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Change {pre,post}-receive hooks to use stdin
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Sergey Vlasov, Andy Parkins and Alex Riesen all pointed out that it
is possible for a single invocation of receive-pack to be given more
refs than the OS might allow us to pass as command line parameters
to a single hook invocation.

We don't want to break these up into multiple invocations (like
xargs might do) as that makes it impossible for the pre-receive
hook to verify multiple related ref updates occur at the same time,
and it makes it harder for post-receive to send out a single batch
notification.

Instead we pass the reference data on a pipe connected to the
hook's stdin, supplying one ref per line to the hook.  This way a
single hook invocation can obtain an infinite amount of ref data,
without bumping into any operating system limits.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
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Shawn O. Pearce authored and Junio C Hamano committed Mar 12, 2007
1 parent 1d9e8b5 commit f43cd49
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Showing 3 changed files with 62 additions and 58 deletions.
32 changes: 16 additions & 16 deletions Documentation/git-receive-pack.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -40,13 +40,13 @@ OPTIONS
pre-receive Hook
----------------
Before any ref is updated, if $GIT_DIR/hooks/pre-receive file exists
and is executable, it will be invoked once, with three parameters
per ref to be updated:
and is executable, it will be invoked once with no parameters. The
standard input of the hook will be one line per ref to be updated:

$GIT_DIR/hooks/pre-receive (refname sha1-old sha1-new)+
sha1-old SP sha1-new SP refname LF

The refname parameter is relative to $GIT_DIR; e.g. for the master
head this is "refs/heads/master". The two sha1 arguments after
The refname value is relative to $GIT_DIR; e.g. for the master
head this is "refs/heads/master". The two sha1 values before
each refname are the object names for the refname before and after
the update. Refs to be created will have sha1-old equal to 0{40},
while refs to be deleted will have sha1-new equal to 0{40}, otherwise
Expand Down Expand Up @@ -86,13 +86,14 @@ post-receive Hook
-----------------
After all refs were updated (or attempted to be updated), if any
ref update was successful, and if $GIT_DIR/hooks/post-receive
file exists and is executable, it will be invoke once with three
parameters for each successfully updated ref:
file exists and is executable, it will be invoke once with no
parameters. The standard input of the hook will be one line
for each successfully updated ref:

$GIT_DIR/hooks/post-receive (refname sha1-old sha1-new)+
sha1-old SP sha1-new SP refname LF

The refname parameter is relative to $GIT_DIR; e.g. for the master
head this is "refs/heads/master". The two sha1 arguments after
The refname value is relative to $GIT_DIR; e.g. for the master
head this is "refs/heads/master". The two sha1 values before
each refname are the object names for the refname before and after
the update. Refs that were created will have sha1-old equal to
0{40}, while refs that were deleted will have sha1-new equal to
Expand All @@ -105,18 +106,17 @@ ref listing the commits pushed to the repository:

#!/bin/sh
# mail out commit update information.
while test $# -gt 0
while read oval nval ref
do
if expr "$2" : '0*$' >/dev/null
if expr "$oval" : '0*$' >/dev/null
then
echo "Created a new ref, with the following commits:"
git-rev-list --pretty "$2"
git-rev-list --pretty "$nval"
else
echo "New commits:"
git-rev-list --pretty "$3" "^$2"
git-rev-list --pretty "$nval" "^$oval"
fi |
mail -s "Changes to ref $1" commit-list@mydomain
shift; shift; shift; # discard this ref's args
mail -s "Changes to ref $ref" commit-list@mydomain
done
exit 0

Expand Down
58 changes: 30 additions & 28 deletions receive-pack.c
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,8 @@ static int hook_status(int code, const char *hook_name)
return error("hook fork failed");
case -ERR_RUN_COMMAND_EXEC:
return error("hook execute failed");
case -ERR_RUN_COMMAND_PIPE:
return error("hook pipe failed");
case -ERR_RUN_COMMAND_WAITPID:
return error("waitpid failed");
case -ERR_RUN_COMMAND_WAITPID_WRONG_PID:
Expand All @@ -93,44 +95,44 @@ static int hook_status(int code, const char *hook_name)
}
}

static int run_hook(const char *hook_name,
struct command *first_cmd,
int single)
static int run_hook(const char *hook_name)
{
static char buf[sizeof(commands->old_sha1) * 2 + PATH_MAX + 4];
struct command *cmd;
int argc, code;
const char **argv;
struct child_process proc;
const char *argv[2];
int have_input = 0, code;

for (argc = 0, cmd = first_cmd; cmd; cmd = cmd->next) {
for (cmd = commands; !have_input && cmd; cmd = cmd->next) {
if (!cmd->error_string)
argc += 3;
if (single)
break;
have_input = 1;
}

if (!argc || access(hook_name, X_OK) < 0)
if (!have_input || access(hook_name, X_OK) < 0)
return 0;

