Re: [PATCH 2/2] avoid using sha1_to_hex output as printf format

[Jeff King <peff@peff.net>]

On Fri, Jul 08, 2016 at 05:25:26AM -0400, Jeff King wrote:

> diff --git a/commit.c b/commit.c
> index 3f4f371..9603379 100644
> --- a/commit.c
> +++ b/commit.c
> @@ -1623,7 +1623,7 @@ void print_commit_list(struct commit_list *list,
>  {
>  	for ( ; list; list = list->next) {
>  		const char *format = list->next ? format_cur : format_last;
> -		printf(format, oid_to_hex(&list->item->object.oid));
> +		printf(format, "%s", oid_to_hex(&list->item->object.oid));

Urgh, this second hunk is clearly bogus. This is a -Wformat-nonliteral
problem, but not because of oid_to_hex(), but rather because of
"format". :-/

Here's a corrected patch. But as this has demonstrated the dangers of
churn, and as it doesn't really get us meaningfully closer to being able
to use -Wformat-nonliteral, perhaps the best course of action is to just
drop it (I do think the "walker_say" patch has more inherent value as a
cleanup, though).

-- >8 --
Subject: [PATCH] avoid using sha1_to_hex output as printf format

We know that it should not contain any percent-signs, but
it's a good habit not to feed non-literals to printf
formatters.

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/worktree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/builtin/worktree.c b/builtin/worktree.c
index e866844..cce555c 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -262,7 +262,7 @@ static int add_worktree(const char *path, const char *refname,
 	 */
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/HEAD", sb_repo.buf);
-	write_file(sb.buf, sha1_to_hex(null_sha1));
+	write_file(sb.buf, "%s", sha1_to_hex(null_sha1));
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
 	write_file(sb.buf, "../..");
-- 
2.9.0.393.g704e522