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 #ifdef __alpha__
  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 static _syscall5(int,_llseek,unsigned int,fd,unsigned long,offset_high,
  39                  unsigned long, offset_low,ext2_loff_t *,result,
  40                  unsigned int, origin)
  41
  42 static ext2_loff_t my_llseek (unsigned int fd, ext2_loff_t offset,
  43                 unsigned int origin)
  44 {
  45         ext2_loff_t result;
  46         int retval;
  47
  48         retval = _llseek (fd, ((unsigned long long) offset) >> 32,
  49                         ((unsigned long long) offset) & 0xffffffff,
  50                         &result, origin);
  51         return (retval == -1 ? (ext2_loff_t) retval : result);
  52 }
  53
  54 #endif /* __alpha__ */
  55
  56 #endif  /* HAVE_LLSEEK */
  57
  58 ext2_loff_t ext2_llseek (unsigned int fd, ext2_loff_t offset,
  59                          unsigned int origin)
  60 {
  61         ext2_loff_t result;
  62         static int do_compat = 0;
  63
  64         if (!do_compat) {
  65                 result = my_llseek (fd, offset, origin);
  66                 if (!(result == -1 && errno == ENOSYS))
  67                         return result;
  68
  69                 /*
  70                  * Just in case this code runs on top of an old kernel
  71                  * which does not support the llseek system call
  72                  */
  73                 do_compat = 1;
  74                 /*
  75                  * Now try ordinary lseek.
  76                  */
  77         }
  78
  79         if ((sizeof(off_t) >= sizeof(ext2_loff_t)) ||
  80             (offset < ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1))))
  81                 return lseek(fd, (off_t) offset, origin);
  82
  83         errno = EINVAL;
  84         return -1;
  85 }
  86
  87 #else /* !linux */
  88
  89 ext2_loff_t ext2_llseek (unsigned int fd, ext2_loff_t offset,
  90                          unsigned int origin)
  91 {
  92         if ((sizeof(off_t) < sizeof(ext2_loff_t)) &&
  93             (offset >= ((ext2_loff_t) 1 << ((sizeof(off_t)*8) -1)))) {
  94                 errno = EINVAL;
  95                 return -1;
  96         }
  97         return lseek (fd, (off_t) offset, origin);
  98 }
  99
 100 #endif  /* linux */
 101
 102