lib/dirfd.c

   1 /* dirfd.c -- return the file descriptor associated with an open DIR*
   2
   3    Copyright (C) 2001, 2006, 2008-2018 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Jim Meyering. */
  19
  20 #include <config.h>
  21
  22 #include <dirent.h>
  23 #include <errno.h>
  24
  25 #ifdef __KLIBC__
  26 # include <stdlib.h>
  27 # include <io.h>
  28
  29 static struct dirp_fd_list
  30 {
  31   DIR *dirp;
  32   int fd;
  33   struct dirp_fd_list *next;
  34 } *dirp_fd_start = NULL;
  35
  36 /* Register fd associated with dirp to dirp_fd_list. */
  37 int
  38 _gl_register_dirp_fd (int fd, DIR *dirp)
  39 {
  40   struct dirp_fd_list *new_dirp_fd = malloc (sizeof *new_dirp_fd);
  41   if (!new_dirp_fd)
  42     return -1;
  43
  44   new_dirp_fd->dirp = dirp;
  45   new_dirp_fd->fd = fd;
  46   new_dirp_fd->next = dirp_fd_start;
  47
  48   dirp_fd_start = new_dirp_fd;
  49
  50   return 0;
  51 }
  52
  53 /* Unregister fd from dirp_fd_list with closing it */
  54 void
  55 _gl_unregister_dirp_fd (int fd)
  56 {
  57   struct dirp_fd_list *dirp_fd;
  58   struct dirp_fd_list *dirp_fd_prev;
  59
  60   for (dirp_fd_prev = NULL, dirp_fd = dirp_fd_start; dirp_fd;
  61        dirp_fd_prev = dirp_fd, dirp_fd = dirp_fd->next)
  62     {
  63       if (dirp_fd->fd == fd)
  64         {
  65           if (dirp_fd_prev)
  66             dirp_fd_prev->next = dirp_fd->next;
  67           else  /* dirp_fd == dirp_fd_start */
  68             dirp_fd_start = dirp_fd_start->next;
  69
  70           close (fd);
  71           free (dirp_fd);
  72           break;
  73         }
  74     }
  75 }
  76 #endif
  77
  78 int
  79 dirfd (DIR *dir_p)
  80 {
  81   int fd = DIR_TO_FD (dir_p);
  82   if (fd == -1)
  83 #ifndef __KLIBC__
  84     errno = ENOTSUP;
  85 #else
  86     {
  87       struct dirp_fd_list *dirp_fd;
  88
  89       for (dirp_fd = dirp_fd_start; dirp_fd; dirp_fd = dirp_fd->next)
  90         if (dirp_fd->dirp == dir_p)
  91           return dirp_fd->fd;
  92
  93       errno = EINVAL;
  94     }
  95 #endif
  96
  97   return fd;
  98 }