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
59 enum r_dir_status dirstatus;
61 size_t machdirnamelen;
62 enum r_dir_status machdirstatus;
64 /* Strings saying where the definition came from. */
68 /* This link is only used in the `all_dirs' member of `r_search_path'. */
69 struct r_search_path_elem *next;
73 /* A data structure for a simple single linked list of strings. */
76 const char *name; /* Name requested (before search). */
77 struct libname_list *next; /* Link to next name for this object. */
81 /* Test whether given NAME matches any of the names of the given object. */
83 __attribute__ ((unused))
84 _dl_name_match_p (const char *__name, struct link_map *__map)
86 int __found = strcmp (__name, __map->l_name) == 0;
87 struct libname_list *__runp = __map->l_libname;
89 while (! __found && __runp != NULL)
90 if (strcmp (__name, __runp->name) == 0)
93 __runp = __runp->next;
98 /* Function used as argument for `_dl_receive_error' function. The
99 arguments are the error code, error string, and the objname the
100 error occurred in. */
101 typedef void (*receiver_fct) (int, const char *, const char *);
103 /* Internal functions of the run-time dynamic linker.
104 These can be accessed if you link again the dynamic linker
105 as a shared library, as in `-lld' or `/lib/ld.so' explicitly;
106 but are not normally of interest to user programs.
108 The `-ldl' library functions in <dlfcn.h> provide a simple
109 user interface to run-time dynamic linking. */
112 /* Parameters passed to the dynamic linker. */
113 extern char **_dl_argv;
115 /* Cached value of `getpagesize ()'. */
116 extern size_t _dl_pagesize;
118 /* File descriptor referring to the zero-fill device. */
119 extern int _dl_zerofd;
121 /* Name of the shared object to be profiled (if any). */
122 extern const char *_dl_profile;
123 /* Map of shared object to be profiled. */
124 extern struct link_map *_dl_profile_map;
126 /* If nonzero the appropriate debug information is printed. */
127 extern int _dl_debug_libs;
128 extern int _dl_debug_impcalls;
129 extern int _dl_debug_bindings;
130 extern int _dl_debug_symbols;
131 extern int _dl_debug_versions;
132 extern int _dl_debug_reloc;
133 extern int _dl_debug_files;
135 /* Expect cache ID. */
136 extern int _dl_correct_cache_id;
138 /* File deccriptor to write debug messages to. */
139 extern int _dl_debug_fd;
141 /* OS-dependent function to open the zero-fill device. */
142 extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
144 /* OS-dependent function to write a message on the specified
145 descriptor FD. All arguments are `const char *'; args until a null
146 pointer are concatenated to form the message to print. */
147 extern void _dl_sysdep_output (int fd, const char *string, ...);
149 /* OS-dependent function to write a debug message on the specified
150 descriptor for this. All arguments are `const char *'; args until
151 a null pointer are concatenated to form the message to print. If
152 NEW_LINE is nonzero it is assumed that the message starts on a new
154 extern void _dl_debug_message (int new_line, const char *string, ...);
156 /* OS-dependent function to write a message on the standard output.
157 All arguments are `const char *'; args until a null pointer
158 are concatenated to form the message to print. */
159 #define _dl_sysdep_message(string, args...) \
160 _dl_sysdep_output (STDOUT_FILENO, string, ##args)
162 /* OS-dependent function to write a message on the standard error.
163 All arguments are `const char *'; args until a null pointer
164 are concatenated to form the message to print. */
165 #define _dl_sysdep_error(string, args...) \
166 _dl_sysdep_output (STDERR_FILENO, string, ##args)
168 /* OS-dependent function to give a fatal error message and exit
169 when the dynamic linker fails before the program is fully linked.
170 All arguments are `const char *'; args until a null pointer
171 are concatenated to form the message to print. */
172 #define _dl_sysdep_fatal(string, args...) \
175 _dl_sysdep_output (STDERR_FILENO, string, ##args); \
180 /* Nonzero if the program should be "secure" (i.e. it's setuid or somesuch).
