[PATCH v7 00/10] refactor the filter process code into a reusable module

[PATCH v7 00/10] refactor the filter process code into a reusable module

[Ben Peart]

Changes from V6 include:

convert: remove erroneous tests for errno == EPIPE
 - split into separate patch to fix a preexisting bug discovered in the review process

pkt-line: Update packet_read_line() to test for len > 0
 - split into separate patch to deal with errors that return negative lengths

pkt-line: add packet_read_line_gently()
 - update documentation to clarify return values
 - update white space in function definition


Refactor the filter.<driver>.process code into a separate sub-process
module that can be used to reduce the cost of starting up a sub-process
for multiple commands.  It does this by keeping the external process
running and processing all commands by communicating over standard input
and standard output using the packet format (pkt-line) based protocol.
Full documentation is in Documentation/technical/api-sub-process.txt.

This code is refactored from:

	Commit edcc85814c ("convert: add filter.<driver>.process option", 2016-10-16)
	keeps the external process running and processes all commands

Ben Peart (10):
  convert: remove erroneous tests for errno == EPIPE
  pkt-line: fix packet_read_line() to handle len < 0 errors
  pkt-line: add packet_read_line_gently()
  convert: move packet_write_line() into pkt-line as packet_writel()
  convert: split start_multi_file_filter() into two separate functions
  convert: Separate generic structures and variables from the filter
    specific ones
  convert: Update generic functions to only use generic data structures
  convert: rename reusable sub-process functions
  sub-process: move sub-process functions into separate files
  convert: Update subprocess_read_status to not die on EOF

 Documentation/technical/api-sub-process.txt |  59 ++++++++++
 Makefile                                    |   1 +
 convert.c                                   | 161 ++++++----------------------
 pkt-line.c                                  |  33 +++++-
 pkt-line.h                                  |  12 +++
 sub-process.c                               | 106 ++++++++++++++++++
 sub-process.h                               |  49 +++++++++
 7 files changed, 292 insertions(+), 129 deletions(-)
 create mode 100644 Documentation/technical/api-sub-process.txt
 create mode 100644 sub-process.c
 create mode 100644 sub-process.h

-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 01/10] convert: remove erroneous tests for errno == EPIPE

[Ben Peart]

start_multi_file_filter() and apply_multi_file_filter() currently test
for errno == EPIPE but treating EPIPE as an error is already happening
from one of the packet_write() functions.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Found/Fixed-by: Jeff King <peff@peff.net>
Acked-by: Lars Schneider <larsxschneider@gmail.com>
---
 convert.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/convert.c b/convert.c
index 4e17e45ed2..bdd528086f 100644
--- a/convert.c
+++ b/convert.c
@@ -661,7 +661,7 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
 done:
 	sigchain_pop(SIGPIPE);
 
-	if (err || errno == EPIPE) {
+	if (err) {
 		error("initialization for external filter '%s' failed", cmd);
 		kill_multi_file_filter(hashmap, entry);
 		return NULL;
@@ -752,7 +752,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 done:
 	sigchain_pop(SIGPIPE);
 
-	if (err || errno == EPIPE) {
+	if (err) {
 		if (!strcmp(filter_status.buf, "error")) {
 			/* The filter signaled a problem with the file. */
 		} else if (!strcmp(filter_status.buf, "abort")) {
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 02/10] pkt-line: fix packet_read_line() to handle len < 0 errors

[Ben Peart]

Update packet_read_line() to test for len > 0 to avoid potential bug
if read functions return lengths less than zero to indicate errors.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Found/Fixed-by: Lars Schneider <larsxschneider@gmail.com>
---
 pkt-line.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkt-line.c b/pkt-line.c
index d4b6bfe076..6f05b1a4a8 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -315,7 +315,7 @@ static char *packet_read_line_generic(int fd,
 			      PACKET_READ_CHOMP_NEWLINE);
 	if (dst_len)
 		*dst_len = len;
-	return len ? packet_buffer : NULL;
+	return (len > 0) ? packet_buffer : NULL;
 }
 
 char *packet_read_line(int fd, int *len_p)
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 03/10] pkt-line: add packet_read_line_gently()

[Ben Peart]

Add packet_read_line_gently() to enable reading a line without dying on
EOF.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 pkt-line.c | 12 ++++++++++++
 pkt-line.h | 11 +++++++++++
 2 files changed, 23 insertions(+)

diff --git a/pkt-line.c b/pkt-line.c
index 6f05b1a4a8..7db9119573 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -323,6 +323,18 @@ char *packet_read_line(int fd, int *len_p)
 	return packet_read_line_generic(fd, NULL, NULL, len_p);
 }
 
+int packet_read_line_gently(int fd, int *dst_len, char **dst_line)
+{
+	int len = packet_read(fd, NULL, NULL,
+			      packet_buffer, sizeof(packet_buffer),
+			      PACKET_READ_CHOMP_NEWLINE|PACKET_READ_GENTLE_ON_EOF);
+	if (dst_len)
+		*dst_len = len;
+	if (dst_line)
+		*dst_line = (len > 0) ? packet_buffer : NULL;
+	return len;
+}
+
 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);
diff --git a/pkt-line.h b/pkt-line.h
index 18eac64830..66ef610fc4 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -74,6 +74,17 @@ int packet_read(int fd, char **src_buffer, size_t *src_len, char
 char *packet_read_line(int fd, int *size);
 
