root/lib/dirfd.c

DEFINITIONS

1. _gl_register_dirp_fd
2. _gl_unregister_dirp_fd
3. dirfd

     1 /* dirfd.c -- return the file descriptor associated with an open DIR*
     2 
     3    Copyright (C) 2001, 2006, 2008-2023 Free Software Foundation, Inc.
     4 
     5    This file is free software: you can redistribute it and/or modify
     6    it under the terms of the GNU Lesser General Public License as
     7    published by the Free Software Foundation; either version 2.1 of the
     8    License, or (at your option) any later version.
     9 
    10    This file 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 Lesser General Public License for more details.
    14 
    15    You should have received a copy of the GNU Lesser 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 }