util-vserver-0.30.208

[util-vserver.git] / lib_internal / util-lockfile.c

diff --git a/lib_internal/util-lockfile.c b/lib_internal/util-lockfile.c
new file mode 100644 (file)
index 0000000..be07329
--- /dev/null
+++ b/lib_internal/util-lockfile.c
@@ -0,0 +1,86 @@
+// $Id: util-lockfile.c,v 1.1 2004/07/02 23:34:52 ensc Exp $    --*- c -*--
+
+// Copyright (C) 2004 Enrico Scholz <enrico.scholz@informatik.tu-chemnitz.de>
+//  
+// 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; version 2 of the License.
+//  
+// 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 02111-1307, USA.
+
+
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#include "util-lockfile.h"
+#include "errinfo.h"
+
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/file.h>
+#include <errno.h>
+
+static volatile sig_atomic_t   alarm_flag = 0;
+
+static void
+alarmFunc(int UNUSED sig)
+{
+  alarm_flag = 1;
+  signal(SIGALRM, alarmFunc);
+}
+
+bool
+lockfile(int *fd, char const *filename, int op, long timeout,
+        struct ErrorInformation *err)
+{
+  char const   *errstr = 0;
+  void         (*old_sighandler)(int) = 0;
+
+  errstr = "open()";
+  *fd = open(filename, O_CREAT|O_RDONLY|O_NOFOLLOW|O_NONBLOCK, 0644);
+  if (*fd==-1) goto err;
+
+  if (timeout!=-1) {
+    errstr = "siginterrupt()";
+    if (siginterrupt(SIGALRM, 1)==-1) goto err;
+
+    errstr = "signal()";
+    old_sighandler = signal(SIGALRM, alarmFunc);
+    if (old_sighandler==SIG_ERR) goto err;
+
+    alarm(timeout);
+  }
+
+  errstr = "flock()";
+  while (flock(*fd, op)==-1) {
+    if ((errno!=EINTR && errno!=EINTR) || alarm_flag) goto err;
+  }
+
+  if (timeout!=-1 && old_sighandler!=0)
+    signal(SIGALRM, old_sighandler);
+
+  errstr = "fcntl()";
+  if (fcntl(*fd, F_SETFD, FD_CLOEXEC)==-1) goto err;
+
+  return true;
+
+  err:
+  if (err) {
+    err->pos = errstr;
+    err->id  = errno;
+  }
+  if (timeout!=-1 && old_sighandler!=0)
+    signal(SIGALRM, old_sighandler);
+  if (*fd!=-1) close(*fd);
+  return false;
+}