xref: /netbsd/include/link_aout.h (revision 2a9a9741)
1 /*	$NetBSD: link_aout.h,v 1.23 2016/01/23 01:26:14 dholland Exp $	*/
2 
3 /*-
4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Paul Kranenburg.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 /*
33  * RRS section definitions.
34  *
35  * The layout of some data structures defined in this header file is
36  * such that we can provide compatibility with the SunOS 4.x shared
37  * library scheme.
38  */
39 
40 #ifndef _LINK_AOUT_H_
41 #define _LINK_AOUT_H_
42 
43 #include <dlfcn.h>			/* for Dl_info */
44 #include <a.out.h>			/* for struct nlist */
45 
46 /*
47  * A `Shared Object Descriptor' describes a shared object that is needed
48  * to complete the link edit process of the object containing it.
49  * A list of such objects (chained through `sod_next') is pointed at
50  * by `sdt_sods' in the section_dispatch_table structure.
51  */
52 
53 struct sod {	/* Shared Object Descriptor */
54 	long	sod_name;		/* name (relative to load address) */
55 	unsigned int sod_library  : 1,	/* Searched for by library rules */
56 		sod_reserved : 31;
57 	short	sod_major;		/* major version number */
58 	short	sod_minor;		/* minor version number */
59 	long	sod_next;		/* next sod */
60 };
61 
62 /*
63  * `Shared Object Map's are used by the run-time link editor (ld.so) to
64  * keep track of all shared objects loaded into a process' address space.
65  * These structures are only used at run-time and do not occur within
66  * the text or data segment of an executable or shared library.
67  */
68 struct so_map {		/* Shared Object Map */
69 	caddr_t		som_addr;	/* Address at which object mapped */
70 	char 		*som_path;	/* Path to mmap'ed file */
71 	struct so_map	*som_next;	/* Next map in chain */
72 	struct sod	*som_sod;	/* Sod responsible for this map */
73 	caddr_t		som_sodbase;	/* Base address of this sod */
74 	unsigned int	som_write : 1;	/* Text is currently writable */
75 	struct _dynamic	*som_dynamic;	/* _dynamic structure */
76 	caddr_t		som_spd;	/* Private data */
77 };
78 
79 /*
80  * Symbol description with size. This is simply an `nlist' with
81  * one field (nz_size) added.
82  * Used to convey size information on items in the data segment
83  * of shared objects. An array of these live in the shared object's
84  * text segment and is addressed by the `sdt_nzlist' field.
85  */
86 struct nzlist {
87 	struct nlist	nlist;
88 	unsigned long	nz_size;
89 #define nz_un		nlist.n_un
90 #define nz_strx		nlist.n_un.n_strx
91 #define nz_name		nlist.n_un.n_name
92 #define nz_type		nlist.n_type
93 #define nz_value	nlist.n_value
94 #define nz_desc		nlist.n_desc
95 #define nz_other	nlist.n_other
96 };
97 
98 #define N_AUX(p)	((p)->n_other & 0xf)
99 #define N_BIND(p)	(((unsigned int)(p)->n_other >> 4) & 0xf)
100 #define N_OTHER(r, v)	(((unsigned int)(r) << 4) | ((v) & 0xf))
101 
102 #define AUX_OBJECT	1
103 #define AUX_FUNC	2
104 #define AUX_LABEL	3
105 /*#define BIND_LOCAL	0	not used */
106 /*#define BIND_GLOBAL	1	not used */
107 #define BIND_WEAK	2
108 
109 
110 /*
111  * The `section_dispatch_table' structure contains offsets to various data
112  * structures needed to do run-time relocation.
