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. */
33 #include <dl-lookupcfg.h>
37 /* We use this macro to refer to ELF types independent of the native wordsize.
38 `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */
39 #define ELFW(type) _ElfW (ELF, __ELF_NATIVE_CLASS, type)
41 /* All references to the value of l_info[DT_PLTGOT],
42 l_info[DT_STRTAB], l_info[DT_SYMTAB], l_info[DT_RELA],
43 l_info[DT_REL], l_info[DT_JMPREL], and l_info[VERSYMIDX (DT_VERSYM)]
44 have to be accessed via the D_PTR macro. The macro is needed since for
45 most architectures the entry is already relocated - but for some not
46 and we need to relocate at access time. */
47 #ifdef DL_RO_DYN_SECTION
48 # define D_PTR(map,i) (map->i->d_un.d_ptr + map->l_addr)
50 # define D_PTR(map,i) map->i->d_un.d_ptr
53 /* On some platforms more information than just the address of the symbol
54 is needed from the lookup functions. In this case we return the whole
56 #ifdef DL_LOOKUP_RETURNS_MAP
57 typedef struct link_map *lookup_t;
58 # define LOOKUP_VALUE(map) map
59 # define LOOKUP_VALUE_ADDRESS(map) (map ? map->l_addr : 0)
61 typedef ElfW(Addr) lookup_t;
62 # define LOOKUP_VALUE(map) map->l_addr
63 # define LOOKUP_VALUE_ADDRESS(address) address
66 /* on some architectures a pointer to a function is not just a pointer
67 to the actual code of the function but rather an architecture
68 specific descriptor. */
69 #ifndef ELF_FUNCTION_PTR_IS_SPECIAL
70 #define DL_SYMBOL_ADDRESS(map, ref) \
71 (void *) (LOOKUP_VALUE_ADDRESS (map) + ref->st_value)
74 /* For the version handling we need an array with only names and their
76 struct r_found_version
85 /* We want to cache information about the searches for shared objects. */
87 enum r_dir_status { unknown, nonexisting, existing };
89 struct r_search_path_elem
91 /* This link is only used in the `all_dirs' member of `r_search_path'. */
92 struct r_search_path_elem *next;
94 /* Strings saying where the definition came from. */
98 /* Basename for this search path element. The string must end with
103 enum r_dir_status status[0];
113 /* A data structure for a simple single linked list of strings. */
116 const char *name; /* Name requested (before search). */
117 struct libname_list *next; /* Link to next name for this object. */
121 /* Test whether given NAME matches any of the names of the given object. */
123 __attribute__ ((unused))
124 _dl_name_match_p (const char *__name, struct link_map *__map)
126 int __found = strcmp (__name, __map->l_name) == 0;
127 struct libname_list *__runp = __map->l_libname;
129 while (! __found && __runp != NULL)
130 if (strcmp (__name, __runp->name) == 0)
133 __runp = __runp->next;
138 /* Function used as argument for `_dl_receive_error' function. The
139 arguments are the error code, error string, and the objname the
140 error occurred in. */
141 typedef void (*receiver_fct) (int, const char *, const char *);
143 /* Internal functions of the run-time dynamic linker.
144 These can be accessed if you link again the dynamic linker
145 as a shared library, as in `-lld' or `/lib/ld.so' explicitly;
146 but are not normally of interest to user programs.
148 The `-ldl' library functions in <dlfcn.h> provide a simple
149 user interface to run-time dynamic linking. */
152 /* Parameters passed to the dynamic linker. */
153 extern char **_dl_argv;
155 /* Cached value of `getpagesize ()'. */
156 extern size_t _dl_pagesize;
158 /* File descriptor referring to the zero-fill device. */
159 extern int _dl_zerofd;
161 /* Name of the shared object to be profiled (if any). */
162 extern const char *_dl_profile;
163 /* Map of shared object to be profiled. */
164 extern struct link_map *_dl_profile_map;
165 /* Filename of the output file. */
166 extern const char *_dl_profile_output;
168 /* If nonzero the appropriate debug information is printed. */
169 extern int _dl_debug_libs;
170 extern int _dl_debug_impcalls;
171 extern int _dl_debug_bindings;
172 extern int _dl_debug_symbols;
173 extern int _dl_debug_versions;
174 extern int _dl_debug_reloc;
175 extern int _dl_debug_files;
177 /* Expect cache ID. */
178 extern int _dl_correct_cache_id;
180 /* Mask for hardware capabilities that are available. */
181 extern unsigned long int _dl_hwcap;
183 /* Mask for important hardware capabilities we honour. */
184 extern unsigned long int _dl_hwcap_mask;
186 /* File descriptor to write debug messages to. */
187 extern int _dl_debug_fd;
189 /* Names of shared object for which the RPATH should be ignored. */
190 extern const char *_dl_inhibit_rpath;
192 /* Nonzero if references should be treated as weak during runtime linking. */
193 extern int _dl_dynamic_weak;
195 /* The array with message we print as a last resort. */
196 extern const char _dl_out_of_memory[];
198 /* OS-dependent function to open the zero-fill device. */
199 extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
201 /* OS-dependent function to write a message on the specified
202 descriptor FD. All arguments are `const char *'; args until a null
203 pointer are concatenated to form the message to print. */
204 extern void _dl_sysdep_output (int fd, const char *string, ...);
206 /* OS-dependent function to write a debug message on the specified
207 descriptor for this. All arguments are `const char *'; args until
208 a null pointer are concatenated to form the message to print. If
209 NEW_LINE is nonzero it is assumed that the message starts on a new
211 extern void _dl_debug_message (int new_line, const char *string, ...);
213 /* OS-dependent function to write a message on the standard output.
