Git Mailing List Archive on lore.kernel.org
 help / color / Atom feed
From: Patrick Steinhardt <ps@pks.im>
To: git <git@vger.kernel.org>
Cc: Christian Couder <christian.couder@gmail.com>,
	Junio C Hamano <gitster@pobox.com>
Subject: [PATCH v3 8/9] update-ref: read commands in a line-wise fashion
Date: Thu, 2 Apr 2020 09:09:57 +0200
Message-ID: <02ff6b7337cd821c74f2221c2c567e0105c01e0d.1585811014.git.ps@pks.im> (raw)
In-Reply-To: <cover.1585811013.git.ps@pks.im>


[-- Attachment #1: Type: text/plain, Size: 6877 bytes --]

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 | 85 +++++++++++++++++++++++---------------------
 1 file changed, 45 insertions(+), 40 deletions(-)

diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 0f34b68904..348407b896 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,
  * depending on how 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;
@@ -209,12 +209,10 @@ 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;
@@ -241,12 +239,10 @@ 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;
@@ -277,12 +273,10 @@ 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;
@@ -306,71 +300,82 @@ 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, "no-deref", &rest) && *rest == line_termination)
 		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 args;
 } command[] = {
-	{ "update", parse_cmd_update },
-	{ "create", parse_cmd_create },
-	{ "delete", parse_cmd_delete },
-	{ "verify", parse_cmd_verify },
-	{ "option", parse_cmd_option },
+	{ "update", parse_cmd_update, 3 },
+	{ "create", parse_cmd_create, 2 },
+	{ "delete", parse_cmd_delete, 2 },
+	{ "verify", parse_cmd_verify, 2 },
+	{ "option", parse_cmd_option, 1 },
 };
 
 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(command); i++) {
 			const char *prefix = command[i].prefix;
+			char c;
 
-			if (!skip_prefix(next, prefix, &next) ||
-			    !skip_prefix(next, " ", &next))
+			if (!starts_with(input.buf, prefix))
+				continue;
+
+			/*
+			 * If the command has arguments, verify that it's
+			 * followed by a space. Otherwise, it shall be followed
+			 * by a line terminator.
+			 */
+			c = command[i].args ? ' ' : line_termination;
+			if (input.buf[strlen(prefix)] != c)
 				continue;
 
 			cmd = &command[i];
 			break;
 		}
 		if (!cmd)
-			die("unknown command: %s", next);
+			die("unknown command: %s", input.buf);
 
-		next = cmd->fn(transaction, next, input.buf + input.len);
-		next++;
+		/*
+		 * Read additional arguments if NUL-terminated. Do not raise an
+		 * error in case there is an early EOF to let the command
+		 * handle missing arguments with a proper error message.
+		 */
+		for (j = 1; line_termination == '\0' && j < cmd->args; j++)
+			if (strbuf_appendwholeline(&input, stdin, line_termination))
+				break;
+
+		cmd->fn(transaction, input.buf + strlen(cmd->prefix) + !!cmd->args,
+			input.buf + input.len);
 	}
 
 	if (ref_transaction_commit(transaction, &err))
-- 
2.26.0


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

  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 ` [PATCH 8/9] update-ref: read commands in a line-wise fashion Patrick Steinhardt
2020-03-27 21:58   ` 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   ` Patrick Steinhardt [this message]
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=02ff6b7337cd821c74f2221c2c567e0105c01e0d.1585811014.git.ps@pks.im \
    --to=ps@pks.im \
    --cc=christian.couder@gmail.com \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Git Mailing List Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/git/0 git/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 git git/ https://lore.kernel.org/git \
		git@vger.kernel.org
	public-inbox-index git

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.git


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git