convert trivial sprintf / strcpy calls to xsnprintf

We sometimes sprintf into fixed-size buffers when we know
that the buffer is large enough to fit the input (either
because it's a constant, or because it's numeric input that
is bounded in size). Likewise with strcpy of constant
strings.

However, these sites make it hard to audit sprintf and
strcpy calls for buffer overflows, as a reader has to
cross-reference the size of the array with the input. Let's
use xsnprintf instead, which communicates to a reader that
we don't expect this to overflow (and catches the mistake in
case we do).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/strbuf.c b/strbuf.c
index f3c44fb3b..107c45d29 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -245,8 +245,8 @@ void strbuf_add_commented_lines(struct strbuf *out, const char *buf, size_t size
 	static char prefix2[2];
 
 	if (prefix1[0] != comment_line_char) {
-		sprintf(prefix1, "%c ", comment_line_char);
-		sprintf(prefix2, "%c", comment_line_char);
+		xsnprintf(prefix1, sizeof(prefix1), "%c ", comment_line_char);
+		xsnprintf(prefix2, sizeof(prefix2), "%c", comment_line_char);
 	}
 	add_lines(out, prefix1, prefix2, buf, size);
 }