199 lines
7.6 KiB
C
199 lines
7.6 KiB
C
/* Data structure for communication from the run-time dynamic linker for
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loaded ELF shared objects.
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Copyright (C) 1995, 1996, 1997, 1998 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#ifndef _LINK_H
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#define _LINK_H 1
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#include <features.h>
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#include <elf.h>
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#include <dlfcn.h>
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/* We use this macro to refer to ELF types independent of the native wordsize.
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`ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */
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#define ElfW(type) _ElfW (Elf, __ELF_NATIVE_CLASS, type)
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#define _ElfW(e,w,t) _ElfW_1 (e, w, _##t)
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#define _ElfW_1(e,w,t) e##w##t
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#include <bits/elfclass.h> /* Defines __ELF_NATIVE_CLASS. */
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/* Rendezvous structure used by the run-time dynamic linker to communicate
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details of shared object loading to the debugger. If the executable's
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dynamic section has a DT_DEBUG element, the run-time linker sets that
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element's value to the address where this structure can be found. */
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struct r_debug
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{
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int r_version; /* Version number for this protocol. */
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struct link_map *r_map; /* Head of the chain of loaded objects. */
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/* This is the address of a function internal to the run-time linker,
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that will always be called when the linker begins to map in a
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library or unmap it, and again when the mapping change is complete.
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The debugger can set a breakpoint at this address if it wants to
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notice shared object mapping changes. */
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ElfW(Addr) r_brk;
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enum
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{
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/* This state value describes the mapping change taking place when
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the `r_brk' address is called. */
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RT_CONSISTENT, /* Mapping change is complete. */
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RT_ADD, /* Beginning to add a new object. */
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RT_DELETE /* Beginning to remove an object mapping. */
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} r_state;
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ElfW(Addr) r_ldbase; /* Base address the linker is loaded at. */
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};
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/* This is the instance of that structure used by the dynamic linker. */
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extern struct r_debug _r_debug;
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/* This symbol refers to the "dynamic structure" in the `.dynamic' section
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of whatever module refers to `_DYNAMIC'. So, to find its own
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`struct r_debug', a program could do:
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for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL)
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if (dyn->d_tag == DT_DEBUG) r_debug = (struct r_debug) dyn->d_un.d_ptr;
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*/
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extern ElfW(Dyn) _DYNAMIC[];
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/* Some internal data structures of the dynamic linker used in the
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linker map. We only provide forward declarations. */
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struct libname_list;
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struct r_found_version;
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struct r_search_path_elem;
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/* Forward declaration. */
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struct link_map;
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/* Structure to describe a single list of scope elements. The lookup
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functions get passed an array of pointers to such structures. */
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struct r_scope_elem
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{
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/* Array of maps for the scope. */
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struct link_map **r_list;
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/* Number of entries in the scope. */
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unsigned int r_nlist;
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/* Array of maps which also includes duplicates. */
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struct link_map **r_duplist;
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/* Number of elements in this list. */
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unsigned int r_nduplist;
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};
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/* Structure describing a loaded shared object. The `l_next' and `l_prev'
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members form a chain of all the shared objects loaded at startup.
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These data structures exist in space used by the run-time dynamic linker;
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modifying them may have disastrous results.
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This data structure might change in future, if necessary. User-level
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programs must avoid defining objects of this type. */
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struct link_map
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{
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/* These first few members are part of the protocol with the debugger.
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This is the same format used in SVR4. */
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ElfW(Addr) l_addr; /* Base address shared object is loaded at. */
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char *l_name; /* Absolute file name object was found in. */
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ElfW(Dyn) *l_ld; /* Dynamic section of the shared object. */
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struct link_map *l_next, *l_prev; /* Chain of loaded objects. */
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/* All following members are internal to the dynamic linker.
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They may change without notice. */
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struct libname_list *l_libname;
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/* Indexed pointers to dynamic section.
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[0,DT_NUM) are indexed by the processor-independent tags.
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[DT_NUM,DT_NUM+DT_PROCNUM) are indexed by the tag minus DT_LOPROC.
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[DT_NUM+DT_PROCNUM,DT_NUM+DT_PROCNUM+DT_EXTRANUM) are indexed
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by DT_EXTRATAGIDX(tagvalue) and
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[DT_NUM+DT_PROCNUM+DT_VERSIONTAGNUM,
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DT_NUM+DT_PROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM)
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are indexed by DT_EXTRATAGIDX(tagvalue) (see <elf.h>). */
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ElfW(Dyn) *l_info[DT_NUM + DT_PROCNUM + DT_VERSIONTAGNUM + DT_EXTRANUM];
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const ElfW(Phdr) *l_phdr; /* Pointer to program header table in core. */
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ElfW(Addr) l_entry; /* Entry point location. */
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ElfW(Half) l_phnum; /* Number of program header entries. */
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/* Array of DT_NEEDED dependencies and their dependencies, in
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dependency order for symbol lookup (with and without
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duplicates). There is no entry before the dependencies have
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been loaded. */
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struct r_scope_elem l_searchlist;
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/* We need a special searchlist to process objects marked with
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DT_SYMBOLIC. */
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struct r_scope_elem l_symbolic_searchlist;
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/* Dependent object that first caused this object to be loaded. */
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struct link_map *l_loader;
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/* Symbol hash table. */
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ElfW(Symndx) l_nbuckets;
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const ElfW(Symndx) *l_buckets, *l_chain;
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unsigned int l_opencount; /* Reference count for dlopen/dlclose. */
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enum /* Where this object came from. */
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{
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lt_executable, /* The main executable program. */
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lt_library, /* Library needed by main executable. */
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lt_loaded /* Extra run-time loaded shared object. */
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} l_type:2;
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unsigned int l_relocated:1; /* Nonzero if object's relocations done. */
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unsigned int l_init_called:1; /* Nonzero if DT_INIT function called. */
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unsigned int l_init_running:1; /* Nonzero while DT_INIT function runs. */
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unsigned int l_global:1; /* Nonzero if object in _dl_global_scope. */
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unsigned int l_reserved:2; /* Reserved for internal use. */
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/* Array with version names. */
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unsigned int l_nversions;
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struct r_found_version *l_versions;
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/* Collected information about own RPATH directories. */
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struct r_search_path_elem **l_rpath_dirs;
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/* Collected results of relocation while profiling. */
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ElfW(Addr) *l_reloc_result;
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/* Pointer to the version information if available. */
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ElfW(Half) *l_versyms;
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/* String specifying the path where this object was found. */
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const char *l_origin;
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/* Start and finish of memory map for this object. l_map_start
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need not be the same as l_addr. */
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ElfW(Addr) l_map_start, l_map_end;
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/* This is an array defining the lookup scope for this link map.
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There are at most three different scope lists. */
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struct r_scope_elem *l_scope[4];
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/* A similar array, this time only with the local scope. This is
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used occasionally. */
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struct r_scope_elem *l_local_scope[2];
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};
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#endif /* link.h */
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