sparse-checkout: check commit_lock_file when writing patterns

When writing a new "sparse-checkout" file, we do the usual strategy of
writing to a lockfile and committing it into place. But we don't check
the outcome of commit_lock_file(). Failing there would prevent us from
writing a bogus file (good), but we would ignore the error and return a
successful exit code (bad).

Fix this by calling die(). Note that we need to keep the sparse_filename
variable valid for longer, since the filename stored in the lock_file
struct will be dropped when we run commit_lock_file().

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: peff

builtin/sparse-checkout.c

@@ -338,7 +338,6 @@ static int write_patterns_and_update(struct pattern_list *pl)
 
 	fd = hold_lock_file_for_update(&lk, sparse_filename,
 				      LOCK_DIE_ON_ERROR);
-	free(sparse_filename);
 
 	result = update_working_directory(pl);
 	if (result) {
@@ -355,10 +354,12 @@ static int write_patterns_and_update(struct pattern_list *pl)
 		write_patterns_to_file(fp, pl);
 
 	fflush(fp);
-	commit_lock_file(&lk);
+	if (commit_lock_file(&lk))
+		die_errno(_("unable to write %s"), sparse_filename);
 
 out:
 	clear_pattern_list(pl);
+	free(sparse_filename);
 	return result;
 }