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 /* OS-dependent function to open the zero-fill device. */
153 extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
155 /* OS-dependent function to write a message on the specified
156 descriptor FD. All arguments are `const char *'; args until a null
157 pointer are concatenated to form the message to print. */
158 extern void _dl_sysdep_output (int fd, const char *string, ...);
160 /* OS-dependent function to write a debug message on the specified
161 descriptor for this. All arguments are `const char *'; args until
162 a null pointer are concatenated to form the message to print. If
163 NEW_LINE is nonzero it is assumed that the message starts on a new
165 extern void _dl_debug_message (int new_line, const char *string, ...);
167 /* OS-dependent function to write a message on the standard output.
168 All arguments are `const char *'; args until a null pointer
169 are concatenated to form the message to print. */
170 #define _dl_sysdep_message(string, args...) \
171 _dl_sysdep_output (STDOUT_FILENO, string, ##args)
173 /* OS-dependent function to write a message on the standard error.
174 All arguments are `const char *'; args until a null pointer
175 are concatenated to form the message to print. */
176 #define _dl_sysdep_error(string, args...) \
177 _dl_sysdep_output (STDERR_FILENO, string, ##args)
179 /* OS-dependent function to give a fatal error message and exit
180 when the dynamic linker fails before the program is fully linked.
181 All arguments are `const char *'; args until a null pointer
182 are concatenated to form the message to print. */
183 #define _dl_sysdep_fatal(string, args...) \
186 _dl_sysdep_output (STDERR_FILENO, string, ##args); \
191 /* Nonzero if the program should be "secure" (i.e. it's setuid or somesuch).
192 This tells the dynamic linker to ignore environment variables. */
193 extern int _dl_secure;
195 /* This function is called by all the internal dynamic linker functions
196 when they encounter an error. ERRCODE is either an `errno' code or
197 zero; OBJECT is the name of the problematical shared object, or null if
198 it is a general problem; ERRSTRING is a string describing the specific
200 extern void _dl_signal_error (int errcode,
202 const char *errstring)
205 /* Call OPERATE, catching errors from `dl_signal_error'. If there is no
206 error, *ERRSTRING is set to null. If there is an error, *ERRSTRING is
207 set to a string constructed from the strings passed to _dl_signal_error,
208 and the error code passed is the return value. ERRSTRING if nonzero
209 points to a malloc'ed string which the caller has to free after use.
210 ARGS is passed as argument to OPERATE. */
211 extern int _dl_catch_error (char **errstring,
212 void (*operate) (void *),
216 /* Call OPERATE, receiving errors from `dl_signal_error'. Unlike
217 `_dl_catch_error' the operation is resumed after the OPERATE
219 ARGS is passed as argument to OPERATE. */
220 extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
225 /* Helper function for <dlfcn.h> functions. Runs the OPERATE function via
226 _dl_catch_error. Returns zero for success, nonzero for failure; and
227 arranges for `dlerror' to return the error details.
228 ARGS is passed as argument to OPERATE. */
229 extern int _dlerror_run (void (*operate) (void *), void *args)
233 /* Open the shared object NAME and map in its segments.
234 LOADER's DT_RPATH is used in searching for NAME.
235 If the object is already opened, returns its existing map.
236 For preloaded shared objects PRELOADED is set to a non-zero
237 value to allow additional security checks. */
238 extern struct link_map *_dl_map_object (struct link_map *loader,
239 const char *name, int preloaded,
240 int type, int trace_mode)
243 /* Call _dl_map_object on the dependencies of MAP, and set up
244 MAP->l_searchlist. PRELOADS points to a vector of NPRELOADS previously
245 loaded objects that will be inserted into MAP->l_searchlist after MAP
246 but before its dependencies. */
247 extern void _dl_map_object_deps (struct link_map *map,
248 struct link_map **preloads,
249 unsigned int npreloads, int trace_mode)
252 /* Cache the locations of MAP's hash table. */
253 extern void _dl_setup_hash (struct link_map *map) internal_function;
256 /* Open the shared object NAME, relocate it, and run its initializer if it
257 hasn't already been run. MODE is as for `dlopen' (see <dlfcn.h>). If
258 the object is already opened, returns its existing map. */
259 extern struct link_map *_dl_open (const char *name, int mode)
262 /* Close an object previously opened by _dl_open. */
263 extern void _dl_close (struct link_map *map)
267 /* Search loaded objects' symbol tables for a definition of the symbol
268 referred to by UNDEF. *SYM is the symbol table entry containing the
269 reference; it is replaced with the defining symbol, and the base load
270 address of the defining object is returned. SYMBOL_SCOPE is a
271 null-terminated list of object scopes to search; each object's
272 l_searchlist (i.e. the segment of the dependency tree starting at that
273 object) is searched in turn. REFERENCE_NAME should name the object
274 containing the reference; it is used in error messages.
