From: Martin Schwenke <martin@meltin.net>
Date: Wed, 13 Oct 2021 09:40:34 +0000 (+1100)
Subject: debug: Optimise early return when header string buffer is full
X-Git-Tag: ldb-2.5.0~460
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cb70eea0536a33583cd57e8dd416bfc2e37fe9d2;p=thirdparty%2Fsamba.git

debug: Optimise early return when header string buffer is full

The existing check is for truncation, not whether the buffer is full.
However, if the buffer is full (i.e. hs_len == sizeof(header_str) - 1)
then there's no use trying subsequent snprintf() calls because there
will be one byte available that already contains the NUL-terminator.
A subsequent call will just do a no-op truncation.

Check for full buffer instead.

This might be confusing because it isn't the standard check that is
done after snprintf() calls.  Is it worth it for a rare corner case?

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Volker Lendecke <vl@samba.org>
---

diff --git a/lib/util/debug.c b/lib/util/debug.c
index c18726759e7..9e4be66da72 100644
--- a/lib/util/debug.c
+++ b/lib/util/debug.c
@@ -1698,7 +1698,7 @@ bool dbghdrclass(int level, int cls, const char *location, const char *func)
 				"[%s, %2d",
 				tvbuf.buf,
 				level);
-	if (state.hs_len >= sizeof(state.header_str)) {
+	if (state.hs_len >= sizeof(state.header_str) - 1) {
 		goto full;
 	}
 
@@ -1711,7 +1711,7 @@ bool dbghdrclass(int level, int cls, const char *location, const char *func)
 					 sizeof(state.header_str) - state.hs_len,
 					 ", pid=%u",
 					 (unsigned int)getpid());
-		if (state.hs_len >= sizeof(state.header_str)) {
+		if (state.hs_len >= sizeof(state.header_str) - 1) {
 			goto full;
 		}
 	}
@@ -1724,7 +1724,7 @@ bool dbghdrclass(int level, int cls, const char *location, const char *func)
 					 (unsigned int)getegid(),
 					 (unsigned int)getuid(),
 					 (unsigned int)getgid());
-		if (state.hs_len >= sizeof(state.header_str)) {
+		if (state.hs_len >= sizeof(state.header_str) - 1) {
 			goto full;
 		}
 	}
@@ -1735,9 +1735,6 @@ bool dbghdrclass(int level, int cls, const char *location, const char *func)
 					 sizeof(state.header_str) - state.hs_len,
 					 ", class=%s",
 					 classname_table[cls]);
-		if (state.hs_len >= sizeof(state.header_str)) {
-			goto full;
-		}
 	}
 
 	if (state.hs_len >= sizeof(state.header_str) - 1) {