dist/ntp/include/isc/offset.h

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (C) 2000, 2001  Internet Software Consortium.
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
  11  * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
  12  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
  13  * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
  14  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
  15  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  16  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  17  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 /* Id: offset.h,v 1.10 2001/01/09 21:58:43 bwelling Exp */
  21
  22 #ifndef ISC_OFFSET_H
  23 #define ISC_OFFSET_H 1
  24
  25 /*
  26  * File offsets are operating-system dependent.
  27  */
  28 #include <limits.h>             /* Required for CHAR_BIT. */
  29 #include <sys/types.h>
  30
  31 typedef off_t isc_offset_t;
  32
  33 /*
  34  * POSIX says "Additionally, blkcnt_t and off_t are extended signed integral
  35  * types", so the maximum value is all 1s except for the high bit.
  36  * This definition is more complex than it really needs to be because it was
  37  * crafted to keep both the SunOS 5.6 and the HP/UX 11 compilers quiet about
  38  * integer overflow.  For example, though this is equivalent to just left
  39  * shifting 1 to the high bit and then inverting the bits, the SunOS compiler
  40  * is unhappy about shifting a positive "1" to negative in a signed integer.
  41  */
  42 #define ISC_OFFSET_MAXIMUM \
  43         (~(((off_t)-1 >> (sizeof(off_t) * CHAR_BIT - 1)) \
  44                       << (sizeof(off_t) * CHAR_BIT - 1)))
  45
  46 #endif /* ISC_OFFSET_H */