int
createPidFile(const char *progName, const char *pidFile, int flags) {
int fd;
char buf[BUF_SIZE];
fd = open(pidFile, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
if (fd == -1) {
errnoMsg(LOG_ERR, "Could not open PID file %s", pidFile);
return -1;
}
if (flags & CPF_CLOEXEC) {
/* Set the close-on-exec file descriptor flag */
/* Instead of the following steps, we could (on Linux) have opened the
file with O_CLOEXEC flag. However, not all systems support open()
O_CLOEXEC (which was only standardized in SUSv4), so instead we use
fcntl() to set the close-on-exec flag after opening the file */
flags = fcntl(fd, F_GETFD); /* Fetch flags */
if (flags == -1)
errnoMsg(LOG_ERR, "Could not get flags for PID file %s", pidFile);
flags |= FD_CLOEXEC; /* Turn on FD_CLOEXEC */
if (fcntl(fd, F_SETFD, flags) == -1) { /* Update flags */
errnoMsg(LOG_ERR, "Could not set flags for PID file %s", pidFile);
return -1;
}
}
if (lockRegion(fd, F_WRLCK, SEEK_SET, 0, 0) == -1) {
if (errno == EAGAIN || errno == EACCES)
errMsg(LOG_ERR, "PID file '%s' is locked; probably "
"'%s' is already running", pidFile, progName);
else
errMsg(LOG_ERR, "Unable to lock PID file '%s'", pidFile);
return -1;
}
if (ftruncate(fd, 0) == -1) {
errnoMsg(LOG_ERR, "Could not truncate PID file '%s'", pidFile);
return -1;
}
snprintf(buf, BUF_SIZE, "%ld\n", (long) getpid());
if (write(fd, buf, strlen(buf)) != strlen(buf)) {
errnoMsg(LOG_ERR, "Could not write to PID file '%s'", pidFile);
return -1;
}
return fd;
}
int
createPidFile(const char *progName, const char *pidFile, int flags)
{
int fd;
char buf[BUF_SIZE];
fd = open(pidFile, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
if (fd == -1)
errExit("Could not open PID file %s", pidFile);
if (flags & CPF_CLOEXEC) {
/* Set the close-on-exec file descriptor flag */
flags = fcntl(fd, F_GETFD); /* Fetch flags */
if (flags == -1)
errExit("Could not get flags for PID file %s", pidFile);
flags |= FD_CLOEXEC; /* Turn on FD_CLOEXEC */
if (fcntl(fd, F_SETFD, flags) == -1) /* Update flags */
errExit("Could not set flags for PID file %s", pidFile);
}
if (lockRegion(fd, F_WRLCK, SEEK_SET, 0, 0) == -1) {
if (errno == EAGAIN || errno == EACCES)
fatal("PID file '%s' is locked; probably "
"'%s' is already running", pidFile, progName);
else
errExit("Unable to lock PID file '%s'", pidFile);
}
if (ftruncate(fd, 0) == -1)
errExit("Could not truncate PID file '%s'", pidFile);
snprintf(buf, BUF_SIZE, "%ld\n", (long) getpid());
if (write(fd, buf, strlen(buf)) != strlen(buf))
fatal("Writing to PID file '%s'", pidFile);
return fd;
}