src/third_party/mac_headers/mach-o/nlist.h - breakpad - Git at Google

 /*
  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
  *
  * @APPLE_LICENSE_HEADER_START@
  *
  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in
  * compliance with the License. Please obtain a copy of the License at
  * http://www.opensource.apple.com/apsl/ and read it before using this
  * file.
  *
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.
  *
  * @APPLE_LICENSE_HEADER_END@
  */
 #ifndef _MACHO_NLIST_H_
 #define _MACHO_NLIST_H_
 /*	$NetBSD: nlist.h,v 1.5 1994/10/26 00:56:11 cgd Exp $	*/

 /*-
  * Copyright (c) 1991, 1993
  *	The Regents of the University of California.  All rights reserved.
  * (c) UNIX System Laboratories, Inc.
  * All or some portions of this file are derived from material licensed
  * to the University of California by American Telephone and Telegraph
  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  * the permission of UNIX System Laboratories, Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. All advertising materials mentioning features or use of this software
  *    must display the following acknowledgement:
  *	This product includes software developed by the University of
  *	California, Berkeley and its contributors.
  * 4. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
  *	@(#)nlist.h	8.2 (Berkeley) 1/21/94
  */
 #include <stdint.h>

 /*
  * Format of a symbol table entry of a Mach-O file for 32-bit architectures.
  * Modified from the BSD format.  The modifications from the original format
  * were changing n_other (an unused field) to n_sect and the addition of the
  * N_SECT type.  These modifications are required to support symbols in a larger
  * number of sections not just the three sections (text, data and bss) in a BSD
  * file.
  */
 struct nlist {
 	union {
 #ifndef __LP64__
 		char *n_name;	/* for use when in-core */
 #endif
 		int32_t n_strx;	/* index into the string table */
 	} n_un;
 	uint8_t n_type;		/* type flag, see below */
 	uint8_t n_sect;		/* section number or NO_SECT */
 	int16_t n_desc;		/* see <mach-o/stab.h> */
 	uint32_t n_value;	/* value of this symbol (or stab offset) */
 };

 /*
  * This is the symbol table entry structure for 64-bit architectures.
  */
 struct nlist_64 {
     union {
         uint32_t  n_strx; /* index into the string table */
     } n_un;
     uint8_t n_type;        /* type flag, see below */
     uint8_t n_sect;        /* section number or NO_SECT */
     uint16_t n_desc;       /* see <mach-o/stab.h> */
     uint64_t n_value;      /* value of this symbol (or stab offset) */
 };

 /*
  * Symbols with a index into the string table of zero (n_un.n_strx == 0) are
  * defined to have a null, "", name.  Therefore all string indexes to non null
  * names must not have a zero string index.  This is bit historical information
  * that has never been well documented.
  */

 /*
  * The n_type field really contains four fields:
  *	unsigned char N_STAB:3,
  *		      N_PEXT:1,
  *		      N_TYPE:3,
  *		      N_EXT:1;
  * which are used via the following masks.
  */
 #define	N_STAB	0xe0  /* if any of these bits set, a symbolic debugging entry */
 #define	N_PEXT	0x10  /* private external symbol bit */
 #define	N_TYPE	0x0e  /* mask for the type bits */
 #define	N_EXT	0x01  /* external symbol bit, set for external symbols */

 /*
  * Only symbolic debugging entries have some of the N_STAB bits set and if any
  * of these bits are set then it is a symbolic debugging entry (a stab).  In
  * which case then the values of the n_type field (the entire field) are given
  * in <mach-o/stab.h>
  */

 /*
  * Values for N_TYPE bits of the n_type field.
  */
 #define	N_UNDF	0x0		/* undefined, n_sect == NO_SECT */
 #define	N_ABS	0x2		/* absolute, n_sect == NO_SECT */
 #define	N_SECT	0xe		/* defined in section number n_sect */
 #define	N_PBUD	0xc		/* prebound undefined (defined in a dylib) */
 #define N_INDR	0xa		/* indirect */

 /*
  * If the type is N_INDR then the symbol is defined to be the same as another
  * symbol.  In this case the n_value field is an index into the string table
  * of the other symbol's name.  When the other symbol is defined then they both
  * take on the defined type and value.
  */

