_filter_fd(const char *path)
 	if (!ca.drv->required)
 		return 0;
 
-	return apply_filter(path, NULL, 0, -1, NULL, ca.drv->clean);
+	return apply_filter(path, NULL, 0, -1, NULL, ca.drv, CAP_CLEAN);
 }
 
 const char *get_convert_attr_ascii(const char *path)
@@ -872,18 +892,12 @@ int convert_to_git(const char *path, const char *src, size_t len,
                    struct strbuf *dst, enum safe_crlf checksafe)
 {
 	int ret = 0;
-	const char *filter = NULL;
-	int required = 0;
 	struct conv_attrs ca;
 
 	convert_attrs(&ca, path);
-	if (ca.drv) {
-		filter = ca.drv->clean;
-		required = ca.drv->required;
-	}
 
-	ret |= apply_filter(path, src, len, -1, dst, filter);
-	if (!ret && required)
+	ret |= apply_filter(path, src, len, -1, dst, ca.drv, CAP_CLEAN);
+	if (!ret && ca.drv && ca.drv->required)
 		die("%s: clean filter '%s' failed", path, ca.drv->name);
 
 	if (ret && dst) {
@@ -907,7 +921,7 @@ void convert_to_git_filter_fd(const char *path, int fd, struct strbuf *dst,
 	assert(ca.drv);
 	assert(ca.drv->clean);
 
-	if (!apply_filter(path, NULL, 0, fd, dst, ca.drv->clean))
+	if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN))
 		die("%s: clean filter '%s' failed", path, ca.drv->name);
 
 	crlf_to_git(path, dst->buf, dst->len, dst, ca.crlf_action, checksafe);
@@ -919,15 +933,9 @@ static int convert_to_working_tree_internal(const char *path, const char *src,
 					    int normalizing)
 {
 	int ret = 0, ret_filter = 0;
-	const char *filter = NULL;
-	int required = 0;
 	struct conv_attrs ca;
 
 	convert_attrs(&ca, path);
-	if (ca.drv) {
-		filter = ca.drv->smudge;
-		required = ca.drv->required;
-	}
 
 	ret |= ident_to_worktree(path, src, len, dst, ca.ident);
 	if (ret) {
@@ -938,7 +946,7 @@ static int convert_to_working_tree_internal(const char *path, const char *src,
 	 * CRLF conversion can be skipped if normalizing, unless there
 	 * is a smudge filter.  The filter might expect CRLFs.
 	 */
-	if (filter || !normalizing) {
+	if ((ca.drv && ca.drv->smudge) || !normalizing) {
 		ret |= crlf_to_worktree(path, src, len, dst, ca.crlf_action);
 		if (ret) {
 			src = dst->buf;
@@ -946,8 +954,8 @@ static int convert_to_working_tree_internal(const char *path, const char *src,
 		}
 	}
 
-	ret_filter = apply_filter(path, src, len, -1, dst, filter);
-	if (!ret_filter && required)
+	ret_filter = apply_filter(path, src, len, -1, dst, ca.drv, CAP_SMUDGE);
+	if (!ret_filter && ca.drv && ca.drv->required)
 		die("%s: smudge filter %s failed", path, ca.drv->name);
 
 	return ret | ret_filter;
-- 
2.10.0

[PATCH v11 13/14] convert: add filter.<driver>.process option

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

Git's clean/smudge mechanism invokes an external filter process for
every single blob that is affected by a filter. If Git filters a lot of
blobs then the startup time of the external filter processes can become
a significant part of the overall Git execution time.

In a preliminary performance test this developer used a clean/smudge
filter written in golang to filter 12,000 files. This process took 364s
with the existing filter mechanism and 5s with the new mechanism. See
details here: https://github.com/github/git-lfs/pull/1382

This patch adds the `filter.<driver>.process` string option which, if
used, keeps the external filter process running and processes all blobs
with the packet format (pkt-line) based protocol over standard input and
standard output. The full protocol is explained in detail in
`Documentation/gitattributes.txt`.

A few key decisions:

* The long running filter process is referred to as filter protocol
  version 2 because the existing single shot filter invocation is
  considered version 1.
* Git sends a welcome message and expects a response right after the
  external filter process has started. This ensures that Git will not
  hang if a version 1 filter is incorrectly used with the
  filter.<driver>.process option for version 2 filters. In addition,
  Git can detect this kind of error and warn the user.
* The status of a filter operation (e.g. "success" or "error) is set
  before the actual response and (if necessary!) re-set after the
  response. The advantage of this two step status response is that if
  the filter detects an error early, then the filter can communicate
  this and Git does not even need to create structures to read the
  response.
* All status responses are pkt-line lists terminated with a flush
  packet. This allows us to send other status fields with the same
  protocol in the future.

Helped-by: Martin-Louis Bright <mlbright@gmail.com>
Reviewed-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/gitattributes.txt | 155 +++++++++++++-
 convert.c                       | 300 ++++++++++++++++++++++++++-
 t/t0021-conversion.sh           | 444 +++++++++++++++++++++++++++++++++++++++-
 t/t0021/rot13-filter.pl         | 192 +++++++++++++++++
 4 files changed, 1081 insertions(+), 10 deletions(-)
 create mode 100755 t/t0021/rot13-filter.pl

diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index 7aff940..3f4d1ed 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -293,7 +293,15 @@ checkout, when the `smudge` command is specified, the command is
 fed the blob object from its standard input, and its standard
 output is used to update the worktree file.  Similarly, the
 `clean` command is used to convert the contents of worktree file
-upon checkin.
+upon checkin. By default these commands process only a single
+blob and terminate. If a long running `process` filter is used
+in place of `clean` and/or `smudge` filters, then Git can process
+all blobs with a single filter command invocation for the entire
+life of a single Git command, for example `git add --all`. If a
+long running `process` filter is configured then it always takes
+precedence over a configured single blob filter. See section
+below for the description of the protocol used to communicate with
+a `process` filter.
 
 One use of the content filtering is to massage the content into a shape
 that is more convenient for the platform, filesystem, and the user to use.
@@ -373,6 +381,151 @@ not exist, or may have different contents. So, smudge and clean commands
 should not try to access the file on disk, but only act as filters on the
 content provided to them on standard input.
 
+Long Running Filter Process
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If the filter command (a string value) is defined via
+`filter.<driver>.process` then Git can process all blobs with a
+single filter invocation for the entire life of a single Git
+command. This is achieved by using a packet format (pkt-line,
+see technical/protocol-common.txt) based protocol over standard
+input and standard output as follows. All packets, except for the
+"*CONTENT" packets and the "0000" flush packet, are considered
+text and therefore are terminated by a LF.
+
+Git starts the filter when it encounters the first file
+that needs to be cleaned or smudged. After the filter started
+Git sends a welcome message ("git-filter-client"), a list of supported
+protocol version numbers, and a flush packet. Git expects to read a welcome
+response message ("git-filter-server"), exactly one protocol version number
+from the previously sent list, and a flush packet. All further
+communication will be based on the selected version. The remaining
+protocol description below documents "version=2". Please note that
+"version=42" in the example below does not exist and is only there
+to illustrate how the protocol would look like with more than one
+version.
+
+After the version negotiation Git sends a list of all capabilities that
+it supports and a flush packet. Git expects to read a list of desired
+capabilities, which must be a subset of the supported capabilities list,
+and a flush packet as response:
+------------------------
+packet:          git> git-filter-client
+packet:          git> version=2
+packet:          git> version=42
+packet:          git> 0000
+packet:          git< git-filter-server
+packet:          git< version=2
+packet:          git< 0000
+packet:          git> capability=clean
+packet:          git> capability=smudge
+packet:          git> capability=not-yet-invented
+packet:          git> 0000
+packet:          git< capability=clean
+packet:          git< capability=smudge
+packet:          git< 0000
+------------------------
+Supported filter capabilities in version 2 are "clean" and
+"smudge".
+
+Afterwards Git sends a list of "key=value" pairs terminated with
+a flush packet. The list will contain at least the filter command
+(based on the supported capabilities) and the pathname of the file
+to filter relative to the repository root. Right after the flush packet
+Git sends the content split in zero or more pkt-line packets and a
+flush packet to terminate content. Please note, that the filter
+must not send any response before it received the content and the
+final flush packet.
+------------------------
+packet:          git> command=smudge
+packet:          git> pathname=path/testfile.dat
+packet:          git> 0000
+packet:          git> CONTENT
+packet:          git> 0000
+------------------------
+
+The filter is expected to respond with a list of "key=value" pairs
+terminated with a flush packet. If the filter does not experience
+problems then the list must contain a "success" status. Right after
+these packets the filter is expected to send the content in zero
+or more pkt-line packets and a flush packet at the end. Finally, a
+second list of "key=value" pairs terminated with a flush packet
+is expected. The filter can change the status in the second list
+or keep the status as is with an empty list. Please note that the
+empty list must be terminated with a flush packet regardless.
+
+------------------------
+packet:          git< status=success
+packet:          git< 0000
+packet:          git< SMUDGED_CONTENT
+packet:          git< 0000
+packet:          git< 0000  # empty list, keep "status=success" unchanged!
+------------------------
+
+If the result content is empty then the filter is expected to respond
+with a "success" status and a flush packet to signal the empty content.
+------------------------
+packet:          git< status=success
+packet:          git< 0000
+packet:          git< 0000  # empty content!
+packet:          git< 0000  # empty list, keep "status=success" unchanged!
+------------------------
+
+In case the filter cannot or does not want to process the content,
+it is expected to respond with an "error" status.
+------------------------
+packet:          git< status=error
+packet:          git< 0000
+------------------------
+
+If the filter experiences an error during processing, then it can
+send the status "error" after the content was (partially or
+completely) sent.
+------------------------
+packet:          git< status=success
+packet:          git< 0000
+packet:          git< HALF_WRITTEN_ERRONEOUS_CONTENT
+packet:          git< 0000
+packet:          git< status=error
+packet:          git< 0000
+------------------------
+
+In case the filter cannot or does not want to process the content
+as well as any future content for the lifetime of the Git process,
+then it is expected to respond with an "abort" status at any point
+in the protocol.
+------------------------
+packet:          git< status=abort
+packet:          git< 0000
+------------------------
+
+Git neither stops nor restarts the filter process in case the
+"error"/"abort" status is set. However, Git sets its exit code
+according to the `filter.<driver>.required` flag, mimicking the
+behavior of the `filter.<driver>.clean` / `filter.<driver>.smudge`
+mechanism.
+
+If the filter dies during the communication or does not adhere to
+the protocol then Git will stop the filter process and restart it
+with the next file that needs to be processed. Depending on the
+`filter.<driver>.required` flag Git will interpret that as error.
+
+After the filter has processed a blob it is expected to wait for
+the next "key=value" list containing a command. Git will close
+the command pipe on exit. The filter is expected to detect EOF
+and exit gracefully on its own. Git will wait until the filter
+process has stopped.
+
+If you develop your own long running filter
+process then the `GIT_TRACE_PACKET` environment variables can be
+very helpful for debugging (see linkgit:git[1]).
+
+Please note that you cannot use an existing `filter.<driver>.clean`
+or `filter.<driver>.smudge` command with `filter.<driver>.process`
+because the former two use a different inter process communication
+protocol than the latter one.
+
+
 Interaction between checkin/checkout attributes
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/convert.c b/convert.c
index 71e11ff..9d2aa68 100644
--- a/convert.c
+++ b/convert.c
@@ -3,6 +3,7 @@
 #include "run-command.h"
 #include "quote.h"
 #include "sigchain.h"
+#include "pkt-line.h"
 
