1 /* Run-time dynamic linker data structures for loaded ELF shared objects.
2 Copyright (C) 1995-1999, 2000 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
35 /* We use this macro to refer to ELF types independent of the native wordsize.
36 `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */
37 #define ELFW(type) _ElfW (ELF, __ELF_NATIVE_CLASS, type)
39 /* All references to the value of l_info[DT_PLTGOT],
40 l_info[DT_STRTAB], l_info[DT_SYMTAB], l_info[DT_RELA],
41 l_info[DT_REL], l_info[DT_JMPREL], l_info[VERSYMIDX (DT_VERSYM)],
42 and l_info[DT_INIT_ARRAY] have to accessed via the D_PTR macro. The
43 macro is needed since for most architectures the entry is already
44 relocated - but for some not and we need to relocate at access time. */
45 #ifdef DL_RO_DYN_SECTION
46 # define D_PTR(map,i) (map->i->d_un.d_ptr + map->l_addr)
48 # define D_PTR(map,i) map->i->d_un.d_ptr
51 /* For the version handling we need an array with only names and their
53 struct r_found_version
62 /* We want to cache information about the searches for shared objects. */
64 enum r_dir_status { unknown, nonexisting, existing };
66 struct r_search_path_elem
68 /* This link is only used in the `all_dirs' member of `r_search_path'. */
69 struct r_search_path_elem *next;
71 /* Strings saying where the definition came from. */
75 /* Basename for this search path element. The string must end with
80 enum r_dir_status status[0];
90 /* A data structure for a simple single linked list of strings. */
93 const char *name; /* Name requested (before search). */
94 struct libname_list *next; /* Link to next name for this object. */
98 /* Test whether given NAME matches any of the names of the given object. */
100 __attribute__ ((unused))
101 _dl_name_match_p (const char *__name, struct link_map *__map)
103 int __found = strcmp (__name, __map->l_name) == 0;
104 struct libname_list *__runp = __map->l_libname;
106 while (! __found && __runp != NULL)
107 if (strcmp (__name, __runp->name) == 0)
110 __runp = __runp->next;
115 /* Function used as argument for `_dl_receive_error' function. The
116 arguments are the error code, error string, and the objname the
117 error occurred in. */
118 typedef void (*receiver_fct) (int, const char *, const char *);
120 /* Internal functions of the run-time dynamic linker.
121 These can be accessed if you link again the dynamic linker
122 as a shared library, as in `-lld' or `/lib/ld.so' explicitly;
123 but are not normally of interest to user programs.
125 The `-ldl' library functions in <dlfcn.h> provide a simple
126 user interface to run-time dynamic linking. */
129 /* Parameters passed to the dynamic linker. */
130 extern char **_dl_argv;
132 /* Cached value of `getpagesize ()'. */
133 extern size_t _dl_pagesize;
135 /* File descriptor referring to the zero-fill device. */
136 extern int _dl_zerofd;
138 /* Name of the shared object to be profiled (if any). */
139 extern const char *_dl_profile;
140 /* Map of shared object to be profiled. */
141 extern struct link_map *_dl_profile_map;
142 /* Filename of the output file. */
143 extern const char *_dl_profile_output;
145 /* If nonzero the appropriate debug information is printed. */
146 extern int _dl_debug_libs;
147 extern int _dl_debug_impcalls;
148 extern int _dl_debug_bindings;
149 extern int _dl_debug_symbols;
150 extern int _dl_debug_versions;
151 extern int _dl_debug_reloc;
152 extern int _dl_debug_files;
154 /* Expect cache ID. */
155 extern int _dl_correct_cache_id;
157 /* Mask for hardware capabilities that are available. */
158 extern unsigned long int _dl_hwcap;
160 /* Mask for important hardware capabilities we honour. */
161 extern unsigned long int _dl_hwcap_mask;
163 /* File descriptor to write debug messages to. */
164 extern int _dl_debug_fd;
166 /* Names of shared object for which the RPATH should be ignored. */
167 extern const char *_dl_inhibit_rpath;
169 /* OS-dependent function to open the zero-fill device. */
170 extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
172 /* OS-dependent function to write a message on the specified
173 descriptor FD. All arguments are `const char *'; args until a null
174 pointer are concatenated to form the message to print. */
175 extern void _dl_sysdep_output (int fd, const char *string, ...);
177 /* OS-dependent function to write a debug message on the specified
178 descriptor for this. All arguments are `const char *'; args until
179 a null pointer are concatenated to form the message to print. If
180 NEW_LINE is nonzero it is assumed that the message starts on a new
182 extern void _dl_debug_message (int new_line, const char *string, ...);
184 /* OS-dependent function to write a message on the standard output.
