selftests/nolibc: avoid passing NULL to printf("%s")

[ Upstream commit f1a58f61d88642ae1e6e97e9d72d73bc70a93cb8 ]

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.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-8-c20f2f5fc7c2@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 994477ee87befc23c3881688b7d89fc8d6039fe1..4bd8360d54225f99b2b101d6728997d0a3ece7d0 100644 (file)
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -534,7 +534,7 @@ 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);
@@ -553,7 +553,7 @@ 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);