 /*
  * convert.c - convert a file when checking it out and checking it in.
@@ -490,11 +491,292 @@ static int apply_single_file_filter(const char *path, const char *src, size_t le
 #define CAP_CLEAN    (1u<<0)
 #define CAP_SMUDGE   (1u<<1)
 
+struct cmd2process {
+	struct hashmap_entry ent; /* must be the first member! */
+	unsigned int supported_capabilities;
+	const char *cmd;
+	struct child_process process;
+};
+
+static int cmd_process_map_initialized;
+static struct hashmap cmd_process_map;
+
+static int cmd2process_cmp(const struct cmd2process *e1,
+			   const struct cmd2process *e2,
+			   const void *unused)
+{
+	return strcmp(e1->cmd, e2->cmd);
+}
+
+static struct cmd2process *find_multi_file_filter_entry(struct hashmap *hashmap, const char *cmd)
+{
+	struct cmd2process key;
+	hashmap_entry_init(&key, strhash(cmd));
+	key.cmd = cmd;
+	return hashmap_get(hashmap, &key, NULL);
+}
+
+static int packet_write_list(int fd, const char *line, ...)
+{
+	va_list args;
+	int err;
+	va_start(args, line);
+	for (;;) {
+		if (!line)
+			break;
+		if (strlen(line) > LARGE_PACKET_DATA_MAX)
+			return -1;
+		err = packet_write_fmt_gently(fd, "%s\n", line);
+		if (err)
+			return err;
+		line = va_arg(args, const char*);
+	}
+	va_end(args);
+	return packet_flush_gently(fd);
+}
+
+static void read_multi_file_filter_status(int fd, struct strbuf *status) {
+	struct strbuf **pair;
+	char *line;
+	for (;;) {
+		line = packet_read_line(fd, NULL);
+		if (!line)
+			break;
+		pair = strbuf_split_str(line, '=', 2);
+		if (pair[0] && pair[0]->len && pair[1]) {
+			/* the last "status=<foo>" line wins */
+			if (!strcmp(pair[0]->buf, "status=")) {
+				strbuf_reset(status);
+				strbuf_addbuf(status, pair[1]);
+			}
+		}
+		strbuf_list_free(pair);
+	}
+}
+
+static void kill_multi_file_filter(struct hashmap *hashmap, struct cmd2process *entry)
+{
+	if (!entry)
+		return;
+
+	entry->process.clean_on_exit = 0;
+	kill(entry->process.pid, SIGTERM);
+	finish_command(&entry->process);
+
+	hashmap_remove(hashmap, entry, NULL);
+	free(entry);
+}
+
+static void stop_multi_file_filter(struct child_process *process)
+{
+	sigchain_push(SIGPIPE, SIG_IGN);
+	/* Closing the pipe signals the filter to initiate a shutdown. */
+	close(process->in);
+	close(process->out);
+	sigchain_pop(SIGPIPE);
+	/* Finish command will wait until the shutdown is complete. */
+	finish_command(process);
+}
+
+static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, const char *cmd)
+{
+	int err;
+	struct cmd2process *entry;
+	struct child_process *process;
+	const char *argv[] = { cmd, NULL };
+	struct string_list cap_list = STRING_LIST_INIT_NODUP;
+	char *cap_buf;
+	const char *cap_name;
+
+	entry = xmalloc(sizeof(*entry));
+	entry->cmd = cmd;
+	entry->supported_capabilities = 0;
+	process = &entry->process;
+
+	child_process_init(process);
+	process->argv = argv;
+	process->use_shell = 1;
+	process->in = -1;
+	process->out = -1;
+	process->clean_on_exit = 1;
+	process->clean_on_exit_handler = stop_multi_file_filter;
+
+	if (start_command(process)) {
+		error("cannot fork to run external filter '%s'", cmd);
+		return NULL;
+	}
+
+	hashmap_entry_init(entry, strhash(cmd));
+
+	sigchain_push(SIGPIPE, SIG_IGN);
+
+	err = packet_write_list(process->in, "git-filter-client", "version=2", NULL);
+	if (err)
+		goto done;
+
+	err = strcmp(packet_read_line(process->out, NULL), "git-filter-server");
+	if (err) {
+		error("external filter '%s' does not support filter protocol version 2", cmd);
+		goto done;
+	}
+	err = strcmp(packet_read_line(process->out, NULL), "version=2");
+	if (err)
+		goto done;
+	err = packet_read_line(process->out, NULL) != NULL;
+	if (err)
+		goto done;
+
+	err = packet_write_list(process->in, "capability=clean", "capability=smudge", NULL);
+
+	for (;;) {
+		cap_buf = packet_read_line(process->out, NULL);
+		if (!cap_buf)
+			break;
+		string_list_split_in_place(&cap_list, cap_buf, '=', 1);
+
+		if (cap_list.nr != 2 || strcmp(cap_list.items[0].string, "capability"))
+			continue;
+
+		cap_name = cap_list.items[1].string;
+		if (!strcmp(cap_name, "clean")) {
+			entry->supported_capabilities |= CAP_CLEAN;
+		} else if (!strcmp(cap_name, "smudge")) {
+			entry->supported_capabilities |= CAP_SMUDGE;
+		} else {
+			warning(
+				"external filter '%s' requested unsupported filter capability '%s'",
+				cmd, cap_name
+			);
+		}
+
+		string_list_clear(&cap_list, 0);
+	}
+
+done:
+	sigchain_pop(SIGPIPE);
+
+	if (err || errno == EPIPE) {
+		error("initialization for external filter '%s' failed", cmd);
+		kill_multi_file_filter(hashmap, entry);
+		return NULL;
+	}
+
+	hashmap_add(hashmap, entry);
+	return entry;
+}
+
+static int apply_multi_file_filter(const char *path, const char *src, size_t len,
+				   int fd, struct strbuf *dst, const char *cmd,
+				   const unsigned int wanted_capability)
+{
+	int err;
+	struct cmd2process *entry;
+	struct child_process *process;
+	struct strbuf nbuf = STRBUF_INIT;
+	struct strbuf filter_status = STRBUF_INIT;
+	const char *filter_type;
+
+	if (!cmd_process_map_initialized) {
+		cmd_process_map_initialized = 1;
+		hashmap_init(&cmd_process_map, (hashmap_cmp_fn) cmd2process_cmp, 0);
+		entry = NULL;
+	} else {
+		entry = find_multi_file_filter_entry(&cmd_process_map, cmd);
+	}
+
+	fflush(NULL);
+
+	if (!entry) {
+		entry = start_multi_file_filter(&cmd_process_map, cmd);
+		if (!entry)
+			return 0;
+	}
+	process = &entry->process;
+
+	if (!(wanted_capability & entry->supported_capabilities))
+		return 0;
+
+	if (CAP_CLEAN & wanted_capability)
+		filter_type = "clean";
+	else if (CAP_SMUDGE & wanted_capability)
+		filter_type = "smudge";
+	else
+		die("unexpected filter type");
+
+	sigchain_push(SIGPIPE, SIG_IGN);
+
+	assert(strlen(filter_type) < LARGE_PACKET_DATA_MAX - strlen("command=\n"));
+	err = packet_write_fmt_gently(process->in, "command=%s\n", filter_type);
+	if (err)
+		goto done;
+
+	err = strlen(path) > LARGE_PACKET_DATA_MAX - strlen("pathname=\n");
+	if (err) {
+		error("path name too long for external filter");
+		goto done;
+	}
+
+	err = packet_write_fmt_gently(process->in, "pathname=%s\n", path);
+	if (err)
+		goto done;
+
+	err = packet_flush_gently(process->in);
+	if (err)
+		goto done;
+
+	if (fd >= 0)
+		err = write_packetized_from_fd(fd, process->in);
+	else
+		err = write_packetized_from_buf(src, len, process->in);
+	if (err)
+		goto done;
+
+	read_multi_file_filter_status(process->out, &filter_status);
+	err = strcmp(filter_status.buf, "success");
+	if (err)
+		goto done;
+
+	err = read_packetized_to_strbuf(process->out, &nbuf) < 0;
+	if (err)
+		goto done;
+
+	read_multi_file_filter_status(process->out, &filter_status);
+	err = strcmp(filter_status.buf, "success");
+
+done:
+	sigchain_pop(SIGPIPE);
+
+	if (err || errno == EPIPE) {
+		if (!strcmp(filter_status.buf, "error")) {
+			/* The filter signaled a problem with the file. */
+		} else if (!strcmp(filter_status.buf, "abort")) {
+			/*
+			 * The filter signaled a permanent problem. Don't try to filter
+			 * files with the same command for the lifetime of the current
+			 * Git process.
+			 */
+			 entry->supported_capabilities &= ~wanted_capability;
+		} else {
+			/*
+			 * Something went wrong with the protocol filter.
+			 * Force shutdown and restart if another blob requires filtering.
+			 */
+			error("external filter '%s' failed", cmd);
+			kill_multi_file_filter(&cmd_process_map, entry);
+		}
+	} else {
+		strbuf_swap(dst, &nbuf);
+	}
+	strbuf_release(&nbuf);
+	return !err;
+}
+
 static struct convert_driver {
 	const char *name;
 	struct convert_driver *next;
 	const char *smudge;
 	const char *clean;
+	const char *process;
 	int required;
 } *user_convert, **user_convert_tail;
 
