On Thu, Oct 17, 2024 at 10:47:11PM -0700, Ian Rogers wrote:
> Using waitpid can cause stdout/stderr of the child process to be
> lost. Use Linux's /prod/<pid>/status file to determine if the process
> has reached the zombie state. Use the 'status' file rather than 'stat'
> to avoid issues around skipping the process name.
>
> Tested-by: James Clark <james.clark@linaro.org>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/lib/subcmd/run-command.c | 33 +++++++++++++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c
> index 4e3a557a2f37..0a764c25c384 100644
> --- a/tools/lib/subcmd/run-command.c
> +++ b/tools/lib/subcmd/run-command.c
> @@ -2,6 +2,7 @@
> #include <unistd.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> +#include <ctype.h>
> #include <fcntl.h>
> #include <string.h>
> #include <linux/string.h>
> @@ -217,8 +218,40 @@ static int wait_or_whine(struct child_process *cmd, bool block)
>
> int check_if_command_finished(struct child_process *cmd)
> {
> +#ifdef __linux__
Well.. I still don't like this part. But I can live with that as I want
the improvements in the test much more. :)
Thanks,
Namhyung
> + char filename[FILENAME_MAX + 12];
> + char status_line[256];
> + FILE *status_file;
> +
> + /*
> + * Check by reading /proc/<pid>/status as calling waitpid causes
> + * stdout/stderr to be closed and data lost.
> + */
> + sprintf(filename, "/proc/%d/status", cmd->pid);
> + status_file = fopen(filename, "r");
> + if (status_file == NULL) {
> + /* Open failed assume finish_command was called. */
> + return true;
> + }
> + while (fgets(status_line, sizeof(status_line), status_file) != NULL) {
> + char *p;
> +
> + if (strncmp(status_line, "State:", 6))
> + continue;
> +
> + fclose(status_file);
> + p = status_line + 6;
> + while (isspace(*p))
> + p++;
> + return *p == 'Z' ? 1 : 0;
> + }
> + /* Read failed assume finish_command was called. */
> + fclose(status_file);
> + return 1;
> +#else
> wait_or_whine(cmd, /*block=*/false);
> return cmd->finished;
> +#endif
> }
>
> int finish_command(struct child_process *cmd)
> --
> 2.47.0.105.g07ac214952-goog
>