Re: [igt-dev] [PATCH i-g-t 2/9] lib/tests: Add support for redirecting fork output to /dev/null

Petri Latvala
2020-02-14T12:01:22Z

On Wed, Feb 12, 2020 at 03:21:16PM +0200, Arkadiusz Hiler wrote:
> Trying to read interleaved writes is a bit tricky, so let's just use
> /dev/null if we care about contents on only one of those pipes.
>
> Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>

Reviewed-by: Petri Latvala <petri.latvala@intel.com>

> ---
> lib/tests/igt_tests_common.h | 35 +++++++++++++++++++++++++++--------
> 1 file changed, 27 insertions(+), 8 deletions(-)
>
> diff --git a/lib/tests/igt_tests_common.h b/lib/tests/igt_tests_common.h
> index b3da3b34..f285d657 100644
> --- a/lib/tests/igt_tests_common.h
> +++ b/lib/tests/igt_tests_common.h
> @@ -28,6 +28,8 @@
> #include <assert.h>
> #include <sys/wait.h>
> #include <errno.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
>
> /*
> * We need to hide assert from the cocci igt test refactor spatch.
> @@ -72,19 +74,32 @@ static inline pid_t do_fork_bg_with_pipes(void (*test_to_run)(void), int *out, i
> int outfd[2], errfd[2];
> pid_t pid;
>
> - internal_assert(pipe(outfd) != -1);
> - internal_assert(pipe(errfd) != -1);
> + if (out != NULL)
> + internal_assert(pipe(outfd) != -1);
> +
> + if (err != NULL)
> + internal_assert(pipe(errfd) != -1);
>
> pid = fork();
> internal_assert(pid != -1);
>
> if (pid == 0) {
> + /* we'll leak the /dev/null fds, let them die with the forked
> + * process, also close reading ends if they are any */
> + if (out == NULL)
> + outfd[1] = open("/dev/null", O_WRONLY);
> + else
> + close(outfd[0]);
> +
> + if (err == NULL)
> + errfd[1] = open("/dev/null", O_WRONLY);
> + else
> + close(errfd[0]);
> +
> while (dup2(outfd[1], STDOUT_FILENO) == -1 && errno == EINTR) {}
> while (dup2(errfd[1], STDERR_FILENO) == -1 && errno == EINTR) {}
>
> - close(outfd[0]);
> close(outfd[1]);
> - close(errfd[0]);
> close(errfd[1]);
>
> test_to_run();
> @@ -92,11 +107,15 @@ static inline pid_t do_fork_bg_with_pipes(void (*test_to_run)(void), int *out, i
> exit(-1);
> } else {
> /* close the writing ends */
> - close(outfd[1]);
> - close(errfd[1]);
> + if (out != NULL) {
> + close(outfd[1]);
> + *out = outfd[0];
> + }
>
> - *out = outfd[0];
> - *err = errfd[0];
> + if (err != NULL) {
> + close(errfd[1]);
> + *err = errfd[0];
> + }
>
> return pid;
> }
> --
> 2.24.1