@@ -510,13 +792,15 @@ static int apply_filter(const char *path, const char *src, size_t len,
 	if (!dst)
 		return 1;
 
-	if ((CAP_CLEAN & wanted_capability) && drv->clean)
+	if ((CAP_CLEAN & wanted_capability) && !drv->process && drv->clean)
 		cmd = drv->clean;
-	else if ((CAP_SMUDGE & wanted_capability) && drv->smudge)
+	else if ((CAP_SMUDGE & wanted_capability) && !drv->process && drv->smudge)
 		cmd = drv->smudge;
 
 	if (cmd && *cmd)
 		return apply_single_file_filter(path, src, len, fd, dst, cmd);
+	else if (drv->process && *drv->process)
+		return apply_multi_file_filter(path, src, len, fd, dst, drv->process, wanted_capability);
 
 	return 0;
 }
@@ -558,6 +842,9 @@ static int read_convert_config(const char *var, const char *value, void *cb)
 	if (!strcmp("clean", key))
 		return git_config_string(&drv->clean, var, value);
 
+	if (!strcmp("process", key))
+		return git_config_string(&drv->process, var, value);
+
 	if (!strcmp("required", key)) {
 		drv->required = git_config_bool(var, value);
 		return 0;
@@ -919,7 +1206,7 @@ void convert_to_git_filter_fd(const char *path, int fd, struct strbuf *dst,
 	convert_attrs(&ca, path);
 
 	assert(ca.drv);
-	assert(ca.drv->clean);
+	assert(ca.drv->clean || ca.drv->process);
 
 	if (!apply_filter(path, NULL, 0, fd, dst, ca.drv, CAP_CLEAN))
 		die("%s: clean filter '%s' failed", path, ca.drv->name);
@@ -944,9 +1231,10 @@ static int convert_to_working_tree_internal(const char *path, const char *src,
 	}
 	/*
 	 * CRLF conversion can be skipped if normalizing, unless there
-	 * is a smudge filter.  The filter might expect CRLFs.
+	 * is a smudge or process filter (even if the process filter doesn't
+	 * support smudge).  The filters might expect CRLFs.
 	 */
-	if ((ca.drv && ca.drv->smudge) || !normalizing) {
+	if ((ca.drv && (ca.drv->smudge || ca.drv->process)) || !normalizing) {
 		ret |= crlf_to_worktree(path, src, len, dst, ca.crlf_action);
 		if (ret) {
 			src = dst->buf;
@@ -1407,7 +1695,7 @@ struct stream_filter *get_stream_filter(const char *path, const unsigned char *s
 	struct stream_filter *filter = NULL;
 
 	convert_attrs(&ca, path);
-	if (ca.drv && (ca.drv->smudge || ca.drv->clean))
+	if (ca.drv && (ca.drv->process || ca.drv->smudge || ca.drv->clean))
 		return NULL;
 
 	if (ca.crlf_action == CRLF_AUTO || ca.crlf_action == CRLF_AUTO_CRLF)
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index dc50938..a20b9f5 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -4,13 +4,72 @@ test_description='blob conversion via gitattributes'
 
 . ./test-lib.sh
 
-cat <<EOF >rot13.sh
+TEST_ROOT="$(pwd)"
+
+cat <<EOF >"$TEST_ROOT/rot13.sh"
 #!$SHELL_PATH
 tr \
   'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ' \
   'nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM'
 EOF
-chmod +x rot13.sh
+chmod +x "$TEST_ROOT/rot13.sh"
+
+generate_random_characters () {
+	LEN=$1
+	NAME=$2
+	test-genrandom some-seed $LEN |
+		perl -pe "s/./chr((ord($&) % 26) + ord('a'))/sge" >"$TEST_ROOT/$NAME"
+}
+
+file_size () {
+	cat "$1" | wc -c | sed "s/^[ ]*//"
+}
+
+filter_git () {
+	rm -f rot13-filter.log &&
+	git "$@" 2>git-stderr.log &&
+	rm -f git-stderr.log
+}
+
+# Compare two files and ensure that `clean` and `smudge` respectively are
+# called at least once if specified in the `expect` file. The actual
+# invocation count is not relevant because their number can vary.
+# c.f. http://public-inbox.org/git/xmqqshv18i8i.fsf@gitster.mtv.corp.google.com/
+test_cmp_count () {
+	expect=$1
+	actual=$2
+	for FILE in "$expect" "$actual"
+	do
+		sort "$FILE" | uniq -c | sed "s/^[ ]*//" |
+			sed "s/^\([0-9]\) IN: clean/x IN: clean/" |
+			sed "s/^\([0-9]\) IN: smudge/x IN: smudge/" >"$FILE.tmp" &&
+		mv "$FILE.tmp" "$FILE"
+	done &&
+	test_cmp "$expect" "$actual"
+}
+
+# Compare two files but exclude all `clean` invocations because Git can
+# call `clean` zero or more times.
+# c.f. http://public-inbox.org/git/xmqqshv18i8i.fsf@gitster.mtv.corp.google.com/
+test_cmp_exclude_clean () {
+	expect=$1
+	actual=$2
+	for FILE in "$expect" "$actual"
+	do
+		grep -v "IN: clean" "$FILE" >"$FILE.tmp" &&
+		mv "$FILE.tmp" "$FILE"
+	done &&
+	test_cmp "$expect" "$actual"
+}
+
+# Check that the contents of two files are equal and that their rot13 version
+# is equal to the committed content.
+test_cmp_committed_rot13 () {
+	test_cmp "$1" "$2" &&
+	"$TEST_ROOT/rot13.sh" <"$1" >expected &&
+	git cat-file blob :"$2" >actual &&
+	test_cmp expected actual
+}
 
 test_expect_success setup '
 	git config filter.rot13.smudge ./rot13.sh &&
@@ -31,7 +90,10 @@ test_expect_success setup '
 	cat test >test.i &&
 	git add test test.t test.i &&
 	rm -f test test.t test.i &&
-	git checkout -- test test.t test.i
+	git checkout -- test test.t test.i &&
+
+	echo "content-test2" >test2.o &&
+	echo "content-test3 - filename with special characters" >"test3 '\''sq'\'',\$x.o"
 '
 
 script='s/^\$Id: \([0-9a-f]*\) \$/\1/p'
@@ -279,4 +341,380 @@ test_expect_success 'diff does not reuse worktree files that need cleaning' '
 	test_line_count = 0 count
 '
 
