sys/crt_externs.c

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