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      1 #ifndef __CARES_RULES_H
      2 #define __CARES_RULES_H
      3 
      4 
      5 /* Copyright (C) 2009 by Daniel Stenberg et al
      6  *
      7  * Permission to use, copy, modify, and distribute this software and its
      8  * documentation for any purpose and without fee is hereby granted, provided
      9  * that the above copyright notice appear in all copies and that both that
     10  * copyright notice and this permission notice appear in supporting
     11  * documentation, and that the name of M.I.T. not be used in advertising or
     12  * publicity pertaining to distribution of the software without specific,
     13  * written prior permission.  M.I.T. makes no representations about the
     14  * suitability of this software for any purpose.  It is provided "as is"
     15  * without express or implied warranty.
     16  */
     17 
     18 /* ================================================================ */
     19 /*                    COMPILE TIME SANITY CHECKS                    */
     20 /* ================================================================ */
     21 
     22 /*
     23  * NOTE 1:
     24  * -------
     25  *
     26  * All checks done in this file are intentionally placed in a public
     27  * header file which is pulled by ares.h when an application is
     28  * being built using an already built c-ares library. Additionally
     29  * this file is also included and used when building the library.
     30  *
     31  * If compilation fails on this file it is certainly sure that the
     32  * problem is elsewhere. It could be a problem in the ares_build.h
     33  * header file, or simply that you are using different compilation
     34  * settings than those used to build the library.
     35  *
     36  * Nothing in this file is intended to be modified or adjusted by the
     37  * c-ares library user nor by the c-ares library builder.
     38  *
     39  * Do not deactivate any check, these are done to make sure that the
     40  * library is properly built and used.
     41  *
     42  * You can find further help on the c-ares development mailing list:
     43  * http://cool.haxx.se/mailman/listinfo/c-ares/
     44  *
     45  * NOTE 2
     46  * ------
     47  *
     48  * Some of the following compile time checks are based on the fact
     49  * that the dimension of a constant array can not be a negative one.
     50  * In this way if the compile time verification fails, the compilation
     51  * will fail issuing an error. The error description wording is compiler
     52  * dependent but it will be quite similar to one of the following:
     53  *
     54  *   "negative subscript or subscript is too large"
     55  *   "array must have at least one element"
     56  *   "-1 is an illegal array size"
     57  *   "size of array is negative"
     58  *
     59  * If you are building an application which tries to use an already
     60  * built c-ares library and you are getting this kind of errors on
     61  * this file, it is a clear indication that there is a mismatch between
     62  * how the library was built and how you are trying to use it for your
     63  * application. Your already compiled or binary library provider is the
     64  * only one who can give you the details you need to properly use it.
     65  */
     66 
     67 /*
     68  * Verify that some macros are actually defined.
     69  */
     70 
     71 #ifndef CARES_SIZEOF_LONG
     72 #  error "CARES_SIZEOF_LONG definition is missing!"
     73    Error Compilation_aborted_CARES_SIZEOF_LONG_is_missing
     74 #endif
     75 
     76 #ifndef CARES_TYPEOF_ARES_SOCKLEN_T
     77 #  error "CARES_TYPEOF_ARES_SOCKLEN_T definition is missing!"
     78    Error Compilation_aborted_CARES_TYPEOF_ARES_SOCKLEN_T_is_missing
     79 #endif
     80 
     81 #ifndef CARES_SIZEOF_ARES_SOCKLEN_T
     82 #  error "CARES_SIZEOF_ARES_SOCKLEN_T definition is missing!"
     83    Error Compilation_aborted_CARES_SIZEOF_ARES_SOCKLEN_T_is_missing
     84 #endif
     85 
     86 /*
     87  * Macros private to this header file.
     88  */
     89 
     90 #define CareschkszEQ(t, s) sizeof(t) == s ? 1 : -1
     91 
     92 #define CareschkszGE(t1, t2) sizeof(t1) >= sizeof(t2) ? 1 : -1
     93 
     94 /*
     95  * Verify that the size previously defined and expected for long
     96  * is the same as the one reported by sizeof() at compile time.
     97  */
     98 
     99 typedef char
    100   __cares_rule_01__
    101     [CareschkszEQ(long, CARES_SIZEOF_LONG)];
    102 
    103 /*
    104  * Verify that the size previously defined and expected for
    105  * ares_socklen_t is actually the the same as the one reported
    106  * by sizeof() at compile time.
    107  */
    108 
    109 typedef char
    110   __cares_rule_02__
    111     [CareschkszEQ(ares_socklen_t, CARES_SIZEOF_ARES_SOCKLEN_T)];
    112 
    113 /*
    114  * Verify at compile time that the size of ares_socklen_t as reported
    115  * by sizeof() is greater or equal than the one reported for int for
    116  * the current compilation.
    117  */
    118 
    119 typedef char
    120   __cares_rule_03__
    121     [CareschkszGE(ares_socklen_t, int)];
    122 
    123 /* ================================================================ */
    124 /*          EXTERNALLY AND INTERNALLY VISIBLE DEFINITIONS           */
    125 /* ================================================================ */
    126 
    127 /*
    128  * Get rid of macros private to this header file.
    129  */
    130 
    131 #undef CareschkszEQ
    132 #undef CareschkszGE
    133 
    134 /*
    135  * Get rid of macros not intended to exist beyond this point.
    136  */
    137 
    138 #undef CARES_PULL_WS2TCPIP_H
    139 #undef CARES_PULL_SYS_TYPES_H
    140 #undef CARES_PULL_SYS_SOCKET_H
    141 
    142 #undef CARES_TYPEOF_ARES_SOCKLEN_T
    143 
    144 #endif /* __CARES_RULES_H */
    145