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/*
* Copyright 2004-2019 the Pacemaker project contributors
*
* The version control history for this file may have further details.
*
* This source code is licensed under the GNU Lesser General Public License
* version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
*/
#include <crm_internal.h>
#ifndef _GNU_SOURCE
# define _GNU_SOURCE
#endif
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <crm/crm.h>
int
crm_pid_active(long pid, const char *daemon)
{
static int last_asked_pid = 0; /* log spam prevention */
#if SUPPORT_PROCFS
static int have_proc_pid = 0;
#else
static int have_proc_pid = -1;
#endif
int rc = 0;
if (have_proc_pid == 0) {
/* evaluation of /proc/PID/exe applicability via self-introspection */
char proc_path[PATH_MAX], exe_path[PATH_MAX];
snprintf(proc_path, sizeof(proc_path), "/proc/%lu/exe",
(long unsigned int) getpid());
have_proc_pid = 1;
if (readlink(proc_path, exe_path, sizeof(exe_path) - 1) < 0) {
have_proc_pid = -1;
}
}
if (pid <= 0) {
return -1;
} else if ((rc = kill(pid, 0)) < 0 && errno == ESRCH) {
return 0; /* no such PID detected */
} else if (rc < 0 && (daemon == NULL || have_proc_pid == -1)) {
if (last_asked_pid != pid) {
crm_info("Cannot examine PID %ld: %s", pid, strerror(errno));
last_asked_pid = pid;
}
return -2; /* errno != ESRCH */
} else if (rc == 0 && (daemon == NULL || have_proc_pid == -1)) {
return 1; /* kill as the only indicator, cannot double check */
} else if (daemon != NULL) {
/* make sure PID hasn't been reused by another process
XXX: might still be just a zombie, which could confuse decisions */
bool checked_through_kill = (rc == 0);
char proc_path[PATH_MAX], exe_path[PATH_MAX], myexe_path[PATH_MAX];
snprintf(proc_path, sizeof(proc_path), "/proc/%ld/exe", pid);
rc = readlink(proc_path, exe_path, sizeof(exe_path) - 1);
if ((rc < 0) && (errno == EACCES)) {
if (last_asked_pid != pid) {
crm_info("Could not read from %s: %s", proc_path,
strerror(errno));
last_asked_pid = pid;
}
return checked_through_kill ? 1 : -2;
} else if (rc < 0) {
if (last_asked_pid != pid) {
crm_err("Could not read from %s: %s (%d)", proc_path,
strerror(errno), errno);
last_asked_pid = pid;
}
return 0; /* most likely errno == ENOENT */
}
exe_path[rc] = '\0';
if (daemon[0] != '/') {
rc = snprintf(myexe_path, sizeof(myexe_path), CRM_DAEMON_DIR"/%s",
daemon);
} else {
rc = snprintf(myexe_path, sizeof(myexe_path), "%s", daemon);
}
if (rc > 0 && rc < sizeof(myexe_path) && !strcmp(exe_path, myexe_path)) {
return 1;
}
}
return 0;
}
#define LOCKSTRLEN 11
long
crm_read_pidfile(const char *filename)
{
int fd;
struct stat sbuf;
long pid = -ENOENT;
char buf[LOCKSTRLEN + 1];
fd = open(filename, O_RDONLY);
if (fd < 0) {
goto bail;
}
if ((fstat(fd, &sbuf) >= 0) && (sbuf.st_size < LOCKSTRLEN)) {
sleep(2); /* if someone was about to create one,
* give'm a sec to do so
*/
}
if (read(fd, buf, sizeof(buf)) < 1) {
goto bail;
}
if (sscanf(buf, "%ld", &pid) > 0) {
if (pid <= 0) {
pid = -ESRCH;
} else {
crm_trace("Got pid %lu from %s\n", pid, filename);
}
}
bail:
if (fd >= 0) {
close(fd);
}
return pid;
}
long
crm_pidfile_inuse(const char *filename, long mypid, const char *daemon)
{
long pid = crm_read_pidfile(filename);
if (pid < 2) {
// Invalid pid
pid = -ENOENT;
unlink(filename);
} else if (mypid && (pid == mypid)) {
// In use by us
pid = pcmk_ok;
} else if (crm_pid_active(pid, daemon) == FALSE) {
// Contains a stale value
unlink(filename);
pid = -ENOENT;
} else if (mypid && (pid != mypid)) {
// Locked by existing process
pid = -EEXIST;
}
return pid;
}
int
crm_lock_pidfile(const char *filename, const char *name)
{
long mypid = 0;
int fd = 0;
int rc = 0;
char buf[LOCKSTRLEN + 2];
mypid = (unsigned long) getpid();
rc = crm_pidfile_inuse(filename, 0, name);
if (rc == -ENOENT) {
// Exists, but the process is not active
} else if (rc != pcmk_ok) {
// Locked by existing process
return rc;
}
fd = open(filename, O_CREAT | O_WRONLY | O_EXCL, 0644);
if (fd < 0) {
return -errno;
}
snprintf(buf, sizeof(buf), "%*ld\n", LOCKSTRLEN - 1, mypid);
rc = write(fd, buf, LOCKSTRLEN);
close(fd);
if (rc != LOCKSTRLEN) {
crm_perror(LOG_ERR, "Incomplete write to %s", filename);
return -errno;
}
return crm_pidfile_inuse(filename, mypid, name);
}
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