275 RELOC_TYPE is a machine-dependent reloc type, which is passed to
276 the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
277 symbols can be chosen. */
278 extern ElfW(Addr) _dl_lookup_symbol (const char *undef,
279 const ElfW(Sym) **sym,
280 struct link_map *symbol_scope[],
281 const char *reference_name,
285 /* Lookup versioned symbol. */
286 extern ElfW(Addr) _dl_lookup_versioned_symbol (const char *undef,
287 const ElfW(Sym) **sym,
288 struct link_map *symbol_scope[],
289 const char *reference_name,
290 const struct r_found_version *version,
294 /* For handling RTLD_NEXT we must be able to skip shared objects. */
295 extern ElfW(Addr) _dl_lookup_symbol_skip (const char *undef,
296 const ElfW(Sym) **sym,
297 struct link_map *symbol_scope[],
298 const char *reference_name,
299 struct link_map *skip_this)
302 /* For handling RTLD_NEXT with versioned symbols we must be able to
303 skip shared objects. */
304 extern ElfW(Addr) _dl_lookup_versioned_symbol_skip (const char *undef,
305 const ElfW(Sym) **sym,
306 struct link_map *symbol_scope[],
307 const char *reference_name,
308 const struct r_found_version *version,
309 struct link_map *skip_this)
312 /* Locate shared object containing the given address. */
313 extern int _dl_addr (const void *address, Dl_info *info)
316 /* Look up symbol NAME in MAP's scope and return its run-time address. */
317 extern ElfW(Addr) _dl_symbol_value (struct link_map *map, const char *name)
321 /* Structure describing the dynamic linker itself. */
322 extern struct link_map _dl_rtld_map;
324 /* The list of objects currently loaded is the third element of the
325 `_dl_default_scope' array, and the fourth element is always null.
326 This leaves two slots before it that are used when resolving
327 DT_SYMBOLIC objects' references one after it for normal references
329 #define _dl_loaded (_dl_default_scope[2])
330 extern struct link_map *_dl_default_scope[5];
332 /* Null-terminated list of objects in the dynamic `global scope'. The
333 list starts at [2]; i.e. &_dl_global_scope[2] is the argument
334 passed to _dl_lookup_symbol to search the global scope. To search
335 a specific object and its dependencies in preference to the global
336 scope, fill in the [1] slot and pass its address; for two specific
337 object scopes, fill [0] and [1]. The list is double-terminated; to
338 search the global scope and then a specific object and its
339 dependencies, set *_dl_global_scope_end. This variable initially
340 points to _dl_default_scope, and _dl_loaded is always kept in [2]
341 of this list. A new list is malloc'd when new objects are loaded
343 extern struct link_map **_dl_global_scope, **_dl_global_scope_end;
344 extern size_t _dl_global_scope_alloc; /* Number of slots malloc'd. */
346 /* Hack _dl_global_scope[0] and [1] as necessary, and return a pointer into
347 _dl_global_scope that should be passed to _dl_lookup_symbol for symbol
348 references made in the object MAP's relocations. */
349 extern struct link_map **_dl_object_relocation_scope (struct link_map *map)
353 /* Allocate a `struct link_map' for a new object being loaded,
354 and enter it into the _dl_loaded list. */
355 extern struct link_map *_dl_new_object (char *realname, const char *libname,
356 int type) internal_function;
358 /* Relocate the given object (if it hasn't already been).
359 SCOPE is passed to _dl_lookup_symbol in symbol lookups.
360 If LAZY is nonzero, don't relocate its PLT. */
361 extern void _dl_relocate_object (struct link_map *map,
362 struct link_map *scope[],
363 int lazy) internal_function;
365 /* Check the version dependencies of all objects available through
366 MAP. If VERBOSE print some more diagnostics. */
367 extern int _dl_check_all_versions (struct link_map *map, int verbose)
370 /* Check the version dependencies for MAP. If VERBOSE print some more
372 extern int _dl_check_map_versions (struct link_map *map, int verbose)
375 /* Return the address of the next initializer function for MAP or one of
376 its dependencies that has not yet been run. When there are no more
377 initializers to be run, this returns zero. The functions are returned
378 in the order they should be called. */
379 extern ElfW(Addr) _dl_init_next (struct link_map *map) internal_function;
381 /* Call the finalizer functions of all shared objects whose
382 initializer functions have completed. */
383 extern void _dl_fini (void) internal_function;
385 /* The dynamic linker calls this function before and having changing
386 any shared object mappings. The `r_state' member of `struct r_debug'
387 says what change is taking place. This function's address is
388 the value of the `r_brk' member. */
389 extern void _dl_debug_state (void);
391 /* Initialize `struct r_debug' if it has not already been done. The
392 argument is the run-time load address of the dynamic linker, to be put
393 in the `r_ldbase' member. Returns the address of the structure. */
394 extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase)
397 /* Initialize the basic data structure for the search paths. */
398 extern void _dl_init_paths (const char *library_path) internal_function;
400 /* Gather the information needed to install the profiling tables and start
402 extern void _dl_start_profile (struct link_map *map, const char *output_dir)
405 /* The actual functions used to keep book on the calls. */
406 extern void _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc)
410 /* Show the members of the auxiliary array passed up from the kernel. */
411 extern void _dl_show_auxv (void) internal_function;
413 /* Return all environment variables starting with `LD_', one after the
415 extern char *_dl_next_ld_env_entry (char ***position) internal_function;
417 /* Return an array with the names of the important hardware capabilities. */
418 extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,
421 size_t *max_capstrlen)
426 #endif /* ldsodefs.h */