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create_bundle(): duplicate file descriptor to avoid closing it twice

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write_pack_data() passes bundle_fd to start_command() to be used as
the stdout of pack-objects. But start_command() closes its stdout if
it is > 1. This is a problem if bundle_fd is the fd of a lock_file,
because commit_lock_file() will also try to close the fd.

So the old code suppressed commit_lock_file()'s usual behavior of
closing the file descriptor by setting the lock_file object's fd field
to -1.

But this is not really kosher. Code here shouldn't be mutating fields
within the lock_file object.

Instead, duplicate the file descriptor before passing it to
write_pack_data(). Then that function can close its copy without
closing the copy held in the lock_file object.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Michael Haggerty 2015-08-10 11:47:37 +02:00 committed by Junio C Hamano
parent 2db69de81d
commit e54c347c1c
1 changed files with 16 additions and 10 deletions
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26
bundle.c
View File

@ -235,7 +235,9 @@ out:
return result;
}
static int write_pack_data(int bundle_fd, struct lock_file *lock, struct rev_info *revs)
/* Write the pack data to bundle_fd, then close it if it is > 1. */
static int write_pack_data(int bundle_fd, struct rev_info *revs)
{
struct child_process pack_objects = CHILD_PROCESS_INIT;
int i;
@ -250,13 +252,6 @@ static int write_pack_data(int bundle_fd, struct lock_file *lock, struct rev_inf
if (start_command(&pack_objects))
return error(_("Could not spawn pack-objects"));
/*
* start_command closed bundle_fd if it was > 1
* so set the lock fd to -1 so commit_lock_file()
* won't fail trying to close it.
*/
lock->fd = -1;
for (i = 0; i < revs->pending.nr; i++) {
struct object *object = revs->pending.objects[i].item;
if (object->flags & UNINTERESTING)
@ -416,10 +411,21 @@ int create_bundle(struct bundle_header *header, const char *path,
bundle_to_stdout = !strcmp(path, "-");
if (bundle_to_stdout)
bundle_fd = 1;
else
else {
bundle_fd = hold_lock_file_for_update(&lock, path,
LOCK_DIE_ON_ERROR);
/*
* write_pack_data() will close the fd passed to it,
* but commit_lock_file() will also try to close the
* lockfile's fd. So make a copy of the file
* descriptor to avoid trying to close it twice.
*/
bundle_fd = dup(bundle_fd);
if (bundle_fd < 0)
die_errno("unable to dup file descriptor");
}
/* write signature */
write_or_die(bundle_fd, bundle_signature, strlen(bundle_signature));
@ -445,7 +451,7 @@ int create_bundle(struct bundle_header *header, const char *path,
return -1;
/* write pack */
if (write_pack_data(bundle_fd, &lock, &revs))
if (write_pack_data(bundle_fd, &revs))
return -1;
if (!bundle_to_stdout) {