 /*
+ * Convenience wrapper for packet_read that sets the PACKET_READ_GENTLE_ON_EOF
+ * and CHOMP_NEWLINE options. The return value specifies the number of bytes
+ * read into the buffer or -1 on truncated input. If the *dst_line parameter
+ * is not NULL it will return NULL for a flush packet or when the number of
+ * bytes copied is zero and otherwise points to a static buffer (that may be
+ * overwritten by subsequent calls). If the size parameter is not NULL, the
+ * length of the packet is written to it.
+ */
+int packet_read_line_gently(int fd, int *size, char **dst_line);
+
+/*
  * Same as packet_read_line, but read from a buf rather than a descriptor;
  * see packet_read for details on how src_* is used.
  */
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 04/10] convert: move packet_write_line() into pkt-line as packet_writel()

[Ben Peart]

Add packet_writel() which writes multiple lines in a single call and
then calls packet_flush_gently(). Update convert.c to use the new
packet_writel() function from pkt-line.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 convert.c  | 23 ++---------------------
 pkt-line.c | 19 +++++++++++++++++++
 pkt-line.h |  1 +
 3 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/convert.c b/convert.c
index bdd528086f..1f18d947b9 100644
--- a/convert.c
+++ b/convert.c
@@ -521,25 +521,6 @@ static struct cmd2process *find_multi_file_filter_entry(struct hashmap *hashmap,
 	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;
@@ -616,7 +597,7 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
 
 	sigchain_push(SIGPIPE, SIG_IGN);
 
-	err = packet_write_list(process->in, "git-filter-client", "version=2", NULL);
+	err = packet_writel(process->in, "git-filter-client", "version=2", NULL);
 	if (err)
 		goto done;
 
@@ -632,7 +613,7 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
 	if (err)
 		goto done;
 
-	err = packet_write_list(process->in, "capability=clean", "capability=smudge", NULL);
+	err = packet_writel(process->in, "capability=clean", "capability=smudge", NULL);
 
 	for (;;) {
 		cap_buf = packet_read_line(process->out, NULL);
diff --git a/pkt-line.c b/pkt-line.c
index 7db9119573..9d845ecc3c 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -171,6 +171,25 @@ int packet_write_fmt_gently(int fd, const char *fmt, ...)
 	return status;
 }
 
+int packet_writel(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 int packet_write_gently(const int fd_out, const char *buf, size_t size)
 {
 	static char packet_write_buffer[LARGE_PACKET_MAX];
diff --git a/pkt-line.h b/pkt-line.h
index 66ef610fc4..b2965869ad 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -25,6 +25,7 @@ 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 packet_writel(int fd, const char *line, ...);
 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);
 
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 05/10] convert: split start_multi_file_filter() into two separate functions

[Ben Peart]

To enable future reuse of the filter.<driver>.process infrastructure,
split start_multi_file_filter() into two separate parts.

start_multi_file_filter() will now only contain the generic logic to
manage the creation and tracking of the child process in a hashmap.

start_multi_file_filter_fn() is a protocol specific initialization
function that will negotiate the multi-file-filter interface version
and capabilities.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 convert.c | 58 ++++++++++++++++++++++++++++++++++------------------------
 1 file changed, 34 insertions(+), 24 deletions(-)

diff --git a/convert.c b/convert.c
index 1f18d947b9..4e1d018577 100644
--- a/convert.c
+++ b/convert.c
@@ -565,35 +565,14 @@ static void stop_multi_file_filter(struct child_process *process)
 	finish_command(process);
 }
 
-static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, const char *cmd)
+static int start_multi_file_filter_fn(struct cmd2process *entry)
 {
 	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));
+	struct child_process *process = &entry->process;
+	const char *cmd = entry->cmd;
 
 	sigchain_push(SIGPIPE, SIG_IGN);
 
@@ -642,6 +621,37 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
 done:
 	sigchain_pop(SIGPIPE);
 
+	return err;
+}
+
+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 };
+
+	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));
+
+	err = start_multi_file_filter_fn(entry);
 	if (err) {
 		error("initialization for external filter '%s' failed", cmd);
 		kill_multi_file_filter(hashmap, entry);
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 06/10] convert: Separate generic structures and variables from the filter specific ones

[Ben Peart]

To enable future reuse of the filter.<driver>.process infrastructure,
split the cmd2process structure into two separate parts.

subprocess_entry will now contain the generic data required to manage
the creation and tracking of the child process in a hashmap.

