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 DECLARE_VAR(var, type)                                  \
  33         static type * var ## _pointer = 0
  34 #define DECLARE_PROGNAME(var, type)                             \
  35         static type * var ## _pointer = 0;                      \
  36         static type _priv_ ## var = 0
  37 #define USE_VAR(var) (var ## _pointer)
  38 #else
  39 #define DECLARE_VAR(var, type) extern type var
  40 #define DECLARE_PROGNAME(var, type) DECLARE_VAR(var, type)
  41 #define USE_VAR(var) (& var)
  42 #endif
  43
  44 DECLARE_VAR(NXArgv, char **);
  45 DECLARE_VAR(NXArgc, int);
  46 DECLARE_VAR(environ, char **);
  47 DECLARE_VAR(_mh_execute_header, struct mach_header);
  48 DECLARE_PROGNAME(__progname, char *);
  49
  50 char ***_NSGetArgv(void) {
  51     return(USE_VAR(NXArgv));
  52 }
  53
  54 int *_NSGetArgc(void) {
  55     return(USE_VAR(NXArgc));
  56 }
  57
  58 char ***_NSGetEnviron(void) {
  59     return(USE_VAR(environ));
  60 }
  61
  62 char **_NSGetProgname(void) {
  63     return(USE_VAR(__progname));
  64 }
  65
  66 struct mach_header *_NSGetMachExecuteHeader(void) {
  67     return(USE_VAR(_mh_execute_header));
  68 }
  69
  70 #if __DYNAMIC__
  71 struct ProgramVars
  72 {
  73     void*       mh;
  74     int*        NXArgcPtr;
  75     char***     NXArgvPtr;
  76     char***     environPtr;
  77     char**      __prognamePtr;
  78 };
  79
  80
  81 #define SUPPORT_PRE_GM_10_5_EXECUTABLES (__ppc__ || __i386__)
  82
  83
  84 /*
  85  * dyld calls libSystem_initializer() and passes it a ProgramVars struct containing pointers to the
  86  * main executable's NXArg* global variables. libSystem_initializer() calls __libc_init() which calls
  87  * _program_vars_init() passing the ProgramVars parameter.
  88  */
  89 void __attribute__((visibility("hidden")))
  90 _program_vars_init(const struct ProgramVars* vars) {
  91 #if SUPPORT_PRE_GM_10_5_EXECUTABLES
  92     // to support transitional 10.5 main executables that don't have extended __dyld section and instead call _NSSetProgramVars,
  93     // don't overwrite values set by _NSSetProgramVars()
  94     if ( NXArgv_pointer != NULL )
  95         return;
  96 #endif
  97     NXArgv_pointer              = vars->NXArgvPtr;
  98     NXArgc_pointer              = vars->NXArgcPtr;
  99     environ_pointer             = vars->environPtr;
 100     __progname_pointer          = vars->__prognamePtr;
 101     _mh_execute_header_pointer  = vars->mh;
 102 }
 103
 104 #if SUPPORT_PRE_GM_10_5_EXECUTABLES
 105 /*
 106  * This is only called by main executables built with pre 10-5 GM crt1.10.5.o.  In those programs,
 107  * there is no extended __dyld section, dyld cannot tell _program_vars_init() where the real program
 108  * variables are, so they get temp values and are set for real here.
 109  */
 110 void _NSSetProgramVars(int* crt_argc, char*** crt_argv, char*** crt_environ, struct mach_header* crt_mh, char** crt_progname) {
 111     NXArgv_pointer              = crt_argv;
 112     NXArgc_pointer              = crt_argc;
 113     environ_pointer             = crt_environ;
 114     __progname_pointer          = crt_progname;
 115     _mh_execute_header_pointer  = crt_mh;
 116 }
 117 #endif
 118 #endif /* __DYNAMIC__ */
 119
 120 #if __ppc__
 121 /*
 122  * Fix for Radar bug 2200596 --
 123  * EH symbol definitions for gcc 2.7.2.x implementation of
 124  * C++ exception handling.  The problem:  the EH implementation
 125  * has "throw" store stuff into these pointers, and then as the
 126  * stack is unwound, the code generated into each function (for
 127  * checking whether this function contains a relevant "catch"
 128  * clause and for calling destructors for local variables) looks
 129  * at these globals to find the type and value thrown.
 130  *
 131  * The problem was that the compiler generated the symbols as
 132  * "common" symbols, and common symbols cannot be placed in
 133  * dynamic shared libraries.  So we must put these guys as
 134  * "data" symbols into crt0.o or the System Framework (library),
 135  * and the compiler must generate code that defines the symbols
 136  * as external references instead of common.
 137  *
 138  * I changed the symbol names (added the "_272") to be utterly
 139  * paranoid about any possible future use of similar names by
 140  * any future versions of gcc.
 141  *                      -- D. Landauer, Jan. 1998
 142  */
 143
 144 void *__eh_pc_gcc_272 = (void *)0;
 145 void *__eh_type_gcc_272 = (void *)0;
 146 void *__eh_value_gcc_272 = (void *)0;
 147
 148 /* This is what egcs uses for its global data pointer */
 149 void *__eh_global_dataptr = (void *)0;
 150 #endif /* __ppc__ */
 151