llseek.c revision 6c6a75dc1ed760f80417dd52a2a7b570fb738a0a 
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#if HAVE_SYS_TYPES_H
16#include <sys/types.h>
17#endif
18
19#if HAVE_ERRNO_H
20#include <errno.h>
21#endif
22#if HAVE_UNISTD_H
23#include <unistd.h>
24#endif
25#ifdef __MSDOS__
26#include <io.h>
27#endif
28#include "et/com_err.h"
29#include "ext2fs/ext2_io.h"
30
31#ifdef __linux__
32
33#if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
34
35#define my_llseek lseek64
36
37#else
38#if defined(HAVE_LLSEEK)
39#include <syscall.h>
40
41#ifndef HAVE_LLSEEK_PROTOTYPE
42extern long long llseek (int fd, long long offset, int origin);
43#endif
44
45#define my_llseek llseek
46
47#else	/* ! HAVE_LLSEEK */
48
49#if SIZEOF_LONG == SIZEOF_LONG_LONG
50
51#define my_llseek lseek
52
53#else /* SIZEOF_LONG != SIZEOF_LONG_LONG */
54
55#include <linux/unistd.h>
56
57#ifndef __NR__llseek
58#define __NR__llseek            140
59#endif
60
61#ifndef __i386__
62static int _llseek (unsigned int, unsigned long,
63		   unsigned long, ext2_loff_t *, unsigned int);
64
65static _syscall5(int,_llseek,unsigned int,fd,unsigned long,offset_high,
66		 unsigned long, offset_low,ext2_loff_t *,result,
67		 unsigned int, origin)
68#endif
69
70static ext2_loff_t my_llseek (int fd, ext2_loff_t offset, int origin)
71{
72	ext2_loff_t result;
73	int retval;
74
75#ifndef __i386__
76	retval = _llseek(fd, ((unsigned long long) offset) >> 32,
77#else
78	retval = syscall(__NR__llseek, fd, (unsigned long long) (offset >> 32),
79#endif
80			  ((unsigned long long) offset) & 0xffffffff,
81			&result, origin);
82	return (retval == -1 ? (ext2_loff_t) retval : result);
83}
84
85#endif	/* SIZE_LONG == SIZEOF_LONG_LONG */
86
87#endif /* HAVE_LLSEEK */
88#endif /* defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE) */
89
90ext2_loff_t ext2fs_llseek (int fd, ext2_loff_t offset, int origin)
91{
92#if SIZEOF_OFF_T >= SIZEOF_LONG_LONG
93	return my_llseek (fd, offset, origin);
94#else
95	ext2_loff_t result;
96	static int do_compat = 0;
97
98	if (do_compat)
99		goto fallback;
100
101	result = my_llseek (fd, offset, origin);
102	if (result == -1 && errno == ENOSYS) {
103		/*
104		 * Just in case this code runs on top of an old kernel
105		 * which does not support the llseek system call
106		 */
107		do_compat++;
108	fallback:
109		if (offset < ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))
110			return lseek(fd, (off_t) offset, origin);
111		errno = EINVAL;
112		return -1;
113	}
114	return result;
115#endif
116}
117
118#else /* !linux */
119
120#ifndef EINVAL
121#define EINVAL EXT2_ET_INVALID_ARGUMENT
122#endif
123
124ext2_loff_t ext2fs_llseek (int fd, ext2_loff_t offset, int origin)
125{
126#if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
127	return lseek64 (fd, offset, origin);
128#else
129	if ((sizeof(off_t) < sizeof(ext2_loff_t)) &&
130	    (offset >= ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))) {
131		errno = EINVAL;
132		return -1;
133	}
134	return lseek (fd, (off_t) offset, origin);
135#endif
136}
137
138#endif 	/* linux */
139
140
141