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 Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the 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 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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. */
99 /* Structure to record search path and allocation mechanism. */
100 struct r_search_path_struct
102 struct r_search_path_elem
**dirs
;
107 /* Structure describing a loaded shared object. The `l_next' and `l_prev'
108 members form a chain of all the shared objects loaded at startup.
110 These data structures exist in space used by the run-time dynamic linker;
111 modifying them may have disastrous results.
113 This data structure might change in future, if necessary. User-level
114 programs must avoid defining objects of this type. */
118 /* These first few members are part of the protocol with the debugger.
119 This is the same format used in SVR4. */
121 ElfW(Addr
) l_addr
; /* Base address shared object is loaded at. */
122 char *l_name
; /* Absolute file name object was found in. */
123 ElfW(Dyn
) *l_ld
; /* Dynamic section of the shared object. */
124 struct link_map
*l_next
, *l_prev
; /* Chain of loaded objects. */
126 /* All following members are internal to the dynamic linker.
127 They may change without notice. */
129 struct libname_list
*l_libname
;
130 /* Indexed pointers to dynamic section.
131 [0,DT_NUM) are indexed by the processor-independent tags.
132 [DT_NUM,DT_NUM+DT_THISPROCNUM) are indexed by the tag minus DT_LOPROC.
133 [DT_NUM+DT_THISPROCNUM,DT_NUM+DT_THISPROCNUM+DT_EXTRANUM) are indexed
134 by DT_EXTRATAGIDX(tagvalue) and
135 [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM,
136 DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM)
137 are indexed by DT_EXTRATAGIDX(tagvalue) (see <elf.h>). */
139 ElfW(Dyn
) *l_info
[DT_NUM
+ DT_THISPROCNUM
+ DT_VERSIONTAGNUM
141 const ElfW(Phdr
) *l_phdr
; /* Pointer to program header table in core. */
142 ElfW(Addr
) l_entry
; /* Entry point location. */
143 ElfW(Half
) l_phnum
; /* Number of program header entries. */
144 ElfW(Half
) l_ldnum
; /* Number of dynamic segment entries. */
146 /* Array of DT_NEEDED dependencies and their dependencies, in
147 dependency order for symbol lookup (with and without
148 duplicates). There is no entry before the dependencies have
150 struct r_scope_elem l_searchlist
;
152 /* We need a special searchlist to process objects marked with
154 struct r_scope_elem l_symbolic_searchlist
;
156 /* Dependent object that first caused this object to be loaded. */
157 struct link_map
*l_loader
;
159 /* Symbol hash table. */
160 Elf_Symndx l_nbuckets
;
161 const Elf_Symndx
*l_buckets
, *l_chain
;
163 unsigned int l_opencount
; /* Reference count for dlopen/dlclose. */
164 enum /* Where this object came from. */
166 lt_executable
, /* The main executable program. */
167 lt_library
, /* Library needed by main executable. */
168 lt_loaded
/* Extra run-time loaded shared object. */
170 unsigned int l_relocated
:1; /* Nonzero if object's relocations done. */
171 unsigned int l_init_called
:1; /* Nonzero if DT_INIT function called. */
172 unsigned int l_global
:1; /* Nonzero if object in _dl_global_scope. */
173 unsigned int l_reserved
:2; /* Reserved for internal use. */
174 unsigned int l_phdr_allocated
:1; /* Nonzero if the data structure pointed
175 to by `l_phdr' is allocated. */
176 unsigned int l_soname_added
:1; /* Nonzero if the SONAME is for sure in
177 the l_libname list. */
178 unsigned int l_faked
:1; /* Nonzero if this is a faked descriptor
179 without associated file. */
181 /* Array with version names. */
182 unsigned int l_nversions
;
183 struct r_found_version
*l_versions
;
185 /* Collected information about own RPATH directories. */
186 struct r_search_path_struct l_rpath_dirs
;
188 /* Collected results of relocation while profiling. */
189 ElfW(Addr
) *l_reloc_result
;
191 /* Pointer to the version information if available. */
192 ElfW(Versym
) *l_versyms
;
194 /* String specifying the path where this object was found. */
195 const char *l_origin
;
197 /* Start and finish of memory map for this object. l_map_start
198 need not be the same as l_addr. */
199 ElfW(Addr
) l_map_start
, l_map_end
;
201 /* This is an array defining the lookup scope for this link map.
202 There are at most three different scope lists. */
203 struct r_scope_elem
*l_scope
[4];
205 /* A similar array, this time only with the local scope. This is
206 used occasionally. */
207 struct r_scope_elem
*l_local_scope
[2];
209 /* This information is kept to check for sure whether a shared
210 object is the same as one already loaded. */
214 /* Collected information about own RUNPATH directories. */
215 struct r_search_path_struct l_runpath_dirs
;
217 /* List of object in order of the init and fini calls. */
218 struct link_map
**l_initfini
;
220 /* List of the dependencies introduced through symbol binding. */
221 unsigned int l_reldepsmax
;
222 unsigned int l_reldepsact
;
223 struct link_map
**l_reldeps
;
225 /* Various flag words. */
226 ElfW(Word
) l_feature_1
;
227 ElfW(Word
) l_flags_1
;
229 /* Temporarily used in `dl_close'. */