 /*
  * If the type is N_SECT then the n_sect field contains an ordinal of the
  * section the symbol is defined in.  The sections are numbered from 1 and
  * refer to sections in order they appear in the load commands for the file
  * they are in.  This means the same ordinal may very well refer to different
  * sections in different files.
  *
  * The n_value field for all symbol table entries (including N_STAB's) gets
  * updated by the link editor based on the value of it's n_sect field and where
  * the section n_sect references gets relocated.  If the value of the n_sect
  * field is NO_SECT then it's n_value field is not changed by the link editor.
  */
 #define	NO_SECT		0	/* symbol is not in any section */
 #define MAX_SECT	255	/* 1 thru 255 inclusive */

 /*
  * Common symbols are represented by undefined (N_UNDF) external (N_EXT) types
  * who's values (n_value) are non-zero.  In which case the value of the n_value
  * field is the size (in bytes) of the common symbol.  The n_sect field is set
  * to NO_SECT.  The alignment of a common symbol may be set as a power of 2
  * between 2^1 and 2^15 as part of the n_desc field using the macros below. If
  * the alignment is not set (a value of zero) then natural alignment based on
  * the size is used.
  */
 #define GET_COMM_ALIGN(n_desc) (((n_desc) >> 8) & 0x0f)
 #define SET_COMM_ALIGN(n_desc,align) \
     (n_desc) = (((n_desc) & 0xf0ff) | (((align) & 0x0f) << 8))

 /*
  * To support the lazy binding of undefined symbols in the dynamic link-editor,
  * the undefined symbols in the symbol table (the nlist structures) are marked
  * with the indication if the undefined reference is a lazy reference or
  * non-lazy reference.  If both a non-lazy reference and a lazy reference is
  * made to the same symbol the non-lazy reference takes precedence.  A reference
  * is lazy only when all references to that symbol are made through a symbol
  * pointer in a lazy symbol pointer section.
  *
  * The implementation of marking nlist structures in the symbol table for
  * undefined symbols will be to use some of the bits of the n_desc field as a
  * reference type.  The mask REFERENCE_TYPE will be applied to the n_desc field
  * of an nlist structure for an undefined symbol to determine the type of
  * undefined reference (lazy or non-lazy).
  *
  * The constants for the REFERENCE FLAGS are propagated to the reference table
  * in a shared library file.  In that case the constant for a defined symbol,
  * REFERENCE_FLAG_DEFINED, is also used.
  */
 /* Reference type bits of the n_desc field of undefined symbols */
 #define REFERENCE_TYPE				0x7
 /* types of references */
 #define REFERENCE_FLAG_UNDEFINED_NON_LAZY		0
 #define REFERENCE_FLAG_UNDEFINED_LAZY			1
 #define REFERENCE_FLAG_DEFINED				2
 #define REFERENCE_FLAG_PRIVATE_DEFINED			3
 #define REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY	4
 #define REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY		5

 /*
  * To simplify stripping of objects that use are used with the dynamic link
  * editor, the static link editor marks the symbols defined an object that are
  * referenced by a dynamicly bound object (dynamic shared libraries, bundles).
  * With this marking strip knows not to strip these symbols.
  */
 #define REFERENCED_DYNAMICALLY	0x0010