cmd2process is a filter protocol specific structure that is used to
track the negotiated capabilities of the filter.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 convert.c | 35 ++++++++++++++++++++---------------
 1 file changed, 20 insertions(+), 15 deletions(-)

diff --git a/convert.c b/convert.c
index 4e1d018577..5876218347 100644
--- a/convert.c
+++ b/convert.c
@@ -496,26 +496,31 @@ 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 subprocess_entry {
 	struct hashmap_entry ent; /* must be the first member! */
-	unsigned int supported_capabilities;
 	const char *cmd;
 	struct child_process process;
 };
 
+struct cmd2process {
+	struct subprocess_entry subprocess; /* must be the first member! */
+	unsigned int supported_capabilities;
+};
+
 static int cmd_process_map_initialized;
 static struct hashmap cmd_process_map;
 
-static int cmd2process_cmp(const struct cmd2process *e1,
-			   const struct cmd2process *e2,
+static int cmd2process_cmp(const struct subprocess_entry *e1,
+			   const struct subprocess_entry *e2,
 			   const void *unused)
 {
 	return strcmp(e1->cmd, e2->cmd);
 }
 
-static struct cmd2process *find_multi_file_filter_entry(struct hashmap *hashmap, const char *cmd)
+static struct subprocess_entry *find_multi_file_filter_entry(struct hashmap *hashmap, const char *cmd)
 {
-	struct cmd2process key;
+	struct subprocess_entry key;
+
 	hashmap_entry_init(&key, strhash(cmd));
 	key.cmd = cmd;
 	return hashmap_get(hashmap, &key, NULL);
@@ -541,7 +546,7 @@ static void read_multi_file_filter_status(int fd, struct strbuf *status)
 	}
 }
 
-static void kill_multi_file_filter(struct hashmap *hashmap, struct cmd2process *entry)
+static void kill_multi_file_filter(struct hashmap *hashmap, struct subprocess_entry *entry)
 {
 	if (!entry)
 		return;
@@ -571,8 +576,8 @@ static int start_multi_file_filter_fn(struct cmd2process *entry)
 	struct string_list cap_list = STRING_LIST_INIT_NODUP;
 	char *cap_buf;
 	const char *cap_name;
-	struct child_process *process = &entry->process;
-	const char *cmd = entry->cmd;
+	struct child_process *process = &entry->subprocess.process;
+	const char *cmd = entry->subprocess.cmd;
 
 	sigchain_push(SIGPIPE, SIG_IGN);
 
@@ -632,9 +637,9 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
 	const char *argv[] = { cmd, NULL };
 
 	entry = xmalloc(sizeof(*entry));
-	entry->cmd = cmd;
+	entry->subprocess.cmd = cmd;
 	entry->supported_capabilities = 0;
-	process = &entry->process;
+	process = &entry->subprocess.process;
 
 	child_process_init(process);
 	process->argv = argv;
@@ -654,7 +659,7 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
 	err = start_multi_file_filter_fn(entry);
 	if (err) {
 		error("initialization for external filter '%s' failed", cmd);
-		kill_multi_file_filter(hashmap, entry);
+		kill_multi_file_filter(hashmap, &entry->subprocess);
 		return NULL;
 	}
 
@@ -678,7 +683,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 		hashmap_init(&cmd_process_map, (hashmap_cmp_fn) cmd2process_cmp, 0);
 		entry = NULL;
 	} else {
-		entry = find_multi_file_filter_entry(&cmd_process_map, cmd);
+		entry = (struct cmd2process *)find_multi_file_filter_entry(&cmd_process_map, cmd);
 	}
 
 	fflush(NULL);
@@ -688,7 +693,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 		if (!entry)
 			return 0;
 	}
-	process = &entry->process;
+	process = &entry->subprocess.process;
 
 	if (!(wanted_capability & entry->supported_capabilities))
 		return 0;
@@ -759,7 +764,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 			 * Force shutdown and restart if another blob requires filtering.
 			 */
 			error("external filter '%s' failed", cmd);
-			kill_multi_file_filter(&cmd_process_map, entry);
+			kill_multi_file_filter(&cmd_process_map, &entry->subprocess);
 		}
 	} else {
 		strbuf_swap(dst, &nbuf);
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 07/10] convert: Update generic functions to only use generic data structures

[Ben Peart]

Update all functions that are going to be moved into a reusable module
so that they only work with the reusable data structures.  Move code
that is specific to the filter out into the filter specific functions.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 convert.c | 41 +++++++++++++++++++++++------------------
 1 file changed, 23 insertions(+), 18 deletions(-)

diff --git a/convert.c b/convert.c
index 5876218347..7d05dcb4aa 100644
--- a/convert.c
+++ b/convert.c
@@ -556,7 +556,6 @@ static void kill_multi_file_filter(struct hashmap *hashmap, struct subprocess_en
 	finish_command(&entry->process);
 
 	hashmap_remove(hashmap, entry, NULL);
-	free(entry);
 }
 
 static void stop_multi_file_filter(struct child_process *process)
@@ -570,14 +569,15 @@ static void stop_multi_file_filter(struct child_process *process)
 	finish_command(process);
 }
 
