1 /* Run-time dynamic linker data structures for loaded ELF shared objects.
2 Copyright (C) 1995, 1996, 1997, 1998 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 /* For the version handling we need an array with only names and their
41 struct r_found_version
50 /* We want to cache information about the searches for shared objects. */
52 enum r_dir_status { unknown, nonexisting, existing };
54 struct r_search_path_elem
56 /* This link is only used in the `all_dirs' member of `r_search_path'. */
57 struct r_search_path_elem *next;
59 /* Strings saying where the definition came from. */
63 /* Basename for this search path element. The string must end with
68 enum r_dir_status status[0];
78 /* A data structure for a simple single linked list of strings. */
81 const char *name; /* Name requested (before search). */
82 struct libname_list *next; /* Link to next name for this object. */
86 /* Test whether given NAME matches any of the names of the given object. */
88 __attribute__ ((unused))
89 _dl_name_match_p (const char *__name, struct link_map *__map)
91 int __found = strcmp (__name, __map->l_name) == 0;
92 struct libname_list *__runp = __map->l_libname;
94 while (! __found && __runp != NULL)
95 if (strcmp (__name, __runp->name) == 0)
98 __runp = __runp->next;
103 /* Function used as argument for `_dl_receive_error' function. The
104 arguments are the error code, error string, and the objname the
105 error occurred in. */
106 typedef void (*receiver_fct) (int, const char *, const char *);
108 /* Internal functions of the run-time dynamic linker.
109 These can be accessed if you link again the dynamic linker
110 as a shared library, as in `-lld' or `/lib/ld.so' explicitly;
111 but are not normally of interest to user programs.
113 The `-ldl' library functions in <dlfcn.h> provide a simple
114 user interface to run-time dynamic linking. */
117 /* Parameters passed to the dynamic linker. */
118 extern char **_dl_argv;
120 /* Cached value of `getpagesize ()'. */
121 extern size_t _dl_pagesize;
123 /* File descriptor referring to the zero-fill device. */
124 extern int _dl_zerofd;
126 /* Name of the shared object to be profiled (if any). */
127 extern const char *_dl_profile;
128 /* Map of shared object to be profiled. */
129 extern struct link_map *_dl_profile_map;
131 /* If nonzero the appropriate debug information is printed. */
132 extern int _dl_debug_libs;
133 extern int _dl_debug_impcalls;
134 extern int _dl_debug_bindings;
135 extern int _dl_debug_symbols;
136 extern int _dl_debug_versions;
137 extern int _dl_debug_reloc;
138 extern int _dl_debug_files;
140 /* Expect cache ID. */
141 extern int _dl_correct_cache_id;
143 /* Mask for hardware capabilities that are available. */
144 extern unsigned long int _dl_hwcap;
146 /* Mask for important hardware capabilities we honour. */
147 extern unsigned long int _dl_hwcap_mask;
149 /* File deccriptor to write debug messages to. */
150 extern int _dl_debug_fd;
152 /* Names of shared object for which the RPATH should be ignored. */
153 extern const char *_dl_inhibit_rpath;
155 /* OS-dependent function to open the zero-fill device. */
156 extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
158 /* OS-dependent function to write a message on the specified
159 descriptor FD. All arguments are `const char *'; args until a null
160 pointer are concatenated to form the message to print. */
161 extern void _dl_sysdep_output (int fd, const char *string, ...);
163 /* OS-dependent function to write a debug message on the specified
164 descriptor for this. All arguments are `const char *'; args until
165 a null pointer are concatenated to form the message to print. If
166 NEW_LINE is nonzero it is assumed that the message starts on a new
168 extern void _dl_debug_message (int new_line, const char *string, ...);
170 /* OS-dependent function to write a message on the standard output.
171 All arguments are `const char *'; args until a null pointer
172 are concatenated to form the message to print. */
173 #define _dl_sysdep_message(string, args...) \
174 _dl_sysdep_output (STDOUT_FILENO, string, ##args)
176 /* OS-dependent function to write a message on the standard error.
177 All arguments are `const char *'; args until a null pointer
178 are concatenated to form the message to print. */
179 #define _dl_sysdep_error(string, args...) \
180 _dl_sysdep_output (STDERR_FILENO, string, ##args)
182 /* OS-dependent function to give a fatal error message and exit
183 when the dynamic linker fails before the program is fully linked.
