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Teach receive-pack to run pre-receive/post-receive hooks
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Bill Lear pointed out that it is easy to send out notifications of
changes with the update hook, but successful execution of the update
hook does not necessarily mean that the ref was actually updated.
Lock contention on the ref or being unable to append to the reflog
may prevent the ref from being changed.  Sending out notifications
prior to the ref actually changing is very misleading.

To help this situation I am introducing two new hooks to the
receive-pack flow: pre-receive and post-receive.  These new hooks
are invoked only once per receive-pack execution and are passed
three arguments per ref (refname, old-sha1, new-sha1).

The new post-receive hook is ideal for sending out notifications,
as it has the complete list of all refnames that were successfully
updated as well as the old and new SHA-1 values.  This allows more
interesting notifications to be sent.  Multiple ref updates could
be easily summarized into one email, for example.

The new pre-receive hook is ideal for logging update attempts, as it
is run only once for the entire receive-pack operation.  It can also
be used to verify multiple updates happen at once, e.g. an update
to the `maint` head must also be accompained by a new annotated tag.

Lots of documentation improvements for receive-pack are included
in this change, as we want to make sure the new hooks are clearly
explained.

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 7, 2007
1 parent 8aaf7d6 commit 05ef58e
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149 changes: 107 additions & 42 deletions Documentation/git-receive-pack.txt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,61 +25,126 @@ The command allows for creation and fast forwarding of sha1 refs
local end receive-pack runs, but to the user who is sitting at
the send-pack end, it is updating the remote. Confused?)

Before each ref is updated, if $GIT_DIR/hooks/update file exists
and executable, it is called with three parameters:
There are other real-world examples of using update and
post-update hooks found in the Documentation/howto directory.

$GIT_DIR/hooks/update refname sha1-old sha1-new
git-receive-pack honours the receive.denyNonFastForwards config
option, which tells it if updates to a ref should be denied if they
are not fast-forwards.

OPTIONS
-------
<directory>::
The repository to sync into.

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:

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

The refname parameter is relative to $GIT_DIR; e.g. for the master
head this is "refs/heads/master". The two sha1 arguments after
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
sha1-old and sha1-new should be valid objects in the repository.

This hook is called before any refname is updated and before any
fast-forward checks are performed.

If the pre-receive hook exits with a non-zero exit status no updates
will be performed, and the update, post-receive and post-update
hooks will not be invoked either. This can be useful to quickly
bail out if the update is not to be supported.

The refname parameter is relative to $GIT_DIR; e.g. for the
master head this is "refs/heads/master". Two sha1 are the
object names for the refname before and after the update. Note
that the hook is called before the refname is updated, so either
sha1-old is 0{40} (meaning there is no such ref yet), or it
should match what is recorded in refname.
update Hook
-----------
Before each ref is updated, if $GIT_DIR/hooks/update file exists
and is executable, it is invoked once per ref, with three parameters:

The hook should exit with non-zero status if it wants to
disallow updating the named ref. Otherwise it should exit with
zero.
$GIT_DIR/hooks/update refname sha1-old sha1-new

Using this hook, it is easy to generate mails on updates to
the local repository. This example script sends a mail with
the commits pushed to the repository:
The refname parameter is relative to $GIT_DIR; e.g. for the master
head this is "refs/heads/master". The two sha1 arguments are
the object names for the refname before and after the update.
Note that the hook is called before the refname is updated,
so either sha1-old is 0{40} (meaning there is no such ref yet),
or it should match what is recorded in refname.

The hook should exit with non-zero status if it wants to disallow
updating the named ref. Otherwise it should exit with zero.

Successful execution (a zero exit status) of this hook does not
ensure the ref will actully be updated, it is only a prerequisite.
As such it is not a good idea to send notices (e.g. email) from
this hook. Consider using the post-receive hook instead.

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:

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

The refname parameter is relative to $GIT_DIR; e.g. for the master
head this is "refs/heads/master". The two sha1 arguments after
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
0{40}, otherwise sha1-old and sha1-new should be valid objects in
the repository.

Using this hook, it is easy to generate mails describing the updates
to the repository. This example script sends one mail message per
ref listing the commits pushed to the repository:

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

Another hook $GIT_DIR/hooks/post-update, if exists and
executable, is called with the list of refs that have been
updated. This can be used to implement repository wide cleanup
task if needed. The exit code from this hook invocation is
ignored; the only thing left for git-receive-pack to do at that
point is to exit itself anyway. This hook can be used, for
example, to run "git-update-server-info" if the repository is
packed and is served via a dumb transport.
The exit code from this hook invocation is ignored, however a
non-zero exit code will generate an error message.

#!/bin/sh
exec git-update-server-info
Note that it is possible for refname to not have sha1-new when this
hook runs. This can easily occur if another user modifies the ref
after it was updated by receive-pack, but before the hook was able
to evaluate it. It is recommended that hooks rely on sha1-new
rather than the current value of refname.

