sysdeps/unix/readdir.c

   1 /* Copyright (C) 1991, 1992, 1993, 1994, 1995 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 #include "dirstream.h"
  30
  31 /* direct.h may have an alternate definition for this.  */
  32 #ifndef D_RECLEN
  33 #define D_RECLEN(dp)    ((dp)->d_reclen)
  34 #endif
  35
  36
  37 /* Read a directory entry from DIRP.  */
  38 struct dirent *
  39 DEFUN(readdir, (dirp), DIR *dirp)
  40 {
  41   if (dirp == NULL || dirp->__data == NULL)
  42     {
  43       errno = EINVAL;
  44       return NULL;
  45     }
  46
  47   while (1)
  48     {
  49       struct direct *dp;
  50
  51       if (dirp->__offset >= dirp->__size)
  52         {
  53           /* We've emptied out our buffer.  Refill it.  */
  54
  55           off_t base;
  56           ssize_t bytes = __getdirentries (dirp->__fd, dirp->__data,
  57                                            dirp->__allocation, &base);
  58           if (bytes <= 0)
  59             return NULL;
  60           dirp->__size = (size_t) bytes;
  61
  62           /* Reset the offset into the buffer.  */
  63           dirp->__offset = 0;
  64         }
  65
  66       dp = (struct direct *) &dirp->__data[dirp->__offset];
  67       dirp->__offset += D_RECLEN (dp);
  68
  69       if (dp->d_ino != 0)
  70         {
  71           /* Not a deleted file.  */
  72           register struct dirent *d = &dirp->__entry;
  73           register const char *p;
  74           d->d_fileno = (ino_t) dp->d_ino;
  75           /* On some systems the name length does not actually mean much.
  76              But we always use it as a maximum.  */
  77           p = memchr ((PTR) dp->d_name, '\0', D_NAMLEN (dp) + 1);
  78           d->d_namlen = (p != NULL) ? p - dp->d_name : D_NAMLEN (dp);
  79           memcpy (d->d_name, dp->d_name, d->d_namlen + 1);
  80           return d;
  81         }
  82     }
  83 }