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SubjectRe: [PATCH v2] selftests/exec: Check if the syscall exists and bail if not
On Tue, Feb 3, 2015 at 3:53 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> 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>

Acked-by: David Drysdale <drysdale@google.com>

> ---
>
> 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.

Thanks!

>
> 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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