1 /* Data structure for communication from the run-time dynamic linker for
2 loaded ELF shared objects.
3 Copyright (C) 1995-1999, 2000 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Library General Public License as
8 published by the Free Software Foundation; either version 2 of the
9 License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Library General Public License for more details.
16 You should have received a copy of the GNU Library General Public
17 License along with the GNU C Library; see the file COPYING.LIB. If not,
18 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
27 #include <sys/types.h>
29 /* We use this macro to refer to ELF types independent of the native wordsize.
30 `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */
31 #define ElfW(type) _ElfW (Elf, __ELF_NATIVE_CLASS, type)
32 #define _ElfW(e,w,t) _ElfW_1 (e, w, _##t)
33 #define _ElfW_1(e,w,t) e##w##t
35 #include <bits/elfclass.h> /* Defines __ELF_NATIVE_CLASS. */
37 /* Rendezvous structure used by the run-time dynamic linker to communicate
38 details of shared object loading to the debugger. If the executable's
39 dynamic section has a DT_DEBUG element, the run-time linker sets that
40 element's value to the address where this structure can be found. */
44 int r_version
; /* Version number for this protocol. */
46 struct link_map
*r_map
; /* Head of the chain of loaded objects. */
48 /* This is the address of a function internal to the run-time linker,
49 that will always be called when the linker begins to map in a
50 library or unmap it, and again when the mapping change is complete.
51 The debugger can set a breakpoint at this address if it wants to
52 notice shared object mapping changes. */
56 /* This state value describes the mapping change taking place when
57 the `r_brk' address is called. */
58 RT_CONSISTENT
, /* Mapping change is complete. */
59 RT_ADD
, /* Beginning to add a new object. */
60 RT_DELETE
/* Beginning to remove an object mapping. */
63 ElfW(Addr
) r_ldbase
; /* Base address the linker is loaded at. */
66 /* This is the instance of that structure used by the dynamic linker. */
67 extern struct r_debug _r_debug
;
69 /* This symbol refers to the "dynamic structure" in the `.dynamic' section
70 of whatever module refers to `_DYNAMIC'. So, to find its own
71 `struct r_debug', a program could do:
72 for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL; ++dyn)
73 if (dyn->d_tag == DT_DEBUG)
74 r_debug = (struct r_debug *) dyn->d_un.d_ptr;
76 extern ElfW(Dyn
) _DYNAMIC
[];
79 /* Some internal data structures of the dynamic linker used in the
80 linker map. We only provide forward declarations. */
82 struct r_found_version
;
83 struct r_search_path_elem
;
85 /* Forward declaration. */
88 /* Structure to describe a single list of scope elements. The lookup
89 functions get passed an array of pointers to such structures. */
92 /* Array of maps for the scope. */
93 struct link_map
**r_list
;
94 /* Number of entries in the scope. */
97 /* Array of maps which also includes duplicates. */
98 struct link_map
**r_duplist
;
99 /* Number of elements in this list. */
100 unsigned int r_nduplist
;
104 /* Structure describing a loaded shared object. The `l_next' and `l_prev'
105 members form a chain of all the shared objects loaded at startup.
107 These data structures exist in space used by the run-time dynamic linker;
108 modifying them may have disastrous results.
110 This data structure might change in future, if necessary. User-level
111 programs must avoid defining objects of this type. */
115 /* These first few members are part of the protocol with the debugger.
116 This is the same format used in SVR4. */
118 ElfW(Addr
) l_addr
; /* Base address shared object is loaded at. */
119 char *l_name
; /* Absolute file name object was found in. */
120 ElfW(Dyn
) *l_ld
; /* Dynamic section of the shared object. */
121 struct link_map
*l_next
, *l_prev
; /* Chain of loaded objects. */
123 /* All following members are internal to the dynamic linker.
124 They may change without notice. */
126 struct libname_list
*l_libname
;
127 /* Indexed pointers to dynamic section.
128 [0,DT_NUM) are indexed by the processor-independent tags.
129 [DT_NUM,DT_NUM+DT_THISPROCNUM) are indexed by the tag minus DT_LOPROC.
130 [DT_NUM+DT_THISPROCNUM,DT_NUM+DT_THISPROCNUM+DT_EXTRANUM) are indexed
131 by DT_EXTRATAGIDX(tagvalue) and
132 [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM,
133 DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM)
134 are indexed by DT_EXTRATAGIDX(tagvalue) (see <elf.h>). */
136 ElfW(Dyn
) *l_info
[DT_NUM
+ DT_THISPROCNUM
+ DT_VERSIONTAGNUM
138 const ElfW(Phdr
) *l_phdr
; /* Pointer to program header table in core. */
139 ElfW(Addr
) l_entry
; /* Entry point location. */
140 ElfW(Half
) l_phnum
; /* Number of program header entries. */
141 ElfW(Half
) l_ldnum
; /* Number of dynamic segment entries. */
143 /* Array of DT_NEEDED dependencies and their dependencies, in
144 dependency order for symbol lookup (with and without
145 duplicates). There is no entry before the dependencies have
147 struct r_scope_elem l_searchlist
;
149 /* We need a special searchlist to process objects marked with
151 struct r_scope_elem l_symbolic_searchlist
;
153 /* Dependent object that first caused this object to be loaded. */
154 struct link_map
*l_loader
;
156 /* Symbol hash table. */
157 Elf_Symndx l_nbuckets
;
158 const Elf_Symndx
*l_buckets
, *l_chain
;
160 unsigned int l_opencount
; /* Reference count for dlopen/dlclose. */
161 enum /* Where this object came from. */
163 lt_executable
, /* The main executable program. */
164 lt_library
, /* Library needed by main executable. */
165 lt_loaded
/* Extra run-time loaded shared object. */
167 unsigned int l_relocated
:1; /* Nonzero if object's relocations done. */
168 unsigned int l_init_called
:1; /* Nonzero if DT_INIT function called. */
169 unsigned int l_global
:1; /* Nonzero if object in _dl_global_scope. */
170 unsigned int l_reserved
:2; /* Reserved for internal use. */
171 unsigned int l_phdr_allocated
:1; /* Nonzero if the data structure pointed
172 to by `l_phdr' is allocated. */
174 /* Array with version names. */
175 unsigned int l_nversions
;
176 struct r_found_version
*l_versions
;
178 /* Collected information about own RPATH directories. */
179 struct r_search_path_elem
**l_rpath_dirs
;
181 /* Collected results of relocation while profiling. */
182 ElfW(Addr
) *l_reloc_result
;
184 /* Pointer to the version information if available. */
185 ElfW(Versym
) *l_versyms
;
187 /* String specifying the path where this object was found. */
188 const char *l_origin
;
190 /* Start and finish of memory map for this object. l_map_start
191 need not be the same as l_addr. */
192 ElfW(Addr
) l_map_start
, l_map_end
;
194 /* This is an array defining the lookup scope for this link map.
195 There are at most three different scope lists. */
196 struct r_scope_elem
*l_scope
[4];
198 /* A similar array, this time only with the local scope. This is
199 used occasionally. */
200 struct r_scope_elem
*l_local_scope
[2];
202 /* This information is kept to check for sure whether a shared
203 object is the same as one already loaded. */
207 /* Collected information about own RUNPATH directories. */
208 struct r_search_path_elem
**l_runpath_dirs
;
210 /* List of object in order of the init and fini calls. */
211 struct link_map
**l_initfini
;
213 /* List of the dependencies introduced through symbol binding. */
214 unsigned int l_reldepsmax
;
215 unsigned int l_reldepsact
;
216 struct link_map
**l_reldeps
;