113  */
114 struct section_dispatch_table {
115 	struct so_map *sdt_loaded;	/* List of loaded objects */
116 	long	sdt_sods;		/* List of shared objects descriptors */
117 	long	sdt_paths;		/* Library search paths */
118 	long	sdt_got;		/* Global offset table */
119 	long	sdt_plt;		/* Procedure linkage table */
120 	long	sdt_rel;		/* Relocation table */
121 	long	sdt_hash;		/* Symbol hash table */
122 	long	sdt_nzlist;		/* Symbol table itself */
123 	long	sdt_filler2;		/* Unused (was: stab_hash) */
124 	long	sdt_buckets;		/* Number of hash buckets */
125 	long	sdt_strings;		/* Symbol strings */
126 	long	sdt_str_sz;		/* Size of symbol strings */
127 	long	sdt_text_sz;		/* Size of text area */
128 	long	sdt_plt_sz;		/* Size of procedure linkage table */
129 };
130 
131 /*
132  * RRS symbol hash table, addressed by `sdt_hash' in section_dispatch_table.
133  * Used to quickly lookup symbols of the shared object by hashing
134  * on the symbol's name. `rh_symbolnum' is the index of the symbol
135  * in the shared object's symbol list (`sdt_nzlist'), `rh_next' is
136  * the next symbol in the hash bucket (in case of collisions).
137  */
138 struct rrs_hash {
139 	int	rh_symbolnum;		/* Symbol number */
140 	int	rh_next;		/* Next hash entry */
141 };
142 
143 /*
144  * `rt_symbols' is used to keep track of run-time allocated commons
145  * and data items copied from shared objects.
146  */
147 struct rt_symbol {
148 	struct nzlist		*rt_sp;		/* The symbol */
149 	struct rt_symbol	*rt_next;	/* Next in linear list */
150 	struct rt_symbol	*rt_link;	/* Next in bucket */
151 	caddr_t			rt_srcaddr;	/* Address of "master" copy */
152 	struct so_map		*rt_smp;	/* Originating map */
153 };
154 
155 /*
156  * Debugger interface structure.
157  */
158 struct so_debug {
159 	int	dd_version;		/* Version # of interface */
160 	int	dd_in_debugger;		/* Set when run by debugger */
161 	int	dd_sym_loaded;		/* Run-time linking brought more
162 					   symbols into scope */
163 	char   	 *dd_bpt_addr;		/* Address of rtld-generated bpt */
164 	int	dd_bpt_shadow;		/* Original contents of bpt */
165 	struct rt_symbol *dd_cc;	/* Allocated commons/copied data */
166 };
167 
168 /*
169  * Entry points into ld.so - user interface to the run-time linker.
170  */
171 struct ld_entry {
172 	void	*(*dlopen)(const char *, int);
173 	int	(*dlclose)(void *);
174 	void	*(*dlsym)(void *, const char *);
175 	int	(*dlctl)(void *, int, void *);
176 	void	(*dlexit)(void);
177 	int	(*dladdr)(const void *, Dl_info *);
178 	void	(*dlrsrvd[2])(void);
179 };
180 
181 /*
182  * This is the structure pointed at by the __DYNAMIC symbol if an
183  * executable requires the attention of the run-time link editor.
184  * __DYNAMIC is given the value zero if no run-time linking needs to
185  * be done (it is always present in shared objects).
186  * The union `d_un' provides for different versions of the dynamic
187  * linking mechanism (switched on by `d_version'). The last version
188  * used by Sun is 3. We leave some room here and go to version number
189  * 8 for NetBSD, the main difference lying in the support for the
190  * `nz_list' type of symbols.
