1 /*************************************************

     2 *      Perl-Compatible Regular Expressions       *

     3 *************************************************/

     4 

     5 /* PCRE is a library of functions to support regular expressions whose syntax

     6 and semantics are as close as possible to those of the Perl 5 language.

     7 

     8                        Written by Philip Hazel

     9            Copyright (c) 1997-2008 University of Cambridge

    10 

    11 -----------------------------------------------------------------------------

    12 Redistribution and use in source and binary forms, with or without

    13 modification, are permitted provided that the following conditions are met:

    14 

    15     * Redistributions of source code must retain the above copyright notice,

    16       this list of conditions and the following disclaimer.

    17 

    18     * Redistributions in binary form must reproduce the above copyright

    19       notice, this list of conditions and the following disclaimer in the

    20       documentation and/or other materials provided with the distribution.

    21 

    22     * Neither the name of the University of Cambridge nor the names of its

    23       contributors may be used to endorse or promote products derived from

    24       this software without specific prior written permission.

    25 

    26 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

    27 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    28 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

    29 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

    30 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    31 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    32 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

    33 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

    34 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    35 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

    36 POSSIBILITY OF SUCH DAMAGE.

    37 -----------------------------------------------------------------------------

    38 */

    39 

    40 

    41 /* This module contains the external function pcre_version(), which returns a

    42 string that identifies the PCRE version that is in use. */

    43 

    44 

    45 #ifdef HAVE_CONFIG_H

    46 #include "config.h"

    47 #endif

    48 

    49 #include "pcre_internal.h"

    50 

    51 

    52 /*************************************************

    53 *          Return version string                 *

    54 *************************************************/

    55 

    56 /* These macros are the standard way of turning unquoted text into C strings.

    57 They allow macros like PCRE_MAJOR to be defined without quotes, which is

    58 convenient for user programs that want to test its value. */

    59 

    60 #define STRING(a)  # a

    61 #define XSTRING(s) STRING(s)

    62 

    63 /* A problem turned up with PCRE_PRERELEASE, which is defined empty for

    64 production releases. Originally, it was used naively in this code:

    65 

    66   return XSTRING(PCRE_MAJOR)

    67          "." XSTRING(PCRE_MINOR)

    68              XSTRING(PCRE_PRERELEASE)

    69          " " XSTRING(PCRE_DATE);

    70 

    71 However, when PCRE_PRERELEASE is empty, this leads to an attempted expansion of

    72 STRING(). The C standard states: "If (before argument substitution) any

    73 argument consists of no preprocessing tokens, the behavior is undefined." It

    74 turns out the gcc treats this case as a single empty string - which is what we

    75 really want - but Visual C grumbles about the lack of an argument for the

    76 macro. Unfortunately, both are within their rights. To cope with both ways of

    77 handling this, I had resort to some messy hackery that does a test at run time.

    78 I could find no way of detecting that a macro is defined as an empty string at

    79 pre-processor time. This hack uses a standard trick for avoiding calling

    80 the STRING macro with an empty argument when doing the test. */

    81 

    82 PCRE_EXP_DEFN const char * PCRE_CALL_CONVENTION

    83 pcre_version(void)

    84 {

    85 return (XSTRING(Z PCRE_PRERELEASE)[1] == 0)?

    86   XSTRING(PCRE_MAJOR.PCRE_MINOR PCRE_DATE) :

    87   XSTRING(PCRE_MAJOR.PCRE_MINOR) XSTRING(PCRE_PRERELEASE PCRE_DATE);

    88 }

    89 

    90 /* End of pcre_version.c */