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Diffstat (limited to 'include/link.h')
| -rw-r--r-- | include/link.h | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/include/link.h b/include/link.h new file mode 100644 index 000000000..070eabb6d --- /dev/null +++ b/include/link.h @@ -0,0 +1,208 @@ +/* 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 <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. */ + +/* 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; + + /* 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 <elf.h>). */ + + 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 */ |