util-vserver-0.30.208

[util-vserver.git] / vserver-start / undo.c

diff --git a/vserver-start/undo.c b/vserver-start/undo.c
new file mode 100644 (file)
index 0000000..25b4d9e
--- /dev/null
+++ b/vserver-start/undo.c
@@ -0,0 +1,92 @@
+// $Id: undo.c,v 1.1 2004/08/19 15:02:57 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 "undo.h"
+
+#include <lib_internal/util.h>
+#include <ensc_vector/vector.h>
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+
+struct FuncData
+{
+    ExitFunction               fn;
+    void const *               args;
+};
+
+struct Undo
+{
+    pid_t              pid_;
+    struct Vector      funcs;
+};
+
+
+static struct Undo     undo_data = {
+  .pid_ = -1
+};
+
+static void
+atexitHandler()
+{
+  struct FuncData const *      ptr;
+
+  if (undo_data.pid_ != getpid())
+    return;    // skip 'exit()' from forked processes
+
+  for (ptr=Vector_end(&undo_data.funcs);
+       ptr!=Vector_begin(&undo_data.funcs);
+       --ptr)
+    (ptr[-1].fn)(ptr[-1].args);
+}
+
+void
+Undo_init()
+{
+  if (undo_data.pid_!=-1) {
+    WRITE_MSG(2, "Undo already initialized; internal error...\n");
+    _exit(1);
+  }
+
+  undo_data.pid_ = getpid();
+  Vector_init(&undo_data.funcs, sizeof(struct FuncData));
+  
+  atexit(&atexitHandler);
+}
+
+void
+Undo_addTask(ExitFunction fn, void const *args)
+{
+  struct FuncData      *tmp = Vector_pushback(&undo_data.funcs);
+  assert(tmp!=0); // Vector_pushback never returns a null-pointer
+
+  tmp->fn   = fn;
+  tmp->args = args;
+}
+
+void
+Undo_detach()
+{
+  Vector_free(&undo_data.funcs);
+  undo_data.pid_ = -1;
+}