linux-kernel - [PATCH v2 08/15] selftests/nolibc: avoid passing NULL to printf("%s")

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Message-Id: <20240807-nolibc-llvm-v2-8-c20f2f5fc7c2@weissschuh.net>
Date: Wed, 07 Aug 2024 23:51:44 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Willy Tarreau <w@....eu>, Shuah Khan <shuah@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>, 
 Shuah Khan <skhan@...uxfoundation.org>
Subject: [PATCH v2 08/15] selftests/nolibc: avoid passing NULL to
 printf("%s")

Clang on higher optimization levels detects that NULL is passed to
printf("%s") and warns about it.
While printf() from nolibc gracefully handles that NULL,
it is undefined behavior as per POSIX, so the warning is reasonable.
Avoid the warning by transforming NULL into a non-NULL placeholder.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
Reviewed-by: Shuah Khan <skhan@...uxfoundation.org>
---
 tools/testing/selftests/nolibc/nolibc-test.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 093d0512f4c5..8cbb51dca0cd 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -542,7 +542,7 @@ int expect_strzr(const char *expr, int llen)
 {
 	int ret = 0;
 
-	llen += printf(" = <%s> ", expr);
+	llen += printf(" = <%s> ", expr ? expr : "(null)");
 	if (expr) {
 		ret = 1;
 		result(llen, FAIL);
@@ -561,7 +561,7 @@ int expect_strnz(const char *expr, int llen)
 {
 	int ret = 0;
 
-	llen += printf(" = <%s> ", expr);
+	llen += printf(" = <%s> ", expr ? expr : "(null)");
 	if (!expr) {
 		ret = 1;
 		result(llen, FAIL);

-- 
2.46.0