181 This tells the dynamic linker to ignore environment variables. */
182 extern int _dl_secure;
184 /* This function is called by all the internal dynamic linker functions
185 when they encounter an error. ERRCODE is either an `errno' code or
186 zero; OBJECT is the name of the problematical shared object, or null if
187 it is a general problem; ERRSTRING is a string describing the specific
189 extern void _dl_signal_error (int errcode,
191 const char *errstring);
193 /* Call OPERATE, catching errors from `dl_signal_error'. If there is no
194 error, *ERRSTRING is set to null. If there is an error, *ERRSTRING is
195 set to a string constructed from the strings passed to _dl_signal_error,
196 and the error code passed is the return value. ERRSTRING if nonzero
197 points to a malloc'ed string which the caller has to free after use.
198 ARGS is passed as argument to OPERATE. */
199 extern int _dl_catch_error (char **errstring,
200 void (*operate) (void *),
203 /* Call OPERATE, receiving errors from `dl_signal_error'. Unlike
204 `_dl_catch_error' the operation is resumed after the OPERATE
206 ARGS is passed as argument to OPERATE. */
207 extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
211 /* Helper function for <dlfcn.h> functions. Runs the OPERATE function via
212 _dl_catch_error. Returns zero for success, nonzero for failure; and
213 arranges for `dlerror' to return the error details.
214 ARGS is passed as argument to OPERATE. */
215 extern int _dlerror_run (void (*operate) (void *), void *args);
218 /* Open the shared object NAME and map in its segments.
219 LOADER's DT_RPATH is used in searching for NAME.
220 If the object is already opened, returns its existing map.
221 For preloaded shared objects PRELOADED is set to a non-zero
222 value to allow additional security checks. */
223 extern struct link_map *_dl_map_object (struct link_map *loader,
224 const char *name, int preloaded,
225 int type, int trace_mode);
227 /* Call _dl_map_object on the dependencies of MAP, and set up
228 MAP->l_searchlist. PRELOADS points to a vector of NPRELOADS previously
229 loaded objects that will be inserted into MAP->l_searchlist after MAP
230 but before its dependencies. */
231 extern void _dl_map_object_deps (struct link_map *map,
232 struct link_map **preloads,
233 unsigned int npreloads, int trace_mode);
235 /* Cache the locations of MAP's hash table. */
236 extern void _dl_setup_hash (struct link_map *map);
239 /* Open the shared object NAME, relocate it, and run its initializer if it
240 hasn't already been run. MODE is as for `dlopen' (see <dlfcn.h>). If
241 the object is already opened, returns its existing map. */
242 extern struct link_map *_dl_open (const char *name, int mode);
244 /* Close an object previously opened by _dl_open. */
245 extern void _dl_close (struct link_map *map);
248 /* Search loaded objects' symbol tables for a definition of the symbol
249 referred to by UNDEF. *SYM is the symbol table entry containing the
250 reference; it is replaced with the defining symbol, and the base load
251 address of the defining object is returned. SYMBOL_SCOPE is a
252 null-terminated list of object scopes to search; each object's
253 l_searchlist (i.e. the segment of the dependency tree starting at that
254 object) is searched in turn. REFERENCE_NAME should name the object
255 containing the reference; it is used in error messages.
