release/src/router/busybox/libbb/pidfile.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * pid file routines
   4  *
   5  * Copyright (C) 2007 by Stephane Billiart <stephane.billiart@gmail.com>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9
  10 /* Override ENABLE_FEATURE_PIDFILE */
  11 #define WANT_PIDFILE 1
  12 #include "libbb.h"
  13
  14 smallint wrote_pidfile;
  15
  16 void FAST_FUNC write_pidfile(const char *path)
  17 {
  18         int pid_fd;
  19         char *end;
  20         char buf[sizeof(int)*3 + 2];
  21         struct stat sb;
  22
  23         if (!path)
  24                 return;
  25         /* we will overwrite stale pidfile */
  26         pid_fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, 0666);
  27         if (pid_fd < 0)
  28                 return;
  29
  30         /* path can be "/dev/null"! Test for such cases */
  31         wrote_pidfile = (fstat(pid_fd, &sb) == 0) && S_ISREG(sb.st_mode);
  32
  33         if (wrote_pidfile) {
  34                 /* few bytes larger, but doesn't use stdio */
  35                 end = utoa_to_buf(getpid(), buf, sizeof(buf));
  36                 *end = '\n';
  37                 full_write(pid_fd, buf, end - buf + 1);
  38         }
  39         close(pid_fd);
  40 }