1/* 2 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved. 3 * 4 * @APPLE_OSREFERENCE_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. The rights granted to you under the License 10 * may not be used to create, or enable the creation or redistribution of, 11 * unlawful or unlicensed copies of an Apple operating system, or to 12 * circumvent, violate, or enable the circumvention or violation of, any 13 * terms of an Apple operating system software license agreement. 14 * 15 * Please obtain a copy of the License at 16 * http://www.opensource.apple.com/apsl/ and read it before using this file. 17 * 18 * The Original Code and all software distributed under the License are 19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 23 * Please see the License for the specific language governing rights and 24 * limitations under the License. 25 * 26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ 27 */ 28#ifndef _MACHO_NLIST_H_ 29#define _MACHO_NLIST_H_ 30/* $NetBSD: nlist.h,v 1.5 1994/10/26 00:56:11 cgd Exp $ */ 31 32/*- 33 * Copyright (c) 1991, 1993 34 * The Regents of the University of California. All rights reserved. 35 * (c) UNIX System Laboratories, Inc. 36 * All or some portions of this file are derived from material licensed 37 * to the University of California by American Telephone and Telegraph 38 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 39 * the permission of UNIX System Laboratories, Inc. 40 * 41 * Redistribution and use in source and binary forms, with or without 42 * modification, are permitted provided that the following conditions 43 * are met: 44 * 1. Redistributions of source code must retain the above copyright 45 * notice, this list of conditions and the following disclaimer. 46 * 2. Redistributions in binary form must reproduce the above copyright 47 * notice, this list of conditions and the following disclaimer in the 48 * documentation and/or other materials provided with the distribution. 49 * 3. All advertising materials mentioning features or use of this software 50 * must display the following acknowledgement: 51 * This product includes software developed by the University of 52 * California, Berkeley and its contributors. 53 * 4. Neither the name of the University nor the names of its contributors 54 * may be used to endorse or promote products derived from this software 55 * without specific prior written permission. 56 * 57 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 58 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 59 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 60 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 61 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 62 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 63 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 64 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 65 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 66 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 67 * SUCH DAMAGE. 68 * 69 * @(#)nlist.h 8.2 (Berkeley) 1/21/94 70 */ 71 72/* 73 * Format of a symbol table entry of a Mach-O file. Modified from the BSD 74 * format. The modifications from the original format were changing n_other 75 * (an unused field) to n_sect and the addition of the N_SECT type. These 76 * modifications are required to support symbols in an arbitrary number of 77 * sections not just the three sections (text, data and bss) in a BSD file. 78 */ 79struct nlist { 80 union { 81 char *n_name; /* for use when in-core */ 82 long n_strx; /* index into the string table */ 83 } n_un; 84 unsigned char n_type; /* type flag, see below */ 85 unsigned char n_sect; /* section number or NO_SECT */ 86 short n_desc; /* see <mach-o/stab.h> */ 87 unsigned long n_value; /* value of this symbol (or stab offset) */ 88}; 89 90/* 91 * This is the symbol table entry structure for 64-bit architectures. 92 */ 93struct nlist_64 { 94 union { 95 uint32_t n_strx; /* index into the string table */ 96 } n_un; 97 uint8_t n_type; /* type flag, see below */ 98 uint8_t n_sect; /* section number or NO_SECT */ 99 uint16_t n_desc; /* see <mach-o/stab.h> */ 100 uint64_t n_value; /* value of this symbol (or stab offset) */ 101}; 102 103 104/* 105 * Symbols with a index into the string table of zero (n_un.n_strx == 0) are 106 * defined to have a null, "", name. Therefore all string indexes to non null 107 * names must not have a zero string index. This is bit historical information 108 * that has never been well documented. 