-static int start_multi_file_filter_fn(struct cmd2process *entry)
+static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
 {
 	int err;
+	struct cmd2process *entry = (struct cmd2process *)subprocess;
 	struct string_list cap_list = STRING_LIST_INIT_NODUP;
 	char *cap_buf;
 	const char *cap_name;
-	struct child_process *process = &entry->subprocess.process;
-	const char *cmd = entry->subprocess.cmd;
+	struct child_process *process = &subprocess->process;
+	const char *cmd = subprocess->cmd;
 
 	sigchain_push(SIGPIPE, SIG_IGN);
 
@@ -629,17 +629,16 @@ static int start_multi_file_filter_fn(struct cmd2process *entry)
 	return err;
 }
 
-static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, const char *cmd)
+typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
+int start_multi_file_filter(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
+	subprocess_start_fn startfn)
 {
 	int err;
-	struct cmd2process *entry;
 	struct child_process *process;
 	const char *argv[] = { cmd, NULL };
 
-	entry = xmalloc(sizeof(*entry));
-	entry->subprocess.cmd = cmd;
-	entry->supported_capabilities = 0;
-	process = &entry->subprocess.process;
+	entry->cmd = cmd;
+	process = &entry->process;
 
 	child_process_init(process);
 	process->argv = argv;
@@ -649,22 +648,23 @@ static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, cons
 	process->clean_on_exit = 1;
 	process->clean_on_exit_handler = stop_multi_file_filter;
 
-	if (start_command(process)) {
+	err = start_command(process);
+	if (err) {
 		error("cannot fork to run external filter '%s'", cmd);
-		return NULL;
+		return err;
 	}
 
 	hashmap_entry_init(entry, strhash(cmd));
 
-	err = start_multi_file_filter_fn(entry);
+	err = startfn(entry);
 	if (err) {
 		error("initialization for external filter '%s' failed", cmd);
-		kill_multi_file_filter(hashmap, &entry->subprocess);
-		return NULL;
+		kill_multi_file_filter(hashmap, entry);
+		return err;
 	}
 
 	hashmap_add(hashmap, entry);
-	return entry;
+	return 0;
 }
 
 static int apply_multi_file_filter(const char *path, const char *src, size_t len,
@@ -689,9 +689,13 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 	fflush(NULL);
 
 	if (!entry) {
-		entry = start_multi_file_filter(&cmd_process_map, cmd);
-		if (!entry)
+		entry = xmalloc(sizeof(*entry));
+		entry->supported_capabilities = 0;
+
+		if (start_multi_file_filter(&cmd_process_map, &entry->subprocess, cmd, start_multi_file_filter_fn)) {
+			free(entry);
 			return 0;
+		}
 	}
 	process = &entry->subprocess.process;
 
@@ -765,6 +769,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 			 */
 			error("external filter '%s' failed", cmd);
 			kill_multi_file_filter(&cmd_process_map, &entry->subprocess);
+			free(entry);
 		}
 	} else {
 		strbuf_swap(dst, &nbuf);
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 08/10] convert: rename reusable sub-process functions

[Ben Peart]

Do a mechanical rename of the functions that will become the reusable
sub-process module.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 convert.c | 40 ++++++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/convert.c b/convert.c
index 7d05dcb4aa..84c4ff8a01 100644
--- a/convert.c
+++ b/convert.c
@@ -507,8 +507,8 @@ struct cmd2process {
 	unsigned int supported_capabilities;
 };
 
-static int cmd_process_map_initialized;
-static struct hashmap cmd_process_map;
+static int subprocess_map_initialized;
+static struct hashmap subprocess_map;
 
 static int cmd2process_cmp(const struct subprocess_entry *e1,
 			   const struct subprocess_entry *e2,
@@ -517,7 +517,7 @@ static int cmd2process_cmp(const struct subprocess_entry *e1,
 	return strcmp(e1->cmd, e2->cmd);
 }
 
-static struct subprocess_entry *find_multi_file_filter_entry(struct hashmap *hashmap, const char *cmd)
+static struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd)
 {
 	struct subprocess_entry key;
 
@@ -526,7 +526,7 @@ static struct subprocess_entry *find_multi_file_filter_entry(struct hashmap *has
 	return hashmap_get(hashmap, &key, NULL);
 }
 
-static void read_multi_file_filter_status(int fd, struct strbuf *status)
+static void subprocess_read_status(int fd, struct strbuf *status)
 {
 	struct strbuf **pair;
 	char *line;
@@ -546,7 +546,7 @@ static void read_multi_file_filter_status(int fd, struct strbuf *status)
 	}
 }
 
-static void kill_multi_file_filter(struct hashmap *hashmap, struct subprocess_entry *entry)
+static void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry)
 {
 	if (!entry)
 		return;
@@ -558,10 +558,10 @@ static void kill_multi_file_filter(struct hashmap *hashmap, struct subprocess_en
 	hashmap_remove(hashmap, entry, NULL);
 }
 
