Add a lockfile function to append to a file

This takes care of copying the original contents into the replacement
file after the lock is held, so that concurrent additions can't miss
each other's changes.

[jc: munged to drop mmap in favor of copy_file.]

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/cache.h b/cache.h
index 5a28dddec9..396eabf6ed 100644
--- a/cache.h
+++ b/cache.h
@@ -391,6 +391,7 @@ struct lock_file {
 	char filename[PATH_MAX];
 };
 extern int hold_lock_file_for_update(struct lock_file *, const char *path, int);
+extern int hold_lock_file_for_append(struct lock_file *, const char *path, int);
 extern int commit_lock_file(struct lock_file *);
 
 extern int hold_locked_index(struct lock_file *, int);