contrib/bind-9.5.2/lib/isc/unix/include/isc/offset.h

   1 /*
   2  * Copyright (C) 2004, 2005, 2007, 2009  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 2000, 2001  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id: offset.h,v 1.15.128.2 2009/02/16 23:46:44 tbox Exp $ */
  19
  20 #ifndef ISC_OFFSET_H
  21 #define ISC_OFFSET_H 1
  22
  23 /*! \file
  24  * \brief
  25  * File offsets are operating-system dependent.
  26  */
  27 #include <limits.h>             /* Required for CHAR_BIT. */
  28 #include <sys/types.h>
  29 #include <stddef.h>             /* For Linux Standard Base. */
  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 */