master
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 */
76struct nlist {
77 union {
78#ifndef __LP64__
79 char *n_name; /* for use when in-core */
80#endif
81 uint32_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 */
92struct 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 dynamically 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/*
300 * The N_ALT_ENTRY bit of the n_desc field indicates that the
301 * symbol is pinned to the previous content.
302 */
303#define N_ALT_ENTRY 0x0200
304
305/*
306 * The N_COLD_FUNC bit of the n_desc field indicates that the symbol is used
307 * infrequently and the linker should order it towards the end of the section.
308 */
309#define N_COLD_FUNC 0x0400
310
311#ifndef __STRICT_BSD__
312#ifdef __cplusplus
313extern "C" {
314#endif /* __cplusplus */
315/*
316 * The function nlist(3) from the C library.
317 */
318extern int nlist (const char *filename, struct nlist *list);
319#ifdef __cplusplus
320}
321#endif /* __cplusplus */
322#endif /* __STRICT_BSD__ */
323
324#endif /* _MACHO_LIST_H_ */