src/dyldLibSystemGlue.c

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2009-2010 Apple Inc. All rights reserved.
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   9  * Version 2.0 (the 'License'). You may not use this file except in
  10  * compliance with the License. Please obtain a copy of the License at
  11  * http://www.opensource.apple.com/apsl/ and read it before using this
  12  * file.
  13  *
  14  * The Original Code and all software distributed under the License are
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  24
  25 #include <Availability.h>
  26 #include <stddef.h>
  27 #include <TargetConditionals.h>
  28
  29
  30 // simulator does not have full libdyld.dylib - just a small libdyld_sim.dylib
  31 #if ! TARGET_IPHONE_SIMULATOR
  32
  33
  34 //
  35 // This is the temporary private interface between libSystem.B.dylib and dyld
  36 //
  37
  38
  39 int          NXArgc = 0;
  40 const char** NXArgv = NULL;
  41 const char** environ = NULL;
  42 const char*  __progname = NULL;
  43
  44
  45
  46 //
  47 // Long ago, the compiler driver added -ldylib1.o to every dylib which caused a
  48 // __DATA,__dyld section to be added every dylib.  The new LINKEDIT format no longer requires
  49 // images to have a __DATA,__dyld section.  But until libdyld.dylib and dyld update
  50 // to some sort of vtable based interface, libdyld still needs a __DATA,__dyld section.
  51 // The code below adds that section.
  52 //
  53 struct __DATA__dyld {
  54         long                    lazy;
  55         int                             (*lookup)(const char*, void**);
  56         // ProgramVars
  57         const void*             mh;
  58         int*                    NXArgcPtr;
  59         const char***   NXArgvPtr;
  60         const char***   environPtr;
  61         const char**    __prognamePtr;
  62 };
  63
  64 static volatile struct __DATA__dyld  myDyldSection __attribute__ ((section ("__DATA,__dyld")))
  65         = { 0, 0, NULL, &NXArgc, &NXArgv, &environ, &__progname };
  66
  67 #if __arm__ && __MAC_OS_X_VERSION_MIN_REQUIRED
  68 // <rdar://problem/8755380>
  69 // For historical reasons, gcc and llvm-gcc added -ldylib1.o to the link line of armv6
  70 // dylibs when targeting MacOSX (but not iOS).  clang cleans up that mistake, but doing
  71 // so would break the libdyld build.  Making _dyld_func_lookup weak,hidden means if
  72 // dylib1.o is used, it overrides this, otherwise this implementation is used.
  73 __attribute__((weak))
  74 #endif
  75 __attribute__((visibility("hidden")))
  76 int _dyld_func_lookup(const char* dyld_func_name, void **address)
  77 {
  78         return (*myDyldSection.lookup)(dyld_func_name, address);
  79 }
  80
  81 #endif //! TARGET_IPHONE_SIMULATOR
  82