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Subject[PATCH v2] selftests/exec: Check if the syscall exists and bail if not
Date
On systems which don't implement sys_execveat(), this test produces a
lot of output.

Add a check at the beginning to see if the syscall is present, and if
not just note one error and return.

When we run on a system that doesn't implement the syscall we will get
ENOSYS back from the kernel, so change the logic that handles
__NR_execveat not being defined to also use ENOSYS rather than -ENOSYS.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---

v2: Switch to positive ENOSYS. Confirmed this works as expected in the
case where the syscall is defined, but then is not present at runtime.


tools/testing/selftests/exec/execveat.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/exec/execveat.c b/tools/testing/selftests/exec/execveat.c
index e238c9559caf..8d5d1d2ee7c1 100644
--- a/tools/testing/selftests/exec/execveat.c
+++ b/tools/testing/selftests/exec/execveat.c
@@ -30,7 +30,7 @@ static int execveat_(int fd, const char *path, char **argv, char **envp,
#ifdef __NR_execveat
return syscall(__NR_execveat, fd, path, argv, envp, flags);
#else
- errno = -ENOSYS;
+ errno = ENOSYS;
return -1;
#endif
}
@@ -234,6 +234,14 @@ static int run_tests(void)
int fd_cloexec = open_or_die("execveat", O_RDONLY|O_CLOEXEC);
int fd_script_cloexec = open_or_die("script", O_RDONLY|O_CLOEXEC);

+ /* Check if we have execveat at all, and bail early if not */
+ errno = 0;
+ execveat_(-1, NULL, NULL, NULL, 0);
+ if (errno == ENOSYS) {
+ printf("[FAIL] ENOSYS calling execveat - no kernel support?\n");
+ return 1;
+ }
+
/* Change file position to confirm it doesn't affect anything */
lseek(fd, 10, SEEK_SET);

--
2.1.0


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