lock_file: move static locks into functions

Placing `struct lock_file`s on the stack used to be a bad idea, because
the temp- and lockfile-machinery would keep a pointer into the struct.
But after 076aa2cbd (tempfile: auto-allocate tempfiles on heap,
2017-09-05), we can safely have lockfiles on the stack. (This applies
even if a user returns early, leaving a locked lock behind.)

Each of these `struct lock_file`s is used from within a single function.
Move them into the respective functions to make the scope clearer and
drop the staticness.

For good measure, I have inspected these sites and come to believe that
they always release the lock, with the possible exception of bailing out
using `die()` or `exit()` or by returning from a `cmd_foo()`.

As pointed out by Jeff King, it would be bad if someone held on to a
`struct lock_file *` for some reason. After some grepping, I agree with
his findings: no-one appears to be doing that.

After this commit, the remaining occurrences of "static struct
lock_file" are locks that are used from within different functions. That
is, they need to remain static. (Short of more intrusive changes like
passing around pointers to non-static locks.)

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/rerere.c b/rerere.c
index ea24d4c2f..04d25691e 100644
--- a/rerere.c
+++ b/rerere.c
@@ -703,10 +703,9 @@ out:
 	return ret;
 }
 
-static struct lock_file index_lock;
-
 static void update_paths(struct string_list *update)
 {
+	struct lock_file index_lock = LOCK_INIT;
 	int i;
 
 	hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);