llseek.c revision 274d46e1d35af423d0292d63c4d0ad7a03be82ba 
1/*
2 * llseek.c -- stub calling the llseek system call
3 *
4 * Copyright (C) 1994, 1995, 1996, 1997 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Library
8 * General Public License, version 2.
9 * %End-Header%
10 */
11
12#define _LARGEFILE_SOURCE
13#define _LARGEFILE64_SOURCE
14
15#include "config.h"
16#if HAVE_SYS_TYPES_H
17#include <sys/types.h>
18#endif
19
20#if HAVE_ERRNO_H
21#include <errno.h>
22#endif
23#if HAVE_UNISTD_H
24#include <unistd.h>
25#endif
26#ifdef __MSDOS__
27#include <io.h>
28#endif
29#include "et/com_err.h"
30#include "ext2fs/ext2_io.h"
31
32#ifdef __linux__
33
34#if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
35
36#define my_llseek lseek64
37
38#else
39#if defined(HAVE_LLSEEK)
40#include <syscall.h>
41
42#ifndef HAVE_LLSEEK_PROTOTYPE
43extern long long llseek (int fd, long long offset, int origin);
44#endif
45
46#define my_llseek llseek
47
48#else	/* ! HAVE_LLSEEK */
49
50#if SIZEOF_LONG == SIZEOF_LONG_LONG
51
52#define llseek lseek
53
54#else /* SIZEOF_LONG != SIZEOF_LONG_LONG */
55
56#include <linux/unistd.h>
57
58#ifndef __NR__llseek
59#define __NR__llseek            140
60#endif
61
62#ifndef __i386__
63static int _llseek (unsigned int, unsigned long,
64		   unsigned long, ext2_loff_t *, unsigned int);
65
66static _syscall5(int,_llseek,unsigned int,fd,unsigned long,offset_high,
67		 unsigned long, offset_low,ext2_loff_t *,result,
68		 unsigned int, origin)
69#endif
70
71static ext2_loff_t my_llseek (int fd, ext2_loff_t offset, int origin)
72{
73	ext2_loff_t result;
74	int retval;
75
76#ifndef __i386__
77	retval = _llseek(fd, ((unsigned long long) offset) >> 32,
78#else
79	retval = syscall(__NR__llseek, fd, (unsigned long long) (offset >> 32),
80#endif
81			  ((unsigned long long) offset) & 0xffffffff,
82			&result, origin);
83	return (retval == -1 ? (ext2_loff_t) retval : result);
84}
85
86#endif	/* __alpha__ || __ia64__ */
87
88#endif /* HAVE_LLSEEK */
89#endif /* defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE) */
90
91ext2_loff_t ext2fs_llseek (int fd, ext2_loff_t offset, int origin)
92{
93#if SIZEOF_OFF_T >= SIZEOF_LONG_LONG
94	return lseek (fd, offset, origin);
95#else
96	ext2_loff_t result;
97	static int do_compat = 0;
98
99	if (do_compat)
100		goto fallback;
101
102	result = my_llseek (fd, offset, origin);
103	if (result == -1 && errno == ENOSYS) {
104		/*
105		 * Just in case this code runs on top of an old kernel
106		 * which does not support the llseek system call
107		 */
108		do_compat++;
109	fallback:
110		if (offset < ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))
111			return lseek(fd, (off_t) offset, origin);
112		errno = EINVAL;
113		return -1;
114	}
115	return result;
116#endif
117}
118
119#else /* !linux */
120
121#ifndef EINVAL
122#define EINVAL EXT2_ET_INVALID_ARGUMENT
123#endif
124
125ext2_loff_t ext2fs_llseek (int fd, ext2_loff_t offset, int origin)
126{
127#if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
128	return lseek64 (fd, offset, origin);
129#else
130	if ((sizeof(off_t) < sizeof(ext2_loff_t)) &&
131	    (offset >= ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))) {
132		errno = EINVAL;
133		return -1;
134	}
135	return lseek (fd, (off_t) offset, origin);
136#endif
137}
138
139#endif 	/* linux */
140
141
142