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/*
* Helper program for strace-DDD.test
*
* Copyright (c) 2019-2021 Dmitry V. Levin <ldv@strace.io>
* All rights reserved.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "tests.h"
#include "xmalloc.h"
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static int
fetch_tracer_pid(const char *str)
{
for (; isspace(*str); ++str)
;
return atoi(str);
}
static int
get_tracer_pid(void)
{
static const char status[] = "/proc/self/status";
FILE *fp = fopen(status, "r");
if (!fp)
perror_msg_and_fail("fopen: %s", status);
static const char prefix[] = "TracerPid:";
const size_t prefix_len = sizeof(prefix) - 1;
const char *str = NULL;
char *line = NULL;
size_t n = 0;
while (getline(&line, &n, fp) > 0) {
if (strncmp(line, prefix, prefix_len) == 0) {
str = line + prefix_len;
break;
}
}
if (!str && !line)
perror_msg_and_fail("getline");
int pid = str ? fetch_tracer_pid(str) : 0;
free(line);
fclose(fp);
return pid;
}
static void
get_ppid_pgid_sid(int pid, int *ppid, int *pgid, int *sid)
{
char *stat = xasprintf("/proc/%d/stat", pid);
FILE *fp = fopen(stat, "r");
if (!fp)
perror_msg_and_fail("fopen: %s", stat);
char buf[4096];
if (!fgets(buf, sizeof(buf), fp))
perror_msg_and_fail("fgets: %s", stat);
fclose(fp);
const char *p = strrchr(buf, ')');
if (!p)
error_msg_and_fail("%s: parenthesis not found", stat);
++p;
if (sscanf(p, " %*c %d %d %d", ppid, pgid, sid) != 3)
error_msg_and_fail("%s: sscanf failed", stat);
}
int
main(void)
{
int tracer_pid = get_tracer_pid();
if (tracer_pid < 0)
error_msg_and_fail("tracer_pid = %d", tracer_pid);
int ppid = 0, pgid = 0, sid = 0;
get_ppid_pgid_sid(tracer_pid, &ppid, &pgid, &sid);
printf("%d %d %d %d\n", tracer_pid, ppid, pgid, sid);
return 0;
}
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