-static void stop_multi_file_filter(struct child_process *process)
+static void subprocess_exit_handler(struct child_process *process)
 {
 	sigchain_push(SIGPIPE, SIG_IGN);
-	/* Closing the pipe signals the filter to initiate a shutdown. */
+	/* Closing the pipe signals the subprocess to initiate a shutdown. */
 	close(process->in);
 	close(process->out);
 	sigchain_pop(SIGPIPE);
@@ -630,7 +630,7 @@ static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
 }
 
 typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
-int start_multi_file_filter(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
+int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
 	subprocess_start_fn startfn)
 {
 	int err;
@@ -646,11 +646,11 @@ int start_multi_file_filter(struct hashmap *hashmap, struct subprocess_entry *en
 	process->in = -1;
 	process->out = -1;
 	process->clean_on_exit = 1;
-	process->clean_on_exit_handler = stop_multi_file_filter;
+	process->clean_on_exit_handler = subprocess_exit_handler;
 
 	err = start_command(process);
 	if (err) {
-		error("cannot fork to run external filter '%s'", cmd);
+		error("cannot fork to run subprocess '%s'", cmd);
 		return err;
 	}
 
@@ -658,8 +658,8 @@ int start_multi_file_filter(struct hashmap *hashmap, struct subprocess_entry *en
 
 	err = startfn(entry);
 	if (err) {
-		error("initialization for external filter '%s' failed", cmd);
-		kill_multi_file_filter(hashmap, entry);
+		error("initialization for subprocess '%s' failed", cmd);
+		subprocess_stop(hashmap, entry);
 		return err;
 	}
 
@@ -678,12 +678,12 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 	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);
+	if (!subprocess_map_initialized) {
+		subprocess_map_initialized = 1;
+		hashmap_init(&subprocess_map, (hashmap_cmp_fn) cmd2process_cmp, 0);
 		entry = NULL;
 	} else {
-		entry = (struct cmd2process *)find_multi_file_filter_entry(&cmd_process_map, cmd);
+		entry = (struct cmd2process *)subprocess_find_entry(&subprocess_map, cmd);
 	}
 
 	fflush(NULL);
@@ -692,7 +692,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 		entry = xmalloc(sizeof(*entry));
 		entry->supported_capabilities = 0;
 
-		if (start_multi_file_filter(&cmd_process_map, &entry->subprocess, cmd, start_multi_file_filter_fn)) {
+		if (subprocess_start(&subprocess_map, &entry->subprocess, cmd, start_multi_file_filter_fn)) {
 			free(entry);
 			return 0;
 		}
@@ -737,7 +737,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 	if (err)
 		goto done;
 
-	read_multi_file_filter_status(process->out, &filter_status);
+	subprocess_read_status(process->out, &filter_status);
 	err = strcmp(filter_status.buf, "success");
 	if (err)
 		goto done;
@@ -746,7 +746,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 	if (err)
 		goto done;
 
-	read_multi_file_filter_status(process->out, &filter_status);
+	subprocess_read_status(process->out, &filter_status);
 	err = strcmp(filter_status.buf, "success");
 
 done:
@@ -768,7 +768,7 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 			 * Force shutdown and restart if another blob requires filtering.
 			 */
 			error("external filter '%s' failed", cmd);
-			kill_multi_file_filter(&cmd_process_map, &entry->subprocess);
+			subprocess_stop(&subprocess_map, &entry->subprocess);
 			free(entry);
 		}
 	} else {
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 09/10] sub-process: move sub-process functions into separate files

[Ben Peart]

Move the sub-proces functions into sub-process.h/c.  Add documentation
for the new module in Documentation/technical/api-sub-process.txt

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 Documentation/technical/api-sub-process.txt |  59 ++++++++++++++++
 Makefile                                    |   1 +
 convert.c                                   | 104 +---------------------------
 sub-process.c                               | 102 +++++++++++++++++++++++++++
 sub-process.h                               |  49 +++++++++++++
 5 files changed, 212 insertions(+), 103 deletions(-)
 create mode 100644 Documentation/technical/api-sub-process.txt
 create mode 100644 sub-process.c
 create mode 100644 sub-process.h

