sys/crt_externs.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26 ** This file contains interfaces to the symbols defined int the crt modules.
  27 ** 3 April 1995
  28 ** Matt Watson (mwatson@next.com)
  29 **
  30 */
  31
  32 #if defined(__DYNAMIC__)
  33 #include "mach-o/dyld.h" /* defines _dyld_lookup_and_bind() */
  34 #define STRINGIFY(a) # a
  35 #define DECLARE_VAR(var, type)                                  \
  36         static type * var ## _pointer = 0
  37 #define DECLARE_PROGNAME(var, type)                             \
  38         static type * var ## _pointer = 0;                      \
  39         static type _priv_ ## var = 0
  40 #define SETUP_VAR(var)                                          \
  41     if ( var ## _pointer == 0) {                                \
  42         _dyld_lookup_and_bind( STRINGIFY(_ ## var),             \
  43                 (unsigned long *) & var ## _pointer, 0);        \
  44     }
  45 #define SETUP_PROGNAME(var)                                     \
  46     if ( var ## _pointer == 0) {                                \
  47         if(NSIsSymbolNameDefined( STRINGIFY(_ ## var) ))        \
  48             _dyld_lookup_and_bind( STRINGIFY(_ ## var),         \
  49                 (unsigned long *) & var ## _pointer, 0);        \
  50         else {                                                  \
  51             char *progname = _dyld_get_image_name(0);           \
  52             if(_priv_ ## var = strrchr(progname, '/'))          \
  53                 _priv_ ## var ++;                               \
  54             else                                                \
  55                 _priv_ ## var = progname;                       \
  56             var ## _pointer = & _priv_ ## var;                  \
  57         }                                                       \
  58     }
  59 #define USE_VAR(var) (var ## _pointer)
  60 #else
  61 #define DECLARE_VAR(var, type) extern type var
  62 #define DECLARE_PROGNAME(var, type) DECLARE_VAR(var, type)
  63 #define SETUP_VAR(var)
  64 #define SETUP_PROGNAME(var) SETUP_VAR(var)
  65 #define USE_VAR(var) (& var)
  66 #endif
  67
  68 char ***_NSGetArgv(void) {
  69     DECLARE_VAR(NXArgv, char **);
  70     SETUP_VAR(NXArgv);
  71     return(USE_VAR(NXArgv));
  72 }
  73
  74 int *_NSGetArgc(void) {
  75     DECLARE_VAR(NXArgc, int);
  76     SETUP_VAR(NXArgc);
  77     return(USE_VAR(NXArgc));
  78 }
  79
  80 char ***_NSGetEnviron(void) {
  81     DECLARE_VAR(environ, char **);
  82     SETUP_VAR(environ);
  83     return(USE_VAR(environ));
  84 }
  85
  86 char **_NSGetProgname(void) {
  87     DECLARE_PROGNAME(__progname, char *);
  88     SETUP_PROGNAME(__progname);
  89     return(USE_VAR(__progname));
  90 }
  91
  92 struct mach_header *_NSGetMachExecuteHeader(void) {
  93     DECLARE_VAR(_mh_execute_header, struct mach_header);
  94     SETUP_VAR(_mh_execute_header);
  95     return(USE_VAR(_mh_execute_header));
  96 }
  97
  98 /*
  99  * Fix for Radar bug 2200596 --
 100  * EH symbol definitions for gcc 2.7.2.x implementation of
 101  * C++ exception handling.  The problem:  the EH implementation
 102  * has "throw" store stuff into these pointers, and then as the
 103  * stack is unwound, the code generated into each function (for
 104  * checking whether this function contains a relevant "catch"
 105  * clause and for calling destructors for local variables) looks
 106  * at these globals to find the type and value thrown.
 107  *
 108  * The problem was that the compiler generated the symbols as
 109  * "common" symbols, and common symbols cannot be placed in
 110  * dynamic shared libraries.  So we must put these guys as
 111  * "data" symbols into crt0.o or the System Framework (library),
 112  * and the compiler must generate code that defines the symbols
 113  * as external references instead of common.
 114  *
 115  * I changed the symbol names (added the "_272") to be utterly
 116  * paranoid about any possible future use of similar names by
 117  * any future versions of gcc.
 118  *                      -- D. Landauer, Jan. 1998
 119  */
 120
 121 void *__eh_pc_gcc_272 = (void *)0;
 122 void *__eh_type_gcc_272 = (void *)0;
 123 void *__eh_value_gcc_272 = (void *)0;
 124
 125 /* This is what egcs uses for its global data pointer */
 126 void *__eh_global_dataptr = (void *)0;