109 */ 110 111/* 112 * The n_type field really contains three fields: 113 * unsigned char N_STAB:3, 114 * N_PEXT:1, 115 * N_TYPE:3, 116 * N_EXT:1; 117 * which are used via the following masks. 118 */ 119#define N_STAB 0xe0 /* if any of these bits set, a symbolic debugging entry */ 120#define N_PEXT 0x10 /* private external symbol bit */ 121#define N_TYPE 0x0e /* mask for the type bits */ 122#define N_EXT 0x01 /* external symbol bit, set for external symbols */ 123 124/* 125 * Only symbolic debugging entries have some of the N_STAB bits set and if any 126 * of these bits are set then it is a symbolic debugging entry (a stab). In 127 * which case then the values of the n_type field (the entire field) are given 128 * in <mach-o/stab.h> 129 */ 130 131/* 132 * Values for N_TYPE bits of the n_type field. 133 */ 134#define N_UNDF 0x0 /* undefined, n_sect == NO_SECT */ 135#define N_ABS 0x2 /* absolute, n_sect == NO_SECT */ 136#define N_SECT 0xe /* defined in section number n_sect */ 137#define N_PBUD 0xc /* prebound undefined (defined in a dylib) */ 138#define N_INDR 0xa /* indirect */ 139 140/* 141 * If the type is N_INDR then the symbol is defined to be the same as another 142 * symbol. In this case the n_value field is an index into the string table 143 * of the other symbol's name. When the other symbol is defined then they both 144 * take on the defined type and value. 145 */ 146 147/* 148 * If the type is N_SECT then the n_sect field contains an ordinal of the 149 * section the symbol is defined in. The sections are numbered from 1 and 150 * refer to sections in order they appear in the load commands for the file 151 * they are in. This means the same ordinal may very well refer to different 152 * sections in different files. 153 * 154 * The n_value field for all symbol table entries (including N_STAB's) gets 155 * updated by the link editor based on the value of it's n_sect field and where 156 * the section n_sect references gets relocated. If the value of the n_sect 157 * field is NO_SECT then it's n_value field is not changed by the link editor. 158 */ 159#define NO_SECT 0 /* symbol is not in any section */ 160#define MAX_SECT 255 /* 1 thru 255 inclusive */ 161 162/* 163 * Common symbols are represented by undefined (N_UNDF) external (N_EXT) types 164 * who's values (n_value) are non-zero. In which case the value of the n_value 165 * field is the size (in bytes) of the common symbol. The n_sect field is set 166 * to NO_SECT. 167 */ 168 169/* 170 * To support the lazy binding of undefined symbols in the dynamic link-editor, 171 * the undefined symbols in the symbol table (the nlist structures) are marked 172 * with the indication if the undefined reference is a lazy reference or 173 * non-lazy reference. If both a non-lazy reference and a lazy reference is 174 * made to the same symbol the non-lazy reference takes precedence. A reference 175 * is lazy only when all references to that symbol are made through a symbol 176 * pointer in a lazy symbol pointer section. 177 * 178 * The implementation of marking nlist structures in the symbol table for 179 * undefined symbols will be to use some of the bits of the n_desc field as a 180 * reference type. The mask REFERENCE_TYPE will be applied to the n_desc field 181 * of an nlist structure for an undefined symbol to determine the type of 182 * undefined reference (lazy or non-lazy). 183 * 184 * The constants for the REFERENCE FLAGS are propagated to the reference table 185 * in a shared library file. In that case the constant for a defined symbol, 186 * REFERENCE_FLAG_DEFINED, is also used. 187 */ 188/* Reference type bits of the n_desc field of undefined symbols */ 189#define REFERENCE_TYPE 0xf 190/* types of references */ 191#define REFERENCE_FLAG_UNDEFINED_NON_LAZY 0 192#define REFERENCE_FLAG_UNDEFINED_LAZY 1 193#define REFERENCE_FLAG_DEFINED 2 194#define REFERENCE_FLAG_PRIVATE_DEFINED 3 195#define REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY 4 196#define REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY 5 197 198/* 199 * To simplify stripping of objects that use are used with the dynamic link 200 * editor, the static link editor marks the symbols defined an object that are 201 * referenced by a dynamicly bound object (dynamic shared libraries, bundles). 202 * With this marking strip knows not to strip these symbols. 203 */ 204#define REFERENCED_DYNAMICALLY 0x0010 205 206/* 207 * The non-reference type bits of the n_desc field for global symbols are 208 * reserved for the dynamic link editor. All of these bits must start out 209 * zero in the object file. 210 */ 211#define N_DESC_DISCARDED 0x8000 /* symbol is discarded */ 212 213#endif 214