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| 1 /* |
| 2 * Copyright (c) 1999-2003 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 #ifndef _MACHO_NLIST_H_ |
| 24 #define _MACHO_NLIST_H_ |
| 25 /* $NetBSD: nlist.h,v 1.5 1994/10/26 00:56:11 cgd Exp $ */ |
| 26 |
| 27 /*- |
| 28 * Copyright (c) 1991, 1993 |
| 29 * The Regents of the University of California. All rights reserved. |
| 30 * (c) UNIX System Laboratories, Inc. |
| 31 * All or some portions of this file are derived from material licensed |
| 32 * to the University of California by American Telephone and Telegraph |
| 33 * Co. or Unix System Laboratories, Inc. and are reproduced herein with |
| 34 * the permission of UNIX System Laboratories, Inc. |
| 35 * |
| 36 * Redistribution and use in source and binary forms, with or without |
| 37 * modification, are permitted provided that the following conditions |
| 38 * are met: |
| 39 * 1. Redistributions of source code must retain the above copyright |
| 40 * notice, this list of conditions and the following disclaimer. |
| 41 * 2. Redistributions in binary form must reproduce the above copyright |
| 42 * notice, this list of conditions and the following disclaimer in the |
| 43 * documentation and/or other materials provided with the distribution. |
| 44 * 3. All advertising materials mentioning features or use of this software |
| 45 * must display the following acknowledgement: |
| 46 * This product includes software developed by the University of |
| 47 * California, Berkeley and its contributors. |
| 48 * 4. Neither the name of the University nor the names of its contributors |
| 49 * may be used to endorse or promote products derived from this software |
| 50 * without specific prior written permission. |
| 51 * |
| 52 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 53 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 55 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 56 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 57 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 58 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 59 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 60 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 61 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 62 * SUCH DAMAGE. |
| 63 * |
| 64 * @(#)nlist.h 8.2 (Berkeley) 1/21/94 |
| 65 */ |
| 66 #include <stdint.h> |
| 67 |
| 68 /* |
| 69 * Format of a symbol table entry of a Mach-O file for 32-bit architectures. |
| 70 * Modified from the BSD format. The modifications from the original format |
| 71 * were changing n_other (an unused field) to n_sect and the addition of the |
| 72 * N_SECT type. These modifications are required to support symbols in a larger |
| 73 * number of sections not just the three sections (text, data and bss) in a BSD |
| 74 * file. |
| 75 */ |
| 76 struct nlist { |
| 77 union { |
| 78 #ifndef __LP64__ |
| 79 char *n_name; /* for use when in-core */ |
| 80 #endif |
| 81 int32_t n_strx; /* index into the string table */ |
| 82 } n_un; |
| 83 uint8_t n_type; /* type flag, see below */ |
| 84 uint8_t n_sect; /* section number or NO_SECT */ |
| 85 int16_t n_desc; /* see <mach-o/stab.h> */ |
| 86 uint32_t n_value; /* value of this symbol (or stab offset) */ |
| 87 }; |
| 88 |
| 89 /* |
| 90 * This is the symbol table entry structure for 64-bit architectures. |
| 91 */ |
| 92 struct nlist_64 { |
| 93 union { |
| 94 uint32_t n_strx; /* index into the string table */ |
| 95 } n_un; |
| 96 uint8_t n_type; /* type flag, see below */ |
| 97 uint8_t n_sect; /* section number or NO_SECT */ |
