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 #ifndef _LARGEFILE_SOURCE
  13 #define _LARGEFILE_SOURCE
  14 #endif
  15 #ifndef _LARGEFILE64_SOURCE
  16 #define _LARGEFILE64_SOURCE
  17 #endif
  18
  19 #include "config.h"
  20 #if HAVE_SYS_TYPES_H
  21 #include <sys/types.h>
  22 #endif
  23
  24 #if HAVE_ERRNO_H
  25 #include <errno.h>
  26 #endif
  27 #if HAVE_UNISTD_H
  28 #include <unistd.h>
  29 #endif
  30 #ifdef __MSDOS__
  31 #include <io.h>
  32 #endif
  33 #include "et/com_err.h"
  34 #include "ext2fs/ext2_io.h"
  35
  36 #ifdef __linux__
  37
  38 #if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
  39
  40 #define my_llseek lseek64
  41
  42 #else
  43 #if defined(HAVE_LLSEEK)
  44 #include <sys/syscall.h>
  45
  46 #ifndef HAVE_LLSEEK_PROTOTYPE
  47 extern long long llseek (int fd, long long offset, int origin);
  48 #endif
  49
  50 #define my_llseek llseek
  51
  52 #else   /* ! HAVE_LLSEEK */
  53
  54 #if SIZEOF_LONG == SIZEOF_LONG_LONG || _FILE_OFFSET_BITS+0 == 64
  55
  56 #define my_llseek lseek
  57
  58 #else /* SIZEOF_LONG != SIZEOF_LONG_LONG */
  59
  60 #include <linux/unistd.h>
  61
  62 #ifndef __NR__llseek
  63 #define __NR__llseek            140
  64 #endif
  65
  66 #ifndef __i386__
  67 static int _llseek (unsigned int, unsigned long,
  68                    unsigned long, ext2_loff_t *, unsigned int);
  69
  70 static _syscall5(int,_llseek,unsigned int,fd,unsigned long,offset_high,
  71                  unsigned long, offset_low,ext2_loff_t *,result,
  72                  unsigned int, origin);
  73 #endif
  74
  75 static ext2_loff_t my_llseek (int fd, ext2_loff_t offset, int origin)
  76 {
  77         ext2_loff_t result;
  78         int retval;
  79
  80 #ifndef __i386__
  81         retval = _llseek(fd, ((unsigned long long) offset) >> 32,
  82 #else
  83         retval = syscall(__NR__llseek, fd, (unsigned long long) (offset >> 32),
  84 #endif
  85                           ((unsigned long long) offset) & 0xffffffff,
  86                         &result, origin);
  87         return (retval == -1 ? (ext2_loff_t) retval : result);
  88 }
  89
  90 #endif  /* SIZE_LONG == SIZEOF_LONG_LONG */
  91
  92 #endif /* HAVE_LLSEEK */
  93 #endif /* defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE) */
  94
  95 ext2_loff_t ext2fs_llseek (int fd, ext2_loff_t offset, int origin)
  96 {
  97 #if SIZEOF_OFF_T >= SIZEOF_LONG_LONG
  98         return my_llseek (fd, offset, origin);
  99 #else
 100         ext2_loff_t result;
 101         static int do_compat = 0;
 102
 103         if (do_compat)
 104                 goto fallback;
 105
 106         result = my_llseek (fd, offset, origin);
 107         if (result == -1 && errno == ENOSYS) {
 108                 /*
 109                  * Just in case this code runs on top of an old kernel
 110                  * which does not support the llseek system call
 111                  */
 112                 do_compat++;
 113         fallback:
 114                 if (offset < ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))
 115                         return lseek(fd, (off_t) offset, origin);
 116                 errno = EINVAL;
 117                 return -1;
 118         }
 119         return result;
 120 #endif
 121 }
 122
 123 #else /* !linux */
 124
 125 #ifndef EINVAL
 126 #define EINVAL EXT2_ET_INVALID_ARGUMENT
 127 #endif
 128
 129 ext2_loff_t ext2fs_llseek (int fd, ext2_loff_t offset, int origin)
 130 {
 131 #if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
 132         return lseek64 (fd, offset, origin);
 133 #else
 134         if ((sizeof(off_t) < sizeof(ext2_loff_t)) &&
 135             (offset >= ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))) {
 136                 errno = EINVAL;
 137                 return -1;
 138         }
 139         return lseek (fd, (off_t) offset, origin);
 140 #endif
 141 }
 142
 143 #endif  /* linux */
 144
 145