/* Data structure for communication from the run-time dynamic linker for loaded ELF shared objects. Copyright (C) 1995, 1996, 1997, 1998, 1999 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 Library General Public License as published by the Free Software Foundation; either version 2 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 Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with the GNU C Library; see the file COPYING.LIB. 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 #include #include #include /* 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 /* Defines __ELF_NATIVE_CLASS. */ /* 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) 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; /* Array of maps which also includes duplicates. */ struct link_map **r_duplist; /* Number of elements in this list. */ unsigned int r_nduplist; }; /* 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_PROCNUM) are indexed by the tag minus DT_LOPROC. [DT_NUM+DT_PROCNUM,DT_NUM+DT_PROCNUM+DT_EXTRANUM) are indexed by DT_EXTRATAGIDX(tagvalue) and [DT_NUM+DT_PROCNUM+DT_VERSIONTAGNUM, DT_NUM+DT_PROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM) are indexed by DT_EXTRATAGIDX(tagvalue) (see ). */ ElfW(Dyn) *l_info[DT_NUM + DT_PROCNUM + DT_VERSIONTAGNUM + DT_EXTRANUM]; 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. */ /* 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. */ ElfW(Symndx) l_nbuckets; const ElfW(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_init_running:1; /* Nonzero while DT_INIT function runs. */ unsigned int l_global:1; /* Nonzero if object in _dl_global_scope. */ unsigned int l_reserved:2; /* Reserved for internal use. */ /* Array with version names. */ unsigned int l_nversions; struct r_found_version *l_versions; /* Collected information about own RPATH directories. */ struct r_search_path_elem **l_rpath_dirs; /* Collected results of relocation while profiling. */ ElfW(Addr) *l_reloc_result; /* Pointer to the version information if available. */ ElfW(Half) *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; /* 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[4]; /* 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; ino_t l_ino; /* Nonzero if the data structure pointed to by `l_phdr' is allocated. */ int l_phdr_allocated; }; #endif /* link.h */