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daemon.c
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daemon.c
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/*
* This file is part of Shairport.
* Copyright (c) Paul Lietar 2013
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include "common.h"
static int lock_fd = -1;
static int daemon_pipe[2] = {-1, -1};
void daemon_init() {
int ret;
ret = pipe(daemon_pipe);
if (ret < 0)
die("couldn't create a pipe?!");
pid_t pid = fork();
if (pid < 0)
die("failed to fork!");
if (pid) {
close(daemon_pipe[1]);
char buf[64];
ret = read(daemon_pipe[0], buf, sizeof(buf));
if (ret < 0) {
// No response from child, something failed
fprintf(stderr, "Spawning the daemon failed.\n");
exit(1);
} else if (buf[0] != 0) {
// First byte is non zero, child sent error message
write_unchecked(STDERR_FILENO, buf, ret);
fprintf(stderr, "\n");
exit(1);
} else {
// Success !
if (!config.pidfile)
printf("%d\n", pid);
exit(0);
}
} else {
close(daemon_pipe[0]);
if (config.pidfile) {
lock_fd = open(config.pidfile, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
if (lock_fd < 0) {
die("Could not open pidfile");
}
ret = lockf(lock_fd,F_TLOCK,0);
if (ret < 0) {
die("Could not lock pidfile. Is an other instance running ?");
}
dprintf(lock_fd, "%d\n", getpid());
}
}
}
void daemon_ready() {
char ok = 0;
write_unchecked(daemon_pipe[1], &ok, 1);
close(daemon_pipe[1]);
daemon_pipe[1] = -1;
}
void daemon_fail(const char *format, va_list arg) {
// Are we still initializing ?
if (daemon_pipe[1] > 0) {
vdprintf(daemon_pipe[1], format, arg);
}
}
void daemon_exit() {
if (lock_fd > 0) {
lockf_unchecked(lock_fd, F_ULOCK, 0);
close(lock_fd);
unlink(config.pidfile);
lock_fd = -1;
}
}