lib/pid_output.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Process id output.
   4  * Copyright (C) 1998, 1999 Kunihiro Ishiguro
   5  */
   6
   7 #include <zebra.h>
   8 #include <fcntl.h>
   9 #include <log.h>
  10 #include "lib/version.h"
  11 #include "network.h"
  12 #include "lib_errors.h"
  13
  14 #define PIDFILE_MASK 0644
  15
  16 pid_t pid_output(const char *path)
  17 {
  18         int tmp;
  19         int fd;
  20         pid_t pid;
  21         char buf[16];
  22         struct flock lock;
  23         mode_t oldumask;
  24
  25         pid = getpid();
  26
  27         oldumask = umask(0777 & ~PIDFILE_MASK);
  28         fd = open(path, O_RDWR | O_CREAT, PIDFILE_MASK);
  29         if (fd < 0) {
  30                 flog_err_sys(EC_LIB_SYSTEM_CALL,
  31                              "Can't create pid lock file %s (%s), exiting",
  32                              path, safe_strerror(errno));
  33                 umask(oldumask);
  34                 exit(1);
  35         } else {
  36                 size_t pidsize;
  37
  38                 umask(oldumask);
  39                 memset(&lock, 0, sizeof(lock));
  40
  41                 set_cloexec(fd);
  42
  43                 lock.l_type = F_WRLCK;
  44                 lock.l_whence = SEEK_SET;
  45
  46                 if (fcntl(fd, F_SETLK, &lock) < 0) {
  47                         flog_err_sys(EC_LIB_SYSTEM_CALL,
  48                                      "Could not lock pid_file %s (%s), exiting.  Please ensure that the daemon is not already running",
  49                                      path, safe_strerror(errno));
  50                         exit(1);
  51                 }
  52
  53                 snprintf(buf, sizeof(buf), "%d\n", (int)pid);
  54                 pidsize = strlen(buf);
  55                 if ((tmp = write(fd, buf, pidsize)) != (int)pidsize)
  56                         flog_err_sys(
  57                                 EC_LIB_SYSTEM_CALL,
  58                                 "Could not write pid %d to pid_file %s, rc was %d: %s",
  59                                 (int)pid, path, tmp, safe_strerror(errno));
  60                 else if (ftruncate(fd, pidsize) < 0)
  61                         flog_err_sys(
  62                                 EC_LIB_SYSTEM_CALL,
  63                                 "Could not truncate pid_file %s to %u bytes: %s",
  64                                 path, (unsigned int)pidsize,
  65                                 safe_strerror(errno));
  66         }
  67         return pid;
  68 }