 /*
  * For images created by the static link editor with the -twolevel_namespace
  * option in effect the flags field of the mach header is marked with
  * MH_TWOLEVEL.  And the binding of the undefined references of the image are
  * determined by the static link editor.  Which library an undefined symbol is
  * bound to is recorded by the static linker in the high 8 bits of the n_desc
  * field using the SET_LIBRARY_ORDINAL macro below.  The ordinal recorded
  * references the libraries listed in the Mach-O's LC_LOAD_DYLIB,
  * LC_LOAD_WEAK_DYLIB, LC_REEXPORT_DYLIB, LC_LOAD_UPWARD_DYLIB, and
  * LC_LAZY_LOAD_DYLIB, etc. load commands in the order they appear in the
  * headers.   The library ordinals start from 1.
  * For a dynamic library that is built as a two-level namespace image the
  * undefined references from module defined in another use the same nlist struct
  * an in that case SELF_LIBRARY_ORDINAL is used as the library ordinal.  For
  * defined symbols in all images they also must have the library ordinal set to
  * SELF_LIBRARY_ORDINAL.  The EXECUTABLE_ORDINAL refers to the executable
  * image for references from plugins that refer to the executable that loads
  * them.
  *
  * The DYNAMIC_LOOKUP_ORDINAL is for undefined symbols in a two-level namespace
  * image that are looked up by the dynamic linker with flat namespace semantics.
  * This ordinal was added as a feature in Mac OS X 10.3 by reducing the
  * value of MAX_LIBRARY_ORDINAL by one.  So it is legal for existing binaries
  * or binaries built with older tools to have 0xfe (254) dynamic libraries.  In
  * this case the ordinal value 0xfe (254) must be treated as a library ordinal
  * for compatibility.
  */
 #define GET_LIBRARY_ORDINAL(n_desc) (((n_desc) >> 8) & 0xff)
 #define SET_LIBRARY_ORDINAL(n_desc,ordinal) \
 	(n_desc) = (((n_desc) & 0x00ff) | (((ordinal) & 0xff) << 8))
 #define SELF_LIBRARY_ORDINAL 0x0
 #define MAX_LIBRARY_ORDINAL 0xfd
 #define DYNAMIC_LOOKUP_ORDINAL 0xfe
 #define EXECUTABLE_ORDINAL 0xff

 /*
  * The bit 0x0020 of the n_desc field is used for two non-overlapping purposes
  * and has two different symbolic names, N_NO_DEAD_STRIP and N_DESC_DISCARDED.
  */

 /*
  * The N_NO_DEAD_STRIP bit of the n_desc field only ever appears in a
  * relocatable .o file (MH_OBJECT filetype). And is used to indicate to the
  * static link editor it is never to dead strip the symbol.
  */
 #define N_NO_DEAD_STRIP 0x0020 /* symbol is not to be dead stripped */

 /*
  * The N_DESC_DISCARDED bit of the n_desc field never appears in linked image.
  * But is used in very rare cases by the dynamic link editor to mark an in
  * memory symbol as discared and longer used for linking.
  */
 #define N_DESC_DISCARDED 0x0020	/* symbol is discarded */

 /*
  * The N_WEAK_REF bit of the n_desc field indicates to the dynamic linker that
  * the undefined symbol is allowed to be missing and is to have the address of
  * zero when missing.
  */
 #define N_WEAK_REF	0x0040 /* symbol is weak referenced */

 /*
  * The N_WEAK_DEF bit of the n_desc field indicates to the static and dynamic
  * linkers that the symbol definition is weak, allowing a non-weak symbol to
  * also be used which causes the weak definition to be discared.  Currently this
  * is only supported for symbols in coalesed sections.
  */
 #define N_WEAK_DEF	0x0080 /* coalesed symbol is a weak definition */

 /*
  * The N_REF_TO_WEAK bit of the n_desc field indicates to the dynamic linker
  * that the undefined symbol should be resolved using flat namespace searching.
  */
 #define	N_REF_TO_WEAK	0x0080 /* reference to a weak symbol */

 /*
  * The N_ARM_THUMB_DEF bit of the n_desc field indicates that the symbol is
  * a defintion of a Thumb function.
  */
 #define N_ARM_THUMB_DEF	0x0008 /* symbol is a Thumb function (ARM) */

 /*
  * The N_SYMBOL_RESOLVER bit of the n_desc field indicates that the
  * that the function is actually a resolver function and should
  * be called to get the address of the real function to use.
  * This bit is only available in .o files (MH_OBJECT filetype)
  */
 #define N_SYMBOL_RESOLVER  0x0100

 #ifndef __STRICT_BSD__
 #if __cplusplus
 extern "C" {
 #endif /* __cplusplus */
 /*
  * The function nlist(3) from the C library.
  */
 extern int nlist (const char *filename, struct nlist *list);
 #if __cplusplus
 }
 #endif /* __cplusplus */
 #endif /* __STRICT_BSD__ */