185 All arguments are `const char *'; args until a null pointer
186 are concatenated to form the message to print. */
187 #define _dl_sysdep_message(string, args...) \
188 _dl_sysdep_output (STDOUT_FILENO, string, ##args)
190 /* OS-dependent function to write a message on the standard error.
191 All arguments are `const char *'; args until a null pointer
192 are concatenated to form the message to print. */
193 #define _dl_sysdep_error(string, args...) \
194 _dl_sysdep_output (STDERR_FILENO, string, ##args)
196 /* OS-dependent function to give a fatal error message and exit
197 when the dynamic linker fails before the program is fully linked.
198 All arguments are `const char *'; args until a null pointer
199 are concatenated to form the message to print. */
200 #define _dl_sysdep_fatal(string, args...) \
203 _dl_sysdep_output (STDERR_FILENO, string, ##args); \
208 /* Nonzero if the program should be "secure" (i.e. it's setuid or somesuch).
209 This tells the dynamic linker to ignore environment variables. */
210 extern int _dl_secure;
212 /* This function is called by all the internal dynamic linker functions
213 when they encounter an error. ERRCODE is either an `errno' code or
214 zero; OBJECT is the name of the problematical shared object, or null if
215 it is a general problem; ERRSTRING is a string describing the specific
217 extern void _dl_signal_error (int errcode,
219 const char *errstring)
221 __attribute__ ((__noreturn__));
223 /* Like _dl_signal_error, but may return when called in the context of
224 _dl_receive_error. */
225 extern void _dl_signal_cerror (int errcode,
227 const char *errstring)
230 /* Call OPERATE, receiving errors from `dl_signal_cerror'. Unlike
231 `_dl_catch_error' the operation is resumed after the OPERATE
233 ARGS is passed as argument to OPERATE. */
234 extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
239 /* Open the shared object NAME and map in its segments.
240 LOADER's DT_RPATH is used in searching for NAME.
241 If the object is already opened, returns its existing map.
242 For preloaded shared objects PRELOADED is set to a non-zero
243 value to allow additional security checks. */
244 extern struct link_map *_dl_map_object (struct link_map *loader,
245 const char *name, int preloaded,
246 int type, int trace_mode)
249 /* Call _dl_map_object on the dependencies of MAP, and set up
250 MAP->l_searchlist. PRELOADS points to a vector of NPRELOADS previously
251 loaded objects that will be inserted into MAP->l_searchlist after MAP
252 but before its dependencies. */
253 extern void _dl_map_object_deps (struct link_map *map,
254 struct link_map **preloads,
255 unsigned int npreloads, int trace_mode)
258 /* Cache the locations of MAP's hash table. */
259 extern void _dl_setup_hash (struct link_map *map) internal_function;
262 /* Search loaded objects' symbol tables for a definition of the symbol
263 referred to by UNDEF. *SYM is the symbol table entry containing the
264 reference; it is replaced with the defining symbol, and the base load
265 address of the defining object is returned. SYMBOL_SCOPE is a
266 null-terminated list of object scopes to search; each object's
267 l_searchlist (i.e. the segment of the dependency tree starting at that
268 object) is searched in turn. REFERENCE_NAME should name the object
269 containing the reference; it is used in error messages.
