test9.c

华清远见应用培训班例程源码

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <syslog.h>

int init_daemon(const char *prog, int facility);

int main(int argc, char **argv)
{
  init_daemon(argv[0], LOG_USER);

  sleep(10);

  // void syslog(int priority, const char *message, ... /* arguments */);
  syslog(LOG_ERR | LOG_USER, "Just a test.");

  closelog();

  return 0;
}

int init_daemon(const char *prog, int facility)
{
  // step 1, fork(), parent process terminate
  pid_t pid;

  if ((pid = fork()) < 0)
  {
    fprintf(stderr, "ERROR: call fork() failed: %s, errno = %d\n", strerror(errno), errno);
    // FIXME: handle this error.
    exit(1);
  }

  if (pid > 0)
  {
    // XXX: parent process
    exit(0);
  }

  // step 2, set session id
  setsid();

  // step 2.5, set signal handler
  // FIXME: process other signals
  //signal(SIGHUP, SIG_IGN);

  // step 3, change work dir
  chdir("/tmp");

  // step 4, set file create mask
  umask(0);

  // step 5, close all opened files.
  int i;

  // FIXME: calculate the maximum file descriptior number
  int fdlimit = sysconf(_SC_OPEN_MAX);

  for (i = 0; i < fdlimit; i++)
  {
    close(i);
  }

  // step 6, open syslog
  // void openlog(const char *ident, int logopt, int facility);
  //openlog(prog,,); 
  openlog(prog, LOG_PID, facility);

  return 0;
}