grep: handle deref_tag() returning NULL

Commit Message

René Scharfe Oct. 11, 2020, 4:03 p.m. UTC

deref_tag() can return NULL.  Exit gracefully in that case instead
of blindly dereferencing the return value.

.name shouldn't ever be NULL, but grep_object() handles that case
explicitly, so let's be defensive here as well and show the broken
object's ID if it happens to lack a name after all.

Signed-off-by: René Scharfe <[e-mail]>
---
Patch generated with --function-context for easier review.

 builtin/grep.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

--
2.28.0

Patch

diff --git a/builtin/grep.c b/builtin/grep.c
index c8037388c6..e58e57504c 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -658,31 +658,42 @@  static int grep_object(struct grep_opt *opt, const struct pathspec *pathspec,
 static int grep_objects(struct grep_opt *opt, const struct pathspec *pathspec,
 			const struct object_array *list)
 {
 	unsigned int i;
 	int hit = 0;
 	const unsigned int nr = list->nr;

 	for (i = 0; i < nr; i++) {
 		struct object *real_obj;

 		obj_read_lock();
 		real_obj = deref_tag(opt->repo, list->objects[i].item,
 				     NULL, 0);
 		obj_read_unlock();

+		if (!real_obj) {
+			char hex[GIT_MAX_HEXSZ + 1];
+			const char *name = list->objects[i].name;
+
+			if (!name) {
+				oid_to_hex_r(hex, &list->objects[i].item->oid);
+				name = hex;
+			}
+			die(_("invalid object '%s' given."), name);
+		}
+
 		/* load the gitmodules file for this rev */
 		if (recurse_submodules) {
 			submodule_free(opt->repo);
 			obj_read_lock();
 			gitmodules_config_oid(&real_obj->oid);
 			obj_read_unlock();
 		}
 		if (grep_object(opt, pathspec, real_obj, list->objects[i].name,
 				list->objects[i].path)) {
 			hit = 1;
 			if (opt->status_only)
 				break;
 		}
 	}
 	return hit;
 }