There are other real-world examples of using update and
post-update hooks found in the Documentation/howto directory.
post-update Hook
----------------
After all other processing, if at least one ref was updated, and
if $GIT_DIR/hooks/post-update file exists and is executable, then
post-update will called with the list of refs that have been updated.
This can be used to implement any repository wide cleanup tasks.

git-receive-pack honours the receive.denyNonFastforwards flag, which
tells it if updates to a ref should be denied if they are not fast-forwards.
The exit code from this hook invocation is ignored; the only thing
left for git-receive-pack to do at that point is to exit itself
anyway.

OPTIONS
-------
<directory>::
The repository to sync into.
This hook can be used, for example, to run "git-update-server-info"
if the repository is packed and is served via a dumb transport.

#!/bin/sh
exec git-update-server-info


SEE ALSO
Expand Down
11 changes: 11 additions & 0 deletions receive-pack.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,8 @@ struct command {
static struct command *commands;

static const char update_hook[] = "hooks/update";
static const char pre_receive_hook[] = "hooks/pre-receive";
static const char post_receive_hook[] = "hooks/post-receive";

static int run_hook(const char *hook_name,
struct command *first_cmd,
Expand Down Expand Up @@ -236,6 +238,14 @@ static void execute_commands(const char *unpacker_error)
return;
}

if (run_hook(pre_receive_hook, commands, 0)) {
while (cmd) {
cmd->error_string = "pre-receive hook declined";
cmd = cmd->next;
}
return;
}

while (cmd) {
cmd->error_string = update(cmd);
cmd = cmd->next;
Expand Down Expand Up @@ -483,6 +493,7 @@ int main(int argc, char **argv)
unlink(pack_lockfile);
if (report_status)
report(unpack_status);
run_hook(post_receive_hook, commands, 0);
run_update_post_hook(commands);
}
return 0;
Expand Down
93 changes: 73 additions & 20 deletions t/t5401-update-hooks.sh
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,71 +11,124 @@ test_expect_success setup '
git-update-index --add a &&
tree0=$(git-write-tree) &&
commit0=$(echo setup | git-commit-tree $tree0) &&
git-update-ref HEAD $commit0 &&
git-clone ./. victim &&
echo We hope it works. >a &&
git-update-index a &&
tree1=$(git-write-tree) &&
commit1=$(echo modify | git-commit-tree $tree1 -p $commit0) &&
git-update-ref HEAD $commit1
git-update-ref refs/heads/master $commit0 &&
git-update-ref refs/heads/tofail $commit1 &&
git-clone ./. victim &&
GIT_DIR=victim/.git git-update-ref refs/heads/tofail $commit1 &&
git-update-ref refs/heads/master $commit1 &&
git-update-ref refs/heads/tofail $commit0
'

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

cat >victim/.git/hooks/update <<'EOF'
#!/bin/sh
echo "$@" >$GIT_DIR/update.args
echo "$@" >>$GIT_DIR/update.args
read x; printf "$x" >$GIT_DIR/update.stdin
echo STDOUT update
echo STDERR update >&2
echo STDOUT update $1
echo STDERR update $1 >&2
test "$1" = refs/heads/master || exit
EOF
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
echo STDOUT post-receive
echo STDERR post-receive >&2
EOF
chmod u+x victim/.git/hooks/post-receive

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

test_expect_success push '
git-send-pack ./victim/.git/ master >send.out 2>send.err
test_expect_failure push '
git-send-pack --force ./victim/.git master tofail >send.out 2>send.err
'

test_expect_success 'updated as expected' '
test $(GIT_DIR=victim/.git git-rev-parse master) = $commit1 &&
test $(GIT_DIR=victim/.git git-rev-parse tofail) = $commit1
'

test_expect_success 'hooks ran' '
test -f victim/.git/pre-receive.args &&
test -f victim/.git/pre-receive.stdin &&
test -f victim/.git/update.args &&
test -f victim/.git/update.stdin &&
test -f victim/.git/post-receive.args &&
test -f victim/.git/post-receive.stdin &&
test -f victim/.git/post-update.args &&
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 \
| diff - victim/.git/pre-receive.args
'

test_expect_success 'update hook arguments' '
(echo refs/heads/master $commit0 $commit1;
echo refs/heads/tofail $commit1 $commit0
) | diff - victim/.git/update.args
'

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

test_expect_success 'post-update hook arguments' '
echo refs/heads/master |
diff -u - victim/.git/post-update.args
'

test_expect_failure 'update hook stdin is /dev/null' '
test -s victim/.git/update.stdin
'

test_expect_failure 'post-update hook stdin is /dev/null' '
test -s victim/.git/post-update.stdin
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_failure 'send-pack produced no output' '
test -s send.out
'

cat <<EOF >expect
STDOUT pre-receive
STDERR pre-receive
STDOUT update refs/heads/master
STDERR update refs/heads/master
STDOUT update refs/heads/tofail
STDERR update refs/heads/tofail
STDOUT post-receive
STDERR post-receive
STDOUT post-update
STDERR post-update
EOF
test_expect_success 'send-pack stderr contains hook messages' '
grep "STDOUT update" send.err &&
grep "STDERR update" send.err &&
grep "STDOUT post-update" send.err &&
grep "STDERR post-update" send.err
egrep ^STD send.err >actual &&
diff - actual <expect
'

test_done

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