llseek.c revision f3db3566b5e1342e49dffc5ec3f418a838584194 
1/*
2 * llseek.c -- stub calling the llseek system call
3 *
4 * Copyright (C) 1994 Remy Card.  This file may be redistributed
5 * under the terms of the GNU Public License.
6 */
7
8#include <sys/types.h>
9
10#include <errno.h>
11#include <unistd.h>
12#include <linux/unistd.h>
13#include "et/com_err.h"
14#include "ext2fs/io.h"
15
16#ifdef __linux__
17
18#ifndef __NR__llseek
19#define __NR__llseek            140
20#endif
21
22static int _llseek (unsigned int, unsigned long,
23		   unsigned long, ext2_loff_t *, unsigned int);
24
25static _syscall5(int,_llseek,unsigned int,fd,unsigned long,offset_high,
26		 unsigned long, offset_low,ext2_loff_t *,result,
27		 unsigned int, origin)
28
29ext2_loff_t ext2_llseek (unsigned int fd, ext2_loff_t offset,
30			 unsigned int origin)
31{
32	unsigned long offset_high;
33	unsigned long offset_low;
34	ext2_loff_t result;
35	int retval;
36	static int do_compat = 0;
37
38	if (do_compat) {
39	compat_lseek:
40		if ((sizeof(off_t) < sizeof(ext2_loff_t)) &&
41		    (offset >= ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))) {
42			errno = -EINVAL;
43			return -1;
44		}
45		return lseek (fd, (off_t) offset, origin);
46	}
47
48	offset_high = ((unsigned long long) offset) >> 32;
49	offset_low = ((unsigned long long) offset) & 0xffffffff;
50	retval = _llseek (fd, offset_high, offset_low, &result, origin);
51	if (retval == -1 && errno == ENOSYS) {
52		/*
53		 * Just in case this code runs on top of an old kernel
54		 * which does not support the llseek system call
55		 */
56		do_compat++;
57		goto compat_lseek;
58	}
59	if (retval == -1)
60		result = -1;
61	return result;
62}
63
64#else
65
66ext2_loff_t ext2_llseek (unsigned int fd, ext2_loff_t offset,
67			 unsigned int origin)
68{
69	if ((sizeof(off_t) < sizeof(ext2_loff_t)) &&
70	    (offset >= ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))) {
71		errno = -EINVAL;
72		return -1;
73	}
74	return lseek (fd, (off_t) offset, origin);
75}
76
77#endif
78
79
80