xref: /freebsd/sys/sys/link_aout.h (revision 0957b409)
1 /*-
2  * SPDX-License-Identifier: BSD-4-Clause
3  *
4  * Copyright (c) 1993 Paul Kranenburg
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *      This product includes software developed by Paul Kranenburg.
18  * 4. The name of the author may not be used to endorse or promote products
19  *    derived from this software without specific prior written permission
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  *
32  * $FreeBSD$
33  */
34 
35 /*
36  * RRS section definitions.
37  *
38  * The layout of some data structures defined in this header file is
39  * such that we can provide compatibility with the SunOS 4.x shared
40  * library scheme.
41  */
42 
43 #ifndef _SYS_LINK_AOUT_H_
44 #define _SYS_LINK_AOUT_H_
45 
46 struct dl_info;
47 
48 /*
49  * A `Shared Object Descriptor' describes a shared object that is needed
50  * to complete the link edit process of the object containing it.
51  * A list of such objects (chained through `sod_next') is pointed at
52  * by `sdt_sods' in the section_dispatch_table structure.
53  */
54 
55 struct sod {	/* Shared Object Descriptor */
56 	long	sod_name;		/* name (relative to load address) */
57 	u_int	sod_library  : 1,	/* Searched for by library rules */
58 		sod_reserved : 31;
59 	short	sod_major;		/* major version number */
60 	short	sod_minor;		/* minor version number */
61 	long	sod_next;		/* next sod */
62 };
63 
64 /*
65  * `Shared Object Map's are used by the run-time link editor (ld.so) to
66  * keep track of all shared objects loaded into a process' address space.
67  * These structures are only used at run-time and do not occur within
68  * the text or data segment of an executable or shared library.
69  */
70 struct so_map {		/* Shared Object Map */
71 	caddr_t		som_addr;	/* Address at which object mapped */
72 	char 		*som_path;	/* Path to mmap'ed file */
73 	struct so_map	*som_next;	/* Next map in chain */
74 	struct sod	*som_sod;	/* Sod responsible for this map */
75 	caddr_t		som_sodbase;	/* Base address of this sod */
76 	u_int		som_write : 1;	/* Text is currently writable */
77 	struct _dynamic	*som_dynamic;	/* _dynamic structure */
78 	caddr_t		som_spd;	/* Private data */
79 };
80 
81 /*
82  * Symbol description with size. This is simply an `nlist' with
83  * one field (nz_size) added.
84  * Used to convey size information on items in the data segment
85  * of shared objects. An array of these live in the shared object's
86  * text segment and is addressed by the `sdt_nzlist' field.
87  */
88 struct nzlist {
89 	struct nlist	nlist;
90 	u_long		nz_size;
91 };
92 
93 #define nz_un		nlist.n_un
94 #define nz_strx		nlist.n_un.n_strx
95 #define nz_name		nlist.n_un.n_name
96 #define nz_type		nlist.n_type
97 #define nz_value	nlist.n_value
98 #define nz_desc		nlist.n_desc
99 #define nz_other	nlist.n_other
100 
101 /*
102  * The `section_dispatch_table' structure contains offsets to various data
103  * structures needed to do run-time relocation.
104  */
105 struct section_dispatch_table {
106 	struct so_map *sdt_loaded;	/* List of loaded objects */
107 	long	sdt_sods;		/* List of shared objects descriptors */
108 	long	sdt_paths;		/* Library search paths */
109 	long	sdt_got;		/* Global offset table */
110 	long	sdt_plt;		/* Procedure linkage table */
111 	long	sdt_rel;		/* Relocation table */
112 	long	sdt_hash;		/* Symbol hash table */
113 	long	sdt_nzlist;		/* Symbol table itself */
114 	long	sdt_filler2;		/* Unused (was: stab_hash) */
115 	long	sdt_buckets;		/* Number of hash buckets */
116 	long	sdt_strings;		/* Symbol strings */
117 	long	sdt_str_sz;		/* Size of symbol strings */
118 	long	sdt_text_sz;		/* Size of text area */
119 	long	sdt_plt_sz;		/* Size of procedure linkage table */
120 };
121 
122 /*
123  * RRS symbol hash table, addressed by `sdt_hash' in section_dispatch_table.
