refs.c: commit_packed_refs to return a meaningful errno on failure

Making errno when returning from commit_packed_refs() meaningful,
which should fix

 * a bug in "git clone" where it prints strerror(errno) based on
   errno, despite errno possibly being zero and potentially having
   been clobbered by that point
 * the same kind of bug in "git pack-refs"

and prepares for repack_without_refs() to get a meaningful
error message when commit_packed_refs() fails without falling into
the same bug.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>

diff --git a/refs.c b/refs.c
index cc6958141cc9568838fec2e7a83dd2d1055434da..7a815be38ea7040cebea931eb3a50ad75aaac756 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -2239,11 +2239,16 @@ int lock_packed_refs(int flags)
        return 0;
 }
 
+/*
+ * Commit the packed refs changes.
+ * On error we must make sure that errno contains a meaningful value.
+ */
 int commit_packed_refs(void)
 {
        struct packed_ref_cache *packed_ref_cache =
                get_packed_ref_cache(&ref_cache);
        int error = 0;
+       int save_errno = 0;
 
        if (!packed_ref_cache->lock)
                die("internal error: packed-refs not locked");
@@ -2253,10 +2258,13 @@ int commit_packed_refs(void)
        do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
                                 0, write_packed_entry_fn,
                                 &packed_ref_cache->lock->fd);
-       if (commit_lock_file(packed_ref_cache->lock))
+       if (commit_lock_file(packed_ref_cache->lock)) {
+               save_errno = errno;
                error = -1;
+       }
        packed_ref_cache->lock = NULL;
        release_packed_ref_cache(packed_ref_cache);
+       errno = save_errno;
        return error;
 }
 

diff --git a/refs.h b/refs.h
index 8d6cac717b31b4eed237c3c417476fd8458873de..e588ff842f8fa80b52ea79a60290350cd355e059 100644 (file)
--- a/refs.h
+++ b/refs.h
@@ -98,6 +98,7 @@ extern void add_packed_ref(const char *refname, const unsigned char *sha1);
  * Write the current version of the packed refs cache from memory to
  * disk.  The packed-refs file must already be locked for writing (see
  * lock_packed_refs()).  Return zero on success.
+ * Sets errno to something meaningful on error.
  */
 extern int commit_packed_refs(void);