184 All arguments are `const char *'; args until a null pointer
185 are concatenated to form the message to print. */
186 #define _dl_sysdep_fatal(string, args...) \
189 _dl_sysdep_output (STDERR_FILENO, string, ##args); \
194 /* Nonzero if the program should be "secure" (i.e. it's setuid or somesuch).
195 This tells the dynamic linker to ignore environment variables. */
196 extern int _dl_secure;
198 /* This function is called by all the internal dynamic linker functions
199 when they encounter an error. ERRCODE is either an `errno' code or
200 zero; OBJECT is the name of the problematical shared object, or null if
201 it is a general problem; ERRSTRING is a string describing the specific
203 extern void _dl_signal_error (int errcode,
205 const char *errstring)
208 /* Call OPERATE, catching errors from `dl_signal_error'. If there is no
209 error, *ERRSTRING is set to null. If there is an error, *ERRSTRING is
210 set to a string constructed from the strings passed to _dl_signal_error,
211 and the error code passed is the return value. ERRSTRING if nonzero
212 points to a malloc'ed string which the caller has to free after use.
213 ARGS is passed as argument to OPERATE. */
214 extern int _dl_catch_error (char **errstring,
215 void (*operate) (void *),
219 /* Call OPERATE, receiving errors from `dl_signal_error'. Unlike
220 `_dl_catch_error' the operation is resumed after the OPERATE
222 ARGS is passed as argument to OPERATE. */
223 extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
228 /* Helper function for <dlfcn.h> functions. Runs the OPERATE function via
229 _dl_catch_error. Returns zero for success, nonzero for failure; and
230 arranges for `dlerror' to return the error details.
231 ARGS is passed as argument to OPERATE. */
232 extern int _dlerror_run (void (*operate) (void *), void *args)
236 /* Open the shared object NAME and map in its segments.
237 LOADER's DT_RPATH is used in searching for NAME.
238 If the object is already opened, returns its existing map.
239 For preloaded shared objects PRELOADED is set to a non-zero
240 value to allow additional security checks. */
241 extern struct link_map *_dl_map_object (struct link_map *loader,
242 const char *name, int preloaded,
243 int type, int trace_mode)
246 /* Call _dl_map_object on the dependencies of MAP, and set up
247 MAP->l_searchlist. PRELOADS points to a vector of NPRELOADS previously
248 loaded objects that will be inserted into MAP->l_searchlist after MAP
249 but before its dependencies. */
250 extern void _dl_map_object_deps (struct link_map *map,
251 struct link_map **preloads,
252 unsigned int npreloads, int trace_mode)
255 /* Cache the locations of MAP's hash table. */
256 extern void _dl_setup_hash (struct link_map *map) internal_function;
259 /* Open the shared object NAME, relocate it, and run its initializer if it
260 hasn't already been run. MODE is as for `dlopen' (see <dlfcn.h>). If
261 the object is already opened, returns its existing map. */
262 extern struct link_map *_dl_open (const char *name, int mode)
265 /* Close an object previously opened by _dl_open. */
266 extern void _dl_close (struct link_map *map)
270 /* Search loaded objects' symbol tables for a definition of the symbol
271 referred to by UNDEF. *SYM is the symbol table entry containing the
272 reference; it is replaced with the defining symbol, and the base load
273 address of the defining object is returned. SYMBOL_SCOPE is a
274 null-terminated list of object scopes to search; each object's
275 l_searchlist (i.e. the segment of the dependency tree starting at that
276 object) is searched in turn. REFERENCE_NAME should name the object
277 containing the reference; it is used in error messages.
278 RELOC_TYPE is a machine-dependent reloc type, which is passed to
279 the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
280 symbols can be chosen. */
281 extern ElfW(Addr) _dl_lookup_symbol (const char *undef,
282 const ElfW(Sym) **sym,
283 struct link_map *symbol_scope[],
284 const char *reference_name,
288 /* Lookup versioned symbol. */
289 extern ElfW(Addr) _dl_lookup_versioned_symbol (const char *undef,
290 const ElfW(Sym) **sym,
291 struct link_map *symbol_scope[],
292 const char *reference_name,
293 const struct r_found_version *version,
297 /* For handling RTLD_NEXT we must be able to skip shared objects. */
298 extern ElfW(Addr) _dl_lookup_symbol_skip (const char *undef,
299 const ElfW(Sym) **sym,
300 struct link_map *symbol_scope[],
301 const char *reference_name,
302 struct link_map *skip_this)
305 /* For handling RTLD_NEXT with versioned symbols we must be able to
306 skip shared objects. */
307 extern ElfW(Addr) _dl_lookup_versioned_symbol_skip (const char *undef,
308 const ElfW(Sym) **sym,
309 struct link_map *symbol_scope[],
310 const char *reference_name,
311 const struct r_found_version *version,
312 struct link_map *skip_this)
315 /* Locate shared object containing the given address. */
316 extern int _dl_addr (const void *address, Dl_info *info)
319 /* Look up symbol NAME in MAP's scope and return its run-time address. */
320 extern ElfW(Addr) _dl_symbol_value (struct link_map *map, const char *name)
324 /* Structure describing the dynamic linker itself. */
325 extern struct link_map _dl_rtld_map;
327 /* The list of objects currently loaded is the third element of the
328 `_dl_default_scope' array, and the fourth element is always null.
