1  /* Read a directory.  Linux LFS version.
       2     Copyright (C) 1997-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library 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 GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  /* When _DIRENT_MATCHES_DIRENT64 is defined we can alias 'readdir64' to
      20     'readdir'.  However the function signatures are not equal due
      21     different return types, so we need to suppress {__}readdir so weak
      22     and strong alias do not throw conflicting types errors.  */
      23  #define readdir   __no_readdir_decl
      24  #define __readdir __no___readdir_decl
      25  #include <dirent.h>
      26  #undef __readdir
      27  #undef readdir
      28  
      29  /* Read a directory entry from DIRP.  */
      30  struct dirent64 *
      31  __readdir64 (DIR *dirp)
      32  {
      33    struct dirent64 *dp;
      34    int saved_errno = errno;
      35  
      36  #if IS_IN (libc)
      37    __libc_lock_lock (dirp->lock);
      38  #endif
      39  
      40    if (dirp->offset >= dirp->size)
      41      {
      42        /* We've emptied out our buffer.  Refill it.  */
      43  
      44        size_t maxread = dirp->allocation;
      45        ssize_t bytes;
      46  
      47        bytes = __getdents64 (dirp->fd, dirp->data, maxread);
      48        if (bytes <= 0)
      49  	{
      50  	  /* Linux may fail with ENOENT on some file systems if the
      51  	     directory inode is marked as dead (deleted).  POSIX
      52  	     treats this as a regular end-of-directory condition, so
      53  	     do not set errno in that case, to indicate success.  */
      54  	  if (bytes == 0 || errno == ENOENT)
      55  	    __set_errno (saved_errno);
      56  #if IS_IN (libc)
      57  	  __libc_lock_unlock (dirp->lock);
      58  #endif
      59  	  return NULL;
      60  	}
      61        dirp->size = (size_t) bytes;
      62  
      63        /* Reset the offset into the buffer.  */
      64        dirp->offset = 0;
      65      }
      66  
      67    dp = (struct dirent64 *) &dirp->data[dirp->offset];
      68    dirp->offset += dp->d_reclen;
      69    dirp->filepos = dp->d_off;
      70  
      71  #if IS_IN (libc)
      72    __libc_lock_unlock (dirp->lock);
      73  #endif
      74  
      75    return dp;
      76  }
      77  libc_hidden_def (__readdir64)
      78  
      79  #if _DIRENT_MATCHES_DIRENT64
      80  strong_alias (__readdir64, __readdir)
      81  weak_alias (__readdir64, readdir64)
      82  weak_alias (__readdir64, readdir)
      83  #else
      84  /* The compat code expects the 'struct direct' with d_ino being a __ino_t
      85     instead of __ino64_t.  */
      86  # include <shlib-compat.h>
      87  # if IS_IN(rtld)
      88  weak_alias (__readdir64, readdir64)
      89  # else
      90  versioned_symbol (libc, __readdir64, readdir64, GLIBC_2_2);
      91  # endif
      92  # if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
      93  #  include <olddirent.h>
      94  
      95  attribute_compat_text_section
      96  struct __old_dirent64 *
      97  __old_readdir64 (DIR *dirp)
      98  {
      99    struct __old_dirent64 *dp;
     100    int saved_errno = errno;
     101  
     102  #if IS_IN (libc)
     103    __libc_lock_lock (dirp->lock);
     104  #endif
     105  
     106    if (dirp->offset >= dirp->size)
     107      {
     108        /* We've emptied out our buffer.  Refill it.  */
     109  
     110        size_t maxread = dirp->allocation;
     111        ssize_t bytes;
     112  
     113        bytes = __old_getdents64 (dirp->fd, dirp->data, maxread);
     114        if (bytes <= 0)
     115  	{
     116  	  /* Linux may fail with ENOENT on some file systems if the
     117  	     directory inode is marked as dead (deleted).  POSIX
     118  	     treats this as a regular end-of-directory condition, so
     119  	     do not set errno in that case, to indicate success.  */
     120  	  if (bytes == 0 || errno == ENOENT)
     121  	    __set_errno (saved_errno);
     122  #if IS_IN (libc)
     123  	  __libc_lock_unlock (dirp->lock);
     124  #endif
     125  	  return NULL;
     126  	}
     127        dirp->size = (size_t) bytes;
     128  
     129        /* Reset the offset into the buffer.  */
     130        dirp->offset = 0;
     131      }
     132  
     133    dp = (struct __old_dirent64 *) &dirp->data[dirp->offset];
     134    dirp->offset += dp->d_reclen;
     135    dirp->filepos = dp->d_off;
     136  
     137  #if IS_IN (libc)
     138    __libc_lock_unlock (dirp->lock);
     139  #endif
     140  
     141    return dp;
     142  }
     143  libc_hidden_def (__old_readdir64)
     144  compat_symbol (libc, __old_readdir64, readdir64, GLIBC_2_1);
     145  # endif /* SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)  */
     146  #endif /* _DIRENT_MATCHES_DIRENT64  */