+test_expect_success PERL 'required process filter should filter data' '
+	test_config_global filter.protocol.process "$TEST_DIRECTORY/t0021/rot13-filter.pl clean smudge" &&
+	test_config_global filter.protocol.required true &&
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		echo "git-stderr.log" >.gitignore &&
+		echo "*.r filter=protocol" >.gitattributes &&
+		git add . &&
+		git commit . -m "test commit 1" &&
+		git branch empty-branch &&
+
+		cp "$TEST_ROOT/test.o" test.r &&
+		cp "$TEST_ROOT/test2.o" test2.r &&
+		mkdir testsubdir &&
+		cp "$TEST_ROOT/test3 '\''sq'\'',\$x.o" "testsubdir/test3 '\''sq'\'',\$x.r" &&
+		>test4-empty.r &&
+
+		S=$(file_size test.r) &&
+		S2=$(file_size test2.r) &&
+		S3=$(file_size "testsubdir/test3 '\''sq'\'',\$x.r") &&
+
+		filter_git add . &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: clean test.r $S [OK] -- OUT: $S . [OK]
+			IN: clean test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: clean test4-empty.r 0 [OK] -- OUT: 0  [OK]
+			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
+			STOP
+		EOF
+		test_cmp_count expected.log rot13-filter.log &&
+
+		filter_git commit . -m "test commit 2" &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: clean test.r $S [OK] -- OUT: $S . [OK]
+			IN: clean test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: clean test4-empty.r 0 [OK] -- OUT: 0  [OK]
+			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
+			IN: clean test.r $S [OK] -- OUT: $S . [OK]
+			IN: clean test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: clean test4-empty.r 0 [OK] -- OUT: 0  [OK]
+			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
+			STOP
+		EOF
+		test_cmp_count expected.log rot13-filter.log &&
+
+		rm -f test2.r "testsubdir/test3 '\''sq'\'',\$x.r" &&
+
+		filter_git checkout --quiet --no-progress . &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
+			STOP
+		EOF
+		test_cmp_exclude_clean expected.log rot13-filter.log &&
+
+		filter_git checkout --quiet --no-progress empty-branch &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: clean test.r $S [OK] -- OUT: $S . [OK]
+			STOP
+		EOF
+		test_cmp_exclude_clean expected.log rot13-filter.log &&
+
+		filter_git checkout --quiet --no-progress master &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: smudge test.r $S [OK] -- OUT: $S . [OK]
+			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: smudge test4-empty.r 0 [OK] -- OUT: 0  [OK]
+			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
+			STOP
+		EOF
+		test_cmp_exclude_clean expected.log rot13-filter.log &&
+
+		test_cmp_committed_rot13 "$TEST_ROOT/test.o" test.r &&
+		test_cmp_committed_rot13 "$TEST_ROOT/test2.o" test2.r &&
+		test_cmp_committed_rot13 "$TEST_ROOT/test3 '\''sq'\'',\$x.o" "testsubdir/test3 '\''sq'\'',\$x.r"
+	)
+'
+
+test_expect_success PERL 'required process filter takes precedence' '
+	test_config_global filter.protocol.clean false &&
+	test_config_global filter.protocol.process "$TEST_DIRECTORY/t0021/rot13-filter.pl clean" &&
+	test_config_global filter.protocol.required true &&
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		echo "*.r filter=protocol" >.gitattributes &&
+		cp "$TEST_ROOT/test.o" test.r &&
+		S=$(file_size test.r) &&
+
+		# Check that the process filter is invoked here
+		filter_git add . &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: clean test.r $S [OK] -- OUT: $S . [OK]
+			STOP
+		EOF
+		test_cmp_count expected.log rot13-filter.log
+	)
+'
+
+test_expect_success PERL 'required process filter should be used only for "clean" operation only' '
+	test_config_global filter.protocol.process "$TEST_DIRECTORY/t0021/rot13-filter.pl clean" &&
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		echo "*.r filter=protocol" >.gitattributes &&
+		cp "$TEST_ROOT/test.o" test.r &&
+		S=$(file_size test.r) &&
+
+		filter_git add . &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: clean test.r $S [OK] -- OUT: $S . [OK]
+			STOP
+		EOF
+		test_cmp_count expected.log rot13-filter.log &&
+
+		rm test.r &&
+
+		filter_git checkout --quiet --no-progress . &&
+		# If the filter would be used for "smudge", too, we would see
+		# "IN: smudge test.r 57 [OK] -- OUT: 57 . [OK]" here
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			STOP
+		EOF
+		test_cmp_exclude_clean expected.log rot13-filter.log
+	)
+'
+
+test_expect_success PERL 'required process filter should process multiple packets' '
+	test_config_global filter.protocol.process "$TEST_DIRECTORY/t0021/rot13-filter.pl clean smudge" &&
+	test_config_global filter.protocol.required true &&
+
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		# Generate data requiring 1, 2, 3 packets
+		S=65516 && # PKTLINE_DATA_MAXLEN -> Maximal size of a packet
+		generate_random_characters $(($S    )) 1pkt_1__.file &&
+		generate_random_characters $(($S  +1)) 2pkt_1+1.file &&
+		generate_random_characters $(($S*2-1)) 2pkt_2-1.file &&
+		generate_random_characters $(($S*2  )) 2pkt_2__.file &&
+		generate_random_characters $(($S*2+1)) 3pkt_2+1.file &&
+
+		for FILE in "$TEST_ROOT"/*.file
+		do
+			cp "$FILE" . &&
+			"$TEST_ROOT/rot13.sh" <"$FILE" >"$FILE.rot13"
+		done &&
+
+		echo "*.file filter=protocol" >.gitattributes &&
+		filter_git add *.file .gitattributes &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: clean 1pkt_1__.file $(($S    )) [OK] -- OUT: $(($S    )) . [OK]
+			IN: clean 2pkt_1+1.file $(($S  +1)) [OK] -- OUT: $(($S  +1)) .. [OK]
+			IN: clean 2pkt_2-1.file $(($S*2-1)) [OK] -- OUT: $(($S*2-1)) .. [OK]
+			IN: clean 2pkt_2__.file $(($S*2  )) [OK] -- OUT: $(($S*2  )) .. [OK]
+			IN: clean 3pkt_2+1.file $(($S*2+1)) [OK] -- OUT: $(($S*2+1)) ... [OK]
+			STOP
+		EOF
+		test_cmp_count expected.log rot13-filter.log &&
+
+		rm -f *.file &&
+
+		filter_git checkout --quiet --no-progress -- *.file &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: smudge 1pkt_1__.file $(($S    )) [OK] -- OUT: $(($S    )) . [OK]
+			IN: smudge 2pkt_1+1.file $(($S  +1)) [OK] -- OUT: $(($S  +1)) .. [OK]
+			IN: smudge 2pkt_2-1.file $(($S*2-1)) [OK] -- OUT: $(($S*2-1)) .. [OK]
+			IN: smudge 2pkt_2__.file $(($S*2  )) [OK] -- OUT: $(($S*2  )) .. [OK]
+			IN: smudge 3pkt_2+1.file $(($S*2+1)) [OK] -- OUT: $(($S*2+1)) ... [OK]
+			STOP
+		EOF
+		test_cmp_exclude_clean expected.log rot13-filter.log &&
+
+		for FILE in *.file
+		do
+			test_cmp_committed_rot13 "$TEST_ROOT/$FILE" $FILE
+		done
+	)
+'
+
+test_expect_success PERL 'required process filter with clean error should fail' '
+	test_config_global filter.protocol.process "$TEST_DIRECTORY/t0021/rot13-filter.pl clean smudge" &&
+	test_config_global filter.protocol.required true &&
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		echo "*.r filter=protocol" >.gitattributes &&
+
+		cp "$TEST_ROOT/test.o" test.r &&
+		echo "this is going to fail" >clean-write-fail.r &&
+		echo "content-test3-subdir" >test3.r &&
+
+		test_must_fail git add .
+	)
+'
+
+test_expect_success PERL 'process filter should restart after unexpected write failure' '
+	test_config_global filter.protocol.process "$TEST_DIRECTORY/t0021/rot13-filter.pl clean smudge" &&
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		echo "*.r filter=protocol" >.gitattributes &&
+
+		cp "$TEST_ROOT/test.o" test.r &&
+		cp "$TEST_ROOT/test2.o" test2.r &&
+		echo "this is going to fail" >smudge-write-fail.o &&
+		cp smudge-write-fail.o smudge-write-fail.r &&
+
+		S=$(file_size test.r) &&
+		S2=$(file_size test2.r) &&
+		SF=$(file_size smudge-write-fail.r) &&
+
+		git add . &&
+		rm -f *.r &&
+
+		rm -f rot13-filter.log &&
+		git checkout --quiet --no-progress . 2>git-stderr.log &&
+
+		grep "smudge write error at" git-stderr.log &&
+		grep "error: external filter" git-stderr.log &&
+
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: smudge smudge-write-fail.r $SF [OK] -- OUT: $SF [WRITE FAIL]
+			START
+			init handshake complete
+			IN: smudge test.r $S [OK] -- OUT: $S . [OK]
+			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			STOP
+		EOF
+		test_cmp_exclude_clean expected.log rot13-filter.log &&
+
+		test_cmp_committed_rot13 "$TEST_ROOT/test.o" test.r &&
+		test_cmp_committed_rot13 "$TEST_ROOT/test2.o" test2.r &&
+
+		# Smudge failed
+		! test_cmp smudge-write-fail.o smudge-write-fail.r &&
+		"$TEST_ROOT/rot13.sh" <smudge-write-fail.o >expected &&
+		git cat-file blob :smudge-write-fail.r >actual &&
+		test_cmp expected actual
+	)
+'
+
+test_expect_success PERL 'process filter should not be restarted if it signals an error' '
+	test_config_global filter.protocol.process "$TEST_DIRECTORY/t0021/rot13-filter.pl clean smudge" &&
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		echo "*.r filter=protocol" >.gitattributes &&
+
+		cp "$TEST_ROOT/test.o" test.r &&
+		cp "$TEST_ROOT/test2.o" test2.r &&
+		echo "this will cause an error" >error.o &&
+		cp error.o error.r &&
+
+		S=$(file_size test.r) &&
+		S2=$(file_size test2.r) &&
+		SE=$(file_size error.r) &&
+
+		git add . &&
+		rm -f *.r &&
+
+		filter_git checkout --quiet --no-progress . &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: smudge error.r $SE [OK] -- OUT: 0 [ERROR]
+			IN: smudge test.r $S [OK] -- OUT: $S . [OK]
+			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			STOP
+		EOF
+		test_cmp_exclude_clean expected.log rot13-filter.log &&
+
+		test_cmp_committed_rot13 "$TEST_ROOT/test.o" test.r &&
+		test_cmp_committed_rot13 "$TEST_ROOT/test2.o" test2.r &&
+		test_cmp error.o error.r
+	)
+'
+
+test_expect_success PERL 'process filter abort stops processing of all further files' '
+	test_config_global filter.protocol.process "$TEST_DIRECTORY/t0021/rot13-filter.pl clean smudge" &&
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		echo "*.r filter=protocol" >.gitattributes &&
+
+		cp "$TEST_ROOT/test.o" test.r &&
+		cp "$TEST_ROOT/test2.o" test2.r &&
+		echo "error this blob and all future blobs" >abort.o &&
+		cp abort.o abort.r &&
+
+		SA=$(file_size abort.r) &&
+
+		git add . &&
+		rm -f *.r &&
+
+		# Note: This test assumes that Git filters files in alphabetical
+		# order ("abort.r" before "test.r").
+		filter_git checkout --quiet --no-progress . &&
+		cat >expected.log <<-EOF &&
+			START
+			init handshake complete
+			IN: smudge abort.r $SA [OK] -- OUT: 0 [ABORT]
+			STOP
+		EOF
+		test_cmp_exclude_clean expected.log rot13-filter.log &&
+
+		test_cmp "$TEST_ROOT/test.o" test.r &&
+		test_cmp "$TEST_ROOT/test2.o" test2.r &&
+		test_cmp abort.o abort.r
+	)
+'
+
+test_expect_success PERL 'invalid process filter must fail (and not hang!)' '
+	test_config_global filter.protocol.process cat &&
+	test_config_global filter.protocol.required true &&
+	rm -rf repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+
+		echo "*.r filter=protocol" >.gitattributes &&
+
+		cp "$TEST_ROOT/test.o" test.r &&
+		test_must_fail git add . 2>git-stderr.log &&
+		grep "does not support filter protocol version" git-stderr.log
+	)
+'
+
 test_done
diff --git a/t/t0021/rot13-filter.pl b/t/t0021/rot13-filter.pl
new file mode 100755
index 0000000..ae4c50f
--- /dev/null
+++ b/t/t0021/rot13-filter.pl
@@ -0,0 +1,192 @@
+#!/usr/bin/perl
+#
+# Example implementation for the Git filter protocol version 2
+# See Documentation/gitattributes.txt, section "Filter Protocol"
+#
+# The script takes the list of supported protocol capabilities as
+# arguments ("clean", "smudge", etc).
+#
+# This implementation supports special test cases:
+# (1) If data with the pathname "clean-write-fail.r" is processed with
+#     a "clean" operation then the write operation will die.
+# (2) If data with the pathname "smudge-write-fail.r" is processed with
+#     a "smudge" operation then the write operation will die.
+# (3) If data with the pathname "error.r" is processed with any
+#     operation then the filter signals that it cannot or does not want
+#     to process the file.
+# (4) If data with the pathname "abort.r" is processed with any
+#     operation then the filter signals that it cannot or does not want
+#     to process the file and any file after that is processed with the
+#     same command.
+#
+
+use strict;
+use warnings;
+
+my $MAX_PACKET_CONTENT_SIZE = 65516;
+my @capabilities            = @ARGV;
+
+open my $debug, ">>", "rot13-filter.log" or die "cannot open log file: $!";
+
+sub rot13 {
+	my $str = shift;
+	$str =~ y/A-Za-z/N-ZA-Mn-za-m/;
+	return $str;
+}
+
+sub packet_bin_read {
+	my $buffer;
+	my $bytes_read = read STDIN, $buffer, 4;
+	if ( $bytes_read == 0 ) {
+		# EOF - Git stopped talking to us!
+		print $debug "STOP\n";
+		exit();
+	}
+	elsif ( $bytes_read != 4 ) {
+		die "invalid packet: '$buffer'";
+	}
+	my $pkt_size = hex($buffer);
+	if ( $pkt_size == 0 ) {
+		return ( 1, "" );
+	}
+	elsif ( $pkt_size > 4 ) {
+		my $content_size = $pkt_size - 4;
+		$bytes_read = read STDIN, $buffer, $content_size;
+		if ( $bytes_read != $content_size ) {
+			die "invalid packet ($content_size bytes expected; $bytes_read bytes read)";
+		}
+		return ( 0, $buffer );
+	}
+	else {
+		die "invalid packet size: $pkt_size";
+	}
+}
+
+sub packet_txt_read {
+	my ( $res, $buf ) = packet_bin_read();
+	unless ( $buf =~ s/\n$// ) {
+		die "A non-binary line MUST be terminated by an LF.";
+	}
+	return ( $res, $buf );
+}
+
+sub packet_bin_write {
+	my $buf = shift;
+	print STDOUT sprintf( "%04x", length($buf) + 4 );
+	print STDOUT $buf;
+	STDOUT->flush();
+}
+
+sub packet_txt_write {
+	packet_bin_write( $_[0] . "\n" );
+}
+
+sub packet_flush {
+	print STDOUT sprintf( "%04x", 0 );
+	STDOUT->flush();
+}
+
+print $debug "START\n";
+$debug->flush();
+
+( packet_txt_read() eq ( 0, "git-filter-client" ) ) || die "bad initialize";
+( packet_txt_read() eq ( 0, "version=2" ) )         || die "bad version";
+( packet_bin_read() eq ( 1, "" ) )                  || die "bad version end";
+
+packet_txt_write("git-filter-server");
+packet_txt_write("version=2");
+packet_flush();
+
+( packet_txt_read() eq ( 0, "capability=clean" ) )  || die "bad capability";
+( packet_txt_read() eq ( 0, "capability=smudge" ) ) || die "bad capability";
+( packet_bin_read() eq ( 1, "" ) )                  || die "bad capability end";
+
+foreach (@capabilities) {
+	packet_txt_write( "capability=" . $_ );
+}
+packet_flush();
+print $debug "init handshake complete\n";
+$debug->flush();
+
+while (1) {
+	my ($command) = packet_txt_read() =~ /^command=([^=]+)$/;
+	print $debug "IN: $command";
+	$debug->flush();
+
+	my ($pathname) = packet_txt_read() =~ /^pathname=([^=]+)$/;
+	print $debug " $pathname";
+	$debug->flush();
+
+	# Flush
+	packet_bin_read();
+
+	my $input = "";
+	{
+		binmode(STDIN);
+		my $buffer;
+		my $done = 0;
+		while ( !$done ) {
+			( $done, $buffer ) = packet_bin_read();
+			$input .= $buffer;
+		}
+		print $debug " " . length($input) . " [OK] -- ";
+		$debug->flush();
+	}
+
+	my $output;
+	if ( $pathname eq "error.r" or $pathname eq "abort.r" ) {
+		$output = "";
+	}
+	elsif ( $command eq "clean" and grep( /^clean$/, @capabilities ) ) {
+		$output = rot13($input);
+	}
+	elsif ( $command eq "smudge" and grep( /^smudge$/, @capabilities ) ) {
+		$output = rot13($input);
+	}
+	else {
+		die "bad command '$command'";
+	}
+
+	print $debug "OUT: " . length($output) . " ";
+	$debug->flush();
+
+	if ( $pathname eq "error.r" ) {
+		print $debug "[ERROR]\n";
+		$debug->flush();
+		packet_txt_write("status=error");
+		packet_flush();
+	}
+	elsif ( $pathname eq "abort.r" ) {
+		print $debug "[ABORT]\n";
+		$debug->flush();
+		packet_txt_write("status=abort");
+		packet_flush();
+	}
+	else {
+		packet_txt_write("status=success");
+		packet_flush();
+
+		if ( $pathname eq "${command}-write-fail.r" ) {
+			print $debug "[WRITE FAIL]\n";
+			$debug->flush();
+			die "${command} write error";
+		}
+
+		while ( length($output) > 0 ) {
+			my $packet = substr( $output, 0, $MAX_PACKET_CONTENT_SIZE );
+			packet_bin_write($packet);
+			# dots represent the number of packets
+			print $debug ".";
+			if ( length($output) > $MAX_PACKET_CONTENT_SIZE ) {
+				$output = substr( $output, $MAX_PACKET_CONTENT_SIZE );
+			}
+			else {
+				$output = "";
+			}
+		}
+		packet_flush();
+		print $debug " [OK]\n";
+		$debug->flush();
+		packet_flush();
+	}
+}
-- 
2.10.0

