mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-04 10:50:07 +00:00
559dce193e
2000-11-28 Andreas Jaeger <aj@suse.de> * sysdeps/unix/sysv/linux/getdents.c: Add _syscall_getdents64 declaration, adjust declaration of __syscall_getdents to match kernel.
253 lines
7.4 KiB
C
253 lines
7.4 KiB
C
/* Copyright (C) 1993, 95, 96, 97, 98, 99, 2000 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 Library General Public License as
|
|
published by the Free Software Foundation; either version 2 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
|
|
Library General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public
|
|
License along with the GNU C Library; see the file COPYING.LIB. If not,
|
|
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include <alloca.h>
|
|
#include <assert.h>
|
|
#include <errno.h>
|
|
#include <dirent.h>
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <sys/param.h>
|
|
#include <sys/types.h>
|
|
|
|
#include <sysdep.h>
|
|
#include <sys/syscall.h>
|
|
#include <bp-checks.h>
|
|
|
|
#include <linux/posix_types.h>
|
|
|
|
#include "kernel-features.h"
|
|
|
|
#ifdef __NR_getdents64
|
|
#ifndef __ASSUME_GETDENTS64_SYSCALL
|
|
#ifndef __GETDENTS
|
|
/* The variable is shared between all *getdents* calls. */
|
|
int __have_no_getdents64;
|
|
#else
|
|
extern int __have_no_getdents64;
|
|
#endif
|
|
#endif
|
|
#endif
|
|
|
|
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
|
|
|
|
extern int __syscall_getdents (int fd, char *__unbounded buf, unsigned int nbytes);
|
|
extern int __syscall_getdents64 (int fd, char *__unbounded buf, unsigned int nbytes);
|
|
|
|
/* For Linux we need a special version of this file since the
|
|
definition of `struct dirent' is not the same for the kernel and
|
|
the libc. There is one additional field which might be introduced
|
|
in the kernel structure in the future.
|
|
|
|
Here is the kernel definition of `struct dirent' as of 2.1.20: */
|
|
|
|
struct kernel_dirent
|
|
{
|
|
long int d_ino;
|
|
__kernel_off_t d_off;
|
|
unsigned short int d_reclen;
|
|
char d_name[256];
|
|
};
|
|
|
|
struct kernel_dirent64
|
|
{
|
|
uint64_t d_ino;
|
|
int64_t d_off;
|
|
unsigned short int d_reclen;
|
|
unsigned char d_type;
|
|
char d_name[256];
|
|
};
|
|
|
|
#ifndef __GETDENTS
|
|
# define __GETDENTS __getdents
|
|
#endif
|
|
#ifndef DIRENT_TYPE
|
|
# define DIRENT_TYPE struct dirent
|
|
#endif
|
|
#ifndef DIRENT_SET_DP_INO
|
|
# define DIRENT_SET_DP_INO(dp, value) (dp)->d_ino = (value)
|
|
#endif
|
|
|
|
/* The problem here is that we cannot simply read the next NBYTES
|
|
bytes. We need to take the additional field into account. We use
|
|
some heuristic. Assuming the directory contains names with 14
|
|
characters on average we can compute an estimated number of entries
|
|
which fit in the buffer. Taking this number allows us to specify a
|
|
reasonable number of bytes to read. If we should be wrong, we can
|
|
reset the file descriptor. In practice the kernel is limiting the
|
|
amount of data returned much more then the reduced buffer size. */
|
|
ssize_t
|
|
internal_function
|
|
__GETDENTS (int fd, char *buf, size_t nbytes)
|
|
{
|
|
DIRENT_TYPE *dp;
|
|
off_t last_offset = -1;
|
|
ssize_t retval;
|
|
|
|
#ifdef __NR_getdents64
|
|
# ifndef __ASSUME_GETDENTS64_SYSCALL
|
|
if (!__have_no_getdents64)
|
|
# endif
|
|
{
|
|
# ifndef __ASSUME_GETDENTS64_SYSCALL
|
|
int saved_errno = errno;
|
|
# endif
|
|
char *kbuf = buf;
|
|
size_t kbytes = nbytes;
|
|
if (offsetof (DIRENT_TYPE, d_name)
|
|
< offsetof (struct kernel_dirent64, d_name)
|
|
&& nbytes <= sizeof (DIRENT_TYPE))
|
|
{
|
|
kbytes = nbytes + offsetof (struct kernel_dirent64, d_name)
|
|
- offsetof (DIRENT_TYPE, d_name);
|
|
kbuf = __alloca(kbytes);
|
|
}
|
|
retval = INLINE_SYSCALL (getdents64, 3, fd, CHECK_N(kbuf, kbytes),
|
|
kbytes);
|
|
