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From: Patrick Steinhardt <ps@pks.im>
To: git <git@vger.kernel.org>
Cc: Christian Couder <christian.couder@gmail.com>
Subject: [PATCH 8/9] update-ref: read commands in a line-wise fashion
Date: Wed, 25 Mar 2020 10:54:22 +0100
Message-ID: <1db63f97ec78fad794cec51c5d96b093f7cd2440.1585129843.git.ps@pks.im> (raw)
In-Reply-To: <cover.1585129842.git.ps@pks.im>


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The git-update-ref(1) supports a `--stdin` mode that allows it to read
all reference updates from standard input. This is mainly used to allow
for atomic reference updates that are all or nothing, so that either all
references will get updated or none.

Currently, git-update-ref(1) reads all commands as a single block of up
to 1000 characters and only starts processing after stdin gets closed.
This is less flexible than one might wish for, as it doesn't really
allow for longer-lived transactions and doesn't allow any verification
without committing everything. E.g. one may imagine the following
exchange:

    > start
    < start: ok
    > update refs/heads/master $NEWOID1 $OLDOID1
    > update refs/heads/branch $NEWOID2 $OLDOID2
    > prepare
    < prepare: ok
    > commit
    < commit: ok

When reading all input as a whole block, the above interactive protocol
is obviously impossible to achieve. But by converting the command to
read commands linewise, we can make it more interactive than before.

Obviously, the linewise interface is only a first step in making
git-update-ref(1) work in a more transaction-oriented way. Missing is
most importantly support for transactional commands that manage the
current transaction.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 builtin/update-ref.c | 70 ++++++++++++++++++++------------------------
 1 file changed, 31 insertions(+), 39 deletions(-)

diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 5f97bb0b75..f35e3ca5ae 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -178,8 +178,8 @@ static int parse_next_oid(const char **next, const char *end,
  * line_termination is set.
  */
 
-static const char *parse_cmd_update(struct ref_transaction *transaction,
-				    const char *next, const char *end)
+static void parse_cmd_update(struct ref_transaction *transaction,
+			     const char *next, const char *end)
 {
 	struct strbuf err = STRBUF_INIT;
 	char *refname;
@@ -212,12 +212,10 @@ static const char *parse_cmd_update(struct ref_transaction *transaction,
 	update_flags = default_flags;
 	free(refname);
 	strbuf_release(&err);
-
-	return next;
 }
 
-static const char *parse_cmd_create(struct ref_transaction *transaction,
-				    const char *next, const char *end)
+static void parse_cmd_create(struct ref_transaction *transaction,
+			     const char *next, const char *end)
 {
 	struct strbuf err = STRBUF_INIT;
 	char *refname;
@@ -247,12 +245,10 @@ static const char *parse_cmd_create(struct ref_transaction *transaction,
 	update_flags = default_flags;
 	free(refname);
 	strbuf_release(&err);
-
-	return next;
 }
 
-static const char *parse_cmd_delete(struct ref_transaction *transaction,
-				    const char *next, const char *end)
+static void parse_cmd_delete(struct ref_transaction *transaction,
+			     const char *next, const char *end)
 {
 	struct strbuf err = STRBUF_INIT;
 	char *refname;
@@ -286,12 +282,10 @@ static const char *parse_cmd_delete(struct ref_transaction *transaction,
 	update_flags = default_flags;
 	free(refname);
 	strbuf_release(&err);
-
-	return next;
 }
 
-static const char *parse_cmd_verify(struct ref_transaction *transaction,
-				    const char *next, const char *end)
+static void parse_cmd_verify(struct ref_transaction *transaction,
+			     const char *next, const char *end)
 {
 	struct strbuf err = STRBUF_INIT;
 	char *refname;
@@ -318,12 +312,10 @@ static const char *parse_cmd_verify(struct ref_transaction *transaction,
 	update_flags = default_flags;
 	free(refname);
 	strbuf_release(&err);
-
-	return next;
 }
 
-static const char *parse_cmd_option(struct ref_transaction *transaction,
-				    const char *next, const char *end)
+static void parse_cmd_option(struct ref_transaction *transaction,
+			     const char *next, const char *end)
 {
 	const char *rest;
 	if (!skip_prefix(next, " ", &next))
@@ -332,60 +324,60 @@ static const char *parse_cmd_option(struct ref_transaction *transaction,
 		update_flags |= REF_NO_DEREF;
 	else
 		die("option unknown: %s", next);
-	return rest;
 }
 
 static const struct parse_cmd {
 	const char *prefix;
-	const char *(*fn)(struct ref_transaction *, const char *, const char *);
+	void (*fn)(struct ref_transaction *, const char *, const char *);
+	unsigned extra_lines;
 } commands[] = {
-	{ "update", parse_cmd_update },
-	{ "create", parse_cmd_create },
-	{ "delete", parse_cmd_delete },
-	{ "verify", parse_cmd_verify },
-	{ "option", parse_cmd_option },
+	{ "update", parse_cmd_update, 2 },
+	{ "create", parse_cmd_create, 1 },
+	{ "delete", parse_cmd_delete, 1 },
+	{ "verify", parse_cmd_verify, 1 },
+	{ "option", parse_cmd_option, 0 },
 };
 
 static void update_refs_stdin(void)
 {
 	struct strbuf input = STRBUF_INIT, err = STRBUF_INIT;
 	struct ref_transaction *transaction;
-	const char *next;
-	int i;
-
-	if (strbuf_read(&input, 0, 1000) < 0)
-		die_errno("could not read from stdin");
-	next = input.buf;
+	int i, j;
 
 	transaction = ref_transaction_begin(&err);
 	if (!transaction)
 		die("%s", err.buf);
 
