cctools/include/mach-o/ldsyms.h

   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 #ifndef _MACHO_LDSYMS_H_
  25 #define _MACHO_LDSYMS_H_
  26
  27 #include <mach-o/loader.h>
  28
  29 /*
  30  * This file describes the link editor defined symbols.  The semantics of a
  31  * link editor symbol is that it is defined by the link editor only if it is
  32  * referenced and it is an error for the user to define them (see the man page
  33  * ld(1)).  The standard UNIX link editor symbols: __end, __etext and __edata
  34  * are not not supported by the Apple Mach-O link editor.  These symbols are
  35  * really not meaningful in a Mach-O object file and the link editor symbols
  36  * that are supported (described here) replace them.  In the case of the
  37  * standard UNIX link editor symbols the program can use the symbol
  38  * __mh_execute_header and walk the load commands of it's program to determine
  39  * the ending (or beginning) of any section or segment in the program.  Note
  40  * that the compiler prepends an underbar to all external symbol names coded
  41  * in a high level language.  Thus in 'C' names are coded without an underbar
  42  * and symbol names in the symbol table have an underbar.  There are two cpp
  43  * macros for each link editor defined name in this file.  The macro with a
  44  * leading underbar is the symbol name and the one without is the name as
  45  * coded in 'C'.
  46  */
  47
  48 /*
  49  * The value of the link editor defined symbol _MH_EXECUTE_SYM is the address
  50  * of the mach header in a Mach-O executable file type.  It does not appear in
  51  * any file type other than a MH_EXECUTE file type.  The type of the symbol is
  52  * absolute as the header is not part of any section.
  53  */
  54 #define _MH_EXECUTE_SYM "__mh_execute_header"
  55 #define MH_EXECUTE_SYM  "_mh_execute_header"
  56 extern const struct
  57 #ifdef __LP64__
  58 mach_header_64
  59 #else
  60 mach_header
  61 #endif
  62 _mh_execute_header;
  63
  64 /*
  65  * The value of the link editor defined symbol _MH_BUNDLE_SYM is the address
  66  * of the mach header in a Mach-O bundle file type.  It does not appear in
  67  * any file type other than a MH_BUNDLE file type.  The type of the symbol is
  68  * an N_SECT symbol even thought the header is not part of any section.  This
  69  * symbol is private to the code in the bundle it is a part of.
  70  */
  71 #define _MH_BUNDLE_SYM  "__mh_bundle_header"
  72 #define MH_BUNDLE_SYM   "_mh_bundle_header"
  73 extern const struct
  74 #ifdef __LP64__
  75 mach_header_64
  76 #else
  77 mach_header
  78 #endif
  79 _mh_bundle_header;
  80
  81 /*
  82  * The value of the link editor defined symbol _MH_DYLIB_SYM is the address
  83  * of the mach header in a Mach-O dylib file type.  It does not appear in
  84  * any file type other than a MH_DYLIB file type.  The type of the symbol is
  85  * an N_SECT symbol even thought the header is not part of any section.  This
  86  * symbol is private to the code in the library it is a part of.
  87  */
  88 #define _MH_DYLIB_SYM   "__mh_dylib_header"
  89 #define MH_DYLIB_SYM    "_mh_dylib_header"
  90 extern const struct
  91 #ifdef __LP64__
  92 mach_header_64
  93 #else
  94 mach_header
  95 #endif
  96 _mh_dylib_header;
  97
  98 /*
  99  * The value of the link editor defined symbol _MH_DYLINKER_SYM is the address
 100  * of the mach header in a Mach-O dylinker file type.  It does not appear in
 101  * any file type other than a MH_DYLINKER file type.  The type of the symbol is
 102  * an N_SECT symbol even thought the header is not part of any section.  This
 103  * symbol is private to the code in the dynamic linker it is a part of.
 104  */
 105 #define _MH_DYLINKER_SYM        "__mh_dylinker_header"
 106 #define MH_DYLINKER_SYM         "_mh_dylinker_header"
 107 extern const struct
 108 #ifdef __LP64__
 109 mach_header_64
 110 #else
 111 mach_header
 112 #endif
 113 _mh_dylinker_header;
 114
 115 /*
 116  * For the MH_PRELOAD file type the headers are not loaded as part of any
 117  * segment so the link editor defines symbols defined for the beginning
 118  * and ending of each segment and each section in each segment.  The names for
 119  * the symbols for a segment's beginning and end will have the form:
 120  * __SEGNAME__begin and  __SEGNAME__end where __SEGNAME is the name of the
 121  * segment.  The names for the symbols for a section's beginning and end will
 122  * have the form: __SEGNAME__sectname__begin and __SEGNAME__sectname__end
 123  * where __sectname is the name of the section and __SEGNAME is the segment it
 124  * is in.
 125  *
 126  * The above symbols' types are those of the section they are referring to.
 127  * This is true even for symbols who's values are end's of a section and
 128  * that value is next address after that section and not really in that
 129  * section.  This results in these symbols having types referring to sections
 130  * who's values are not in that section.
 131  */
 132
 133 #endif /* _MACHO_LDSYMS_H_ */