sysdeps/unix/readdir.c

   1 /* Copyright (C) 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <errno.h>
  21 #include <limits.h>
  22 #include <stddef.h>
  23 #include <string.h>
  24 #include <dirent.h>
  25 #include <unistd.h>
  26 #include <sys/types.h>
  27
  28 #include "direct.h"             /* This file defines `struct direct'.  */
  29
  30 /* direct.h may have an alternate definition for this.  */
  31 #ifndef D_RECLEN
  32 #define D_RECLEN(dp)    ((dp)->d_reclen)
  33 #endif
  34
  35
  36 /* Read a directory entry from DIRP.  */
  37 struct dirent *
  38 DEFUN(readdir, (dirp), DIR *dirp)
  39 {
  40   if (dirp == NULL || dirp->__data == NULL)
  41     {
  42       errno = EINVAL;
  43       return NULL;
  44     }
  45
  46   while (1)
  47     {
  48       struct direct *dp;
  49
  50       if (dirp->__offset >= dirp->__size)
  51         {
  52           /* We've emptied out our buffer.  Refill it.  */
  53
  54           off_t base;
  55           ssize_t bytes = __getdirentries (dirp->__fd, dirp->__data,
  56                                            dirp->__allocation, &base);
  57           if (bytes <= 0)
  58             return NULL;
  59           dirp->__size = (size_t) bytes;
  60
  61           /* Reset the offset into the buffer.  */
  62           dirp->__offset = 0;
  63         }
  64
  65       dp = (struct direct *) &dirp->__data[dirp->__offset];
  66       dirp->__offset += D_RECLEN (dp);
  67
  68       if (dp->d_ino != 0)
  69         {
  70           /* Not a deleted file.  */
  71           register struct dirent *d = &dirp->__entry;
  72           register const char *p;
  73           d->d_fileno = (ino_t) dp->d_ino;
  74           /* On some systems the name length does not actually mean much.
  75              But we always use it as a maximum.  */
  76           p = memchr ((PTR) dp->d_name, '\0', D_NAMLEN (dp) + 1);
  77           d->d_namlen = (p != NULL) ? p - dp->d_name : D_NAMLEN (dp);
  78           memcpy (d->d_name, dp->d_name, d->d_namlen + 1);
  79           return d;
  80         }
  81     }
  82 }