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