| 98 uint16_t n_desc; /* see <mach-o/stab.h> */ |
| 99 uint64_t n_value; /* value of this symbol (or stab offset) */ |
| 100 }; |
| 101 |
| 102 /* |
| 103 * Symbols with a index into the string table of zero (n_un.n_strx == 0) are |
| 104 * defined to have a null, "", name. Therefore all string indexes to non null |
| 105 * names must not have a zero string index. This is bit historical information |
| 106 * that has never been well documented. |
| 107 */ |
| 108 |
| 109 /* |
| 110 * The n_type field really contains four fields: |
| 111 * unsigned char N_STAB:3, |
| 112 * N_PEXT:1, |
| 113 * N_TYPE:3, |
| 114 * N_EXT:1; |
| 115 * which are used via the following masks. |
| 116 */ |
| 117 #define N_STAB 0xe0 /* if any of these bits set, a symbolic debugging entry */ |
| 118 #define N_PEXT 0x10 /* private external symbol bit */ |
| 119 #define N_TYPE 0x0e /* mask for the type bits */ |
| 120 #define N_EXT 0x01 /* external symbol bit, set for external symbols */ |
| 121 |
| 122 /* |
| 123 * Only symbolic debugging entries have some of the N_STAB bits set and if any |
| 124 * of these bits are set then it is a symbolic debugging entry (a stab). In |
| 125 * which case then the values of the n_type field (the entire field) are given |
| 126 * in <mach-o/stab.h> |
| 127 */ |
| 128 |
| 129 /* |
| 130 * Values for N_TYPE bits of the n_type field. |
| 131 */ |
| 132 #define N_UNDF 0x0 /* undefined, n_sect == NO_SECT */ |
| 133 #define N_ABS 0x2 /* absolute, n_sect == NO_SECT */ |
| 134 #define N_SECT 0xe /* defined in section number n_sect */ |
| 135 #define N_PBUD 0xc /* prebound undefined (defined in a dylib) */ |
| 136 #define N_INDR 0xa /* indirect */ |
| 137 |
| 138 /* |
| 139 * If the type is N_INDR then the symbol is defined to be the same as another |
| 140 * symbol. In this case the n_value field is an index into the string table |
| 141 * of the other symbol's name. When the other symbol is defined then they both |
| 142 * take on the defined type and value. |
| 143 */ |
| 144 |
| 145 /* |
| 146 * If the type is N_SECT then the n_sect field contains an ordinal of the |
| 147 * section the symbol is defined in. The sections are numbered from 1 and |
| 148 * refer to sections in order they appear in the load commands for the file |
| 149 * they are in. This means the same ordinal may very well refer to different |
| 150 * sections in different files. |
| 151 * |
| 152 * The n_value field for all symbol table entries (including N_STAB's) gets |
| 153 * updated by the link editor based on the value of it's n_sect field and where |
| 154 * the section n_sect references gets relocated. If the value of the n_sect |
| 155 * field is NO_SECT then it's n_value field is not changed by the link editor. |
| 156 */ |
| 157 #define NO_SECT 0 /* symbol is not in any section */ |
| 158 #define MAX_SECT 255 /* 1 thru 255 inclusive */ |
| 159 |
| 160 /* |
| 161 * Common symbols are represented by undefined (N_UNDF) external (N_EXT) types |
| 162 * who's values (n_value) are non-zero. In which case the value of the n_value |
| 163 * field is the size (in bytes) of the common symbol. The n_sect field is set |
| 164 * to NO_SECT. The alignment of a common symbol may be set as a power of 2 |
| 165 * between 2^1 and 2^15 as part of the n_desc field using the macros below. If |
| 166 * the alignment is not set (a value of zero) then natural alignment based on |
| 167 * the size is used. |
| 168 */ |
| 169 #define GET_COMM_ALIGN(n_desc) (((n_desc) >> 8) & 0x0f) |
| 170 #define SET_COMM_ALIGN(n_desc,align) \ |
| 171 (n_desc) = (((n_desc) & 0xf0ff) | (((align) & 0x0f) << 8)) |
| 172 |