 #endif /* _MACHO_LIST_H_ */
	/*
	* Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
	*
	* @APPLE_LICENSE_HEADER_START@
	*
	* This file contains Original Code and/or Modifications of Original Code
	* as defined in and that are subject to the Apple Public Source License
	* Version 2.0 (the 'License'). You may not use this file except in
	* compliance with the License. Please obtain a copy of the License at
	* http://www.opensource.apple.com/apsl/ and read it before using this
	* file.
	*
	* The Original Code and all software distributed under the License are
	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	* Please see the License for the specific language governing rights and
	* limitations under the License.
	*
	* @APPLE_LICENSE_HEADER_END@
	*/
	#ifndef _MACHO_NLIST_H_
	#define _MACHO_NLIST_H_
	/* $NetBSD: nlist.h,v 1.5 1994/10/26 00:56:11 cgd Exp $ */

	/*-
	* Copyright (c) 1991, 1993
	* The Regents of the University of California. All rights reserved.
	* (c) UNIX System Laboratories, Inc.
	* All or some portions of this file are derived from material licensed
	* to the University of California by American Telephone and Telegraph
	* Co. or Unix System Laboratories, Inc. and are reproduced herein with
	* the permission of UNIX System Laboratories, Inc.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. All advertising materials mentioning features or use of this software
	* must display the following acknowledgement:
	* This product includes software developed by the University of
	* California, Berkeley and its contributors.
	* 4. Neither the name of the University nor the names of its contributors
	* may be used to endorse or promote products derived from this software
	* without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	* SUCH DAMAGE.
	*
	* @(#)nlist.h 8.2 (Berkeley) 1/21/94
	*/
	#include <stdint.h>

	/*
	* Format of a symbol table entry of a Mach-O file for 32-bit architectures.
	* Modified from the BSD format. The modifications from the original format
	* were changing n_other (an unused field) to n_sect and the addition of the
	* N_SECT type. These modifications are required to support symbols in a larger
	* number of sections not just the three sections (text, data and bss) in a BSD
	* file.
	*/
	struct nlist {
	union {
	#ifndef __LP64__
	char n_name; / for use when in-core */
	#endif
	int32_t n_strx; /* index into the string table */
	} n_un;
	uint8_t n_type; /* type flag, see below */
	uint8_t n_sect; /* section number or NO_SECT */
	int16_t n_desc; /* see <mach-o/stab.h> */
	uint32_t n_value; /* value of this symbol (or stab offset) */
	};

	/*
	* This is the symbol table entry structure for 64-bit architectures.
	*/
	struct nlist_64 {
	union {
	uint32_t n_strx; /* index into the string table */
	} n_un;
	uint8_t n_type; /* type flag, see below */
	uint8_t n_sect; /* section number or NO_SECT */
	uint16_t n_desc; /* see <mach-o/stab.h> */
	uint64_t n_value; /* value of this symbol (or stab offset) */
	};

	/*
	* Symbols with a index into the string table of zero (n_un.n_strx == 0) are
	* defined to have a null, "", name. Therefore all string indexes to non null
	* names must not have a zero string index. This is bit historical information
	* that has never been well documented.
	*/

	/*
	* The n_type field really contains four fields:
	* unsigned char N_STAB:3,
	* N_PEXT:1,
	* N_TYPE:3,
	* N_EXT:1;
	* which are used via the following masks.
	*/
	#define N_STAB 0xe0 /* if any of these bits set, a symbolic debugging entry */
	#define N_PEXT 0x10 /* private external symbol bit */
	#define N_TYPE 0x0e /* mask for the type bits */
	#define N_EXT 0x01 /* external symbol bit, set for external symbols */

	/*
	* Only symbolic debugging entries have some of the N_STAB bits set and if any
	* of these bits are set then it is a symbolic debugging entry (a stab). In
	* which case then the values of the n_type field (the entire field) are given
	* in <mach-o/stab.h>
	*/

	/*
	* Values for N_TYPE bits of the n_type field.
	*/
	#define N_UNDF 0x0 /* undefined, n_sect == NO_SECT */
	#define N_ABS 0x2 /* absolute, n_sect == NO_SECT */
	#define N_SECT 0xe /* defined in section number n_sect */
	#define N_PBUD 0xc /* prebound undefined (defined in a dylib) */
	#define N_INDR 0xa /* indirect */