214 All arguments are `const char *'; args until a null pointer
215 are concatenated to form the message to print. */
216 #define _dl_sysdep_message(string, args...) \
217 _dl_sysdep_output (STDOUT_FILENO, string, ##args)
219 /* OS-dependent function to write a message on the standard error.
220 All arguments are `const char *'; args until a null pointer
221 are concatenated to form the message to print. */
222 #define _dl_sysdep_error(string, args...) \
223 _dl_sysdep_output (STDERR_FILENO, string, ##args)
225 /* OS-dependent function to give a fatal error message and exit
226 when the dynamic linker fails before the program is fully linked.
227 All arguments are `const char *'; args until a null pointer
228 are concatenated to form the message to print. */
229 #define _dl_sysdep_fatal(string, args...) \
232 _dl_sysdep_output (STDERR_FILENO, string, ##args); \
237 /* Nonzero if the program should be "secure" (i.e. it's setuid or somesuch).
238 This tells the dynamic linker to ignore environment variables. */
239 extern int _dl_secure;
241 /* This function is called by all the internal dynamic linker functions
242 when they encounter an error. ERRCODE is either an `errno' code or
243 zero; OBJECT is the name of the problematical shared object, or null if
244 it is a general problem; ERRSTRING is a string describing the specific
246 extern void _dl_signal_error (int errcode, const char *object,
247 const char *errstring)
249 __attribute__ ((__noreturn__));
251 /* Like _dl_signal_error, but may return when called in the context of
252 _dl_receive_error. */
253 extern void _dl_signal_cerror (int errcode,
255 const char *errstring)
258 /* Call OPERATE, receiving errors from `dl_signal_cerror'. Unlike
259 `_dl_catch_error' the operation is resumed after the OPERATE
261 ARGS is passed as argument to OPERATE. */
262 extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
267 /* Open the shared object NAME and map in its segments.
268 LOADER's DT_RPATH is used in searching for NAME.
269 If the object is already opened, returns its existing map.
270 For preloaded shared objects PRELOADED is set to a non-zero
271 value to allow additional security checks. */
272 extern struct link_map *_dl_map_object (struct link_map *loader,
273 const char *name, int preloaded,
274 int type, int trace_mode, int mode)
277 /* Call _dl_map_object on the dependencies of MAP, and set up
278 MAP->l_searchlist. PRELOADS points to a vector of NPRELOADS previously
279 loaded objects that will be inserted into MAP->l_searchlist after MAP
280 but before its dependencies. */
281 extern void _dl_map_object_deps (struct link_map *map,
282 struct link_map **preloads,
283 unsigned int npreloads, int trace_mode)
286 /* Cache the locations of MAP's hash table. */
287 extern void _dl_setup_hash (struct link_map *map) internal_function;
290 /* Search loaded objects' symbol tables for a definition of the symbol
291 referred to by UNDEF. *SYM is the symbol table entry containing the
292 reference; it is replaced with the defining symbol, and the base load
293 address of the defining object is returned. SYMBOL_SCOPE is a
294 null-terminated list of object scopes to search; each object's
295 l_searchlist (i.e. the segment of the dependency tree starting at that
296 object) is searched in turn. REFERENCE_NAME should name the object
297 containing the reference; it is used in error messages.
