- #include <syslog.h>
- #include <fcntl.h>
- #include <sys/resource.h>
- #include <signal.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <sys/types.h>
- #include <sys/stat.h>
- #include <unistd.h>
- void init_daemon(const char *cmd)
- {
- int i, fd0, fd1, fd2;
- pid_t pid;
- struct rlimit rl;
- struct sigaction sa;
- /*
- * Clear file creation mask.
- */
- umask(0);
- /*
- * Get maximum number of file descriptors.
- */
- if (getrlimit(RLIMIT_NOFILE, &rl) < 0) {
- fprintf(stderr, "%s: can't get file limit", cmd);
- exit(1);
- }
- /*
- * Become a session leader to lose controllong TTY.
- */
- if ((pid = fork()) < 0) {
- fprintf(stderr, "%s: can't fork", cmd);
- exit(1);
- } else if (pid > 0) {
- exit(0);
- }
- setsid();
- /*
- * Ensure future opens won't allocate controlling TTYs.
- */
- sa.sa_handler = SIG_IGN;
- sigemptyset(&sa.sa_mask);
- sa.sa_flags = 0;
- if (sigaction(SIGHUP, &sa, NULL) < 0) {
- fprintf(stderr, "%s: can't ignore SIGHUP", cmd);
- exit(1);
- }
- if ((pid = fork()) < 0) {
- fprintf(stderr, "%s: can't fork", cmd);
- exit(1);
- } else if (pid > 0) {
- exit(0);
- }
- /*
- * Change the current working directory to the root so
- * we won't prevent file systems from being unmounted.
- */
- if (chdir("/") < 0) {
- fprintf(stderr, "%s: can't change directoryto /", cmd);
- exit(1);
- }
- /*
- * Close all open file descriptors.
- */
- if (rl.rlim_max == RLIM_INFINITY)
- rl.rlim_max = 1024;
- for (i = 0; i < rl.rlim_max; i++)
- close(i);
- /*
- * Attach file descriprots 0, 1 and 2 to /dev/null
- */
- fd0 = open("/dev/null", O_RDWR);
- fd1 = dup(0);
- fd2 = dup(0);
- /*
- * Initialize the log file
- */
- openlog(cmd, LOG_CONS, LOG_DAEMON);
- if (fd0 != 0 || fd1 != 1 || fd2 != 2) {
- syslog(LOG_ERR, "unexpected file descriptors %d %d %d", fd0, fd1, fd2);
- exit(1);
- }
- }
- //该片段来自于http://www.codesnippet.cn/detail/121120137071.html
来源: http://www.codesnippet.cn/detail/121120137071.html