diff --git a/Documentation/technical/api-sub-process.txt b/Documentation/technical/api-sub-process.txt
new file mode 100644
index 0000000000..793508cf3e
--- /dev/null
+++ b/Documentation/technical/api-sub-process.txt
@@ -0,0 +1,59 @@
+sub-process API
+===============
+
+The sub-process API makes it possible to run background sub-processes
+for the entire lifetime of a Git invocation. If Git needs to communicate
+with an external process multiple times, then this can reduces the process
+invocation overhead. Git and the sub-process communicate through stdin and
+stdout.
+
+The sub-processes are kept in a hashmap by command name and looked up
+via the subprocess_find_entry function.  If an existing instance can not
+be found then a new process should be created and started.  When the
+parent git command terminates, all sub-processes are also terminated.
+
+This API is based on the run-command API.
+
+Data structures
+---------------
+
+* `struct subprocess_entry`
+
+The sub-process structure.  Members should not be accessed directly.
+
+Types
+-----
+
+'int(*subprocess_start_fn)(struct subprocess_entry *entry)'::
+
+	User-supplied function to initialize the sub-process.  This is
+	typically used to negotiate the interface version and capabilities.
+
+
+Functions
+---------
+
+`cmd2process_cmp`::
+
+	Function to test two subprocess hashmap entries for equality.
+
+`subprocess_start`::
+
+	Start a subprocess and add it to the subprocess hashmap.
+
+`subprocess_stop`::
+
+	Kill a subprocess and remove it from the subprocess hashmap.
+
+`subprocess_find_entry`::
+
+	Find a subprocess in the subprocess hashmap.
+
+`subprocess_get_child_process`::
+
+	Get the underlying `struct child_process` from a subprocess.
+
+`subprocess_read_status`::
+
+	Helper function to read packets looking for the last "status=<foo>"
+	key/value pair.
diff --git a/Makefile b/Makefile
index 47827aa129..3239dcbf0a 100644
--- a/Makefile
+++ b/Makefile
@@ -832,6 +832,7 @@ LIB_OBJS += streaming.o
 LIB_OBJS += string-list.o
 LIB_OBJS += submodule.o
 LIB_OBJS += submodule-config.o
+LIB_OBJS += sub-process.o
 LIB_OBJS += symlinks.o
 LIB_OBJS += tag.o
 LIB_OBJS += tempfile.o
diff --git a/convert.c b/convert.c
index 84c4ff8a01..acf51416d1 100644
--- a/convert.c
+++ b/convert.c
@@ -4,6 +4,7 @@
 #include "quote.h"
 #include "sigchain.h"
 #include "pkt-line.h"
+#include "sub-process.h"
 
 /*
  * convert.c - convert a file when checking it out and checking it in.
@@ -496,12 +497,6 @@ 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 subprocess_entry {
-	struct hashmap_entry ent; /* must be the first member! */
-	const char *cmd;
-	struct child_process process;
-};
-
 struct cmd2process {
 	struct subprocess_entry subprocess; /* must be the first member! */
 	unsigned int supported_capabilities;
@@ -510,65 +505,6 @@ struct cmd2process {
 static int subprocess_map_initialized;
 static struct hashmap subprocess_map;
 
-static int cmd2process_cmp(const struct subprocess_entry *e1,
-			   const struct subprocess_entry *e2,
-			   const void *unused)
-{
-	return strcmp(e1->cmd, e2->cmd);
-}
-
-static struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd)
-{
-	struct subprocess_entry key;
-
-	hashmap_entry_init(&key, strhash(cmd));
-	key.cmd = cmd;
-	return hashmap_get(hashmap, &key, NULL);
-}
-
-static void subprocess_read_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 subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry)
-{
-	if (!entry)
-		return;
-
-	entry->process.clean_on_exit = 0;
-	kill(entry->process.pid, SIGTERM);
-	finish_command(&entry->process);
-
-	hashmap_remove(hashmap, entry, NULL);
-}
-
-static void subprocess_exit_handler(struct child_process *process)
-{
-	sigchain_push(SIGPIPE, SIG_IGN);
-	/* Closing the pipe signals the subprocess 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 int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
 {
 	int err;
@@ -629,44 +565,6 @@ static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
 	return err;
 }
 
-typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
-int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
-	subprocess_start_fn startfn)
-{
-	int err;
-	struct child_process *process;
-	const char *argv[] = { cmd, NULL };
-
-	entry->cmd = cmd;
-	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 = subprocess_exit_handler;
-
-	err = start_command(process);
-	if (err) {
-		error("cannot fork to run subprocess '%s'", cmd);
-		return err;
-	}
-
-	hashmap_entry_init(entry, strhash(cmd));
-
-	err = startfn(entry);
-	if (err) {
-		error("initialization for subprocess '%s' failed", cmd);
-		subprocess_stop(hashmap, entry);
-		return err;
-	}
-
-	hashmap_add(hashmap, entry);
-	return 0;
-}
-
 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)
diff --git a/sub-process.c b/sub-process.c
new file mode 100644
index 0000000000..536b60cced
--- /dev/null
+++ b/sub-process.c
@@ -0,0 +1,102 @@
+/*
+ * Generic implementation of background process infrastructure.
+ */
+#include "sub-process.h"
+#include "sigchain.h"
+#include "pkt-line.h"
+
+int cmd2process_cmp(const struct subprocess_entry *e1,
+			   const struct subprocess_entry *e2,
+			   const void *unused)
+{
+	return strcmp(e1->cmd, e2->cmd);
+}
+
+struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd)
+{
+	struct subprocess_entry key;
+
+	hashmap_entry_init(&key, strhash(cmd));
+	key.cmd = cmd;
+	return hashmap_get(hashmap, &key, NULL);
+}
+
+void subprocess_read_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);
+	}
+}
+
+void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry)
+{
+	if (!entry)
+		return;
+
+	entry->process.clean_on_exit = 0;
+	kill(entry->process.pid, SIGTERM);
+	finish_command(&entry->process);
+
+	hashmap_remove(hashmap, entry, NULL);
+}
+
+static void subprocess_exit_handler(struct child_process *process)
+{
+	sigchain_push(SIGPIPE, SIG_IGN);
+	/* Closing the pipe signals the subprocess 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);
+}
+
+int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
+	subprocess_start_fn startfn)
+{
+	int err;
+	struct child_process *process;
+	const char *argv[] = { cmd, NULL };
+
+	entry->cmd = cmd;
+	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 = subprocess_exit_handler;
+
+	err = start_command(process);
+	if (err) {
+		error("cannot fork to run subprocess '%s'", cmd);
+		return err;
+	}
+
+	hashmap_entry_init(entry, strhash(cmd));
+
+	err = startfn(entry);
+	if (err) {
+		error("initialization for subprocess '%s' failed", cmd);
+		subprocess_stop(hashmap, entry);
+		return err;
+	}
+
+	hashmap_add(hashmap, entry);
+	return 0;
+}
diff --git a/sub-process.h b/sub-process.h
new file mode 100644
index 0000000000..a88e782bfc
--- /dev/null
+++ b/sub-process.h
@@ -0,0 +1,49 @@
+#ifndef SUBPROCESS_H
+#define SUBPROCESS_H
+
+#include "git-compat-util.h"
+#include "hashmap.h"
+#include "run-command.h"
+
+/*
+ * Generic implementation of background process infrastructure.
+ * See Documentation/technical/api-background-process.txt.
+ */
+
+ /* data structures */
+
+struct subprocess_entry {
+	struct hashmap_entry ent; /* must be the first member! */
+	const char *cmd;
+	struct child_process process;
+};
+
+/* subprocess functions */
+
+int cmd2process_cmp(const struct subprocess_entry *e1,
+	const struct subprocess_entry *e2, const void *unused);
+
+typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
+int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
+		subprocess_start_fn startfn);
+
+void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry);
+
+struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd);
+
+/* subprocess helper functions */
+
+static inline struct child_process *subprocess_get_child_process(
+		struct subprocess_entry *entry)
+{
+	return &entry->process;
+}
+
+/*
+ * Helper function that will read packets looking for "status=<foo>"
+ * key/value pairs and return the value from the last "status" packet
+ */
+
+void subprocess_read_status(int fd, struct strbuf *status);
+
+#endif
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

[PATCH v7 10/10] convert: Update subprocess_read_status to not die on EOF

[Ben Peart]

Enable sub-processes to gracefully handle when the process dies by
updating subprocess_read_status to return an error on EOF instead of
dying.

Update apply_multi_file_filter to take advantage of the revised
subprocess_read_status.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
---
 convert.c     | 10 ++++++++--
 sub-process.c | 10 +++++++---
 sub-process.h |  2 +-
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/convert.c b/convert.c
index acf51416d1..85238e4976 100644
--- a/convert.c
+++ b/convert.c
@@ -635,7 +635,10 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 	if (err)
 		goto done;
 
-	subprocess_read_status(process->out, &filter_status);
+	err = subprocess_read_status(process->out, &filter_status);
+	if (err)
+		goto done;
+
 	err = strcmp(filter_status.buf, "success");
 	if (err)
 		goto done;
@@ -644,7 +647,10 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 	if (err)
 		goto done;
 
-	subprocess_read_status(process->out, &filter_status);
+	err = subprocess_read_status(process->out, &filter_status);
+	if (err)
+		goto done;
+
 	err = strcmp(filter_status.buf, "success");
 
 done:
diff --git a/sub-process.c b/sub-process.c
index 536b60cced..92f8aea70a 100644
--- a/sub-process.c
+++ b/sub-process.c
@@ -21,13 +21,15 @@ struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const ch
 	return hashmap_get(hashmap, &key, NULL);
 }
 
-void subprocess_read_status(int fd, struct strbuf *status)
+int subprocess_read_status(int fd, struct strbuf *status)
 {
 	struct strbuf **pair;
 	char *line;
+	int len;
+
 	for (;;) {
-		line = packet_read_line(fd, NULL);
-		if (!line)
+		len = packet_read_line_gently(fd, NULL, &line);
+		if ((len < 0) || !line)
 			break;
 		pair = strbuf_split_str(line, '=', 2);
 		if (pair[0] && pair[0]->len && pair[1]) {
@@ -39,6 +41,8 @@ void subprocess_read_status(int fd, struct strbuf *status)
 		}
 		strbuf_list_free(pair);
 	}
+
+	return (len < 0) ? len : 0;
 }
 
 void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry)
diff --git a/sub-process.h b/sub-process.h
index a88e782bfc..7d451e1cde 100644
--- a/sub-process.h
+++ b/sub-process.h
@@ -44,6 +44,6 @@ static inline struct child_process *subprocess_get_child_process(
  * key/value pairs and return the value from the last "status" packet
  */
 
-void subprocess_read_status(int fd, struct strbuf *status);
+int subprocess_read_status(int fd, struct strbuf *status);
 
 #endif
-- 
2.12.2.gvfs.2.20.g3624a68d62.dirty

Re: [PATCH v7 00/10] refactor the filter process code into a reusable module

[Junio C Hamano]

Ben Peart <peartben@gmail.com> writes:

> Changes from V6 include:
>
> convert: remove erroneous tests for errno == EPIPE
>  - split into separate patch to fix a preexisting bug discovered in the review process

Thanks.


