1/* 2 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved. 3 * 4 * @APPLE_LICENSE_HEADER_START@ 5 * 6 * The contents of this file constitute Original Code as defined in and 7 * are subject to the Apple Public Source License Version 1.1 (the 8 * "License"). You may not use this file except in compliance with the 9 * License. Please obtain a copy of the License at 10 * http://www.apple.com/publicsource and read it before using this file. 11 * 12 * This Original Code and all software distributed under the License are 13 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER 14 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 15 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 16 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the 17 * License for the specific language governing rights and limitations 18 * under the License. 19 * 20 * @APPLE_LICENSE_HEADER_END@ 21 */ 22#ifndef _MACHO_NLIST_H_ 23#define _MACHO_NLIST_H_ 24/* $NetBSD: nlist.h,v 1.5 1994/10/26 00:56:11 cgd Exp $ */ 25 26/*- 27 * Copyright (c) 1991, 1993 28 * The Regents of the University of California. All rights reserved. 29 * (c) UNIX System Laboratories, Inc. 30 * All or some portions of this file are derived from material licensed 31 * to the University of California by American Telephone and Telegraph 32 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 33 * the permission of UNIX System Laboratories, Inc. 34 * 35 * Redistribution and use in source and binary forms, with or without 36 * modification, are permitted provided that the following conditions 37 * are met: 38 * 1. Redistributions of source code must retain the above copyright 39 * notice, this list of conditions and the following disclaimer. 40 * 2. Redistributions in binary form must reproduce the above copyright 41 * notice, this list of conditions and the following disclaimer in the 42 * documentation and/or other materials provided with the distribution. 43 * 3. All advertising materials mentioning features or use of this software 44 * must display the following acknowledgement: 45 * This product includes software developed by the University of 46 * California, Berkeley and its contributors. 47 * 4. Neither the name of the University nor the names of its contributors 48 * may be used to endorse or promote products derived from this software 49 * without specific prior written permission. 50 * 51 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 52 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 53 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 54 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 55 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 56 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 57 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 58 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 59 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 60 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 61 * SUCH DAMAGE. 62 * 63 * @(#)nlist.h 8.2 (Berkeley) 1/21/94 64 */ 65 66/* 67 * Format of a symbol table entry of a Mach-O file. Modified from the BSD 68 * format. The modifications from the original format were changing n_other 69 * (an unused field) to n_sect and the addition of the N_SECT type. These 70 * modifications are required to support symbols in an arbitrary number of 71 * sections not just the three sections (text, data and bss) in a BSD file. 72 */ 73struct nlist { 74 union { 75 char *n_name; /* for use when in-core */ 76 long n_strx; /* index into the string table */ 77 } n_un; 78 unsigned char n_type; /* type flag, see below */ 79 unsigned char n_sect; /* section number or NO_SECT */ 80 short n_desc; /* see <mach-o/stab.h> */ 81 unsigned long n_value; /* value of this symbol (or stab offset) */ 82}; 83 84/* 85 * This is the symbol table entry structure for 64-bit architectures. 86 */ 87struct nlist_64 { 88 union { 89 uint32_t n_strx; /* index into the string table */ 90 } n_un; 91 uint8_t n_type; /* type flag, see below */ 92 uint8_t n_sect; /* section number or NO_SECT */ 93 uint16_t n_desc; /* see <mach-o/stab.h> */ 94 uint64_t n_value; /* value of this symbol (or stab offset) */ 95}; 96 97 98/* 99 * Symbols with a index into the string table of zero (n_un.n_strx == 0) are 100 * defined to have a null, "", name. Therefore all string indexes to non null 101 * names must not have a zero string index. This is bit historical information 102 * that has never been well documented. 103 */ 104 105/* 106 * The n_type field really contains three fields: 107 * unsigned char N_STAB:3, 108 * N_PEXT:1, 109 * N_TYPE:3, 110 * N_EXT:1; 111 * which are used via the following masks. 