src/dyldLibSystemGlue.c

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2009-2010 Apple Inc. All rights reserved.
   4  *
   5  * @APPLE_LICENSE_HEADER_START@
   6  *
   7  * This file contains Original Code and/or Modifications of Original Code
   8  * as defined in and that are subject to the Apple Public Source License
   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
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  19  * Please see the License for the specific language governing rights and
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  23  */
  24
  25 #include <Availability.h>
  26 #include <stddef.h>
  27
  28 //
  29 // This is the temporary private interface between libSystem.B.dylib and dyld
  30 //
  31
  32
  33 int          NXArgc = 0;
  34 const char** NXArgv = NULL;
  35 const char** environ = NULL;
  36 const char*  __progname = NULL;
  37
  38
  39
  40 //
  41 // Long ago, the compiler driver added -ldylib1.o to every dylib which caused a
  42 // __DATA,__dyld section to be added every dylib.  The new LINKEDIT format no longer requires
  43 // images to have a __DATA,__dyld section.  But until libdyld.dylib and dyld update
  44 // to some sort of vtable based interface, libdyld still needs a __DATA,__dyld section.
  45 // The code below adds that section.
  46 //
  47 struct __DATA__dyld {
  48         long                    lazy;
  49         int                             (*lookup)(const char*, void**);
  50         // ProgramVars
  51         const void*             mh;
  52         int*                    NXArgcPtr;
  53         const char***   NXArgvPtr;
  54         const char***   environPtr;
  55         const char**    __prognamePtr;
  56 };
  57
  58 static volatile struct __DATA__dyld  myDyldSection __attribute__ ((section ("__DATA,__dyld")))
  59         = { 0, 0, NULL, &NXArgc, &NXArgv, &environ, &__progname };
  60
  61 #if __arm__ && __MAC_OS_X_VERSION_MIN_REQUIRED
  62 // <rdar://problem/8755380>
  63 // For historical reasons, gcc and llvm-gcc added -ldylib1.o to the link line of armv6
  64 // dylibs when targeting MacOSX (but not iOS).  clang cleans up that mistake, but doing
  65 // so would break the libdyld build.  Making _dyld_func_lookup weak,hidden means if
  66 // dylib1.o is used, it overrides this, otherwise this implementation is used.
  67 __attribute__((weak))
  68 #endif
  69 __attribute__((visibility("hidden")))
  70 int _dyld_func_lookup(const char* dyld_func_name, void **address)
  71 {
  72         return (*myDyldSection.lookup)(dyld_func_name, address);
  73 }
  74
  75