[lcd4linux @ 2003-08-08 08:05:23 by reinelt]

added PID file handling

git-svn-id: https://ssl.bulix.org/svn/lcd4linux/trunk@208 3ae390bd-cb1e-0410-b409-cd5a39f66f1f

1 files changed, 143 insertions, 0 deletions

diff --git a/pid.c b/pid.c
new file mode 100644
index 0000000..b7bfe3c
--- /dev/null
+++ b/pid.c
@@ -0,0 +1,143 @@
+/* $Id: pid.c,v 1.1 2003/08/08 08:05:23 reinelt Exp $
+ *
+ * PID file handling
+ *
+ * Copyright 1999, 2000 by Michael Reinelt (reinelt@eunet.at)
+ *
+ * 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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ *
+ * $Log: pid.c,v $
+ * Revision 1.1  2003/08/08 08:05:23  reinelt
+ * added PID file handling
+ *
+ */
+
+/* 
+ * exported functions:
+ * 
+ * int pid_init (const char *pidfile)
+ *   returns 0 if PID file could be successfully created
+ *   returns PID of an already running process
+ *   returns -1 in case of an error
+
+ * int pid_exit (const char *pidfile)
+ *   returns 0 if PID file could be successfully deleted
+ *   otherwise returns error from unlink() call
+ *
+ */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "debug.h"
+#include "pid.h"
+
+
+int pid_init (const char *pidfile)
+{
+  char tmpfile[256];
+  char buffer[16];
+  int fd, len, pid;
+  
+  snprintf(tmpfile, sizeof(tmpfile), "%s.%s", pidfile, "XXXXXX");
+
+  if ((fd=mkstemp(tmpfile))==-1) {
+    error ("mkstemp(%s) failed: %s", tmpfile, strerror(errno));
+    return -1;
+  }
+  
+  if (fchmod(fd,S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)==-1) {
+    error ("fchmod(%s) failed: %s", tmpfile, strerror(errno));
+    close(fd);
+    unlink(tmpfile);
+    return -1;
+  }
+  
+  snprintf (buffer, sizeof(buffer), "%d\n", (int)getpid());
+  if (write(fd, buffer, strlen(buffer))!=strlen(buffer)) {
+    error ("write(%s) failed: %s", tmpfile, strerror(errno));
+    close(fd);
+    unlink(tmpfile);
+    return -1;
+  }
+  close (fd);
+  
+  
+  while (link(tmpfile, pidfile)==-1) {
+
+    if (errno!=EEXIST) {
+      error ("link(%s, %s) failed: %s", tmpfile, pidfile, strerror(errno));
+      unlink(tmpfile);
+      return -1;
+    }
+
+    if ((fd=open(pidfile, O_RDONLY))==-1) {
+      if (errno==ENOENT) continue; // pidfile disappared
+      error ("open(%s) failed: %s", pidfile, strerror(errno));
+      unlink (tmpfile);
+      return -1;
+    }
+
+    len=read(fd, buffer, sizeof(buffer)-1);
+    if (len<0) {
+      error ("read(%s) failed: %s", pidfile, strerror(errno));
+      unlink (tmpfile);
+      return -1;
+    }
+    
+    buffer[len]='\0';
+    if (sscanf(buffer, "%d", &pid)!=1 || pid==0) {
+      error ("scan(%s) failed.", pidfile);
+      unlink (tmpfile);
+      return -1;
+    }
+
+    if (pid==getpid()) {
+      error ("%s already locked by us. uh-oh...", pidfile);
+      unlink(tmpfile);
+      return 0;
+    }
+    
+    if ((kill(pid, 0)==-1) && errno==ESRCH) {
+      error ("removing stale PID file %s", pidfile);
+      if (unlink(pidfile)==-1 && errno!=ENOENT) {
+	error ("unlink(%s) failed: %s", pidfile, strerror(errno));
+	unlink(tmpfile);
+	return pid;
+      }
+      continue;
+    }
+    unlink (tmpfile);
+    return pid;
+  }
+  
+  unlink (tmpfile);
+  return 0;
+}
+
+
+int pid_exit (const char *pidfile)
+{
+  return unlink(pidfile);
+}