Initial revision

1 files changed, 130 insertions, 0 deletions

diff --git a/pidfile.c b/pidfile.c
new file mode 100644
index 00000000..08520293
--- /dev/null
+++ b/pidfile.c
@@ -0,0 +1,130 @@
+/*
+    pidfile.c - interact with pidfiles
+    Copyright (c) 1995  Martin Schulze <Martin.Schulze@Linux.DE>
+
+    This file is part of the sysklogd package, a kernel and system log daemon.
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA
+*/
+
+/*
+ * Sat Aug 19 13:24:33 MET DST 1995: Martin Schulze
+ *	First version (v0.2) released
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/file.h>
+#include <string.h>
+#include <errno.h>
+#include <signal.h>
+
+/* read_pid
+ *
+ * Reads the specified pidfile and returns the read pid.
+ * 0 is returned if either there's no pidfile, it's empty
+ * or no pid can be read.
+ */
+int read_pid (char *pidfile)
+{
+  FILE *f;
+  int pid;
+
+  if (!(f=fopen(pidfile,"r")))
+    return 0;
+  fscanf(f,"%d", &pid);
+  fclose(f);
+  return pid;
+}
+
+/* check_pid
+ *
+ * Reads the pid using read_pid and looks up the pid in the process
+ * table (using /proc) to determine if the process already exists. If
+ * so 1 is returned, otherwise 0.
+ */
+int check_pid (char *pidfile)
+{
+  int pid = read_pid(pidfile);
+
+  /* Amazing ! _I_ am already holding the pid file... */
+  if ((!pid) || (pid == getpid ()))
+    return 0;
+
+  /*
+   * The 'standard' method of doing this is to try and do a 'fake' kill
+   * of the process.  If an ESRCH error is returned the process cannot
+   * be found -- GW
+   */
+  /* But... errno is usually changed only on error.. */
+  if (kill(pid, 0) && errno == ESRCH)
+	  return(0);
+
+  return pid;
+}
+
+/* write_pid
+ *
+ * Writes the pid to the specified file. If that fails 0 is
+ * returned, otherwise the pid.
+ */
+int write_pid (char *pidfile)
+{
+  FILE *f;
+  int fd;
+  int pid;
+
+  if ( ((fd = open(pidfile, O_RDWR|O_CREAT, 0644)) == -1)
+       || ((f = fdopen(fd, "r+")) == NULL) ) {
+      fprintf(stderr, "Can't open or create %s.\n", pidfile);
+      return 0;
+  }
+
+  if (flock(fd, LOCK_EX|LOCK_NB) == -1) {
+      fscanf(f, "%d", &pid);
+      fclose(f);
+      printf("Can't lock, lock is held by pid %d.\n", pid);
+      return 0;
+  }
+
+  pid = getpid();
+  if (!fprintf(f,"%d\n", pid)) {
+      printf("Can't write pid , %s.\n", strerror(errno));
+      close(fd);
+      return 0;
+  }
+  fflush(f);
+
+  if (flock(fd, LOCK_UN) == -1) {
+      printf("Can't unlock pidfile %s, %s.\n", pidfile, strerror(errno));
+      close(fd);
+      return 0;
+  }
+  close(fd);
+
+  return pid;
+}
+
+/* remove_pid
+ *
+ * Remove the the specified file. The result from unlink(2)
+ * is returned
+ */
+int remove_pid (char *pidfile)
+{
+  return unlink (pidfile);
+}
+