linux-kernel - [PATCH] selftests/nolibc: disable brk()/sbrk() tests on musl

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Message-Id: <20240424-nolibc-musl-brk-v1-1-b49882dd9a93@weissschuh.net>
Date: Wed, 24 Apr 2024 00:15:33 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Willy Tarreau <w@....eu>, Shuah Khan <shuah@...nel.org>
Cc: linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH] selftests/nolibc: disable brk()/sbrk() tests on musl

On musl calls to brk() and sbrk() always fail with ENOMEM.
Detect this and skip the tests on musl.

Tested on glibc 2.39 and musl 1.2.5 in addition to nolibc.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 tools/testing/selftests/nolibc/nolibc-test.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 94bb6e11c16f..89be9ba95179 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -942,6 +942,7 @@ int run_syscall(int min, int max)
 	int ret = 0;
 	void *p1, *p2;
 	int has_gettid = 1;
+	int has_brk;
 
 	/* <proc> indicates whether or not /proc is mounted */
 	proc = stat("/proc", &stat_buf) == 0;
@@ -954,6 +955,9 @@ int run_syscall(int min, int max)
 	has_gettid = __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 30);
 #endif
 
+	/* on musl setting brk()/sbrk() always fails */
+	has_brk = brk(0) == 0;
+
 	for (test = min; test >= 0 && test <= max; test++) {
 		int llen = 0; /* line length */
 
@@ -969,9 +973,9 @@ int run_syscall(int min, int max)
 		CASE_TEST(kill_0);            EXPECT_SYSZR(1, kill(getpid(), 0)); break;
 		CASE_TEST(kill_CONT);         EXPECT_SYSZR(1, kill(getpid(), 0)); break;
 		CASE_TEST(kill_BADPID);       EXPECT_SYSER(1, kill(INT_MAX, 0), -1, ESRCH); break;
-		CASE_TEST(sbrk_0);            EXPECT_PTRNE(1, sbrk(0), (void *)-1); break;
-		CASE_TEST(sbrk);              if ((p1 = p2 = sbrk(4096)) != (void *)-1) p2 = sbrk(-4096); EXPECT_SYSZR(1, (p2 == (void *)-1) || p2 == p1); break;
-		CASE_TEST(brk);               EXPECT_SYSZR(1, brk(sbrk(0))); break;
+		CASE_TEST(sbrk_0);            EXPECT_PTRNE(has_brk, sbrk(0), (void *)-1); break;
+		CASE_TEST(sbrk);              if ((p1 = p2 = sbrk(4096)) != (void *)-1) p2 = sbrk(-4096); EXPECT_SYSZR(has_brk, (p2 == (void *)-1) || p2 == p1); break;
+		CASE_TEST(brk);               EXPECT_SYSZR(has_brk, brk(sbrk(0))); break;
 		CASE_TEST(chdir_root);        EXPECT_SYSZR(1, chdir("/")); chdir(getenv("PWD")); break;
 		CASE_TEST(chdir_dot);         EXPECT_SYSZR(1, chdir(".")); break;
 		CASE_TEST(chdir_blah);        EXPECT_SYSER(1, chdir("/blah"), -1, ENOENT); break;

---
base-commit: 0adab2b6b7336fb6ee3c6456a432dad3b1d25647
change-id: 20240423-nolibc-musl-brk-7784add29801

Best regards,
-- 
Thomas Weißschuh <linux@...ssschuh.net>