fdisk/llseek.c

   1 /*
   2  * llseek.c -- stub calling the llseek system call
   3  *
   4  * Copyright (C) 1994 Remy Card.  This file may be redistributed
   5  * under the terms of the GNU Public License.
   6  */
   7
   8 #include <sys/types.h>
   9
  10 #include <errno.h>
  11 #include <unistd.h>
  12
  13 #if defined(__GNUC__) || defined(HAS_LONG_LONG)
  14 typedef long long       ext2_loff_t;
  15 #else
  16 typedef long            ext2_loff_t;
  17 #endif
  18
  19 extern ext2_loff_t ext2_llseek (unsigned int, ext2_loff_t, unsigned int);
  20
  21 #ifdef __linux__
  22
  23 #ifdef HAVE_LLSEEK
  24 #include <syscall.h>
  25
  26 #else   /* HAVE_LLSEEK */
  27
  28 #if defined(__alpha__) || defined(__ia64__)
  29
  30 #define my_llseek lseek
  31
  32 #else
  33 #include <linux/unistd.h>       /* for __NR__llseek */
  34
  35 static int _llseek (unsigned int, unsigned long,
  36                    unsigned long, ext2_loff_t *, unsigned int);
  37
  38 #ifdef __NR__llseek
  39
  40 static _syscall5(int,_llseek,unsigned int,fd,unsigned long,offset_high,
  41                  unsigned long, offset_low,ext2_loff_t *,result,
  42                  unsigned int, origin)
  43
  44 #else
  45
  46 /* no __NR__llseek on compilation machine - might give it explicitly */
  47 static int _llseek (unsigned int fd, unsigned long oh,
  48                     unsigned long ol, ext2_loff_t *result,
  49                     unsigned int origin) {
  50         errno = ENOSYS;
  51         return -1;
  52 }
  53
  54 #endif
  55
  56 static ext2_loff_t my_llseek (unsigned int fd, ext2_loff_t offset,
  57                 unsigned int origin)
  58 {
  59         ext2_loff_t result;
  60         int retval;
  61
  62         retval = _llseek (fd, ((unsigned long long) offset) >> 32,
  63                         ((unsigned long long) offset) & 0xffffffff,
  64                         &result, origin);
  65         return (retval == -1 ? (ext2_loff_t) retval : result);
  66 }
  67
  68 #endif /* __alpha__ */
  69
  70 #endif  /* HAVE_LLSEEK */
  71
  72 ext2_loff_t ext2_llseek (unsigned int fd, ext2_loff_t offset,
  73                          unsigned int origin)
  74 {
  75         ext2_loff_t result;
  76         static int do_compat = 0;
  77
  78         if (!do_compat) {
  79                 result = my_llseek (fd, offset, origin);
  80                 if (!(result == -1 && errno == ENOSYS))
  81                         return result;
  82
  83                 /*
  84                  * Just in case this code runs on top of an old kernel
  85                  * which does not support the llseek system call
  86                  */
  87                 do_compat = 1;
  88                 /*
  89                  * Now try ordinary lseek.
  90                  */
  91         }
  92
  93         if ((sizeof(off_t) >= sizeof(ext2_loff_t)) ||
  94             (offset < ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1))))
  95                 return lseek(fd, (off_t) offset, origin);
  96
  97         errno = EINVAL;
  98         return -1;
  99 }
 100
 101 #else /* !linux */
 102
 103 ext2_loff_t ext2_llseek (unsigned int fd, ext2_loff_t offset,
 104                          unsigned int origin)
 105 {
 106         if ((sizeof(off_t) < sizeof(ext2_loff_t)) &&
 107             (offset >= ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))) {
 108                 errno = EINVAL;
 109                 return -1;
 110         }
 111         return lseek (fd, (off_t) offset, origin);
 112 }
 113
 114 #endif  /* linux */
 115
 116