builtin/describe: fix leaking array when running diff-index

When running git-describe(1) with `--dirty`, we will set up a `struct
rev_info` with arguments for git-diff-index(1). The way we assemble the
arguments it causes two memory leaks though:

  - We never release the `struct strvec`.

  - `setup_revisions()` may end up removing some entries from the
    `strvec`, which we wouldn't free even if we released the struct.

While we could plug those leaks, this is ultimately unnecessary as the
arguments we pass are part of a static array anyway. So instead,
refactor the code to drop the `struct strvec` and just pass this static
array directly.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

builtin/describe.c

@@ -695,7 +695,6 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 		} else if (dirty) {
 			struct lock_file index_lock = LOCK_INIT;
 			struct rev_info revs;
-			struct strvec args = STRVEC_INIT;
 			int fd;
 
 			setup_work_tree();
@@ -710,8 +709,9 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 				repo_update_index_if_able(the_repository, &index_lock);
 
 			repo_init_revisions(the_repository, &revs, prefix);
-			strvec_pushv(&args, diff_index_args);
-			if (setup_revisions(args.nr, args.v, &revs, NULL) != 1)
+
+			if (setup_revisions(ARRAY_SIZE(diff_index_args) - 1,
+					    diff_index_args, &revs, NULL) != 1)
 				BUG("malformed internal diff-index command line");
 			run_diff_index(&revs, 0);