[PATCH v11 14/14] contrib/long-running-filter: add long running filter example

[larsxschneider]

From: Lars Schneider <larsxschneider@gmail.com>

Add a simple pass-thru filter as example implementation for the Git
filter protocol version 2. See Documentation/gitattributes.txt, section
"Filter Protocol" for more info.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
---
 Documentation/gitattributes.txt        |   4 +-
 contrib/long-running-filter/example.pl | 128 +++++++++++++++++++++++++++++++++
 2 files changed, 131 insertions(+), 1 deletion(-)
 create mode 100755 contrib/long-running-filter/example.pl

diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index 3f4d1ed..976243a 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -516,7 +516,9 @@ the command pipe on exit. The filter is expected to detect EOF
 and exit gracefully on its own. Git will wait until the filter
 process has stopped.
 
-If you develop your own long running filter
+A long running filter demo implementation can be found in
+`contrib/long-running-filter/example.pl` located in the Git
+core repository. If you develop your own long running filter
 process then the `GIT_TRACE_PACKET` environment variables can be
 very helpful for debugging (see linkgit:git[1]).
 
diff --git a/contrib/long-running-filter/example.pl b/contrib/long-running-filter/example.pl
new file mode 100755
index 0000000..3945705
--- /dev/null
+++ b/contrib/long-running-filter/example.pl
@@ -0,0 +1,128 @@
+#!/usr/bin/perl
+#
+# Example implementation for the Git filter protocol version 2
+# See Documentation/gitattributes.txt, section "Filter Protocol"
+#
+# Please note, this pass-thru filter is a minimal skeleton. No proper
+# error handling was implemented.
+#
+
+use strict;
+use warnings;
+
+my $MAX_PACKET_CONTENT_SIZE = 65516;
+
+sub packet_bin_read {
+	my $buffer;
+	my $bytes_read = read STDIN, $buffer, 4;
+	if ( $bytes_read == 0 ) {
+
+		# EOF - Git stopped talking to us!
+		exit();
+	}
+	elsif ( $bytes_read != 4 ) {
+		die "invalid packet: '$buffer'";
+	}
+	my $pkt_size = hex($buffer);
+	if ( $pkt_size == 0 ) {
+		return ( 1, "" );
+	}
+	elsif ( $pkt_size > 4 ) {
+		my $content_size = $pkt_size - 4;
+		$bytes_read = read STDIN, $buffer, $content_size;
+		if ( $bytes_read != $content_size ) {
+			die "invalid packet ($content_size bytes expected; $bytes_read bytes read)";
+		}
+		return ( 0, $buffer );
+	}
+	else {
+		die "invalid packet size: $pkt_size";
+	}
+}
+
+sub packet_txt_read {
+	my ( $res, $buf ) = packet_bin_read();
+	unless ( $buf =~ s/\n$// ) {
+		die "A non-binary line MUST be terminated by an LF.";
+	}
+	return ( $res, $buf );
+}
+
+sub packet_bin_write {
+	my $buf = shift;
+	print STDOUT sprintf( "%04x", length($buf) + 4 );
+	print STDOUT $buf;
+	STDOUT->flush();
+}
+
+sub packet_txt_write {
+	packet_bin_write( $_[0] . "\n" );
+}
+
+sub packet_flush {
+	print STDOUT sprintf( "%04x", 0 );
+	STDOUT->flush();
+}
+
+( packet_txt_read() eq ( 0, "git-filter-client" ) ) || die "bad initialize";
+( packet_txt_read() eq ( 0, "version=2" ) )         || die "bad version";
+( packet_bin_read() eq ( 1, "" ) )                  || die "bad version end";
+
+packet_txt_write("git-filter-server");
+packet_txt_write("version=2");
+packet_flush();
+
+( packet_txt_read() eq ( 0, "capability=clean" ) )  || die "bad capability";
+( packet_txt_read() eq ( 0, "capability=smudge" ) ) || die "bad capability";
+( packet_bin_read() eq ( 1, "" ) )                  || die "bad capability end";
+
+packet_txt_write("capability=clean");
+packet_txt_write("capability=smudge");
+packet_flush();
+
+while (1) {
+	my ($command)  = packet_txt_read() =~ /^command=([^=]+)$/;
+	my ($pathname) = packet_txt_read() =~ /^pathname=([^=]+)$/;
+
+	packet_bin_read();
+
+	my $input = "";
+	{
+		binmode(STDIN);
+		my $buffer;
+		my $done = 0;
+		while ( !$done ) {
+			( $done, $buffer ) = packet_bin_read();
+			$input .= $buffer;
+		}
+	}
+
+	my $output;
+	if ( $command eq "clean" ) {
+		### Perform clean here ###
+		$output = $input;
+	}
+	elsif ( $command eq "smudge" ) {
+		### Perform smudge here ###
+		$output = $input;
+	}
+	else {
+		die "bad command '$command'";
+	}
+
+	packet_txt_write("status=success");
+	packet_flush();
+	while ( length($output) > 0 ) {
+		my $packet = substr( $output, 0, $MAX_PACKET_CONTENT_SIZE );
+		packet_bin_write($packet);
+		if ( length($output) > $MAX_PACKET_CONTENT_SIZE ) {
+			$output = substr( $output, $MAX_PACKET_CONTENT_SIZE );
+		}
+		else {
+			$output = "";
+		}
+	}
+	packet_flush();    # flush content!
+	packet_flush();    # empty list, keep "status=success" unchanged!
+
+}
-- 
2.10.0

