sequencer: lib'ify checkout_fast_forward()

Instead of dying there, let the caller high up in the callchain
notice the error and handle it (by dying, still).

The only callers of checkout_fast_forward(), cmd_merge(),
pull_into_void(), cmd_pull() and sequencer's fast_forward_to(),
already check the return value and handle it appropriately. With this
step, we make it notice an error return from this function.

So this is a safe conversion to make checkout_fast_forward()
callable from new callers that want it not to die, without changing
the external behaviour of anything existing.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/merge.c b/merge.c
index 5db7d56b90c3413bbd831f90de73d3306e10ce2f..23866c91655638d9e1a7213478772b78aa9d7c69 100644 (file)
--- a/merge.c
+++ b/merge.c
@@ -57,7 +57,8 @@ int checkout_fast_forward(const unsigned char *head,
 
        refresh_cache(REFRESH_QUIET);
 
-       hold_locked_index(lock_file, 1);
+       if (hold_locked_index(lock_file, 0) < 0)
+               return -1;
 
        memset(&trees, 0, sizeof(trees));
        memset(&opts, 0, sizeof(opts));
@@ -90,7 +91,9 @@ int checkout_fast_forward(const unsigned char *head,
        }
        if (unpack_trees(nr_trees, t, &opts))
                return -1;
-       if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
-               die(_("unable to write new index file"));
+       if (write_locked_index(&the_index, lock_file, COMMIT_LOCK)) {
+               rollback_lock_file(lock_file);
+               return error(_("unable to write new index file"));
+       }
        return 0;
 }