Fix infinite loop when deleting multiple packed refs.

It was stupid to link the same element twice to lock_file_list
and end up in a loop, so we certainly need a fix.

But it is not like we are taking a lock on multiple files in
this case.  It is just that we leave the linked element on the
list even after commit_lock_file() successfully removes the
cruft.

We cannot remove the list element in commit_lock_file(); if we
are interrupted in the middle of list manipulation, the call to
remove_lock_file_on_signal() will happen with a broken list
structure pointed by lock_file_list, which would cause the cruft
to remain, so not removing the list element is the right thing
to do.  Instead we should be reusing the element already on the
list.

There is already a code for that in lock_file() function in
lockfile.c.  The code checks lk->next and the element is linked
only when it is not already on the list -- which is incorrect
for the last element on the list (which has NULL in its next
field), but if you read the check as "is this element already on
the list?" it actually makes sense.  We do not want to link it
on the list again, nor we would want to set up signal/atexit
over and over.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/cache.h b/cache.h
index f2ec5c8c1416e3167d49813965212d414e6a5a7a..a0e9727a0bb750657325b323b00ad47f5f6fabdb 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -174,6 +174,7 @@ extern int refresh_cache(unsigned int flags);
 
 struct lock_file {
        struct lock_file *next;
+       char on_list;
        char filename[PATH_MAX];
 };
 extern int hold_lock_file_for_update(struct lock_file *, const char *path, int);

diff --git a/lockfile.c b/lockfile.c
index 2a2fea3cb6bd1de059e7c0f8c2008c5fe8376b93..143d7d85b653019e8082b332e17c0a72831bd319 100644 (file)
--- a/lockfile.c
+++ b/lockfile.c
@@ -28,9 +28,12 @@ static int lock_file(struct lock_file *lk, const char *path)
        sprintf(lk->filename, "%s.lock", path);
        fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666);
        if (0 <= fd) {
-               if (!lk->next) {
+               if (!lk->on_list) {
                        lk->next = lock_file_list;
                        lock_file_list = lk;
+                       lk->on_list = 1;
+               }
+               if (lock_file_list) {
                        signal(SIGINT, remove_lock_file_on_signal);
                        atexit(remove_lock_file);
                }
@@ -38,6 +41,8 @@ static int lock_file(struct lock_file *lk, const char *path)
                        return error("cannot fix permission bits on %s",
                                     lk->filename);
        }
+       else
+               lk->filename[0] = 0;
        return fd;
 }
 

diff --git a/refs.c b/refs.c
index 0e156c5dee1edff895c576a4491ec71f931ff492..1549f2ae06c28570ddc9ff9aa6cb361567067e7b 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -644,7 +644,6 @@ static int repack_without_ref(const char *refname)
        }
        if (!found)
                return 0;
-       memset(&packlock, 0, sizeof(packlock));
        fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
        if (fd < 0)
                return error("cannot delete '%s' from packed refs", refname);