 	/* Read each line dispatch its command */
-	while (next < input.buf + input.len) {
+	while (!strbuf_getwholeline(&input, stdin, line_termination)) {
 		const struct parse_cmd *cmd = NULL;
 
-		if (*next == line_termination)
+		if (*input.buf == line_termination)
 			die("empty command in input");
-		else if (isspace(*next))
-			die("whitespace before command: %s", next);
+		else if (isspace(*input.buf))
+			die("whitespace before command: %s", input.buf);
 
 		for (i = 0; i < ARRAY_SIZE(commands); i++) {
-			if (!skip_prefix(next, commands[i].prefix , &next))
+			if (!starts_with(input.buf, commands[i].prefix))
 				continue;
 			cmd = &commands[i];
 			break;
 		}
 		if (!cmd)
-			die("unknown command: %s", next);
+			die("unknown command: %s", input.buf);
 
 		if (input.buf[strlen(cmd->prefix)] != line_termination &&
 		    input.buf[strlen(cmd->prefix)] != '\0' &&
 		    input.buf[strlen(cmd->prefix)] != ' ')
 			die("%s: no separator after command", cmd->prefix);
 
-		next = cmd->fn(transaction, next, input.buf + input.len);
-		next++;
+		/* Read extra lines if NUL-terminated */
+		for (j = 0; line_termination == '\0' && j < cmd->extra_lines; j++)
+			if (strbuf_appendwholeline(&input, stdin, line_termination))
+				break;
+
+		cmd->fn(transaction, input.buf + strlen(cmd->prefix),
+			input.buf + input.len);
 	}
 
 	if (ref_transaction_commit(transaction, &err))
-- 
2.26.0


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  parent reply index

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-25  9:53 [PATCH 0/9] Support for transactions in `git-update-ref --stdin` Patrick Steinhardt
2020-03-25  9:53 ` [PATCH 1/9] refs: fix segfault when aborting empty transaction Patrick Steinhardt
2020-03-27 19:59   ` Junio C Hamano
2020-03-25  9:53 ` [PATCH 2/9] git-update-ref.txt: add missing word Patrick Steinhardt
2020-03-25  9:53 ` [PATCH 3/9] strbuf: provide function to append whole lines Patrick Steinhardt
2020-03-27 21:04   ` Junio C Hamano
2020-03-30 13:25     ` Patrick Steinhardt
2020-03-30 17:12       ` Junio C Hamano
2020-03-25  9:53 ` [PATCH 4/9] update-ref: organize commands in an array Patrick Steinhardt
2020-03-27 21:25   ` Junio C Hamano
2020-03-30  8:05     ` Patrick Steinhardt
2020-03-30 16:55       ` Junio C Hamano
2020-03-30 17:37         ` Patrick Steinhardt
2020-03-25  9:54 ` [PATCH 5/9] update-ref: drop unused argument for `parse_refname` Patrick Steinhardt
2020-03-25  9:54 ` [PATCH 6/9] update-ref: pass end pointer instead of strbuf Patrick Steinhardt
2020-03-25  9:54 ` [PATCH 7/9] update-ref: move transaction handling into `update_refs_stdin()` Patrick Steinhardt
2020-03-27 21:44   ` Junio C Hamano
2020-03-25  9:54 ` Patrick Steinhardt [this message]
2020-03-27 21:58   ` [PATCH 8/9] update-ref: read commands in a line-wise fashion Junio C Hamano
2020-03-30  8:11     ` Patrick Steinhardt
2020-03-30 17:39       ` Junio C Hamano
2020-03-25  9:54 ` [PATCH 9/9] update-ref: implement interactive transaction handling Patrick Steinhardt
2020-03-27 22:00   ` Junio C Hamano
2020-03-30 13:46 ` [PATCH v2 0/9] Support for transactions in `git-update-ref --stdin` Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 1/9] refs: fix segfault when aborting empty transaction Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 2/9] git-update-ref.txt: add missing word Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 3/9] strbuf: provide function to append whole lines Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 4/9] update-ref: organize commands in an array Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 5/9] update-ref: drop unused argument for `parse_refname` Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 6/9] update-ref: pass end pointer instead of strbuf Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 7/9] update-ref: move transaction handling into `update_refs_stdin()` Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 8/9] update-ref: read commands in a line-wise fashion Patrick Steinhardt
2020-03-30 13:47   ` [PATCH v2 9/9] update-ref: implement interactive transaction handling Patrick Steinhardt
2020-04-02  7:09 ` [PATCH v3 0/9] Support for transactions in `git-update-ref --stdin` Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 1/9] refs: fix segfault when aborting empty transaction Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 2/9] git-update-ref.txt: add missing word Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 3/9] strbuf: provide function to append whole lines Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 4/9] update-ref: organize commands in an array Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 5/9] update-ref: drop unused argument for `parse_refname` Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 6/9] update-ref: pass end pointer instead of strbuf Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 7/9] update-ref: move transaction handling into `update_refs_stdin()` Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 8/9] update-ref: read commands in a line-wise fashion Patrick Steinhardt
2020-04-02  7:10   ` [PATCH v3 9/9] update-ref: implement interactive transaction handling Patrick Steinhardt
2020-04-03 13:40     ` Phillip Wood
2020-04-03 16:51       ` Patrick Steinhardt
2020-04-03 17:33       ` Junio C Hamano
2020-04-03 17:35         ` Junio C Hamano
2020-04-06  7:10         ` Patrick Steinhardt

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