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/* Read a directory. Linux no-LFS version.
Copyright (C) 2018-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <dirent.h>
#if !_DIRENT_MATCHES_DIRENT64
#include <dirstream.h>
#include <unistd.h>
# ifndef DIRENT_SET_DP_INO
# define DIRENT_SET_DP_INO(dp, value) (dp)->d_ino = (value)
# endif
/* Read a directory entry from DIRP. */
struct dirent *
__readdir_unlocked (DIR *dirp)
{
int saved_errno = errno;
while (1)
{
if (dirp->offset >= dirp->size)
{
ssize_t bytes = __getdents64 (dirp->fd, dirp->data,
dirp->allocation);
if (bytes <= 0)
{
/* Linux may fail with ENOENT on some file systems if the
directory inode is marked as dead (deleted). POSIX
treats this as a regular end-of-directory condition, so
do not set errno in that case, to indicate success. */
if (bytes < 0 && errno == ENOENT)
__set_errno (saved_errno);
return NULL;
}
dirp->size = bytes;
/* Reset the offset into the buffer. */
dirp->offset = 0;
}
/* These two pointers might alias the same memory buffer. Standard C
requires that we always use the same type for them, so we must use the
union type. */
union
{
struct dirent64 dp64;
struct dirent dp;
char *b;
} *inp, *outp;
inp = (void*) &dirp->data[dirp->offset];
outp = (void*) &dirp->data[dirp->offset];
const size_t size_diff = offsetof (struct dirent64, d_name)
- offsetof (struct dirent, d_name);
/* Since inp->dp64.d_reclen is already aligned for the kernel structure
this may compute a value that is bigger than necessary. */
size_t old_reclen = inp->dp64.d_reclen;
size_t new_reclen = ALIGN_UP (old_reclen - size_diff,
_Alignof (struct dirent));
if (!in_ino_t_range (inp->dp64.d_ino)
|| !in_off_t_range (inp->dp64.d_off))
{
/* Overflow. If there was at least one entry before this one,
return them without error, otherwise signal overflow. */
if (dirp->offset != 0)
{
__lseek64 (dirp->fd, dirp->offset, SEEK_SET);
outp = (void*)(outp->b - dirp->data);
return &outp->dp;
}
__set_errno (EOVERFLOW);
return NULL;
}
/* Copy the data from INP and access only OUTP. */
const uint64_t d_ino = inp->dp64.d_ino;
const int64_t d_off = inp->dp64.d_off;
const uint8_t d_type = inp->dp64.d_type;
outp->dp.d_ino = d_ino;
outp->dp.d_off = d_off;
outp->dp.d_reclen = new_reclen;
outp->dp.d_type = d_type;
memmove (outp->dp.d_name, inp->dp64.d_name,
old_reclen - offsetof (struct dirent64, d_name));
dirp->filepos = d_off;
dirp->offset += old_reclen;
return &outp->dp;
}
}
struct dirent *
__readdir (DIR *dirp)
{
struct dirent *dp;
#if IS_IN (libc)
__libc_lock_lock (dirp->lock);
#endif
dp = __readdir_unlocked (dirp);
#if IS_IN (libc)
__libc_lock_unlock (dirp->lock);
#endif
return dp;
}
weak_alias (__readdir, readdir)
#endif
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