argv = xmalloc(sizeof(*argv) * (2 + argc));
argv[0] = hook_name;
for (argc = 1, cmd = first_cmd; cmd; cmd = cmd->next) {
argv[1] = NULL;

memset(&proc, 0, sizeof(proc));
proc.argv = argv;
proc.in = -1;
proc.stdout_to_stderr = 1;

code = start_command(&proc);
if (code)
return hook_status(code, hook_name);
for (cmd = commands; cmd; cmd = cmd->next) {
if (!cmd->error_string) {
argv[argc++] = xstrdup(cmd->ref_name);
argv[argc++] = xstrdup(sha1_to_hex(cmd->old_sha1));
argv[argc++] = xstrdup(sha1_to_hex(cmd->new_sha1));
size_t n = snprintf(buf, sizeof(buf), "%s %s %s\n",
sha1_to_hex(cmd->old_sha1),
sha1_to_hex(cmd->new_sha1),
cmd->ref_name);
if (write_in_full(proc.in, buf, n) != n)
break;
}
if (single)
break;
}
argv[argc] = NULL;

code = run_command_v_opt(argv,
RUN_COMMAND_NO_STDIN | RUN_COMMAND_STDOUT_TO_STDERR);
while (--argc > 0)
free((char*)argv[argc]);
free(argv);

return hook_status(code, hook_name);
return hook_status(finish_command(&proc), hook_name);
}

static int run_update_hook(struct command *cmd)
Expand Down Expand Up @@ -265,7 +267,7 @@ static void execute_commands(const char *unpacker_error)
return;
}

if (run_hook(pre_receive_hook, commands, 0)) {
if (run_hook(pre_receive_hook)) {
while (cmd) {
cmd->error_string = "pre-receive hook declined";
cmd = cmd->next;
Expand Down Expand Up @@ -520,7 +522,7 @@ int main(int argc, char **argv)
unlink(pack_lockfile);
if (report_status)
report(unpack_status);
run_hook(post_receive_hook, commands, 0);
run_hook(post_receive_hook);
run_update_post_hook(commands);
}
return 0;
Expand Down
30 changes: 16 additions & 14 deletions t/t5401-update-hooks.sh
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,8 +25,8 @@ test_expect_success setup '

cat >victim/.git/hooks/pre-receive <<'EOF'
#!/bin/sh
echo "$@" >>$GIT_DIR/pre-receive.args
read x; printf "$x" >$GIT_DIR/pre-receive.stdin
printf "$@" >>$GIT_DIR/pre-receive.args
cat - >$GIT_DIR/pre-receive.stdin
echo STDOUT pre-receive
echo STDERR pre-receive >&2
EOF
Expand All @@ -44,8 +44,8 @@ chmod u+x victim/.git/hooks/update

cat >victim/.git/hooks/post-receive <<'EOF'
#!/bin/sh
echo "$@" >>$GIT_DIR/post-receive.args
read x; printf "$x" >$GIT_DIR/post-receive.stdin
printf "$@" >>$GIT_DIR/post-receive.args
cat - >$GIT_DIR/post-receive.stdin
echo STDOUT post-receive
echo STDERR post-receive >&2
EOF
Expand Down Expand Up @@ -80,11 +80,10 @@ test_expect_success 'hooks ran' '
test -f victim/.git/post-update.stdin
'

test_expect_success 'pre-receive hook arguments' '
echo \
refs/heads/master $commit0 $commit1 \
refs/heads/tofail $commit1 $commit0 \
| git diff - victim/.git/pre-receive.args
test_expect_success 'pre-receive hook input' '
(echo $commit0 $commit1 refs/heads/master;
echo $commit1 $commit0 refs/heads/tofail
) | git diff - victim/.git/pre-receive.stdin
'

test_expect_success 'update hook arguments' '
Expand All @@ -93,9 +92,9 @@ test_expect_success 'update hook arguments' '
) | git diff - victim/.git/update.args
'

test_expect_success 'post-receive hook arguments' '
echo refs/heads/master $commit0 $commit1 |
git diff - victim/.git/post-receive.args
test_expect_success 'post-receive hook input' '
echo $commit0 $commit1 refs/heads/master |
git diff - victim/.git/post-receive.stdin
'

test_expect_success 'post-update hook arguments' '
Expand All @@ -104,12 +103,15 @@ test_expect_success 'post-update hook arguments' '
'

test_expect_success 'all hook stdin is /dev/null' '
! test -s victim/.git/pre-receive.stdin &&
! test -s victim/.git/update.stdin &&
! test -s victim/.git/post-receive.stdin &&
! test -s victim/.git/post-update.stdin
'

test_expect_success 'all *-receive hook args are empty' '
! test -s victim/.git/pre-receive.args &&
! test -s victim/.git/post-receive.args
'

test_expect_failure 'send-pack produced no output' '
test -s send.out
'
Expand Down

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