sys/crt_externs.c

   1 /*
   2  * Copyright (c) 1999-2007 Apple 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 DECLARE_VAR(NXArgv, char **);
  67 DECLARE_VAR(NXArgc, int);
  68 DECLARE_VAR(environ, char **);
  69 DECLARE_VAR(_mh_execute_header, struct mach_header);
  70 DECLARE_PROGNAME(__progname, char *);
  71
  72 char ***_NSGetArgv(void) {
  73     SETUP_VAR(NXArgv);
  74     return(USE_VAR(NXArgv));
  75 }
  76
  77 int *_NSGetArgc(void) {
  78     SETUP_VAR(NXArgc);
  79     return(USE_VAR(NXArgc));
  80 }
  81
  82 char ***_NSGetEnviron(void) {
  83     SETUP_VAR(environ);
  84     return(USE_VAR(environ));
  85 }
  86
  87 char **_NSGetProgname(void) {
  88     SETUP_PROGNAME(__progname);
  89     return(USE_VAR(__progname));
  90 }
  91
  92 struct mach_header *_NSGetMachExecuteHeader(void) {
  93     SETUP_VAR(_mh_execute_header);
  94     return(USE_VAR(_mh_execute_header));
  95 }
  96
  97 #if __DYNAMIC__
  98 struct ProgramVars
  99 {
 100     void*       mh;
 101     int*        NXArgcPtr;
 102     char***     NXArgvPtr;
 103     char***     environPtr;
 104     char**      __prognamePtr;
 105 };
 106
 107 /*
 108  * dyld calls libSystem_initializer() and passes it a ProgramVars struct containing pointers to the
 109  * main executable's NXArg* global variables. libSystem_initializer() calls __libc_init() which calls
 110  * _program_vars_init() passing the ProgramVars parameter.
 111  */
 112 void __attribute__((visibility("hidden")))
 113 _program_vars_init(const struct ProgramVars* vars) {
 114     // to support transitional 10.5 main executables that don't have extended __dyld section and instead call _NSSetProgramVars,
 115     // don't overwrite values set by _NSSetProgramVars()
 116     if ( NXArgv_pointer != NULL )
 117         return;
 118     NXArgv_pointer              = vars->NXArgvPtr;
 119     NXArgc_pointer              = vars->NXArgcPtr;
 120     environ_pointer             = vars->environPtr;
 121     __progname_pointer          = vars->__prognamePtr;
 122     _mh_execute_header_pointer  = vars->mh;
 123 }
 124
 125 /*
 126  * This is only called by main executables built with pre 10-5 GM crt1.10.5.o.  In those programs,
 127  * there is no extended __dyld section, dyld cannot tell _program_vars_init() where the real program
 128  * variables are, so they get temp values and are set for real here.
 129  */
 130 void _NSSetProgramVars(int* crt_argc, char*** crt_argv, char*** crt_environ, struct mach_header* crt_mh, char** crt_progname) {
 131     NXArgv_pointer              = crt_argv;
 132     NXArgc_pointer              = crt_argc;
 133     environ_pointer             = crt_environ;
 134     __progname_pointer          = crt_progname;
 135     _mh_execute_header_pointer  = crt_mh;
 136 }
 137 #endif
 138
 139 /*
 140  * Fix for Radar bug 2200596 --
 141  * EH symbol definitions for gcc 2.7.2.x implementation of
 142  * C++ exception handling.  The problem:  the EH implementation
 143  * has "throw" store stuff into these pointers, and then as the
 144  * stack is unwound, the code generated into each function (for
 145  * checking whether this function contains a relevant "catch"
 146  * clause and for calling destructors for local variables) looks
 147  * at these globals to find the type and value thrown.
 148  *
 149  * The problem was that the compiler generated the symbols as
 150  * "common" symbols, and common symbols cannot be placed in
 151  * dynamic shared libraries.  So we must put these guys as
 152  * "data" symbols into crt0.o or the System Framework (library),
 153  * and the compiler must generate code that defines the symbols
 154  * as external references instead of common.
 155  *
 156  * I changed the symbol names (added the "_272") to be utterly
 157  * paranoid about any possible future use of similar names by
 158  * any future versions of gcc.
 159  *                      -- D. Landauer, Jan. 1998
 160  */
 161
 162 void *__eh_pc_gcc_272 = (void *)0;
 163 void *__eh_type_gcc_272 = (void *)0;
 164 void *__eh_value_gcc_272 = (void *)0;
 165
 166 /* This is what egcs uses for its global data pointer */
 167 void *__eh_global_dataptr = (void *)0;