Re: [PATCH v11 00/14] Git filter protocol

[Junio C Hamano]

larsxschneider@gmail.com writes:

> The goal of this series is to avoid launching a new clean/smudge filter
> process for each file that is filtered.
>
> A short summary about v1 to v5 can be found here:
> https://git.github.io/rev_news/2016/08/17/edition-18/
>
> This series is also published on web:
> https://github.com/larsxschneider/git/pull/15
>
> Patches 1 and 2 are cleanups and not strictly necessary for the series.
> Patches 3 to 12 are required preparation. Patch 13 is the main patch.
> Patch 14 adds an example how to use the Git filter protocol in contrib.

Will replace.  If you ever need tor reroll 13, please squash the
following in (which I already did locally so there is no need to
resend only to correct it).

Thanks.

 convert.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/convert.c b/convert.c
index 9d2aa68df9..bc242276ff 100644
--- a/convert.c
+++ b/convert.c
@@ -535,7 +535,8 @@ static int packet_write_list(int fd, const char *line, ...)
 	return packet_flush_gently(fd);
 }
 
-static void read_multi_file_filter_status(int fd, struct strbuf *status) {
+static void read_multi_file_filter_status(int fd, struct strbuf *status)
+{
 	struct strbuf **pair;
 	char *line;
 	for (;;) {
-- 
2.10.1-613-g6ad57fc60c

Re: [PATCH v11 13/14] convert: add filter.<driver>.process option

[Johannes Sixt]

Am 17.10.2016 um 01:20 schrieb larsxschneider@gmail.com:
> +# Compare two files and ensure that `clean` and `smudge` respectively are
> +# called at least once if specified in the `expect` file. The actual
> +# invocation count is not relevant because their number can vary.
> +# c.f. http://public-inbox.org/git/xmqqshv18i8i.fsf@gitster.mtv.corp.google.com/
> +test_cmp_count () {
> +	expect=$1
> +	actual=$2
> +	for FILE in "$expect" "$actual"
> +	do
> +		sort "$FILE" | uniq -c | sed "s/^[ ]*//" |
> +			sed "s/^\([0-9]\) IN: clean/x IN: clean/" |
> +			sed "s/^\([0-9]\) IN: smudge/x IN: smudge/" >"$FILE.tmp" &&

This is not sufficiently portable. Some versions of uniq write the
count left-adjusted, not right-adjusted. How about this on top:

diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index a20b9f58e3..f60858c517 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -40,10 +40,9 @@ test_cmp_count () {
 	actual=$2
 	for FILE in "$expect" "$actual"
 	do
-		sort "$FILE" | uniq -c | sed "s/^[ ]*//" |
-			sed "s/^\([0-9]\) IN: clean/x IN: clean/" |
-			sed "s/^\([0-9]\) IN: smudge/x IN: smudge/" >"$FILE.tmp" &&
-		mv "$FILE.tmp" "$FILE"
+		sort "$FILE" | uniq -c |
+		sed -e "s/^ *[0-9][0-9]* *IN: /x IN: /" >"$FILE.tmp" &&
+		mv "$FILE.tmp" "$FILE" || return
 	done &&
 	test_cmp "$expect" "$actual"
 }

-- Hannes

Re: [PATCH v11 13/14] convert: add filter.<driver>.process option

[Lars Schneider]

> On 2 Nov 2016, at 18:03, Johannes Sixt <j6t@kdbg.org> wrote:
> 
>> Am 17.10.2016 um 01:20 schrieb larsxschneider@gmail.com:
>> +# Compare two files and ensure that `clean` and `smudge` respectively are
>> +# called at least once if specified in the `expect` file. The actual
>> +# invocation count is not relevant because their number can vary.
>> +# c.f. http://public-inbox.org/git/xmqqshv18i8i.fsf@gitster.mtv.corp.google.com/
>> +test_cmp_count () {
>> +    expect=$1
>> +    actual=$2
>> +    for FILE in "$expect" "$actual"
>> +    do
>> +        sort "$FILE" | uniq -c | sed "s/^[ ]*//" |
>> +            sed "s/^\([0-9]\) IN: clean/x IN: clean/" |
>> +            sed "s/^\([0-9]\) IN: smudge/x IN: smudge/" >"$FILE.tmp" &&
> 
> This is not sufficiently portable. Some versions of uniq write the
> count left-adjusted, not right-adjusted. How about this on top:
> 
> diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
> index a20b9f58e3..f60858c517 100755
> --- a/t/t0021-conversion.sh
> +++ b/t/t0021-conversion.sh
> @@ -40,10 +40,9 @@ test_cmp_count () {
>    actual=$2
>    for FILE in "$expect" "$actual"
>    do
> -        sort "$FILE" | uniq -c | sed "s/^[ ]*//" |
> -            sed "s/^\([0-9]\) IN: clean/x IN: clean/" |
> -            sed "s/^\([0-9]\) IN: smudge/x IN: smudge/" >"$FILE.tmp" &&
> -        mv "$FILE.tmp" "$FILE"
> +        sort "$FILE" | uniq -c |
> +        sed -e "s/^ *[0-9][0-9]* *IN: /x IN: /" >"$FILE.tmp" &&

This looks good (thanks for cleaning up the redundant clean/smudge stuff - that was a refactoring artifact!). One minor nit: doesn't sed understand '[0-9]+' ?

> +        mv "$FILE.tmp" "$FILE" || return

Why '|| return' here?

>    done &&
>    test_cmp "$expect" "$actual"
> }

Thank you,
Lars

[PATCH] t0021: expect more variations in the output of uniq -c

[Johannes Sixt]

Some versions of uniq -c write the count left-justified, other version
write it right-justified. Be prepared for both kinds.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
Here it is as a proper patch.

Am 03.11.2016 um 01:41 schrieb Lars Schneider:
>> On 2 Nov 2016, at 18:03, Johannes Sixt <j6t@kdbg.org> wrote:
>> +        sort "$FILE" | uniq -c |
>> +        sed -e "s/^ *[0-9][0-9]* *IN: /x IN: /" >"$FILE.tmp" &&
> 
> This looks good (thanks for cleaning up the redundant clean/smudge
> stuff - that was a refactoring artifact!). One minor nit: doesn't sed
> understand '[0-9]+' ?

I don't think so.

>> +        mv "$FILE.tmp" "$FILE" || return
> 
> Why '|| return' here?

If there is an error in the pipeline or in the mv command, the for loop
would not exit otherwise. The subsequent test_cmp most likely fails,
but the || return is more correct.

 t/t0021-conversion.sh | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index a20b9f58e3..db71acacb3 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -40,10 +40,9 @@ test_cmp_count () {
 	actual=$2
 	for FILE in "$expect" "$actual"
 	do
-		sort "$FILE" | uniq -c | sed "s/^[ ]*//" |
-			sed "s/^\([0-9]\) IN: clean/x IN: clean/" |
-			sed "s/^\([0-9]\) IN: smudge/x IN: smudge/" >"$FILE.tmp" &&
-		mv "$FILE.tmp" "$FILE"
+		sort "$FILE" | uniq -c |
+		sed -e "s/^ *[0-9][0-9]*[ 	]*IN: /x IN: /" >"$FILE.tmp" &&
+		mv "$FILE.tmp" "$FILE" || return
 	done &&
 	test_cmp "$expect" "$actual"
 }
-- 
2.11.0.rc0.55.gd967357

[PATCH (optional)] t0021: use arithmetic expansion to trim whitespace from wc -c output

[Johannes Sixt]

Instead of a pipeline with sed and a useless use of cat, return the
unmodified text of wc -c from function file_size, but substitute the
result with arithmetic expansion to get rid of the leading whitespace
that some version of wc -c print.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
This is a pure optimization that reduces the number of forks, which
helps a bit on Windows.

