glibc/sysdeps/unix/readdir_r.c
Ulrich Drepper 1a81139728 Handle unnecessary padding in getdents64.
The getdents64 syscall adds on 32-but platforms padding which isn't needed
and not included in the userlevel data structure definition.  We have to
avoid copying those padding bytes in the readdir64_r function.
2010-04-03 23:51:40 -07:00

138 lines
3.5 KiB
C

/* Copyright (C) 1991,92,93,94,95,96,97,98,99,2000,02,10
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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <errno.h>
#include <limits.h>
#include <stddef.h>
#include <string.h>
#include <dirent.h>
#include <unistd.h>
#include <sys/types.h>
#include <assert.h>
#include <dirstream.h>
#ifndef __READDIR_R
# define __READDIR_R __readdir_r
# define __GETDENTS __getdents
# define DIRENT_TYPE struct dirent
# define __READDIR_R_ALIAS
#endif
/* Read a directory entry from DIRP. */
int
__READDIR_R (DIR *dirp, DIRENT_TYPE *entry, DIRENT_TYPE **result)
{
DIRENT_TYPE *dp;
size_t reclen;
const int saved_errno = errno;
__libc_lock_lock (dirp->lock);
do
{
if (dirp->offset >= dirp->size)
{
/* We've emptied out our buffer. Refill it. */
size_t maxread;
ssize_t bytes;
#ifndef _DIRENT_HAVE_D_RECLEN
/* Fixed-size struct; must read one at a time (see below). */
maxread = sizeof *dp;
#else
maxread = dirp->allocation;
#endif
bytes = __GETDENTS (dirp->fd, dirp->data, maxread);
if (bytes <= 0)
{
/* On some systems getdents fails with ENOENT when the
open directory has been rmdir'd already. POSIX.1
requires that we treat this condition like normal EOF. */
if (bytes < 0 && errno == ENOENT)
{
bytes = 0;
__set_errno (saved_errno);
}
dp = NULL;
/* Reclen != 0 signals that an error occurred. */
reclen = bytes != 0;
break;
}
dirp->size = (size_t) bytes;
/* Reset the offset into the buffer. */
dirp->offset = 0;
}
dp = (DIRENT_TYPE *) &dirp->data[dirp->offset];
#ifdef _DIRENT_HAVE_D_RECLEN
reclen = dp->d_reclen;
#else
/* The only version of `struct dirent*' that lacks `d_reclen'
is fixed-size. */
assert (sizeof dp->d_name > 1);
reclen = sizeof *dp;
/* The name is not terminated if it is the largest possible size.
Clobber the following byte to ensure proper null termination. We
read just one entry at a time above so we know that byte will not
be used later. */
dp->d_name[sizeof dp->d_name] = '\0';
#endif
dirp->offset += reclen;
#ifdef _DIRENT_HAVE_D_OFF
dirp->filepos = dp->d_off;
#else
dirp->filepos += reclen;
#endif
/* Skip deleted files. */
}
while (dp->d_ino == 0);
if (dp != NULL)
{
#ifdef GETDENTS_64BIT_ALIGNED
/* The d_reclen value might include padding which is not part of
the DIRENT_TYPE data structure. */
reclen = MIN (reclen, sizeof (DIRENT_TYPE));
#endif
*result = memcpy (entry, dp, reclen);
#ifdef GETDENTS_64BIT_ALIGNED
entry->d_reclen = reclen;
#endif
}
else
*result = NULL;
__libc_lock_unlock (dirp->lock);
return dp != NULL ? 0 : reclen ? errno : 0;
}
#ifdef __READDIR_R_ALIAS
weak_alias (__readdir_r, readdir_r)
#endif