191  */
192 
193 struct	_dynamic {
194 	int		d_version;	/* version # of this interface */
195 	struct so_debug	*d_debug;
196 	union {
197 		struct section_dispatch_table *d_sdt;
198 	} d_un;
199 	struct ld_entry *d_entry;	/* compat - now in crt_ldso */
200 };
201 
202 #define LD_VERSION_SUN		(3)
203 #define LD_VERSION_BSD		(8)
204 #define LD_VERSION_NZLIST_P(v)	((v) >= 8)
205 
206 #define LD_GOT(x)	((x)->d_un.d_sdt->sdt_got)
207 #define LD_PLT(x)	((x)->d_un.d_sdt->sdt_plt)
208 #define LD_REL(x)	((x)->d_un.d_sdt->sdt_rel)
209 #define LD_SYMBOL(x)	((x)->d_un.d_sdt->sdt_nzlist)
210 #define LD_HASH(x)	((x)->d_un.d_sdt->sdt_hash)
211 #define LD_STRINGS(x)	((x)->d_un.d_sdt->sdt_strings)
212 #define LD_NEED(x)	((x)->d_un.d_sdt->sdt_sods)
213 #define LD_BUCKETS(x)	((x)->d_un.d_sdt->sdt_buckets)
214 #define LD_PATHS(x)	((x)->d_un.d_sdt->sdt_paths)
215 
216 #define LD_GOTSZ(x)	((x)->d_un.d_sdt->sdt_plt - (x)->d_un.d_sdt->sdt_got)
217 #define LD_RELSZ(x)	((x)->d_un.d_sdt->sdt_hash - (x)->d_un.d_sdt->sdt_rel)
218 #define LD_HASHSZ(x)	((x)->d_un.d_sdt->sdt_nzlist - (x)->d_un.d_sdt->sdt_hash)
219 #define LD_STABSZ(x)	((x)->d_un.d_sdt->sdt_strings - (x)->d_un.d_sdt->sdt_nzlist)
220 #define LD_PLTSZ(x)	((x)->d_un.d_sdt->sdt_plt_sz)
221 #define LD_STRSZ(x)	((x)->d_un.d_sdt->sdt_str_sz)
222 #define LD_TEXTSZ(x)	((x)->d_un.d_sdt->sdt_text_sz)
223 
224 /*
225  * Interface to ld.so
226  */
227 struct crt_ldso {
228 	int		crt_ba;		/* Base address of ld.so */
229 	int		crt_dzfd;	/* "/dev/zero" file descriptor (SunOS) */
230 	int		crt_ldfd;	/* ld.so file descriptor */
231 	struct _dynamic	*crt_dp;	/* Main's __DYNAMIC */
232 	char		**crt_ep;	/* environment strings */
233 	caddr_t		crt_bp;		/* Breakpoint if run from debugger */
234 	char		*crt_prog;	/* Program name (v3) */
235 	char		*crt_ldso;	/* Link editor name (v4) */
236 	struct ld_entry	*crt_ldentry;	/* dl*() access (v4) */
237 };
238 
239 /*
240  * Version passed from crt0 to ld.so (1st argument to _rtld()).
241  */
242 #define CRT_VERSION_SUN		1
243 #define CRT_VERSION_BSD_2	2
244 #define CRT_VERSION_BSD_3	3
245 #define CRT_VERSION_BSD_4	4
246 
247 
248 /*
249  * Maximum number of recognized shared object version numbers.
250  */
251 #define MAXDEWEY	8
252 
253 /*
254  * Header of the hints file.
255  */
256 struct hints_header {
257 	long		hh_magic;
258 #define HH_MAGIC	011421044151
259 	long		hh_version;	/* Interface version number */
260 #define LD_HINTS_VERSION_1	1
261 #define LD_HINTS_VERSION_2	2
262 	long		hh_hashtab;	/* Location of hash table */
263 	long		hh_nbucket;	/* Number of buckets in hashtab */
264 	long		hh_strtab;	/* Location of strings */
265 	long		hh_strtab_sz;	/* Size of strings */
266 	long		hh_ehints;	/* End of hints (max offset in file) */
267 	long		hh_dirlist;	/* Colon-separated list of srch dirs */
268 };
269 
270 #define HH_BADMAG(hdr)	((hdr).hh_magic != HH_MAGIC)
271 
272 /*
273  * Hash table element in hints file.
274  */
275 struct hints_bucket {
276 	/* namex and pathx are indices into the string table */
277 	int		hi_namex;		/* Library name */
278 	int		hi_pathx;		/* Full path */
279 	int		hi_dewey[MAXDEWEY];	/* The versions */
280 	int		hi_ndewey;		/* Number of version numbers */
281 #define hi_major hi_dewey[0]
282 #define hi_minor hi_dewey[1]
283 	int		hi_next;		/* Next in this bucket */
284 };
285 
286 #define _PATH_LD_HINTS		"/var/run/ld.so.hints"
287 
288 #endif /* _LINK_AOUT_H_ */
289