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/*
Unix SMB/CIFS implementation.
pidfile handling
Copyright (C) Andrew Tridgell 1998
Copyright (C) Amitay Isaccs 2016
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "replace.h"
#include "system/filesys.h"
#include "lib/util/blocking.h"
#include "lib/util/debug.h"
#include "lib/util/samba_util.h" /* For process_exists_by_pid() */
#include "lib/util/pidfile.h"
int pidfile_path_create(const char *path, int *pfd, pid_t *existing_pid)
{
struct flock lck;
char tmp[64] = { 0 };
int fd, ret = 0;
int len;
ssize_t nwritten;
bool retried = false;
fd = open(path, O_CREAT|O_WRONLY|O_NONBLOCK, 0644);
if (fd == -1) {
return errno;
}
if (! set_close_on_exec(fd)) {
ret = errno;
goto fail;
}
retry:
lck = (struct flock) {
.l_type = F_WRLCK,
.l_whence = SEEK_SET,
};
do {
ret = fcntl(fd, F_SETLK, &lck);
} while ((ret == -1) && (errno == EINTR));
if (ret != 0) {
ret = errno;
if ((ret == EACCES) || (ret == EAGAIN)) {
do {
ret = fcntl(fd, F_GETLK, &lck);
} while ((ret == -1) && (errno == EINTR));
if (ret == -1) {
ret = errno;
goto fail;
}
if (lck.l_type == F_UNLCK) {
if (!retried) {
/* Lock holder died, retry once */
retried = true;
goto retry;
}
/* Something badly wrong */
ret = EIO;
goto fail;
}
if (existing_pid != NULL) {
*existing_pid = lck.l_pid;
}
return EAGAIN;
}
goto fail;
}
/*
* PID file is locked by us so from here on we should unlink
* on failure
*/
len = snprintf(tmp, sizeof(tmp), "%u\n", getpid());
if (len < 0) {
ret = errno;
goto fail_unlink;
}
if ((size_t)len >= sizeof(tmp)) {
ret = ENOSPC;
goto fail_unlink;
}
do {
nwritten = write(fd, tmp, len);
} while ((nwritten == -1) && (errno == EINTR));
if ((nwritten == -1) || (nwritten != len)) {
ret = errno;
goto fail_unlink;
}
do {
ret = ftruncate(fd, len);
} while ((ret == -1) && (errno == EINTR));
if (ret == -1) {
ret = errno;
goto fail_unlink;
}
*pfd = fd;
return 0;
fail_unlink:
unlink(path);
fail:
close(fd);
return ret;
}
void pidfile_fd_close(int fd)
{
struct flock lck = {
.l_type = F_UNLCK,
.l_whence = SEEK_SET,
};
int ret;
do {
ret = fcntl(fd, F_SETLK, &lck);
} while ((ret == -1) && (errno == EINTR));
do {
ret = close(fd);
} while ((ret == -1) && (errno == EINTR));
}
/**
* return the pid in a pidfile. return 0 if the process (or pidfile)
* does not exist
*/
pid_t pidfile_pid(const char *piddir, const char *name)
{
size_t len = strlen(piddir) + strlen(name) + 6;
char pidFile[len];
int fd;
char pidstr[20] = { 0, };
pid_t ret = -1;
snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
fd = open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
if (fd == -1) {
return 0;
}
if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
goto noproc;
}
ret = (pid_t)atoi(pidstr);
if (ret <= 0) {
DEBUG(1, ("Could not parse contents of pidfile %s\n",
pidFile));
goto noproc;
}
if (!process_exists_by_pid(ret)) {
DEBUG(10, ("Process with PID=%d does not exist.\n", (int)ret));
goto noproc;
}
if (fcntl_lock(fd,F_SETLK,0,1,F_RDLCK)) {
/* we could get the lock - it can't be a Samba process */
DEBUG(10, ("Process with PID=%d is not a Samba process.\n",
(int)ret));
goto noproc;
}
close(fd);
DEBUG(10, ("Process with PID=%d is running.\n", (int)ret));
return ret;
noproc:
close(fd);
return 0;
}
/**
* create a pid file in the pid directory. open it and leave it locked
*/
void pidfile_create(const char *piddir, const char *name)
{
size_t len = strlen(piddir) + strlen(name) + 6;
char pidFile[len];
pid_t pid = (pid_t)-1;
int ret, fd;
snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
ret = pidfile_path_create(pidFile, &fd, &pid);
if (ret == EAGAIN) {
DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
name, pidFile, (int)pid));
exit(1);
}
/* Leave pid file open & locked for the duration... */
}
void pidfile_unlink(const char *piddir, const char *name)
{
size_t len = strlen(piddir) + strlen(name) + 6;
char pidFile[len];
int ret;
snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
ret = unlink(pidFile);
if (ret == -1) {
DEBUG(0,("Failed to delete pidfile %s. Error was %s\n",
pidFile, strerror(errno)));
}
}
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