127 lines
2.1 KiB
C
127 lines
2.1 KiB
C
#include <stdio.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/file.h>
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#include <signal.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include "skynet_daemon.h"
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static int
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check_pid(const char *pidfile) {
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int pid = 0;
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FILE *f = fopen(pidfile,"r");
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if (f == NULL)
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return 0;
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int n = fscanf(f,"%d", &pid);
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fclose(f);
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if (n !=1 || pid == 0 || pid == getpid()) {
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return 0;
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}
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if (kill(pid, 0) && errno == ESRCH)
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return 0;
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return pid;
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}
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static int
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write_pid(const char *pidfile) {
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FILE *f;
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int pid = 0;
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int fd = open(pidfile, O_RDWR|O_CREAT, 0644);
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if (fd == -1) {
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fprintf(stderr, "Can't create pidfile [%s].\n", pidfile);
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return 0;
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}
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f = fdopen(fd, "w+");
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if (f == NULL) {
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fprintf(stderr, "Can't open pidfile [%s].\n", pidfile);
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return 0;
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}
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if (flock(fd, LOCK_EX|LOCK_NB) == -1) {
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int n = fscanf(f, "%d", &pid);
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fclose(f);
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if (n != 1) {
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fprintf(stderr, "Can't lock and read pidfile.\n");
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} else {
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fprintf(stderr, "Can't lock pidfile, lock is held by pid %d.\n", pid);
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}
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return 0;
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}
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pid = getpid();
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if (!fprintf(f,"%d\n", pid)) {
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fprintf(stderr, "Can't write pid.\n");
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close(fd);
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return 0;
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}
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fflush(f);
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return pid;
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}
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static int
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redirect_fds() {
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int nfd = open("/dev/null", O_RDWR);
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if (nfd == -1) {
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perror("Unable to open /dev/null: ");
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return -1;
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}
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if (dup2(nfd, 0) < 0) {
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perror("Unable to dup2 stdin(0): ");
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return -1;
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}
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if (dup2(nfd, 1) < 0) {
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perror("Unable to dup2 stdout(1): ");
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return -1;
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}
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if (dup2(nfd, 2) < 0) {
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perror("Unable to dup2 stderr(2): ");
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return -1;
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}
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close(nfd);
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return 0;
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}
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int
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daemon_init(const char *pidfile) {
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int pid = check_pid(pidfile);
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if (pid) {
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fprintf(stderr, "Skynet is already running, pid = %d.\n", pid);
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return 1;
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}
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#ifdef __APPLE__
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fprintf(stderr, "'daemon' is deprecated: first deprecated in OS X 10.5 , use launchd instead.\n");
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#else
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if (daemon(1,1)) {
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fprintf(stderr, "Can't daemonize.\n");
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return 1;
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}
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#endif
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pid = write_pid(pidfile);
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if (pid == 0) {
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return 1;
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}
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if (redirect_fds()) {
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return 1;
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}
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return 0;
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}
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int
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daemon_exit(const char *pidfile) {
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return unlink(pidfile);
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}
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