lib/ext2fs/llseek.c

   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
  43 extern 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__
  63 static int _llseek (unsigned int, unsigned long,
  64                    unsigned long, ext2_loff_t *, unsigned int);
  65
  66 static _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
  71 static 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
  91 ext2_loff_t ext2fs_llseek (int fd, ext2_loff_t offset, int origin)
  92 {
  93         ext2_loff_t result;
  94         static int do_compat = 0;
  95
  96         if ((sizeof(off_t) >= sizeof(ext2_loff_t)) ||
  97             (offset < ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1))))
  98                 return lseek(fd, (off_t) offset, origin);
  99
 100         if (do_compat) {
 101                 errno = EINVAL;
 102                 return -1;
 103         }
 104
 105         result = my_llseek (fd, offset, origin);
 106         if (result == -1 && errno == ENOSYS) {
 107                 /*
 108                  * Just in case this code runs on top of an old kernel
 109                  * which does not support the llseek system call
 110                  */
 111                 do_compat++;
 112                 errno = EINVAL;
 113         }
 114         return result;
 115 }
 116
 117 #else /* !linux */
 118
 119 #ifndef EINVAL
 120 #define EINVAL EXT2_ET_INVALID_ARGUMENT
 121 #endif
 122
 123 ext2_loff_t ext2fs_llseek (int fd, ext2_loff_t offset, int origin)
 124 {
 125 #if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
 126         return lseek64 (fd, offset, origin);
 127 #else
 128         if ((sizeof(off_t) < sizeof(ext2_loff_t)) &&
 129             (offset >= ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))) {
 130                 errno = EINVAL;
 131                 return -1;
 132         }
 133         return lseek (fd, (off_t) offset, origin);
 134 #endif
 135 }
 136
 137 #endif  /* linux */
 138
 139