--- /dev/null
+// $Id$ --*- 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;
+}