pkt-line: simplify starts_with checks in packet tracing

We carefully check that our pkt buffer has enough characters
before seeing if it starts with "PACK". The intent is to
avoid reading random memory if we get a short buffer like
"PAC".

However, we know that the traced packets are always
NUL-terminated. They come from one of these sources:

  1. A string literal.

  2. `format_packet`, which uses a strbuf.

  3. `packet_read`, which defensively NUL-terminates what we
     read.

We can therefore drop the length checks, as we know we will
hit the trailing NUL if we have a short input.

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

diff --git a/pkt-line.c b/pkt-line.c
index 187a2293e7d9a36ba294fe775efcf2b87f4e9233..0477d2eefec2c225812cf0e923f0997cbf7e209c 100644 (file)
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -24,8 +24,7 @@ static void packet_trace(const char *buf, unsigned int len, int write)
        strbuf_addf(&out, "packet: %12s%c ",
                    packet_trace_prefix, write ? '>' : '<');
 
-       if ((len >= 4 && starts_with(buf, "PACK")) ||
-           (len >= 5 && starts_with(buf+1, "PACK"))) {
+       if (starts_with(buf, "PACK") || starts_with(buf + 1, "PACK")) {
                strbuf_addstr(&out, "PACK ...");
                trace_disable(&trace_packet);
        }