v0 protocol: use size_t for capability length/offset

When parsing server capabilities, we use "int" to store lengths and
offsets. At first glance this seems like a spot where our parser may be
confused by integer overflow if somebody sent us a malicious response.

In practice these strings are all bounded by the 64k limit of a
pkt-line, so using "int" is OK. However, it makes the code simpler to
audit if they just use size_t everywhere. Note that because we take
these parameters as pointers, this also forces many callers to update
their declared types.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/fetch-pack.c b/fetch-pack.c
index 368f2ed..97a44ed 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -1099,7 +1099,7 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
 	struct ref *ref = copy_ref_list(orig_ref);
 	struct object_id oid;
 	const char *agent_feature;
-	int agent_len;
+	size_t agent_len;
 	struct fetch_negotiator negotiator_alloc;
 	struct fetch_negotiator *negotiator;
 
@@ -1117,7 +1117,7 @@ static struct ref *do_fetch_pack(struct fetch_pack_args *args,
 		agent_supported = 1;
 		if (agent_len)
 			print_verbose(args, _("Server version is %.*s"),
-				      agent_len, agent_feature);
+				      (int)agent_len, agent_feature);
 	}
 
 	if (!server_supports("session-id"))