124  * Used to quickly lookup symbols of the shared object by hashing
125  * on the symbol's name. `rh_symbolnum' is the index of the symbol
126  * in the shared object's symbol list (`sdt_nzlist'), `rh_next' is
127  * the next symbol in the hash bucket (in case of collisions).
128  */
129 struct rrs_hash {
130 	int	rh_symbolnum;		/* Symbol number */
131 	int	rh_next;		/* Next hash entry */
132 };
133 
134 /*
135  * `rt_symbols' is used to keep track of run-time allocated commons
136  * and data items copied from shared objects.
137  */
138 struct rt_symbol {
139 	struct nzlist		*rt_sp;		/* The symbol */
140 	struct rt_symbol	*rt_next;	/* Next in linear list */
141 	struct rt_symbol	*rt_link;	/* Next in bucket */
142 	caddr_t			rt_srcaddr;	/* Address of "master" copy */
143 	struct so_map		*rt_smp;	/* Originating map */
144 };
145 
146 /*
147  * Debugger interface structure.
148  */
149 struct so_debug {
150 	int	dd_version;		/* Version # of interface */
151 	int	dd_in_debugger;		/* Set when run by debugger */
152 	int	dd_sym_loaded;		/* Run-time linking brought more
153 					   symbols into scope */
154 	char   	 *dd_bpt_addr;		/* Address of rtld-generated bpt */
155 	int	dd_bpt_shadow;		/* Original contents of bpt */
156 	struct rt_symbol *dd_cc;	/* Allocated commons/copied data */
157 };
158 
159 /*
160  * Version returned to crt0 from ld.so
161  */
162 #define LDSO_VERSION_NONE	0	/* FreeBSD2.0, 2.0.5 */
163 #define LDSO_VERSION_HAS_DLEXIT	1	/* includes dlexit in ld_entry */
164 #define LDSO_VERSION_HAS_DLSYM3	2	/* includes 3-argument dlsym */
165 #define LDSO_VERSION_HAS_DLADDR	3	/* includes dladdr in ld_entry */
166 
167 /*
168  * Entry points into ld.so - user interface to the run-time linker.
169  * Entries are valid for the given version numbers returned by ld.so
170  * to crt0.
171  */
172 struct ld_entry {
173 	void	*(*dlopen)(const char *, int);	/* NONE */
174 	int	(*dlclose)(void *);		/* NONE */
175 	void	*(*dlsym)(void *, const char *);	/* NONE */
176 	const char *(*dlerror)(void);		/* NONE */
177 	void	(*dlexit)(void);			/* HAS_DLEXIT */
178 	void	*(*dlsym3)(void *, const char *, void *); /* HAS_DLSYM3 */
179 	int	 (*dladdr)(const void *, struct dl_info *); /* HAS_DLADDR */
180 };
181 
182 /*
183  * This is the structure pointed at by the __DYNAMIC symbol if an
184  * executable requires the attention of the run-time link editor.
185  * __DYNAMIC is given the value zero if no run-time linking needs to
186  * be done (it is always present in shared objects).
187  * The union `d_un' provides for different versions of the dynamic
188  * linking mechanism (switched on by `d_version'). The last version
189  * used by Sun is 3. We leave some room here and go to version number
190  * 8 for NetBSD, the main difference lying in the support for the
191  * `nz_list' type of symbols.