	/*
	* If the type is N_INDR then the symbol is defined to be the same as another
	* symbol. In this case the n_value field is an index into the string table
	* of the other symbol's name. When the other symbol is defined then they both
	* take on the defined type and value.
	*/

	/*
	* If the type is N_SECT then the n_sect field contains an ordinal of the
	* section the symbol is defined in. The sections are numbered from 1 and
	* refer to sections in order they appear in the load commands for the file
	* they are in. This means the same ordinal may very well refer to different
	* sections in different files.
	*
	* The n_value field for all symbol table entries (including N_STAB's) gets
	* updated by the link editor based on the value of it's n_sect field and where
	* the section n_sect references gets relocated. If the value of the n_sect
	* field is NO_SECT then it's n_value field is not changed by the link editor.
	*/
	#define NO_SECT 0 /* symbol is not in any section */
	#define MAX_SECT 255 /* 1 thru 255 inclusive */

	/*
	* Common symbols are represented by undefined (N_UNDF) external (N_EXT) types
	* who's values (n_value) are non-zero. In which case the value of the n_value
	* field is the size (in bytes) of the common symbol. The n_sect field is set
	* to NO_SECT. The alignment of a common symbol may be set as a power of 2
	* between 2^1 and 2^15 as part of the n_desc field using the macros below. If
	* the alignment is not set (a value of zero) then natural alignment based on
	* the size is used.
	*/
	#define GET_COMM_ALIGN(n_desc) (((n_desc) >> 8) & 0x0f)
	#define SET_COMM_ALIGN(n_desc,align) \
	(n_desc) = (((n_desc) & 0xf0ff) \| (((align) & 0x0f) << 8))

	/*
	* To support the lazy binding of undefined symbols in the dynamic link-editor,
	* the undefined symbols in the symbol table (the nlist structures) are marked
	* with the indication if the undefined reference is a lazy reference or
	* non-lazy reference. If both a non-lazy reference and a lazy reference is
	* made to the same symbol the non-lazy reference takes precedence. A reference
	* is lazy only when all references to that symbol are made through a symbol
	* pointer in a lazy symbol pointer section.
	*
	* The implementation of marking nlist structures in the symbol table for
	* undefined symbols will be to use some of the bits of the n_desc field as a
	* reference type. The mask REFERENCE_TYPE will be applied to the n_desc field
	* of an nlist structure for an undefined symbol to determine the type of
	* undefined reference (lazy or non-lazy).
	*
	* The constants for the REFERENCE FLAGS are propagated to the reference table
	* in a shared library file. In that case the constant for a defined symbol,
	* REFERENCE_FLAG_DEFINED, is also used.
	*/
	/* Reference type bits of the n_desc field of undefined symbols */
	#define REFERENCE_TYPE 0x7
	/* types of references */
	#define REFERENCE_FLAG_UNDEFINED_NON_LAZY 0
	#define REFERENCE_FLAG_UNDEFINED_LAZY 1
	#define REFERENCE_FLAG_DEFINED 2
	#define REFERENCE_FLAG_PRIVATE_DEFINED 3
	#define REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY 4
	#define REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY 5

	/*
	* To simplify stripping of objects that use are used with the dynamic link
	* editor, the static link editor marks the symbols defined an object that are
	* referenced by a dynamicly bound object (dynamic shared libraries, bundles).
	* With this marking strip knows not to strip these symbols.
	*/
	#define REFERENCED_DYNAMICALLY 0x0010

