1 files changed, 109 insertions, 0 deletions
diff --git a/lib/dirfd.c b/lib/dirfd.c
new file mode 100644
index 0000000..75b2163
--- /dev/null
+++ b/lib/dirfd.c
@@ -0,0 +1,109 @@
+/* dirfd.c -- return the file descriptor associated with an open DIR*
+
+   Copyright (C) 2001, 2006, 2008-2023 Free Software Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file 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 Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Jim Meyering. */
+
+#include <config.h>
+
+#include <dirent.h>
+#include <errno.h>
+
+#if GNULIB_defined_DIR
+# include "dirent-private.h"
+#endif
+
+#ifdef __KLIBC__
+# include <stdlib.h>
+# include <io.h>
+
+static struct dirp_fd_list
+{
+  DIR *dirp;
+  int fd;
+  struct dirp_fd_list *next;
+} *dirp_fd_start = NULL;
+
+/* Register fd associated with dirp to dirp_fd_list. */
+int
+_gl_register_dirp_fd (int fd, DIR *dirp)
+{
+  struct dirp_fd_list *new_dirp_fd = malloc (sizeof *new_dirp_fd);
+  if (!new_dirp_fd)
+    return -1;
+
+  new_dirp_fd->dirp = dirp;
+  new_dirp_fd->fd = fd;
+  new_dirp_fd->next = dirp_fd_start;
+
+  dirp_fd_start = new_dirp_fd;
+
+  return 0;
+}
+
+/* Unregister fd from dirp_fd_list with closing it */
+void
+_gl_unregister_dirp_fd (int fd)
+{
+  struct dirp_fd_list *dirp_fd;
+  struct dirp_fd_list *dirp_fd_prev;
+
+  for (dirp_fd_prev = NULL, dirp_fd = dirp_fd_start; dirp_fd;
+       dirp_fd_prev = dirp_fd, dirp_fd = dirp_fd->next)
+    {
+      if (dirp_fd->fd == fd)
+        {
+          if (dirp_fd_prev)
+            dirp_fd_prev->next = dirp_fd->next;
+          else  /* dirp_fd == dirp_fd_start */
+            dirp_fd_start = dirp_fd_start->next;
+
+          close (fd);
+          free (dirp_fd);
+          break;
+        }
+    }
+}
+#endif
+
+int
+dirfd (DIR *dir_p)
+{
+#if GNULIB_defined_DIR
+  int fd = dir_p->fd_to_close;
+  if (fd == -1)
+    errno = EINVAL;
+  return fd;
+#else
+  int fd = DIR_TO_FD (dir_p);
+  if (fd == -1)
+# ifndef __KLIBC__
+    errno = ENOTSUP;
+# else
+    {
+      struct dirp_fd_list *dirp_fd;
+
+      for (dirp_fd = dirp_fd_start; dirp_fd; dirp_fd = dirp_fd->next)
+        if (dirp_fd->dirp == dir_p)
+          return dirp_fd->fd;
+
+      errno = EINVAL;
+    }
+# endif
+
+  return fd;
+#endif
+}