298 RELOC_TYPE is a machine-dependent reloc type, which is passed to
299 the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
300 symbols can be chosen. */
301 extern lookup_t _dl_lookup_symbol (const char *undef,
302 struct link_map *undef_map,
303 const ElfW(Sym) **sym,
304 struct r_scope_elem *symbol_scope[],
308 /* Lookup versioned symbol. */
309 extern lookup_t _dl_lookup_versioned_symbol (const char *undef,
310 struct link_map *undef_map,
311 const ElfW(Sym) **sym,
312 struct r_scope_elem *symbol_scope[],
313 const struct r_found_version *version,
317 /* For handling RTLD_NEXT we must be able to skip shared objects. */
318 extern lookup_t _dl_lookup_symbol_skip (const char *undef,
319 struct link_map *undef_map,
320 const ElfW(Sym) **sym,
321 struct r_scope_elem *symbol_scope[],
322 struct link_map *skip_this)
325 /* For handling RTLD_NEXT with versioned symbols we must be able to
326 skip shared objects. */
327 extern lookup_t _dl_lookup_versioned_symbol_skip (const char *undef,
328 struct link_map *undef_map,
329 const ElfW(Sym) **sym,
330 struct r_scope_elem *symbol_scope[],
331 const struct r_found_version *version,
332 struct link_map *skip_this)
335 /* Look up symbol NAME in MAP's scope and return its run-time address. */
336 extern ElfW(Addr) _dl_symbol_value (struct link_map *map, const char *name)
340 /* Structure describing the dynamic linker itself. */
341 extern struct link_map _dl_rtld_map;
342 /* And a pointer to the map for the main map. */
343 extern struct link_map *_dl_loaded;
344 /* Array representing global scope. */
345 extern struct r_scope_elem *_dl_global_scope[2];
346 /* Direct pointer to the searchlist of the main object. */
347 extern struct r_scope_elem *_dl_main_searchlist;
348 /* Copy of the content of `_dl_main_searchlist'. */
349 extern struct r_scope_elem _dl_initial_searchlist;
350 /* This is zero at program start to signal that the global scope map is
351 allocated by rtld. Later it keeps the size of the map. It might be
352 reset if in _dl_close if the last global object is removed. */
353 extern size_t _dl_global_scope_alloc;
355 /* Allocate a `struct link_map' for a new object being loaded,
356 and enter it into the _dl_main_map list. */
357 extern struct link_map *_dl_new_object (char *realname, const char *libname,
358 int type, struct link_map *loader)
361 /* Relocate the given object (if it hasn't already been).
362 SCOPE is passed to _dl_lookup_symbol in symbol lookups.
363 If LAZY is nonzero, don't relocate its PLT. */
364 extern void _dl_relocate_object (struct link_map *map,
365 struct r_scope_elem *scope[],
366 int lazy, int consider_profiling);
368 /* Call _dl_signal_error with a message about an unhandled reloc type.
369 TYPE is the result of ELFW(R_TYPE) (r_info), i.e. an R_<CPU>_* value.
370 PLT is nonzero if this was a PLT reloc; it just affects the message. */
371 extern void _dl_reloc_bad_type (struct link_map *map,
372 uint_fast8_t type, int plt)
375 /* Check the version dependencies of all objects available through
376 MAP. If VERBOSE print some more diagnostics. */
377 extern int _dl_check_all_versions (struct link_map *map, int verbose,
381 /* Check the version dependencies for MAP. If VERBOSE print some more
383 extern int _dl_check_map_versions (struct link_map *map, int verbose,
387 /* Initialize the object in SCOPE by calling the constructors with
388 ARGC, ARGV, and ENV as the parameters. */
389 extern void _dl_init (struct link_map *main_map, int argc, char **argv,
390 char **env) internal_function;
392 /* Call the finalizer functions of all shared objects whose
393 initializer functions have completed. */
394 extern void _dl_fini (void) internal_function;
396 /* The dynamic linker calls this function before and having changing
397 any shared object mappings. The `r_state' member of `struct r_debug'
398 says what change is taking place. This function's address is
399 the value of the `r_brk' member. */
400 extern void _dl_debug_state (void);
402 /* Initialize `struct r_debug' if it has not already been done. The
403 argument is the run-time load address of the dynamic linker, to be put
404 in the `r_ldbase' member. Returns the address of the structure. */
405 extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase)
408 /* Initialize the basic data structure for the search paths. */
409 extern void _dl_init_paths (const char *library_path) internal_function;
411 /* Gather the information needed to install the profiling tables and start
413 extern void _dl_start_profile (struct link_map *map, const char *output_dir)
416 /* The actual functions used to keep book on the calls. */
417 extern void _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc);
419 /* This function is simply a wrapper around the _dl_mcount function
420 which does not require a FROMPC parameter since this is the
422 extern void _dl_mcount_wrapper (void *selfpc);
424 /* Show the members of the auxiliary array passed up from the kernel. */
425 extern void _dl_show_auxv (void) internal_function;
427 /* Return all environment variables starting with `LD_', one after the
429 extern char *_dl_next_ld_env_entry (char ***position) internal_function;
431 /* Return an array with the names of the important hardware capabilities. */
432 extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,
435 size_t *max_capstrlen)
440 #endif /* ldsodefs.h */