> pkt-line: Update packet_read_line() to test for len > 0
>  - split into separate patch to deal with errors that return negative lengths
>
> pkt-line: add packet_read_line_gently()
>  - update documentation to clarify return values
>  - update white space in function definition
>

I also see some style fixes applied to a few patches.  Thanks for
paying attention to details.

Will queue; during the pre-release freeze, new things would move
slowly, but let's see if we have more comments from others and then
merge it to 'next' soon after the 2.13 final.

Thanks.

Re: [PATCH v7 04/10] convert: move packet_write_line() into pkt-line as packet_writel()

[Jeff King]

On Fri, May 05, 2017 at 11:27:56AM -0400, Ben Peart wrote:

> +int packet_writel(int fd, const char *line, ...);

This isn't a new problem, but I noticed that this function should
probably get annotated to describe its interface.

Junio, can you pick up the patch below on top of Ben's series (or I'd be
fine if it were squashed into this patch)?

-- >8 --
Subject: [PATCH] pkt-line: annotate packet_writel with LAST_ARG_MUST_BE_NULL

packet_writel() takes a variable-sized list and reads to
the first NULL. Let's let the compiler know so that it can
help us catch mistakes in the callers.

This should have been annotated similarly when it was a
static function, but it's doubly important now that the
function is available to the whole code-base.

Signed-off-by: Jeff King <peff@peff.net>
---
 pkt-line.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pkt-line.h b/pkt-line.h
index b2965869a..450183b64 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -25,6 +25,7 @@ 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)));
+LAST_ARG_MUST_BE_NULL
 int packet_writel(int fd, const char *line, ...);
 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);
-- 
2.13.0.452.g0afc8e12b

Re: [PATCH v7 09/10] sub-process: move sub-process functions into separate files

[Jeff King]

On Fri, May 05, 2017 at 11:28:01AM -0400, Ben Peart wrote:

> +static void subprocess_exit_handler(struct child_process *process)
> +{
> +	sigchain_push(SIGPIPE, SIG_IGN);
> +	/* Closing the pipe signals the subprocess 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);
> +}

This isn't a new issue with your series, but the SIGPIPEs here seem odd.
I don't think you can get SIGPIPE from closing descriptors.

I suspect this is a hold-over from when Lars' original design, where we
actually sent an "exit" message to the filter. It's not hurting
anything, and I don't think it's worth holding up your series for. But
when you are working in this area further, it might be worth cleaning
up.

-Peff

Re: [PATCH v7 00/10] refactor the filter process code into a reusable module

[Jeff King]

On Mon, May 08, 2017 at 10:58:46AM +0900, Junio C Hamano wrote:

> Will queue; during the pre-release freeze, new things would move
> slowly, but let's see if we have more comments from others and then
> merge it to 'next' soon after the 2.13 final.

I gave it a fresh read-through. I had a few comments, but nothing that I
think should hold up moving these patches to 'next'.

I do find the convert/sub-process split a little funny. Most of the
protocol bits from convert didn't get moved over, and you could use a
sub-process that spoke any arbitrary protocol. The odd man out is
subprocess_read_status(), which assumes not only pktlines, but also
a "status=foo" key/value pair inside them.

I have a feeling that funny split is because this is a preliminary
refactoring step that will have more features built on it, and the end
result may be more consistent. We _could_ hold these back and pass
judgement once we see more. But they're a reasonable-sized chunk that's
already been through 7 rounds of review. It makes sense to me to
graduate them at least to 'next' and let the next steps use them as a
stable base.

-Peff

Re: [PATCH v7 04/10] convert: move packet_write_line() into pkt-line as packet_writel()

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

> This isn't a new problem, but I noticed that this function should
> probably get annotated to describe its interface.
>
> Junio, can you pick up the patch below on top of Ben's series (or I'd be
> fine if it were squashed into this patch)?

Surely.  Thanks for a careful review.

>
> -- >8 --
> Subject: [PATCH] pkt-line: annotate packet_writel with LAST_ARG_MUST_BE_NULL
>
> packet_writel() takes a variable-sized list and reads to
> the first NULL. Let's let the compiler know so that it can
> help us catch mistakes in the callers.
>
> This should have been annotated similarly when it was a
> static function, but it's doubly important now that the
> function is available to the whole code-base.
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
>  pkt-line.h | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/pkt-line.h b/pkt-line.h
> index b2965869a..450183b64 100644
> --- a/pkt-line.h
> +++ b/pkt-line.h
> @@ -25,6 +25,7 @@ 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)));
> +LAST_ARG_MUST_BE_NULL
>  int packet_writel(int fd, const char *line, ...);
>  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);