Re: [PATCH v2] selftests/exec: Check if the syscall exists and bail if not
From: David Drysdale <hidden>
Date: 2015-02-03 07:59:22
Also in:
lkml
On Tue, Feb 3, 2015 at 3:53 AM, Michael Ellerman [off-list ref] 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-Gsx/Oe8HsFggBc27wqDAHg@public.gmane.org>
Acked-by: David Drysdale <redacted>
--- 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!
quoted hunk ↗ jump to hunk
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