	/*
	* For images created by the static link editor with the -twolevel_namespace
	* option in effect the flags field of the mach header is marked with
	* MH_TWOLEVEL. And the binding of the undefined references of the image are
	* determined by the static link editor. Which library an undefined symbol is
	* bound to is recorded by the static linker in the high 8 bits of the n_desc
	* field using the SET_LIBRARY_ORDINAL macro below. The ordinal recorded
	* references the libraries listed in the Mach-O's LC_LOAD_DYLIB,
	* LC_LOAD_WEAK_DYLIB, LC_REEXPORT_DYLIB, LC_LOAD_UPWARD_DYLIB, and
	* LC_LAZY_LOAD_DYLIB, etc. load commands in the order they appear in the
	* headers. The library ordinals start from 1.
	* For a dynamic library that is built as a two-level namespace image the
	* undefined references from module defined in another use the same nlist struct
	* an in that case SELF_LIBRARY_ORDINAL is used as the library ordinal. For
	* defined symbols in all images they also must have the library ordinal set to
	* SELF_LIBRARY_ORDINAL. The EXECUTABLE_ORDINAL refers to the executable
	* image for references from plugins that refer to the executable that loads
	* them.
	*
	* The DYNAMIC_LOOKUP_ORDINAL is for undefined symbols in a two-level namespace
	* image that are looked up by the dynamic linker with flat namespace semantics.
	* This ordinal was added as a feature in Mac OS X 10.3 by reducing the
	* value of MAX_LIBRARY_ORDINAL by one. So it is legal for existing binaries
	* or binaries built with older tools to have 0xfe (254) dynamic libraries. In
	* this case the ordinal value 0xfe (254) must be treated as a library ordinal
	* for compatibility.
	*/
	#define GET_LIBRARY_ORDINAL(n_desc) (((n_desc) >> 8) & 0xff)
	#define SET_LIBRARY_ORDINAL(n_desc,ordinal) \
	(n_desc) = (((n_desc) & 0x00ff) \| (((ordinal) & 0xff) << 8))
	#define SELF_LIBRARY_ORDINAL 0x0
	#define MAX_LIBRARY_ORDINAL 0xfd
	#define DYNAMIC_LOOKUP_ORDINAL 0xfe
	#define EXECUTABLE_ORDINAL 0xff

	/*
	* The bit 0x0020 of the n_desc field is used for two non-overlapping purposes
	* and has two different symbolic names, N_NO_DEAD_STRIP and N_DESC_DISCARDED.
	*/

	/*
	* The N_NO_DEAD_STRIP bit of the n_desc field only ever appears in a
	* relocatable .o file (MH_OBJECT filetype). And is used to indicate to the
	* static link editor it is never to dead strip the symbol.
	*/
	#define N_NO_DEAD_STRIP 0x0020 /* symbol is not to be dead stripped */

	/*
	* The N_DESC_DISCARDED bit of the n_desc field never appears in linked image.
	* But is used in very rare cases by the dynamic link editor to mark an in
	* memory symbol as discared and longer used for linking.
	*/
	#define N_DESC_DISCARDED 0x0020 /* symbol is discarded */

	/*
	* The N_WEAK_REF bit of the n_desc field indicates to the dynamic linker that
	* the undefined symbol is allowed to be missing and is to have the address of
	* zero when missing.
	*/
	#define N_WEAK_REF 0x0040 /* symbol is weak referenced */

	/*
	* The N_WEAK_DEF bit of the n_desc field indicates to the static and dynamic
	* linkers that the symbol definition is weak, allowing a non-weak symbol to
	* also be used which causes the weak definition to be discared. Currently this
	* is only supported for symbols in coalesed sections.
	*/
	#define N_WEAK_DEF 0x0080 /* coalesed symbol is a weak definition */

	/*
	* The N_REF_TO_WEAK bit of the n_desc field indicates to the dynamic linker
	* that the undefined symbol should be resolved using flat namespace searching.
	*/
	#define N_REF_TO_WEAK 0x0080 /* reference to a weak symbol */

	/*
	* The N_ARM_THUMB_DEF bit of the n_desc field indicates that the symbol is
	* a defintion of a Thumb function.
	*/
	#define N_ARM_THUMB_DEF 0x0008 /* symbol is a Thumb function (ARM) */

	/*
	* The N_SYMBOL_RESOLVER bit of the n_desc field indicates that the
	* that the function is actually a resolver function and should
	* be called to get the address of the real function to use.
	* This bit is only available in .o files (MH_OBJECT filetype)
	*/
	#define N_SYMBOL_RESOLVER 0x0100

	#ifndef __STRICT_BSD__
	#if __cplusplus
	extern "C" {
	#endif /* __cplusplus */
	/*
	* The function nlist(3) from the C library.
	*/
	extern int nlist (const char filename, struct nlist list);
	#if __cplusplus
	}
	#endif /* __cplusplus */
	#endif /* __STRICT_BSD__ */

	#endif /* _MACHO_LIST_H_ */