There would be a solution with perl that does not require trimming
of whitespace, but perl startup times are unbearable on Windows.
wc -c is better.

 t/t0021-conversion.sh | 50 +++++++++++++++++++++++++-------------------------
 1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index db71acacb3..42b529f615 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -22,7 +22,7 @@ generate_random_characters () {
 }
 
 file_size () {
-	cat "$1" | wc -c | sed "s/^[ ]*//"
+	wc -c <"$1"
 }
 
 filter_git () {
@@ -369,10 +369,10 @@ test_expect_success PERL 'required process filter should filter data' '
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: clean test.r $S [OK] -- OUT: $S . [OK]
-			IN: clean test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
+			IN: clean test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
 			IN: clean test4-empty.r 0 [OK] -- OUT: 0  [OK]
-			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
+			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
 			STOP
 		EOF
 		test_cmp_count expected.log rot13-filter.log &&
@@ -381,14 +381,14 @@ test_expect_success PERL 'required process filter should filter data' '
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: clean test.r $S [OK] -- OUT: $S . [OK]
-			IN: clean test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
+			IN: clean test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
 			IN: clean test4-empty.r 0 [OK] -- OUT: 0  [OK]
-			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
-			IN: clean test.r $S [OK] -- OUT: $S . [OK]
-			IN: clean test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
+			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
+			IN: clean test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
 			IN: clean test4-empty.r 0 [OK] -- OUT: 0  [OK]
-			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
+			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
 			STOP
 		EOF
 		test_cmp_count expected.log rot13-filter.log &&
@@ -399,8 +399,8 @@ test_expect_success PERL 'required process filter should filter data' '
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
-			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
+			IN: smudge test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
+			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
 			STOP
 		EOF
 		test_cmp_exclude_clean expected.log rot13-filter.log &&
@@ -409,7 +409,7 @@ test_expect_success PERL 'required process filter should filter data' '
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: clean test.r $S [OK] -- OUT: $S . [OK]
+			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
 			STOP
 		EOF
 		test_cmp_exclude_clean expected.log rot13-filter.log &&
@@ -418,10 +418,10 @@ test_expect_success PERL 'required process filter should filter data' '
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: smudge test.r $S [OK] -- OUT: $S . [OK]
-			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: smudge test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
+			IN: smudge test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
 			IN: smudge test4-empty.r 0 [OK] -- OUT: 0  [OK]
-			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
+			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
 			STOP
 		EOF
 		test_cmp_exclude_clean expected.log rot13-filter.log &&
@@ -451,7 +451,7 @@ test_expect_success PERL 'required process filter takes precedence' '
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: clean test.r $S [OK] -- OUT: $S . [OK]
+			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
 			STOP
 		EOF
 		test_cmp_count expected.log rot13-filter.log
@@ -474,7 +474,7 @@ test_expect_success PERL 'required process filter should be used only for "clean
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: clean test.r $S [OK] -- OUT: $S . [OK]
+			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
 			STOP
 		EOF
 		test_cmp_count expected.log rot13-filter.log &&
@@ -603,11 +603,11 @@ test_expect_success PERL 'process filter should restart after unexpected write f
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: smudge smudge-write-fail.r $SF [OK] -- OUT: $SF [WRITE FAIL]
+			IN: smudge smudge-write-fail.r $(($SF)) [OK] -- OUT: $(($SF)) [WRITE FAIL]
 			START
 			init handshake complete
-			IN: smudge test.r $S [OK] -- OUT: $S . [OK]
-			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: smudge test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
+			IN: smudge test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
 			STOP
 		EOF
 		test_cmp_exclude_clean expected.log rot13-filter.log &&
@@ -649,9 +649,9 @@ test_expect_success PERL 'process filter should not be restarted if it signals a
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: smudge error.r $SE [OK] -- OUT: 0 [ERROR]
-			IN: smudge test.r $S [OK] -- OUT: $S . [OK]
-			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
+			IN: smudge error.r $(($SE)) [OK] -- OUT: 0 [ERROR]
+			IN: smudge test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
+			IN: smudge test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
 			STOP
 		EOF
 		test_cmp_exclude_clean expected.log rot13-filter.log &&
@@ -688,7 +688,7 @@ test_expect_success PERL 'process filter abort stops processing of all further f
 		cat >expected.log <<-EOF &&
 			START
 			init handshake complete
-			IN: smudge abort.r $SA [OK] -- OUT: 0 [ABORT]
+			IN: smudge abort.r $(($SA)) [OK] -- OUT: 0 [ABORT]
 			STOP
 		EOF
 		test_cmp_exclude_clean expected.log rot13-filter.log &&
-- 
2.11.0.rc0.55.gd967357

Re: [PATCH] t0021: expect more variations in the output of uniq -c

[Lars Schneider]

> On 03 Nov 2016, at 21:12, Johannes Sixt <j6t@kdbg.org> wrote:
> 
> Some versions of uniq -c write the count left-justified, other version
> write it right-justified. Be prepared for both kinds.
> 
> Signed-off-by: Johannes Sixt <j6t@kdbg.org>
> ---
> Here it is as a proper patch.
> 
> Am 03.11.2016 um 01:41 schrieb Lars Schneider:
>>> On 2 Nov 2016, at 18:03, Johannes Sixt <j6t@kdbg.org> wrote:
>>> +        sort "$FILE" | uniq -c |
>>> +        sed -e "s/^ *[0-9][0-9]* *IN: /x IN: /" >"$FILE.tmp" &&
>> 
>> This looks good (thanks for cleaning up the redundant clean/smudge
>> stuff - that was a refactoring artifact!). One minor nit: doesn't sed
>> understand '[0-9]+' ?
> 
> I don't think so.
> 
>>> +        mv "$FILE.tmp" "$FILE" || return
>> 
>> Why '|| return' here?
> 
> If there is an error in the pipeline or in the mv command, the for loop
> would not exit otherwise. The subsequent test_cmp most likely fails,
> but the || return is more correct.
> 
> t/t0021-conversion.sh | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
> index a20b9f58e3..db71acacb3 100755
> --- a/t/t0021-conversion.sh
> +++ b/t/t0021-conversion.sh
> @@ -40,10 +40,9 @@ test_cmp_count () {
> 	actual=$2
> 	for FILE in "$expect" "$actual"
> 	do
> -		sort "$FILE" | uniq -c | sed "s/^[ ]*//" |
> -			sed "s/^\([0-9]\) IN: clean/x IN: clean/" |
> -			sed "s/^\([0-9]\) IN: smudge/x IN: smudge/" >"$FILE.tmp" &&
> -		mv "$FILE.tmp" "$FILE"
> +		sort "$FILE" | uniq -c |
> +		sed -e "s/^ *[0-9][0-9]*[ 	]*IN: /x IN: /" >"$FILE.tmp" &&
> +		mv "$FILE.tmp" "$FILE" || return
> 	done &&
> 	test_cmp "$expect" "$actual"
> }
> -- 
> 2.11.0.rc0.55.gd967357
> 

This looks good to me. I wonder if I should post a patch 
to add the "|| return" trick to the following function
"test_cmp_exclude_clean", too?!

Thanks,
Lars

Re: [PATCH (optional)] t0021: use arithmetic expansion to trim whitespace from wc -c output

[Lars Schneider]

> On 03 Nov 2016, at 21:22, Johannes Sixt <j6t@kdbg.org> wrote:
> 
> Instead of a pipeline with sed and a useless use of cat, return the
> unmodified text of wc -c from function file_size, but substitute the
> result with arithmetic expansion to get rid of the leading whitespace
> that some version of wc -c print.
> 
> Signed-off-by: Johannes Sixt <j6t@kdbg.org>
> ---
> This is a pure optimization that reduces the number of forks, which
> helps a bit on Windows.
> 
> There would be a solution with perl that does not require trimming
> of whitespace, but perl startup times are unbearable on Windows.
> wc -c is better.
> 
> t/t0021-conversion.sh | 50 +++++++++++++++++++++++++-------------------------
> 1 file changed, 25 insertions(+), 25 deletions(-)
> 
> diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
> index db71acacb3..42b529f615 100755
> --- a/t/t0021-conversion.sh
> +++ b/t/t0021-conversion.sh
> @@ -22,7 +22,7 @@ generate_random_characters () {
> }
> 
> file_size () {
> -	cat "$1" | wc -c | sed "s/^[ ]*//"
> +	wc -c <"$1"
> }
> 
> filter_git () {
> @@ -369,10 +369,10 @@ test_expect_success PERL 'required process filter should filter data' '
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: clean test.r $S [OK] -- OUT: $S . [OK]
> -			IN: clean test2.r $S2 [OK] -- OUT: $S2 . [OK]
> +			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
> +			IN: clean test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
> 			IN: clean test4-empty.r 0 [OK] -- OUT: 0  [OK]
> -			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
> +			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
> 			STOP
> 		EOF
> 		test_cmp_count expected.log rot13-filter.log &&
> @@ -381,14 +381,14 @@ test_expect_success PERL 'required process filter should filter data' '
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: clean test.r $S [OK] -- OUT: $S . [OK]
> -			IN: clean test2.r $S2 [OK] -- OUT: $S2 . [OK]
> +			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
> +			IN: clean test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
> 			IN: clean test4-empty.r 0 [OK] -- OUT: 0  [OK]
> -			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
> -			IN: clean test.r $S [OK] -- OUT: $S . [OK]
> -			IN: clean test2.r $S2 [OK] -- OUT: $S2 . [OK]
> +			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
> +			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
> +			IN: clean test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
> 			IN: clean test4-empty.r 0 [OK] -- OUT: 0  [OK]
> -			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
> +			IN: clean testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
> 			STOP
> 		EOF
> 		test_cmp_count expected.log rot13-filter.log &&
> @@ -399,8 +399,8 @@ test_expect_success PERL 'required process filter should filter data' '
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
> -			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
> +			IN: smudge test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
> +			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
> 			STOP
> 		EOF
> 		test_cmp_exclude_clean expected.log rot13-filter.log &&
> @@ -409,7 +409,7 @@ test_expect_success PERL 'required process filter should filter data' '
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: clean test.r $S [OK] -- OUT: $S . [OK]
> +			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
> 			STOP
> 		EOF
> 		test_cmp_exclude_clean expected.log rot13-filter.log &&
> @@ -418,10 +418,10 @@ test_expect_success PERL 'required process filter should filter data' '
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: smudge test.r $S [OK] -- OUT: $S . [OK]
> -			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
> +			IN: smudge test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
> +			IN: smudge test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
> 			IN: smudge test4-empty.r 0 [OK] -- OUT: 0  [OK]
> -			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $S3 [OK] -- OUT: $S3 . [OK]
> +			IN: smudge testsubdir/test3 '\''sq'\'',\$x.r $(($S3)) [OK] -- OUT: $(($S3)) . [OK]
> 			STOP
> 		EOF
> 		test_cmp_exclude_clean expected.log rot13-filter.log &&
> @@ -451,7 +451,7 @@ test_expect_success PERL 'required process filter takes precedence' '
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: clean test.r $S [OK] -- OUT: $S . [OK]
> +			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
> 			STOP
> 		EOF
> 		test_cmp_count expected.log rot13-filter.log
> @@ -474,7 +474,7 @@ test_expect_success PERL 'required process filter should be used only for "clean
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: clean test.r $S [OK] -- OUT: $S . [OK]
> +			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
> 			STOP
> 		EOF
> 		test_cmp_count expected.log rot13-filter.log &&
> @@ -603,11 +603,11 @@ test_expect_success PERL 'process filter should restart after unexpected write f
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: smudge smudge-write-fail.r $SF [OK] -- OUT: $SF [WRITE FAIL]
> +			IN: smudge smudge-write-fail.r $(($SF)) [OK] -- OUT: $(($SF)) [WRITE FAIL]
> 			START
> 			init handshake complete
> -			IN: smudge test.r $S [OK] -- OUT: $S . [OK]
> -			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
> +			IN: smudge test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
> +			IN: smudge test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
> 			STOP
> 		EOF
> 		test_cmp_exclude_clean expected.log rot13-filter.log &&
> @@ -649,9 +649,9 @@ test_expect_success PERL 'process filter should not be restarted if it signals a
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: smudge error.r $SE [OK] -- OUT: 0 [ERROR]
> -			IN: smudge test.r $S [OK] -- OUT: $S . [OK]
> -			IN: smudge test2.r $S2 [OK] -- OUT: $S2 . [OK]
> +			IN: smudge error.r $(($SE)) [OK] -- OUT: 0 [ERROR]
> +			IN: smudge test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]
> +			IN: smudge test2.r $(($S2)) [OK] -- OUT: $(($S2)) . [OK]
> 			STOP
> 		EOF
> 		test_cmp_exclude_clean expected.log rot13-filter.log &&
> @@ -688,7 +688,7 @@ test_expect_success PERL 'process filter abort stops processing of all further f
> 		cat >expected.log <<-EOF &&
> 			START
> 			init handshake complete
> -			IN: smudge abort.r $SA [OK] -- OUT: 0 [ABORT]
> +			IN: smudge abort.r $(($SA)) [OK] -- OUT: 0 [ABORT]
> 			STOP
> 		EOF
> 		test_cmp_exclude_clean expected.log rot13-filter.log &&
> -- 
> 2.11.0.rc0.55.gd967357
> 