112 */ 113#define N_STAB 0xe0 /* if any of these bits set, a symbolic debugging entry */ 114#define N_PEXT 0x10 /* private external symbol bit */ 115#define N_TYPE 0x0e /* mask for the type bits */ 116#define N_EXT 0x01 /* external symbol bit, set for external symbols */ 117 118/* 119 * Only symbolic debugging entries have some of the N_STAB bits set and if any 120 * of these bits are set then it is a symbolic debugging entry (a stab). In 121 * which case then the values of the n_type field (the entire field) are given 122 * in <mach-o/stab.h> 123 */ 124 125/* 126 * Values for N_TYPE bits of the n_type field. 127 */ 128#define N_UNDF 0x0 /* undefined, n_sect == NO_SECT */ 129#define N_ABS 0x2 /* absolute, n_sect == NO_SECT */ 130#define N_SECT 0xe /* defined in section number n_sect */ 131#define N_PBUD 0xc /* prebound undefined (defined in a dylib) */ 132#define N_INDR 0xa /* indirect */ 133 134/* 135 * If the type is N_INDR then the symbol is defined to be the same as another 136 * symbol. In this case the n_value field is an index into the string table 137 * of the other symbol's name. When the other symbol is defined then they both 138 * take on the defined type and value. 139 */ 140 141/* 142 * If the type is N_SECT then the n_sect field contains an ordinal of the 143 * section the symbol is defined in. The sections are numbered from 1 and 144 * refer to sections in order they appear in the load commands for the file 145 * they are in. This means the same ordinal may very well refer to different 146 * sections in different files. 147 * 148 * The n_value field for all symbol table entries (including N_STAB's) gets 149 * updated by the link editor based on the value of it's n_sect field and where 150 * the section n_sect references gets relocated. If the value of the n_sect 151 * field is NO_SECT then it's n_value field is not changed by the link editor. 152 */ 153#define NO_SECT 0 /* symbol is not in any section */ 154#define MAX_SECT 255 /* 1 thru 255 inclusive */ 155 156/* 157 * Common symbols are represented by undefined (N_UNDF) external (N_EXT) types 158 * who's values (n_value) are non-zero. In which case the value of the n_value 159 * field is the size (in bytes) of the common symbol. The n_sect field is set 160 * to NO_SECT. 161 */ 162 163/* 164 * To support the lazy binding of undefined symbols in the dynamic link-editor, 165 * the undefined symbols in the symbol table (the nlist structures) are marked 166 * with the indication if the undefined reference is a lazy reference or 167 * non-lazy reference. If both a non-lazy reference and a lazy reference is 168 * made to the same symbol the non-lazy reference takes precedence. A reference 169 * is lazy only when all references to that symbol are made through a symbol 170 * pointer in a lazy symbol pointer section. 171 * 172 * The implementation of marking nlist structures in the symbol table for 173 * undefined symbols will be to use some of the bits of the n_desc field as a 174 * reference type. The mask REFERENCE_TYPE will be applied to the n_desc field 175 * of an nlist structure for an undefined symbol to determine the type of 176 * undefined reference (lazy or non-lazy). 177 * 178 * The constants for the REFERENCE FLAGS are propagated to the reference table 179 * in a shared library file. In that case the constant for a defined symbol, 180 * REFERENCE_FLAG_DEFINED, is also used. 181 */ 182/* Reference type bits of the n_desc field of undefined symbols */ 183#define REFERENCE_TYPE 0xf 184/* types of references */ 185#define REFERENCE_FLAG_UNDEFINED_NON_LAZY 0 186#define REFERENCE_FLAG_UNDEFINED_LAZY 1 187#define REFERENCE_FLAG_DEFINED 2 188#define REFERENCE_FLAG_PRIVATE_DEFINED 3 189#define REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY 4 190#define REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY 5 191 192/* 193 * To simplify stripping of objects that use are used with the dynamic link 194 * editor, the static link editor marks the symbols defined an object that are 195 * referenced by a dynamicly bound object (dynamic shared libraries, bundles). 196 * With this marking strip knows not to strip these symbols. 197 */ 198#define REFERENCED_DYNAMICALLY 0x0010 199 200/* 201 * The non-reference type bits of the n_desc field for global symbols are 202 * reserved for the dynamic link editor. All of these bits must start out 203 * zero in the object file. 204 */ 205#define N_DESC_DISCARDED 0x8000 /* symbol is discarded */ 206 207#endif 208