lib/fdopendir-glibc.c

   1 /* fdopendir implementation derived from glibc.
   2
   3    Copyright (C) 2006 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 2, or (at your option)
   8    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 along
  16    with this program; if not, write to the Free Software Foundation,
  17    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 #include <config.h>
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include <string.h>
  25 #include <stdbool.h>
  26 #include <dirent.h>
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #include <sys/stat.h>
  30
  31 #if _LIBC
  32 # include <dirstream.h>
  33 # include <not-cancel.h>
  34
  35 #else
  36
  37 # if __GNUC__ < 3
  38 #  define __builtin_expect(expr, expected_val) expr
  39 # endif
  40
  41 # include "openat.h"
  42 # define stat64 stat
  43 # define dirent64 dirent
  44 # define __fxstat64(V, fd, sb) fstat(fd, sb)
  45 # define __fcntl fcntl
  46 # define __set_errno(Val) do { errno = (Val); } while (0)
  47 # define __libc_lock_init(NAME) ((NAME) = 0, 0)
  48 # define close_not_cancel_no_status(fd) close (fd)
  49 # ifdef __i386__
  50 #  define internal_function __attribute ((regparm (3), stdcall))
  51 # else
  52 #  define internal_function
  53 # endif
  54
  55 struct __dirstream
  56   {
  57     int fd;                     /* File descriptor.  */
  58
  59     char *data;                 /* Directory block.  */
  60     size_t allocation;          /* Space allocated for the block.  */
  61     size_t size;                /* Total valid data in the block.  */
  62     size_t offset;              /* Current offset into the block.  */
  63
  64     off_t filepos;              /* Position of next entry to read.  */
  65     int lock;
  66   };
  67 #endif
  68
  69 #undef _STATBUF_ST_BLKSIZE
  70
  71 static DIR *
  72 internal_function
  73 __alloc_dir (int fd, bool close_fd)
  74 {
  75   if (__builtin_expect (__fcntl (fd, F_SETFD, FD_CLOEXEC), 0) < 0)
  76     goto lose;
  77
  78   size_t allocation;
  79 #ifdef _STATBUF_ST_BLKSIZE
  80   if (__builtin_expect ((size_t) statp->st_blksize >= sizeof (struct dirent64),
  81                         1))
  82     allocation = statp->st_blksize;
  83   else
  84 #endif
  85     allocation = (BUFSIZ < sizeof (struct dirent64)
  86                   ? sizeof (struct dirent64) : BUFSIZ);
  87
  88   const int pad = -sizeof (DIR) % __alignof__ (struct dirent64);
  89
  90   DIR *dirp = (DIR *) malloc (sizeof (DIR) + allocation + pad);
  91   if (dirp == NULL)
  92   lose:
  93     {
  94       if (close_fd)
  95         {
  96           int save_errno = errno;
  97           close_not_cancel_no_status (fd);
  98           __set_errno (save_errno);
  99         }
 100       return NULL;
 101     }
 102   memset (dirp, '\0', sizeof (DIR));
 103   dirp->data = (char *) (dirp + 1) + pad;
 104   dirp->allocation = allocation;
 105   dirp->fd = fd;
 106
 107   __libc_lock_init (dirp->lock);
 108
 109   return dirp;
 110 }
 111
 112 DIR *
 113 fdopendir (int fd)
 114 {
 115 #if 0
 116   struct stat64 statbuf;
 117
 118   if (__builtin_expect (__fxstat64 (_STAT_VER, fd, &statbuf), 0) < 0)
 119     return NULL;
 120   if (__builtin_expect (! S_ISDIR (statbuf.st_mode), 0))
 121     {
 122       __set_errno (ENOTDIR);
 123       return NULL;
 124     }
 125   /* Make sure the descriptor allows for reading.  */
 126   int flags = __fcntl (fd, F_GETFL);
 127   if (__builtin_expect (flags == -1, 0))
 128     return NULL;
 129   if (__builtin_expect ((flags & O_ACCMODE) == O_WRONLY, 0))
 130     {
 131       __set_errno (EINVAL);
 132       return NULL;
 133     }
 134 #endif
 135
 136   return __alloc_dir (fd, false);
 137 }