mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-04 19:00:09 +00:00
115 lines
3.7 KiB
C
115 lines
3.7 KiB
C
/* Copyright (C) 1993,95,96,97,98 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 <dirent.h>
|
|
#include <stddef.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <sys/param.h>
|
|
#include <sys/types.h>
|
|
|
|
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
|
|
|
|
|
|
extern int __getdents __P ((int fd, char *buf, size_t nbytes));
|
|
|
|
/* For Solaris 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.
|
|
|
|
He is the system definition of `struct dirent' as of 2.6: */
|
|
|
|
struct kernel_dirent
|
|
{
|
|
ino_t d_ino;
|
|
off_t d_off;
|
|
unsigned short int d_reclen;
|
|
char d_name[256];
|
|
};
|
|
|
|
#ifdef GETDENTS64
|
|
#define __getdirentries __getdirentries64
|
|
#define dirent dirent64
|
|
#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 estimate number of entries
|
|
which fit in the buffer. Taking this number allows us to specify a
|
|
correct number of bytes to read. If we should be wrong, we can reset
|
|
the file descriptor. */
|
|
ssize_t
|
|
__getdirentries (int fd, char *buf, size_t nbytes, off_t *basep)
|
|
{
|
|
off_t base = __lseek (fd, (off_t) 0, SEEK_CUR);
|
|
off_t last_offset = base;
|
|
size_t red_nbytes;
|
|
struct kernel_dirent *skdp, *kdp;
|
|
struct dirent *dp;
|
|
int retval;
|
|
const size_t size_diff = (offsetof (struct dirent, d_name)
|
|
- offsetof (struct kernel_dirent, d_name));
|
|
|
|
red_nbytes = nbytes - ((nbytes / (offsetof (struct dirent, d_name) + 14))
|
|
* size_diff);
|
|
|
|
dp = (struct dirent *) buf;
|
|
skdp = kdp = __alloca (red_nbytes);
|
|
|
|
retval = __getdents (fd, (char *) kdp, red_nbytes);
|
|
|
|
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. */
|
|
__lseek (fd, last_offset, SEEK_SET);
|
|
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);
|
|
}
|
|
|
|
if (basep)
|
|
*basep = base;
|
|
|
|
return (char *) dp - buf;
|
|
}
|
|
|
|
#ifndef GETDENTS64
|
|
weak_alias (__getdirentries, getdirentries)
|
|
#endif
|