# ifndef __ASSUME_GETDENTS64_SYSCALL
|
|
if (retval != -1 && errno != -EINVAL)
|
|
# endif
|
|
{
|
|
struct kernel_dirent64 *kdp;
|
|
const size_t size_diff = (offsetof (struct kernel_dirent64, d_name)
|
|
- offsetof (DIRENT_TYPE, d_name));
|
|
|
|
/* If the structure returned by the kernel is identical to what we
|
|
need, don't do any conversions. */
|
|
if (offsetof (DIRENT_TYPE, d_name)
|
|
== offsetof (struct kernel_dirent64, d_name)
|
|
&& sizeof (dp->d_ino) == sizeof (kdp->d_ino)
|
|
&& sizeof (dp->d_off) == sizeof (kdp->d_off))
|
|
return retval;
|
|
|
|
dp = (DIRENT_TYPE *)buf;
|
|
kdp = (struct kernel_dirent64 *)kbuf;
|
|
while ((char *) kdp < kbuf + retval)
|
|
{
|
|
const size_t alignment = __alignof__ (DIRENT_TYPE);
|
|
/* Since kdp->d_reclen is already aligned for the kernel
|
|
structure this may compute a value that is bigger
|
|
than necessary. */
|
|
size_t old_reclen = kdp->d_reclen;
|
|
size_t new_reclen = ((old_reclen - size_diff + alignment - 1)
|
|
& ~(alignment - 1));
|
|
uint64_t d_ino = kdp->d_ino;
|
|
int64_t d_off = kdp->d_off;
|
|
unsigned char d_type = kdp->d_type;
|
|
|
|
DIRENT_SET_DP_INO(dp, d_ino);
|
|
dp->d_off = d_off;
|
|
if ((sizeof (dp->d_ino) != sizeof (kdp->d_ino)
|
|
&& dp->d_ino != d_ino)
|
|
|| (sizeof (dp->d_off) != sizeof (kdp->d_off)
|
|
&& dp->d_off != d_off))
|
|
{
|
|
/* Overflow. If there was at least one entry
|
|
before this one, return them without error,
|
|
otherwise signal overflow. */
|
|
if (last_offset != -1)
|
|
{
|
|
__lseek (fd, last_offset, SEEK_SET);
|
|
return (char *) dp - buf;
|
|
}
|
|
__set_errno (EOVERFLOW);
|
|
return -1;
|
|
}
|
|
|
|
last_offset = d_off;
|
|
dp->d_reclen = new_reclen;
|
|
dp->d_type = d_type;
|
|
memmove (dp->d_name, kdp->d_name,
|
|
old_reclen - offsetof (struct kernel_dirent64, d_name));
|
|
|
|
dp = (DIRENT_TYPE *) ((char *) dp + new_reclen);
|
|
kdp = (struct kernel_dirent64 *) ((char *) kdp + old_reclen);
|
|
}
|
|
|
|
return (char *) dp - buf;
|
|
}
|
|
|
|
# ifndef __ASSUME_GETDENTS64_SYSCALL
|
|
__set_errno (saved_errno);
|
|
__have_no_getdents64 = 1;
|
|
# endif
|
|
}
|
|
#endif
|
|
{
|
|
size_t red_nbytes;
|
|
struct kernel_dirent *skdp, *kdp;
|
|
const size_t size_diff = (offsetof (DIRENT_TYPE, d_name)
|
|
- offsetof (struct kernel_dirent, d_name));
|
|
|
|
red_nbytes = MIN (nbytes
|
|
- ((nbytes / (offsetof (DIRENT_TYPE, d_name) + 14))
|
|
* size_diff),
|
|
nbytes - size_diff);
|
|
|
|
dp = (DIRENT_TYPE *) buf;
|
|
skdp = kdp = __alloca (red_nbytes);
|
|
|
|
retval = INLINE_SYSCALL (getdents, 3, fd,
|
|
CHECK_N ((char *) kdp, red_nbytes), red_nbytes);
|
|
|
|
if (retval == -1)
|
|
return -1;
|
|
|
|
while ((char *) kdp < (char *) skdp + retval)
|
|
{
|
|
const size_t alignment = __alignof__ (DIRENT_TYPE);
|
|
/* Since kdp->d_reclen is already aligned for the kernel structure
|
|
this may compute a value that is bigger than necessary. */
|
|
size_t new_reclen = ((kdp->d_reclen + size_diff + alignment - 1)
|
|
& ~(alignment - 1));
|
|
if ((char *) dp + new_reclen > buf + nbytes)
|
|
{
|
|
/* Our heuristic failed. We read too many entries. Reset
|
|
the stream. */
|
|
assert (last_offset != -1);
|
|
__lseek (fd, last_offset, SEEK_SET);
|
|
|
|
if ((char *) dp == buf)
|
|
{
|
|
/* The buffer the user passed in is too small to hold even
|
|
one entry. */
|
|
__set_errno (EINVAL);
|
|
return -1;
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
last_offset = kdp->d_off;
|
|
DIRENT_SET_DP_INO(dp, kdp->d_ino);
|
|
dp->d_off = kdp->d_off;
|
|
dp->d_reclen = new_reclen;
|
|
dp->d_type = DT_UNKNOWN;
|
|
memcpy (dp->d_name, kdp->d_name,
|
|
kdp->d_reclen - offsetof (struct kernel_dirent, d_name));
|
|
|
|
dp = (DIRENT_TYPE *) ((char *) dp + new_reclen);
|
|
kdp = (struct kernel_dirent *) (((char *) kdp) + kdp->d_reclen);
|
|
}
|
|
}
|
|
|
|
return (char *) dp - buf;
|
|
}
|