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/* Copyright (C) 1993, 1995-2002 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 <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 <sys/syscall.h>
#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif
struct kernel_dirent
{
long d_ino;
__kernel_off_t d_off;
unsigned short d_reclen;
char d_name[256];
};
#define __NR___syscall_getdents __NR_getdents
static inline _syscall3(int, __syscall_getdents, int, fd, unsigned char *, kdirp, size_t, count);
ssize_t attribute_hidden __getdents (int fd, char *buf, size_t nbytes)
{
struct dirent *dp;
off_t last_offset = -1;
ssize_t retval;
size_t red_nbytes;
struct kernel_dirent *skdp, *kdp;
const size_t size_diff = (offsetof (struct dirent, d_name)
- offsetof (struct kernel_dirent, d_name));
red_nbytes = MIN (nbytes - ((nbytes /
(offsetof (struct dirent, d_name) + 14)) * size_diff),
nbytes - size_diff);
dp = (struct dirent *) buf;
skdp = kdp = alloca (red_nbytes);
retval = __syscall_getdents(fd, (char *)kdp, red_nbytes);
if (retval == -1)
return -1;
while ((char *) kdp < (char *) skdp + retval) {
const size_t alignment = __alignof__ (struct dirent);
/* 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;
dp->d_ino = 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 = (struct dirent *) ((char *) dp + new_reclen);
kdp = (struct kernel_dirent *) (((char *) kdp) + kdp->d_reclen);
}
return (char *) dp - buf;
}
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