lib/blkid/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
   8  * GNU Lesser General Public License.
   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
  34 #include "blkidP.h"
  35
  36 #ifdef __linux__
  37
  38 #if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
  39
  40 #define my_llseek lseek64
  41
  42 #elif defined(HAVE_LLSEEK)
  43 #include <sys/syscall.h>
  44
  45 #ifndef HAVE_LLSEEK_PROTOTYPE
  46 extern long long llseek(int fd, long long offset, int origin);
  47 #endif
  48
  49 #define my_llseek llseek
  50
  51 #else   /* ! HAVE_LLSEEK */
  52
  53 #if SIZEOF_LONG == SIZEOF_LONG_LONG
  54
  55 #define llseek lseek
  56
  57 #else /* SIZEOF_LONG != SIZEOF_LONG_LONG */
  58
  59 #include <linux/unistd.h>
  60
  61 #ifndef __NR__llseek
  62 #define __NR__llseek            140
  63 #endif
  64
  65 #ifndef __i386__
  66 static int _llseek(unsigned int, unsigned long, unsigned long,
  67                    blkid_loff_t *, unsigned int);
  68
  69 static _syscall5(int, _llseek, unsigned int, fd, unsigned long, offset_high,
  70                  unsigned long, offset_low, blkid_loff_t *, result,
  71                  unsigned int, origin)
  72 #endif
  73
  74 static blkid_loff_t my_llseek(int fd, blkid_loff_t offset, int origin)
  75 {
  76         blkid_loff_t result;
  77         int retval;
  78
  79 #ifndef __i386__
  80         retval = _llseek(fd, ((unsigned long long) offset) >> 32,
  81                          ((unsigned long long)offset) & 0xffffffff,
  82                          &result, origin);
  83 #else
  84         retval = syscall(__NR__llseek, fd, ((unsigned long long) offset) >> 32,
  85                          ((unsigned long long)offset) & 0xffffffff,
  86                          &result, origin);
  87 #endif
  88         return (retval == -1 ? (blkid_loff_t) retval : result);
  89 }
  90
  91 #endif  /* __alpha__ || __ia64__ */
  92
  93 #endif /* HAVE_LLSEEK */
  94
  95 blkid_loff_t blkid_llseek(int fd, blkid_loff_t offset, int whence)
  96 {
  97         blkid_loff_t result;
  98         static int do_compat = 0;
  99
 100         if ((sizeof(off_t) >= sizeof(blkid_loff_t)) ||
 101             (offset < ((blkid_loff_t) 1 << ((sizeof(off_t)*8) -1))))
 102                 return lseek(fd, (off_t) offset, whence);
 103
 104         if (do_compat) {
 105                 errno = EOVERFLOW;
 106                 return -1;
 107         }
 108
 109         result = my_llseek(fd, offset, whence);
 110         if (result == -1 && errno == ENOSYS) {
 111                 /*
 112                  * Just in case this code runs on top of an old kernel
 113                  * which does not support the llseek system call
 114                  */
 115                 do_compat++;
 116                 errno = EOVERFLOW;
 117         }
 118         return result;
 119 }
 120
 121 #else /* !linux */
 122
 123 #ifndef EOVERFLOW
 124 #ifdef EXT2_ET_INVALID_ARGUMENT
 125 #define EOVERFLOW EXT2_ET_INVALID_ARGUMENT
 126 #else
 127 #define EOVERFLOW 112
 128 #endif
 129 #endif
 130
 131 blkid_loff_t blkid_llseek(int fd, blkid_loff_t offset, int origin)
 132 {
 133 #if defined(HAVE_LSEEK64) && defined(HAVE_LSEEK64_PROTOTYPE)
 134         return lseek64 (fd, offset, origin);
 135 #else
 136         if ((sizeof(off_t) < sizeof(blkid_loff_t)) &&
 137             (offset >= ((blkid_loff_t) 1 << ((sizeof(off_t)*8) - 1)))) {
 138                 errno = EOVERFLOW;
 139                 return -1;
 140         }
 141         return lseek(fd, (off_t) offset, origin);
 142 #endif
 143 }
 144
 145 #endif  /* linux */
 146
 147