270 RELOC_TYPE is a machine-dependent reloc type, which is passed to
271 the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
272 symbols can be chosen. */
273 extern ElfW(Addr) _dl_lookup_symbol (const char *undef,
274 struct link_map *undef_map,
275 const ElfW(Sym) **sym,
276 struct r_scope_elem *symbol_scope[],
280 /* Lookup versioned symbol. */
281 extern ElfW(Addr) _dl_lookup_versioned_symbol (const char *undef,
282 struct link_map *undef_map,
283 const ElfW(Sym) **sym,
284 struct r_scope_elem *symbol_scope[],
285 const struct r_found_version *version,
289 /* For handling RTLD_NEXT we must be able to skip shared objects. */
290 extern ElfW(Addr) _dl_lookup_symbol_skip (const char *undef,
291 struct link_map *undef_map,
292 const ElfW(Sym) **sym,
293 struct r_scope_elem *symbol_scope[],
294 struct link_map *skip_this)
297 /* For handling RTLD_NEXT with versioned symbols we must be able to
298 skip shared objects. */
299 extern ElfW(Addr) _dl_lookup_versioned_symbol_skip (const char *undef,
300 struct link_map *undef_map,
301 const ElfW(Sym) **sym,
302 struct r_scope_elem *symbol_scope[],
303 const struct r_found_version *version,
304 struct link_map *skip_this)
307 /* Look up symbol NAME in MAP's scope and return its run-time address. */
308 extern ElfW(Addr) _dl_symbol_value (struct link_map *map, const char *name)
312 /* Structure describing the dynamic linker itself. */
313 extern struct link_map _dl_rtld_map;
314 /* And a pointer to the map for the main map. */
315 extern struct link_map *_dl_loaded;
316 /* Array representing global scope. */
317 extern struct r_scope_elem *_dl_global_scope[2];
318 /* Direct pointer to the searchlist of the main object. */
319 extern struct r_scope_elem *_dl_main_searchlist;
320 /* Copy of the content of `_dl_main_searchlist'. */
321 extern struct r_scope_elem _dl_initial_searchlist;
322 /* This is zero at program start to signal that the global scope map is
323 allocated by rtld. Later it keeps the size of the map. It might be
324 reset if in _dl_close if the last global object is removed. */
325 extern size_t _dl_global_scope_alloc;
327 /* Allocate a `struct link_map' for a new object being loaded,
328 and enter it into the _dl_main_map list. */
329 extern struct link_map *_dl_new_object (char *realname, const char *libname,
330 int type, struct link_map *loader)
333 /* Relocate the given object (if it hasn't already been).
334 SCOPE is passed to _dl_lookup_symbol in symbol lookups.
335 If LAZY is nonzero, don't relocate its PLT. */
336 extern void _dl_relocate_object (struct link_map *map,
337 struct r_scope_elem *scope[],
338 int lazy, int consider_profiling);
340 /* Call _dl_signal_error with a message about an unhandled reloc type.
341 TYPE is the result of ELFW(R_TYPE) (r_info), i.e. an R_<CPU>_* value.
342 PLT is nonzero if this was a PLT reloc; it just affects the message. */
343 extern void _dl_reloc_bad_type (struct link_map *map,
344 uint_fast8_t type, int plt)
347 /* Check the version dependencies of all objects available through
348 MAP. If VERBOSE print some more diagnostics. */
349 extern int _dl_check_all_versions (struct link_map *map, int verbose)
352 /* Check the version dependencies for MAP. If VERBOSE print some more
354 extern int _dl_check_map_versions (struct link_map *map, int verbose)
357 /* Return the address of the next initializer function for SCOPE or one of
358 its dependencies that has not yet been run. When there are no more
359 initializers to be run, this returns zero. The functions are returned
360 in the order they should be called. */
361 extern ElfW(Addr) _dl_init_next (struct r_scope_elem *scope) internal_function;
363 /* Call the finalizer functions of all shared objects whose
364 initializer functions have completed. */
365 extern void _dl_fini (void) internal_function;
367 /* The dynamic linker calls this function before and having changing
368 any shared object mappings. The `r_state' member of `struct r_debug'
369 says what change is taking place. This function's address is
370 the value of the `r_brk' member. */
371 extern void _dl_debug_state (void);
373 /* Initialize `struct r_debug' if it has not already been done. The
374 argument is the run-time load address of the dynamic linker, to be put
375 in the `r_ldbase' member. Returns the address of the structure. */
376 extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase)
379 /* Initialize the basic data structure for the search paths. */
380 extern void _dl_init_paths (const char *library_path) internal_function;
382 /* Gather the information needed to install the profiling tables and start
384 extern void _dl_start_profile (struct link_map *map, const char *output_dir)
387 /* The actual functions used to keep book on the calls. */
388 extern void _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc);
390 /* This function is simply a wrapper around the _dl_mcount function
391 which does not require a FROMPC parameter since this is the
393 extern void _dl_mcount_wrapper (void *selfpc);
395 /* Show the members of the auxiliary array passed up from the kernel. */
396 extern void _dl_show_auxv (void) internal_function;
398 /* Return all environment variables starting with `LD_', one after the
400 extern char *_dl_next_ld_env_entry (char ***position) internal_function;
402 /* Return an array with the names of the important hardware capabilities. */
403 extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,
406 size_t *max_capstrlen)
411 #endif /* ldsodefs.h */