bundle: fix wrong check of read_header()'s return value & add tests

If read_header() fails, it returns <0, not 0. Further, an open(/dev/null)
was not checked for errors.

Also, this adds two tests to make sure that the bundle file looks
correct, by checking if it has the header has the expected form, and that
the pack contains the right amount of objects.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-bundle.c

@@ -404,6 +404,8 @@ static int unbundle(struct bundle_header *header, int bundle_fd,
 	if (verify_bundle(header, 0))
 		return -1;
 	dev_null = open("/dev/null", O_WRONLY);
+	if (dev_null < 0)
+		return error("Could not open /dev/null");
 	pid = fork_with_pipe(argv_index_pack, &bundle_fd, &dev_null);
 	if (pid < 0)
 		return error("Could not spawn index-pack");
@@ -440,7 +442,7 @@ int cmd_bundle(int argc, const char **argv, const char *prefix)
 
 	memset(&header, 0, sizeof(header));
 	if (strcmp(cmd, "create") &&
-			!(bundle_fd = read_header(bundle_file, &header)))
+			(bundle_fd = read_header(bundle_file, &header)) < 0)
 		return 1;
 
 	if (!strcmp(cmd, "verify")) {

t/t5510-fetch.sh

@@ -90,6 +90,13 @@ test_expect_success 'create bundle 1' '
 	git bundle create bundle1 master^..master
 '
 
+test_expect_success 'header of bundle looks right' '
+	head -n 1 "$D"/bundle1 | grep "^#" &&
+	head -n 2 "$D"/bundle1 | grep "^-[0-9a-f]\{40\} " &&
+	head -n 3 "$D"/bundle1 | grep "^[0-9a-f]\{40\} " &&
+	head -n 4 "$D"/bundle1 | grep "^$"
+'
+
 test_expect_success 'create bundle 2' '
 	cd "$D" &&
 	git bundle create bundle2 master~2..master
@@ -101,6 +108,20 @@ test_expect_failure 'unbundle 1' '
 	git fetch "$D/bundle1" master:master
 '
 
+test_expect_success 'bundle 1 has only 3 files ' '
+	cd "$D" &&
+	(
+		while read x && test -n "$x"
+		do
+			:;
+		done
+		cat
+	) <bundle1 >bundle.pack &&
+	git index-pack bundle.pack &&
+	verify=$(git verify-pack -v bundle.pack) &&
+	test 4 = $(echo "$verify" | wc -l)
+'
+
 test_expect_success 'unbundle 2' '
 	cd "$D/bundle" &&
 	git fetch ../bundle2 master:master &&