diff: make sure --output=/bad/path is caught

The return value from fopen wasn't being checked.

Signed-off-by: Larry D'Anna <larry@elder-gods.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/diff.c b/diff.c
index 17a2b4d..8d8405a 100644
--- a/diff.c
+++ b/diff.c
@@ -2799,6 +2799,8 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		;
 	else if (!prefixcmp(arg, "--output=")) {
 		options->file = fopen(arg + strlen("--output="), "w");
+		if (!options->file)
+			die_errno("Could not open '%s'", arg + strlen("--output="));
 		options->close_file = 1;
 	} else
 		return 0;