Jeff King <[email protected]> writes: >> diff --git a/builtin/commit.c b/builtin/commit.c >> index 2be7bdb331..60f30b3780 100644 >> --- a/builtin/commit.c >> +++ b/builtin/commit.c >> @@ -432,6 +432,7 @@ static const char *prepare_index(int argc, const char >> **argv, const char *prefix >> if (update_main_cache_tree(WRITE_TREE_SILENT) == 0) { >> if (reopen_lock_file(&index_lock) < 0) >> die(_("unable to write index file")); >> + ftruncate(index_lock.tempfile->fd, 0); >> if (write_locked_index(&the_index, &index_lock, 0)) >> die(_("unable to update temporary index")); >> } else > > Doh, of course. I even thought about this issue and dug all the way into > reopen_lock_file(), but for some reason temporarily forgot that O_WRONLY > does not imply O_TRUNC. > > Arguably this should be the default for reopen_lockfile(), as getting a > write pointer into an existing file is not ever going to be useful for > the way Git uses lockfiles. Opening with O_APPEND could conceivably be > useful, but it's pretty unlikely (and certainly not helpful here, and > this is the only caller). Alternatively, the function should just take > open(2) flags. > > At any rate, I think this perfectly explains the behavior we're seeing.
Thanks all for digging this down (I am a bit jealous to see that I seem to have missed all this fun over the weekend X-<).
