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/*
* Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
#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>
/* With newer versions of linux, the getdents syscall returns d_type
* information after the name field. Someday, we should add support for
* that instead of always calling getdents64 ...
*
* See __ASSUME_GETDENTS32_D_TYPE in glibc's kernel-features.h for specific
* version / arch details.
*/
#ifndef offsetof
# define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif
struct kernel_dirent
{
long int d_ino;
__kernel_off_t d_off;
unsigned short int d_reclen;
char d_name[256];
};
ssize_t __getdents (int fd, char *buf, size_t nbytes) attribute_hidden;
#if ! defined __UCLIBC_HAS_LFS__ || ! defined __NR_getdents64
libc_hidden_proto(memcpy)
libc_hidden_proto(lseek)
#define __NR___syscall_getdents __NR_getdents
static inline _syscall3(int, __syscall_getdents, int, fd, unsigned char *, kdirp, size_t, count);
ssize_t __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, (unsigned 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;
}
#if defined __UCLIBC_HAS_LFS__ && ! defined __NR_getdents64
attribute_hidden strong_alias(__getdents,__getdents64)
#endif
#elif __WORDSIZE == 32
libc_hidden_proto(memmove)
extern __typeof(__getdents) __getdents64 attribute_hidden;
ssize_t __getdents (int fd, char *buf, size_t nbytes)
{
struct dirent *dp;
struct dirent64 *dp64;
ssize_t ret = __getdents64 (fd, buf, nbytes);
if (ret <= 0)
return ret;
dp64 = (struct dirent64 *) buf;
buf += ret;
while ((void *) dp64 < (void *) buf) {
dp = (struct dirent *) dp64;
dp->d_ino = dp64->d_ino;
dp->d_off = dp64->d_off;
dp->d_reclen = dp64->d_reclen;
dp->d_type = dp64->d_type;
memmove (dp->d_name, dp64->d_name, dp->d_reclen - offsetof (struct dirent64, d_name));
memmove (dp64, dp, dp->d_reclen);
dp64 = ((void *) dp64) + dp->d_reclen;
}
return ret;
}
#endif
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