summary refs log tree commit diff
path: root/include/link.h
blob: 244235045749c0266ac30d8caf5c38b494b896a0 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
/* Data structure for communication from the run-time dynamic linker for
   loaded ELF shared objects.
   Copyright (C) 1995-1999, 2000, 2001 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef	_LINK_H
#define	_LINK_H	1

#include <features.h>
#include <elf.h>
#include <dlfcn.h>
#include <sys/types.h>

/* We use this macro to refer to ELF types independent of the native wordsize.
   `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'.  */
#define ElfW(type)	_ElfW (Elf, __ELF_NATIVE_CLASS, type)
#define _ElfW(e,w,t)	_ElfW_1 (e, w, _##t)
#define _ElfW_1(e,w,t)	e##w##t

#include <bits/elfclass.h>		/* Defines __ELF_NATIVE_CLASS.  */
#include <bits/link.h>
#include <dl-lookupcfg.h>

/* Rendezvous structure used by the run-time dynamic linker to communicate
   details of shared object loading to the debugger.  If the executable's
   dynamic section has a DT_DEBUG element, the run-time linker sets that
   element's value to the address where this structure can be found.  */

struct r_debug
  {
    int r_version;		/* Version number for this protocol.  */

    struct link_map *r_map;	/* Head of the chain of loaded objects.  */

    /* This is the address of a function internal to the run-time linker,
       that will always be called when the linker begins to map in a
       library or unmap it, and again when the mapping change is complete.
       The debugger can set a breakpoint at this address if it wants to
       notice shared object mapping changes.  */
    ElfW(Addr) r_brk;
    enum
      {
	/* This state value describes the mapping change taking place when
	   the `r_brk' address is called.  */
	RT_CONSISTENT,		/* Mapping change is complete.  */
	RT_ADD,			/* Beginning to add a new object.  */
	RT_DELETE		/* Beginning to remove an object mapping.  */
      } r_state;

    ElfW(Addr) r_ldbase;	/* Base address the linker is loaded at.  */
  };

/* This is the instance of that structure used by the dynamic linker.  */
extern struct r_debug _r_debug;

/* This symbol refers to the "dynamic structure" in the `.dynamic' section
   of whatever module refers to `_DYNAMIC'.  So, to find its own
   `struct r_debug', a program could do:
     for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL; ++dyn)
       if (dyn->d_tag == DT_DEBUG)
	 r_debug = (struct r_debug *) dyn->d_un.d_ptr;
   */
extern ElfW(Dyn) _DYNAMIC[];


/* Some internal data structures of the dynamic linker used in the
   linker map.  We only provide forward declarations.  */
struct libname_list;
struct r_found_version;
struct r_search_path_elem;

/* Forward declaration.  */
struct link_map;

/* Structure to describe a single list of scope elements.  The lookup
   functions get passed an array of pointers to such structures.  */
struct r_scope_elem
{
  /* Array of maps for the scope.  */
  struct link_map **r_list;
  /* Number of entries in the scope.  */
  unsigned int r_nlist;
};


/* Structure to record search path and allocation mechanism.  */
struct r_search_path_struct
  {
    struct r_search_path_elem **dirs;
    int malloced;
  };


/* Structure describing a loaded shared object.  The `l_next' and `l_prev'
   members form a chain of all the shared objects loaded at startup.

   These data structures exist in space used by the run-time dynamic linker;
   modifying them may have disastrous results.

   This data structure might change in future, if necessary.  User-level
   programs must avoid defining objects of this type.  */

struct link_map
  {
    /* These first few members are part of the protocol with the debugger.
       This is the same format used in SVR4.  */

    ElfW(Addr) l_addr;		/* Base address shared object is loaded at.  */
    char *l_name;		/* Absolute file name object was found in.  */
    ElfW(Dyn) *l_ld;		/* Dynamic section of the shared object.  */
    struct link_map *l_next, *l_prev; /* Chain of loaded objects.  */

    /* All following members are internal to the dynamic linker.
       They may change without notice.  */

    struct libname_list *l_libname;
    /* Indexed pointers to dynamic section.
       [0,DT_NUM) are indexed by the processor-independent tags.
       [DT_NUM,DT_NUM+DT_THISPROCNUM) are indexed by the tag minus DT_LOPROC.
       [DT_NUM+DT_THISPROCNUM,DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM) are
       indexed by DT_VERSIONTAGIDX(tagvalue).
       [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM,
	DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM) are indexed by
       DT_EXTRATAGIDX(tagvalue).
       [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM,
	DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM) are
       indexed by DT_VALTAGIDX(tagvalue) and
       [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM,
	DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM+DT_ADDRNUM)
       are indexed by DT_ADDRTAGIDX(tagvalue), see <elf.h>.  */