| 173 /* |
| 174 * To support the lazy binding of undefined symbols in the dynamic link-editor, |
| 175 * the undefined symbols in the symbol table (the nlist structures) are marked |
| 176 * with the indication if the undefined reference is a lazy reference or |
| 177 * non-lazy reference. If both a non-lazy reference and a lazy reference is |
| 178 * made to the same symbol the non-lazy reference takes precedence. A reference |
| 179 * is lazy only when all references to that symbol are made through a symbol |
| 180 * pointer in a lazy symbol pointer section. |
| 181 * |
| 182 * The implementation of marking nlist structures in the symbol table for |
| 183 * undefined symbols will be to use some of the bits of the n_desc field as a |
| 184 * reference type. The mask REFERENCE_TYPE will be applied to the n_desc field |
| 185 * of an nlist structure for an undefined symbol to determine the type of |
| 186 * undefined reference (lazy or non-lazy). |
| 187 * |
| 188 * The constants for the REFERENCE FLAGS are propagated to the reference table |
| 189 * in a shared library file. In that case the constant for a defined symbol, |
| 190 * REFERENCE_FLAG_DEFINED, is also used. |
| 191 */ |
| 192 /* Reference type bits of the n_desc field of undefined symbols */ |
| 193 #define REFERENCE_TYPE 0x7 |
| 194 /* types of references */ |
| 195 #define REFERENCE_FLAG_UNDEFINED_NON_LAZY 0 |
| 196 #define REFERENCE_FLAG_UNDEFINED_LAZY 1 |
| 197 #define REFERENCE_FLAG_DEFINED 2 |
| 198 #define REFERENCE_FLAG_PRIVATE_DEFINED 3 |
| 199 #define REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY 4 |
| 200 #define REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY 5 |
| 201 |
| 202 /* |
| 203 * To simplify stripping of objects that use are used with the dynamic link |
| 204 * editor, the static link editor marks the symbols defined an object that are |
| 205 * referenced by a dynamicly bound object (dynamic shared libraries, bundles). |
| 206 * With this marking strip knows not to strip these symbols. |
| 207 */ |
| 208 #define REFERENCED_DYNAMICALLY 0x0010 |
| 209 |
| 210 /* |
| 211 * For images created by the static link editor with the -twolevel_namespace |
| 212 * option in effect the flags field of the mach header is marked with |
| 213 * MH_TWOLEVEL. And the binding of the undefined references of the image are |
| 214 * determined by the static link editor. Which library an undefined symbol is |
| 215 * bound to is recorded by the static linker in the high 8 bits of the n_desc |
| 216 * field using the SET_LIBRARY_ORDINAL macro below. The ordinal recorded |
| 217 * references the libraries listed in the Mach-O's LC_LOAD_DYLIB, |
| 218 * LC_LOAD_WEAK_DYLIB, LC_REEXPORT_DYLIB, LC_LOAD_UPWARD_DYLIB, and |
| 219 * LC_LAZY_LOAD_DYLIB, etc. load commands in the order they appear in the |
| 220 * headers. The library ordinals start from 1. |
| 221 * For a dynamic library that is built as a two-level namespace image the |
| 222 * undefined references from module defined in another use the same nlist struct |
| 223 * an in that case SELF_LIBRARY_ORDINAL is used as the library ordinal. For |
| 224 * defined symbols in all images they also must have the library ordinal set to |
| 225 * SELF_LIBRARY_ORDINAL. The EXECUTABLE_ORDINAL refers to the executable |
| 226 * image for references from plugins that refer to the executable that loads |
| 227 * them. |
| 228 * |
| 229 * The DYNAMIC_LOOKUP_ORDINAL is for undefined symbols in a two-level namespace |
| 230 * image that are looked up by the dynamic linker with flat namespace semantics. |
