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/* Read a directory. Linux LFS version.
Copyright (C) 1997-2025 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/>. */
/* When _DIRENT_MATCHES_DIRENT64 is defined we can alias 'readdir64' to
'readdir'. However the function signatures are not equal due
different return types, so we need to suppress {__}readdir so weak
and strong alias do not throw conflicting types errors. */
#define readdir __no_readdir_decl
#define __readdir __no___readdir_decl
#include <dirent.h>
#undef __readdir
#undef readdir
/* Read a directory entry from DIRP. No locking. */
static struct dirent64 *
__readdir64_unlocked (DIR *dirp)
{
struct dirent64 *dp;
int saved_errno = errno;
if (dirp->offset >= dirp->size)
{
/* We've emptied out our buffer. Refill it. */
size_t maxread = dirp->allocation;
ssize_t bytes;
bytes = __getdents64 (dirp->fd, dirp->data, maxread);
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 = (size_t) bytes;
/* Reset the offset into the buffer. */
dirp->offset = 0;
}
dp = (struct dirent64 *) &dirp->data[dirp->offset];
dirp->offset += dp->d_reclen;
dirp->filepos = dp->d_off;
return dp;
}
/* Read a directory entry from DIRP. */
struct dirent64 *
__readdir64 (DIR *dirp)
{
__libc_lock_lock (dirp->lock);
struct dirent64 *dp = __readdir64_unlocked (dirp);
__libc_lock_unlock (dirp->lock);
return dp;
}
libc_hidden_def (__readdir64)
#if _DIRENT_MATCHES_DIRENT64
strong_alias (__readdir64, __readdir)
weak_alias (__readdir64, readdir64)
weak_alias (__readdir64, readdir)
#else
/* The compat code expects the 'struct direct' with d_ino being a __ino_t
instead of __ino64_t. */
# include <shlib-compat.h>
# if IS_IN(rtld)
weak_alias (__readdir64, readdir64)
# else
versioned_symbol (libc, __readdir64, readdir64, GLIBC_2_2);
# endif
# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
# include <olddirent.h>
attribute_compat_text_section
struct __old_dirent64 *
__old_readdir64 (DIR *dirp)
{
struct __old_dirent64 *dp;
int saved_errno = errno;
__libc_lock_lock (dirp->lock);
while (1)
{
errno = 0;
struct dirent64 *newdp = __readdir64_unlocked (dirp);
if (newdp == NULL)
{
if (errno == 0 && dirp->errcode != 0)
__set_errno (dirp->errcode);
else if (errno == 0)
__set_errno (saved_errno);
dp = NULL;
break;
}
/* Convert to the target layout. Use a separate struct and
memcpy to side-step aliasing issues. */
struct __old_dirent64 result;
result.d_ino = newdp->d_ino;
result.d_off = newdp->d_off;
result.d_reclen = newdp->d_reclen;
result.d_type = newdp->d_type;
/* Check for ino_t overflow. */
if (__glibc_unlikely (result.d_ino != newdp->d_ino))
{
dirp->errcode = ENAMETOOLONG;
continue;
}
/* Overwrite the fixed-sized part. */
dp = (struct __old_dirent64 *) newdp;
memcpy (dp, &result, offsetof (struct __old_dirent64, d_name));
/* Move the name. */
_Static_assert (offsetof (struct __old_dirent64, d_name)
<= offsetof (struct dirent64, d_name),
"old struct must be smaller");
if (offsetof (struct __old_dirent64, d_name)
!= offsetof (struct dirent64, d_name))
memmove (dp->d_name, newdp->d_name, strlen (newdp->d_name) + 1);
__set_errno (saved_errno);
break;
}
__libc_lock_unlock (dirp->lock);
return dp;
}
libc_hidden_def (__old_readdir64)
compat_symbol (libc, __old_readdir64, readdir64, GLIBC_2_1);
# endif /* SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2) */
#endif /* _DIRENT_MATCHES_DIRENT64 */
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