329 This leaves two slots before it that are used when resolving
330 DT_SYMBOLIC objects' references one after it for normal references
332 #define _dl_loaded (_dl_default_scope[2])
333 extern struct link_map *_dl_default_scope[5];
335 /* Null-terminated list of objects in the dynamic `global scope'. The
336 list starts at [2]; i.e. &_dl_global_scope[2] is the argument
337 passed to _dl_lookup_symbol to search the global scope. To search
338 a specific object and its dependencies in preference to the global
339 scope, fill in the [1] slot and pass its address; for two specific
340 object scopes, fill [0] and [1]. The list is double-terminated; to
341 search the global scope and then a specific object and its
342 dependencies, set *_dl_global_scope_end. This variable initially
343 points to _dl_default_scope, and _dl_loaded is always kept in [2]
344 of this list. A new list is malloc'd when new objects are loaded
346 extern struct link_map **_dl_global_scope, **_dl_global_scope_end;
347 extern size_t _dl_global_scope_alloc; /* Number of slots malloc'd. */
349 /* Hack _dl_global_scope[0] and [1] as necessary, and return a pointer into
350 _dl_global_scope that should be passed to _dl_lookup_symbol for symbol
351 references made in the object MAP's relocations. */
352 extern struct link_map **_dl_object_relocation_scope (struct link_map *map)
356 /* Allocate a `struct link_map' for a new object being loaded,
357 and enter it into the _dl_loaded list. */
358 extern struct link_map *_dl_new_object (char *realname, const char *libname,
359 int type) internal_function;
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 link_map *scope[],
366 int lazy, int consider_profiling)
369 /* Check the version dependencies of all objects available through
370 MAP. If VERBOSE print some more diagnostics. */
371 extern int _dl_check_all_versions (struct link_map *map, int verbose)
374 /* Check the version dependencies for MAP. If VERBOSE print some more
376 extern int _dl_check_map_versions (struct link_map *map, int verbose)
379 /* Return the address of the next initializer function for MAP or one of
380 its dependencies that has not yet been run. When there are no more
381 initializers to be run, this returns zero. The functions are returned
382 in the order they should be called. */
383 extern ElfW(Addr) _dl_init_next (struct link_map *map) internal_function;
385 /* Call the finalizer functions of all shared objects whose
386 initializer functions have completed. */
387 extern void _dl_fini (void) internal_function;
389 /* The dynamic linker calls this function before and having changing
390 any shared object mappings. The `r_state' member of `struct r_debug'
391 says what change is taking place. This function's address is
392 the value of the `r_brk' member. */
393 extern void _dl_debug_state (void);
395 /* Initialize `struct r_debug' if it has not already been done. The
396 argument is the run-time load address of the dynamic linker, to be put
397 in the `r_ldbase' member. Returns the address of the structure. */
398 extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase)
401 /* Initialize the basic data structure for the search paths. */
402 extern void _dl_init_paths (const char *library_path) internal_function;
404 /* Gather the information needed to install the profiling tables and start
406 extern void _dl_start_profile (struct link_map *map, const char *output_dir)
409 /* The actual functions used to keep book on the calls. */
410 extern void _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc);
413 /* Show the members of the auxiliary array passed up from the kernel. */
414 extern void _dl_show_auxv (void) internal_function;
416 /* Return all environment variables starting with `LD_', one after the
418 extern char *_dl_next_ld_env_entry (char ***position) internal_function;
420 /* Return an array with the names of the important hardware capabilities. */
421 extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,
424 size_t *max_capstrlen)
429 #endif /* ldsodefs.h */