| 231 * This ordinal was added as a feature in Mac OS X 10.3 by reducing the |
| 232 * value of MAX_LIBRARY_ORDINAL by one. So it is legal for existing binaries |
| 233 * or binaries built with older tools to have 0xfe (254) dynamic libraries. In |
| 234 * this case the ordinal value 0xfe (254) must be treated as a library ordinal |
| 235 * for compatibility. |
| 236 */ |
| 237 #define GET_LIBRARY_ORDINAL(n_desc) (((n_desc) >> 8) & 0xff) |
| 238 #define SET_LIBRARY_ORDINAL(n_desc,ordinal) \ |
| 239 (n_desc) = (((n_desc) & 0x00ff) | (((ordinal) & 0xff) << 8)) |
| 240 #define SELF_LIBRARY_ORDINAL 0x0 |
| 241 #define MAX_LIBRARY_ORDINAL 0xfd |
| 242 #define DYNAMIC_LOOKUP_ORDINAL 0xfe |
| 243 #define EXECUTABLE_ORDINAL 0xff |
| 244 |
| 245 /* |
| 246 * The bit 0x0020 of the n_desc field is used for two non-overlapping purposes |
| 247 * and has two different symbolic names, N_NO_DEAD_STRIP and N_DESC_DISCARDED. |
| 248 */ |
| 249 |
| 250 /* |
| 251 * The N_NO_DEAD_STRIP bit of the n_desc field only ever appears in a |
| 252 * relocatable .o file (MH_OBJECT filetype). And is used to indicate to the |
| 253 * static link editor it is never to dead strip the symbol. |
| 254 */ |
| 255 #define N_NO_DEAD_STRIP 0x0020 /* symbol is not to be dead stripped */ |
| 256 |
| 257 /* |
| 258 * The N_DESC_DISCARDED bit of the n_desc field never appears in linked image. |
| 259 * But is used in very rare cases by the dynamic link editor to mark an in |
| 260 * memory symbol as discared and longer used for linking. |
| 261 */ |
| 262 #define N_DESC_DISCARDED 0x0020 /* symbol is discarded */ |
| 263 |
| 264 /* |
| 265 * The N_WEAK_REF bit of the n_desc field indicates to the dynamic linker that |
| 266 * the undefined symbol is allowed to be missing and is to have the address of |
| 267 * zero when missing. |
| 268 */ |
| 269 #define N_WEAK_REF 0x0040 /* symbol is weak referenced */ |
| 270 |
| 271 /* |
| 272 * The N_WEAK_DEF bit of the n_desc field indicates to the static and dynamic |
| 273 * linkers that the symbol definition is weak, allowing a non-weak symbol to |
| 274 * also be used which causes the weak definition to be discared. Currently this |
| 275 * is only supported for symbols in coalesed sections. |
| 276 */ |
| 277 #define N_WEAK_DEF 0x0080 /* coalesed symbol is a weak definition */ |
| 278 |
| 279 /* |
| 280 * The N_REF_TO_WEAK bit of the n_desc field indicates to the dynamic linker |
| 281 * that the undefined symbol should be resolved using flat namespace searching. |
| 282 */ |
| 283 #define N_REF_TO_WEAK 0x0080 /* reference to a weak symbol */ |
| 284 |
| 285 /* |
| 286 * The N_ARM_THUMB_DEF bit of the n_desc field indicates that the symbol is |
| 287 * a defintion of a Thumb function. |
| 288 */ |
| 289 #define N_ARM_THUMB_DEF 0x0008 /* symbol is a Thumb function (ARM) */ |
| 290 |
| 291 /* |
| 292 * The N_SYMBOL_RESOLVER bit of the n_desc field indicates that the |
| 293 * that the function is actually a resolver function and should |
| 294 * be called to get the address of the real function to use. |
| 295 * This bit is only available in .o files (MH_OBJECT filetype) |
| 296 */ |
| 297 #define N_SYMBOL_RESOLVER 0x0100 |
| 298 |
| 299 #ifndef __STRICT_BSD__ |
| 300 #if __cplusplus |
| 301 extern "C" { |
| 302 #endif /* __cplusplus */ |
| 303 /* |
| 304 * The function nlist(3) from the C library. |
| 305 */ |
| 306 extern int nlist (const char *filename, struct nlist *list); |
| 307 #if __cplusplus |
| 308 } |
| 309 #endif /* __cplusplus */ |
| 310 #endif /* __STRICT_BSD__ */ |
| 311 |
| 312 #endif /* _MACHO_LIST_H_ */ |
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