This looks good to me! As I run the Windows tests once in a while, too, 
I am in full support to make them faster :-)

Since the file size function became very simple with your patch,
shouldn't we get rid of it? If you agree, then we could squash the 
patch below into your patch.

I also would like to move the arithmetic expansion to the variable
to make the `expected.log` better readable. That means I would like
to have this:

S=$(($(wc -c <test.r))) &&
...
			IN: clean test.r $S [OK] -- OUT: $S . [OK]


Instead of this:

S=$(wc -c <test.r) &&
...
			IN: clean test.r $(($S)) [OK] -- OUT: $(($S)) . [OK]

Would you agree?


Thanks,
Lars



diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index 9968465..4454587 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -23,10 +23,6 @@ generate_random_characters () {
 		perl -pe "s/./chr((ord($&) % 26) + ord('a'))/sge" >"$TEST_ROOT/$NAME"
 }
 
-file_size () {
-	wc -c <"$1"
-}
-
 filter_git () {
 	rm -f rot13-filter.log &&
 	git "$@" 2>git-stderr.log &&
@@ -363,9 +359,9 @@ test_expect_success PERL 'required process filter should filter data' '
 		cp "$TEST_ROOT/test3 '\''sq'\'',\$x.o" "testsubdir/test3 '\''sq'\'',\$x.r" &&
 		>test4-empty.r &&
 
-		S=$(file_size test.r) &&
-		S2=$(file_size test2.r) &&
-		S3=$(file_size "testsubdir/test3 '\''sq'\'',\$x.r") &&
+		S=$(wc -c <test.r) &&
+		S2=$(wc -c <test2.r) &&
+		S3=$(wc -c <"testsubdir/test3 '\''sq'\'',\$x.r") &&
 
 		filter_git add . &&
 		cat >expected.log <<-EOF &&
@@ -446,7 +442,7 @@ test_expect_success PERL 'required process filter takes precedence' '
 
 		echo "*.r filter=protocol" >.gitattributes &&
 		cp "$TEST_ROOT/test.o" test.r &&
-		S=$(file_size test.r) &&
+		S=$(wc -c <test.r) &&
 
 		# Check that the process filter is invoked here
 		filter_git add . &&
@@ -470,7 +466,7 @@ test_expect_success PERL 'required process filter should be used only for "clean
 
 		echo "*.r filter=protocol" >.gitattributes &&
 		cp "$TEST_ROOT/test.o" test.r &&
-		S=$(file_size test.r) &&
+		S=$(wc -c <test.r) &&
 
 		filter_git add . &&
 		cat >expected.log <<-EOF &&
@@ -589,9 +585,9 @@ test_expect_success PERL 'process filter should restart after unexpected write f
 		echo "this is going to fail" >smudge-write-fail.o &&
 		cp smudge-write-fail.o smudge-write-fail.r &&
 
-		S=$(file_size test.r) &&
-		S2=$(file_size test2.r) &&
-		SF=$(file_size smudge-write-fail.r) &&
+		S=$(wc -c <test.r) &&
+		S2=$(wc -c <test2.r) &&
+		SF=$(wc -c <smudge-write-fail.r) &&
 
 		git add . &&
 		rm -f *.r &&
@@ -640,9 +636,9 @@ test_expect_success PERL 'process filter should not be restarted if it signals a
 		echo "this will cause an error" >error.o &&
 		cp error.o error.r &&
 
-		S=$(file_size test.r) &&
-		S2=$(file_size test2.r) &&
-		SE=$(file_size error.r) &&
+		S=$(wc -c <test.r) &&
+		S2=$(wc -c <test2.r) &&
+		SE=$(wc -c <error.r) &&
 
 		git add . &&
 		rm -f *.r &&
@@ -679,7 +675,7 @@ test_expect_success PERL 'process filter abort stops processing of all further f
 		echo "error this blob and all future blobs" >abort.o &&
 		cp abort.o abort.r &&
 
-		SA=$(file_size abort.r) &&
+		SA=$(wc -c <abort.r) &&
 
 		git add . &&
 		rm -f *.r &&

Re: [PATCH (optional)] t0021: use arithmetic expansion to trim whitespace from wc -c output

[Johannes Sixt]

Am 06.11.2016 um 16:45 schrieb Lars Schneider:
> 
>> On 03 Nov 2016, at 21:22, Johannes Sixt <j6t@kdbg.org> wrote:
>> This is a pure optimization that reduces the number of forks, which
>> helps a bit on Windows.
>>
>> There would be a solution with perl that does not require trimming
>> of whitespace, but perl startup times are unbearable on Windows.
>> wc -c is better.

I was wrong here. I had looked at the perl invocations due to
git-sendemail, and they are awfully slow. A do-almost-nothing perl
invocation is in the same ballpark as wc. Therefore I changed my mind
and suggest the patch below instead.

> Since the file size function became very simple with your patch,
> shouldn't we get rid of it? If you agree, then we could squash the 
> patch below into your patch.

In the new patch, the function is not that trivial (it uses perl), and
the call sites can remain as they are (simple shell variables and
substitutions).

---- 8< ----
[PATCH] t0021: compute file size with a single process instead of a pipeline

Avoid unwanted coding patterns (prodigal use of pipelines), and in
particular a useless use of cat.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
 t/t0021-conversion.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index db71acacb3..cb72fa49de 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -22,7 +22,7 @@ generate_random_characters () {
 }
 
 file_size () {
-	cat "$1" | wc -c | sed "s/^[ ]*//"
+	perl -e 'print -s $ARGV[0]' "$1"
 }
 
 filter_git () {
-- 
2.11.0.rc0.55.gd967357

Re: [PATCH (optional)] t0021: use arithmetic expansion to trim whitespace from wc -c output

[Lars Schneider]

> On 06 Nov 2016, at 20:31, Johannes Sixt <j6t@kdbg.org> wrote:
> 
> Am 06.11.2016 um 16:45 schrieb Lars Schneider:
>> 
>>> On 03 Nov 2016, at 21:22, Johannes Sixt <j6t@kdbg.org> wrote:
>>> This is a pure optimization that reduces the number of forks, which
>>> helps a bit on Windows.
>>> 
>>> There would be a solution with perl that does not require trimming
>>> of whitespace, but perl startup times are unbearable on Windows.
>>> wc -c is better.
> 
> I was wrong here. I had looked at the perl invocations due to
> git-sendemail, and they are awfully slow. A do-almost-nothing perl
> invocation is in the same ballpark as wc. Therefore I changed my mind
> and suggest the patch below instead.
> 
>> Since the file size function became very simple with your patch,
>> shouldn't we get rid of it? If you agree, then we could squash the 
>> patch below into your patch.
> 
> In the new patch, the function is not that trivial (it uses perl), and
> the call sites can remain as they are (simple shell variables and
> substitutions).
> 
> ---- 8< ----
> [PATCH] t0021: compute file size with a single process instead of a pipeline
> 
> Avoid unwanted coding patterns (prodigal use of pipelines), and in
> particular a useless use of cat.
> 
> Signed-off-by: Johannes Sixt <j6t@kdbg.org>
> ---
> t/t0021-conversion.sh | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
> index db71acacb3..cb72fa49de 100755
> --- a/t/t0021-conversion.sh
> +++ b/t/t0021-conversion.sh
> @@ -22,7 +22,7 @@ generate_random_characters () {
> }
> 
> file_size () {
> -	cat "$1" | wc -c | sed "s/^[ ]*//"
> +	perl -e 'print -s $ARGV[0]' "$1"
> }
> 
> filter_git () {
> -- 
> 2.11.0.rc0.55.gd967357
> 

I like this better, too. Looks good to me and works on macOS.

Thanks,
Lars

Re: [PATCH] t0021: expect more variations in the output of uniq -c

[Johannes Sixt]

Am 06.11.2016 um 16:31 schrieb Lars Schneider:
> This looks good to me. I wonder if I should post a patch
> to add the "|| return" trick to the following function
> "test_cmp_exclude_clean", too?!

The function does this:

         for FILE in "$expect" "$actual"
         do
                 grep -v "IN: clean" "$FILE" >"$FILE.tmp" &&
                 mv "$FILE.tmp" "$FILE"
         done &&

It is an interesting case: If only matching lines are in the file, 
nothing would be printed, and grep returns failure. But we shouldn't 
care, because, strictly speaking, the function only wants to remove 
lines with a certain pattern. Here, it actually hurts to &&-chain grep!

It wouldn't hurt to write 'mv ... || return', but at the same time, && 
after grep should be removed.

-- Hannes