    ElfW(Dyn) *l_info[DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM
		     + DT_EXTRANUM + DT_VALNUM + DT_ADDRNUM];
    const ElfW(Phdr) *l_phdr;	/* Pointer to program header table in core.  */
    ElfW(Addr) l_entry;		/* Entry point location.  */
    ElfW(Half) l_phnum;		/* Number of program header entries.  */
    ElfW(Half) l_ldnum;	/* Number of dynamic segment entries.  */

    /* Array of DT_NEEDED dependencies and their dependencies, in
       dependency order for symbol lookup (with and without
       duplicates).  There is no entry before the dependencies have
       been loaded.  */
    struct r_scope_elem l_searchlist;

    /* We need a special searchlist to process objects marked with
       DT_SYMBOLIC.  */
    struct r_scope_elem l_symbolic_searchlist;

    /* Dependent object that first caused this object to be loaded.  */
    struct link_map *l_loader;

    /* Symbol hash table.  */
    Elf_Symndx l_nbuckets;
    const Elf_Symndx *l_buckets, *l_chain;

    unsigned int l_opencount;	/* Reference count for dlopen/dlclose.  */
    enum			/* Where this object came from.  */
      {
	lt_executable,		/* The main executable program.  */
	lt_library,		/* Library needed by main executable.  */
	lt_loaded		/* Extra run-time loaded shared object.  */
      } l_type:2;
    unsigned int l_relocated:1;	/* Nonzero if object's relocations done.  */
    unsigned int l_init_called:1; /* Nonzero if DT_INIT function called.  */
    unsigned int l_global:1;	/* Nonzero if object in _dl_global_scope.  */
    unsigned int l_reserved:2;	/* Reserved for internal use.  */
    unsigned int l_phdr_allocated:1; /* Nonzero if the data structure pointed
					to by `l_phdr' is allocated.  */
    unsigned int l_soname_added:1; /* Nonzero if the SONAME is for sure in
				      the l_libname list.  */
    unsigned int l_faked:1;	/* Nonzero if this is a faked descriptor
				   without associated file.  */

    /* Array with version names.  */
    unsigned int l_nversions;
    struct r_found_version *l_versions;

    /* Collected information about own RPATH directories.  */
    struct r_search_path_struct l_rpath_dirs;

    /* Collected results of relocation while profiling.  */
    ElfW(Addr) *l_reloc_result;

    /* Pointer to the version information if available.  */
    ElfW(Versym) *l_versyms;

    /* String specifying the path where this object was found.  */
    const char *l_origin;

    /* Start and finish of memory map for this object.  l_map_start
       need not be the same as l_addr.  */
    ElfW(Addr) l_map_start, l_map_end;

    /* Default array for 'l_scope'.  */
    struct r_scope_elem *l_scope_mem[4];
    /* Size of array allocated for 'l_scope'.  */
    size_t l_scope_max;
    /* This is an array defining the lookup scope for this link map.
       There are at most three different scope lists.  */
    struct r_scope_elem **l_scope;

    /* A similar array, this time only with the local scope.  This is
       used occasionally.  */
    struct r_scope_elem *l_local_scope[2];

    /* This information is kept to check for sure whether a shared
       object is the same as one already loaded.  */
    dev_t l_dev;
    ino64_t l_ino;

    /* Collected information about own RUNPATH directories.  */
    struct r_search_path_struct l_runpath_dirs;

    /* List of object in order of the init and fini calls.  */
    struct link_map **l_initfini;

    /* List of the dependencies introduced through symbol binding.  */
    unsigned int l_reldepsmax;
    unsigned int l_reldepsact;
    struct link_map **l_reldeps;

    /* Various flag words.  */
    ElfW(Word) l_feature_1;
    ElfW(Word) l_flags_1;

    /* Temporarily used in `dl_close'.  */
    unsigned int l_idx;

    struct link_map_machine l_mach;

    struct
    {
      const ElfW(Sym) *sym;
      int type_class;
#ifdef DL_LOOKUP_RETURNS_MAP
      struct link_map *value;
#else
      ElfW(Addr) value;
#endif
      const ElfW(Sym) *ret;
    } l_lookup_cache;
  };

struct dl_phdr_info
  {
    ElfW(Addr) dlpi_addr;
    const char *dlpi_name;
    const ElfW(Phdr) *dlpi_phdr;
    ElfW(Half) dlpi_phnum;
  };

extern int dl_iterate_phdr (int (*callback) (struct dl_phdr_info *info,
					     size_t size, void *data),
			    void *data);
extern int __dl_iterate_phdr (int (*callback) (struct dl_phdr_info *info,
					       size_t size, void *data),
			      void *data);

#endif /* link.h */