192  */
193 
194 struct _dynamic {
195 	int		d_version;	/* version # of this interface */
196 	struct so_debug	*d_debug;
197 	union {
198 		struct section_dispatch_table *d_sdt;
199 	} d_un;
200 	struct ld_entry *d_entry;	/* XXX */
201 };
202 
203 #define LD_VERSION_SUN		(3)
204 #define LD_VERSION_BSD		(8)
205 #define LD_VERSION_NZLIST_P(v)	((v) >= 8)
206 
207 #define LD_GOT(x)	((x)->d_un.d_sdt->sdt_got)
208 #define LD_PLT(x)	((x)->d_un.d_sdt->sdt_plt)
209 #define LD_REL(x)	((x)->d_un.d_sdt->sdt_rel)
210 #define LD_SYMBOL(x)	((x)->d_un.d_sdt->sdt_nzlist)
211 #define LD_HASH(x)	((x)->d_un.d_sdt->sdt_hash)
212 #define LD_STRINGS(x)	((x)->d_un.d_sdt->sdt_strings)
213 #define LD_NEED(x)	((x)->d_un.d_sdt->sdt_sods)
214 #define LD_BUCKETS(x)	((x)->d_un.d_sdt->sdt_buckets)
215 #define LD_PATHS(x)	((x)->d_un.d_sdt->sdt_paths)
216 
217 #define LD_GOTSZ(x)	((x)->d_un.d_sdt->sdt_plt - (x)->d_un.d_sdt->sdt_got)
218 #define LD_RELSZ(x)	((x)->d_un.d_sdt->sdt_hash - (x)->d_un.d_sdt->sdt_rel)
219 #define LD_HASHSZ(x)	((x)->d_un.d_sdt->sdt_nzlist - (x)->d_un.d_sdt->sdt_hash)
220 #define LD_STABSZ(x)	((x)->d_un.d_sdt->sdt_strings - (x)->d_un.d_sdt->sdt_nzlist)
221 #define LD_PLTSZ(x)	((x)->d_un.d_sdt->sdt_plt_sz)
222 #define LD_STRSZ(x)	((x)->d_un.d_sdt->sdt_str_sz)
223 #define LD_TEXTSZ(x)	((x)->d_un.d_sdt->sdt_text_sz)
224 
225 /*
226  * Interface to ld.so
227  */
228 struct crt_ldso {
229 	int		crt_ba;		/* Base address of ld.so */
230 	int		crt_dzfd;	/* "/dev/zero" file descriptor (SunOS) */
231 	int		crt_ldfd;	/* ld.so file descriptor */
232 	struct _dynamic	*crt_dp;	/* Main's __DYNAMIC */
233 	char		**crt_ep;	/* environment strings */
234 	caddr_t		crt_bp;		/* Breakpoint if run from debugger */
235 	char		*crt_prog;	/* Program name (v3) */
236 	char		*crt_ldso;	/* Link editor name (v4) */
237 	struct ld_entry	*crt_ldentry;	/* dl*() access (v4) */
238 	char		**crt_argv;	/* argument strings (v5) */
239 };
240 
241 /*
242  * Version passed from crt0 to ld.so (1st argument to _rtld()).
243  */
244 #define CRT_VERSION_SUN		1
245 #define CRT_VERSION_BSD_2	2
246 #define CRT_VERSION_BSD_3	3
247 #define CRT_VERSION_BSD_4	4
248 #define CRT_VERSION_BSD_5	5
249 
250 /*
251  * Maximum number of recognized shared object version numbers.
252  */
253 #define MAXDEWEY	8
254 
255 /*
256  * Header of the hints file.
257  */
258 struct hints_header {
259 	long		hh_magic;
260 #define HH_MAGIC	011421044151
261 	long		hh_version;	/* Interface version number */
262 #define LD_HINTS_VERSION_1	1
263 #define LD_HINTS_VERSION_2	2
264 	long		hh_hashtab;	/* Location of hash table */
265 	long		hh_nbucket;	/* Number of buckets in hashtab */
266 	long		hh_strtab;	/* Location of strings */
267 	long		hh_strtab_sz;	/* Size of strings */
268 	long		hh_ehints;	/* End of hints (max offset in file) */
269 	long		hh_dirlist;	/* Colon-separated list of srch dirs */
270 };
271 
272 #define HH_BADMAG(hdr)	((hdr).hh_magic != HH_MAGIC)
273 
274 /*
275  * Hash table element in hints file.
276  */
277 struct hints_bucket {
278 	/* namex and pathx are indices into the string table */
279 	int		hi_namex;		/* Library name */
280 	int		hi_pathx;		/* Full path */
281 	int		hi_dewey[MAXDEWEY];	/* The versions */
282 	int		hi_ndewey;		/* Number of version numbers */
283 #define hi_major hi_dewey[0]
284 #define hi_minor hi_dewey[1]
285 	int		hi_next;		/* Next in this bucket */
286 };
287 
288 #define _PATH_LD_HINTS		"/var/run/ld.so.hints"
289 
290 #endif /* _SYS_LINK_AOUT_H_ */
291