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tools subcmd: Add non-waitpid check_if_command_finished()

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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>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Veronika Molnarova <vmolnaro@redhat.com>
Link: https://lore.kernel.org/r/20241025192109.132482-2-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Ian Rogers 2024-10-25 12:21:00 -07:00 committed by Namhyung Kim
parent 150dab31d5
commit 5ce42b5de4
1 changed files with 33 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

33
tools/lib/subcmd/run-command.c
View file

@ -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__
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)