1 files changed, 91 insertions, 0 deletions
diff --git a/gl/close-hook.c b/gl/close-hook.c
new file mode 100644
index 0000000000..fe1f22c780
--- /dev/null
+++ b/gl/close-hook.c
@@ -0,0 +1,91 @@
+/* Hook for making the close() function extensible.
+   Copyright (C) 2009 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2009.
+
+   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 3 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "close-hook.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+
+#undef close
+
+
+/* Currently, this entire code is only needed for the handling of sockets
+   on native Windows platforms.  */
+#if WINDOWS_SOCKETS
+
+/* The first and last link in the doubly linked list.
+   Initially the list is empty.  */
+static struct close_hook anchor = { &anchor, &anchor, NULL };
+
+int
+execute_close_hooks (int fd, const struct close_hook *remaining_list)
+{
+  if (remaining_list == &anchor)
+    /* End of list reached.  */
+    return close (fd);
+  else
+    return remaining_list->private_fn (fd, remaining_list->private_next);
+}
+
+int
+execute_all_close_hooks (int fd)
+{
+  return execute_close_hooks (fd, anchor.private_next);
+}
+
+void
+register_close_hook (close_hook_fn hook, struct close_hook *link)
+{
+  if (link->private_next == NULL && link->private_prev == NULL)
+    {
+      /* Add the link to the doubly linked list.  */
+      link->private_next = anchor.private_next;
+      link->private_prev = &anchor;
+      link->private_fn = hook;
+      anchor.private_next->private_prev = link;
+      anchor.private_next = link;
+    }
+  else
+    {
+      /* The link is already in use.  */
+      if (link->private_fn != hook)
+	abort ();
+    }
+}
+
+void
+unregister_close_hook (struct close_hook *link)
+{
+  struct close_hook *next = link->private_next;
+  struct close_hook *prev = link->private_prev;
+
+  if (next != NULL && prev != NULL)
+    {
+      /* The link is in use.  Remove it from the doubly linked list.  */
+      prev->private_next = next;
+      next->private_prev = prev;
+      /* Clear the link, to mark it unused.  */
+      link->private_next = NULL;
+      link->private_prev = NULL;
+      link->private_fn = NULL;
+    }
+}
+
+#endif