256 RELOC_TYPE is a machine-dependent reloc type, which is passed to
257 the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
258 symbols can be chosen. */
259 extern ElfW(Addr) _dl_lookup_symbol (const char *undef,
260 const ElfW(Sym) **sym,
261 struct link_map *symbol_scope[],
262 const char *reference_name,
265 /* Lookup versioned symbol. */
266 extern ElfW(Addr) _dl_lookup_versioned_symbol (const char *undef,
267 const ElfW(Sym) **sym,
268 struct link_map *symbol_scope[],
269 const char *reference_name,
270 const struct r_found_version *version,
273 /* For handling RTLD_NEXT we must be able to skip shared objects. */
274 extern ElfW(Addr) _dl_lookup_symbol_skip (const char *undef,
275 const ElfW(Sym) **sym,
276 struct link_map *symbol_scope[],
277 const char *reference_name,
278 struct link_map *skip_this);
280 /* For handling RTLD_NEXT with versioned symbols we must be able to
281 skip shared objects. */
282 extern ElfW(Addr) _dl_lookup_versioned_symbol_skip (const char *undef,
283 const ElfW(Sym) **sym,
284 struct link_map *symbol_scope[],
285 const char *reference_name,
286 const struct r_found_version *version,
287 struct link_map *skip_this);
289 /* Locate shared object containing the given address. */
290 extern int _dl_addr (const void *address, Dl_info *info);
292 /* Look up symbol NAME in MAP's scope and return its run-time address. */
293 extern ElfW(Addr) _dl_symbol_value (struct link_map *map, const char *name);
296 /* Structure describing the dynamic linker itself. */
297 extern struct link_map _dl_rtld_map;
299 /* The list of objects currently loaded is the third element of the
300 `_dl_default_scope' array, and the fourth element is always null.
301 This leaves two slots before it that are used when resolving
302 DT_SYMBOLIC objects' references one after it for normal references
304 #define _dl_loaded (_dl_default_scope[2])
305 extern struct link_map *_dl_default_scope[5];
307 /* Null-terminated list of objects in the dynamic `global scope'. The
308 list starts at [2]; i.e. &_dl_global_scope[2] is the argument
309 passed to _dl_lookup_symbol to search the global scope. To search
310 a specific object and its dependencies in preference to the global
311 scope, fill in the [1] slot and pass its address; for two specific
312 object scopes, fill [0] and [1]. The list is double-terminated; to
313 search the global scope and then a specific object and its
314 dependencies, set *_dl_global_scope_end. This variable initially
315 points to _dl_default_scope, and _dl_loaded is always kept in [2]
316 of this list. A new list is malloc'd when new objects are loaded
318 extern struct link_map **_dl_global_scope, **_dl_global_scope_end;
319 extern size_t _dl_global_scope_alloc; /* Number of slots malloc'd. */
321 /* Hack _dl_global_scope[0] and [1] as necessary, and return a pointer into
322 _dl_global_scope that should be passed to _dl_lookup_symbol for symbol
323 references made in the object MAP's relocations. */
324 extern struct link_map **_dl_object_relocation_scope (struct link_map *map);
327 /* Allocate a `struct link_map' for a new object being loaded,
328 and enter it into the _dl_loaded list. */
329 extern struct link_map *_dl_new_object (char *realname, const char *libname,
332 /* Relocate the given object (if it hasn't already been).
333 SCOPE is passed to _dl_lookup_symbol in symbol lookups.
334 If LAZY is nonzero, don't relocate its PLT. */
335 extern void _dl_relocate_object (struct link_map *map,
336 struct link_map *scope[],
339 /* Check the version dependencies of all objects available through
340 MAP. If VERBOSE print some more diagnostics. */
341 extern int _dl_check_all_versions (struct link_map *map, int verbose);
343 /* Check the version dependencies for MAP. If VERBOSE print some more
345 extern int _dl_check_map_versions (struct link_map *map, int verbose);
347 /* Return the address of the next initializer function for MAP or one of
348 its dependencies that has not yet been run. When there are no more
349 initializers to be run, this returns zero. The functions are returned
350 in the order they should be called. */
351 extern ElfW(Addr) _dl_init_next (struct link_map *map);
353 /* Call the finalizer functions of all shared objects whose
354 initializer functions have completed. */
355 extern void _dl_fini (void);
357 /* The dynamic linker calls this function before and having changing
358 any shared object mappings. The `r_state' member of `struct r_debug'
359 says what change is taking place. This function's address is
360 the value of the `r_brk' member. */
361 extern void _dl_debug_state (void);
363 /* Initialize `struct r_debug' if it has not already been done. The
364 argument is the run-time load address of the dynamic linker, to be put
365 in the `r_ldbase' member. Returns the address of the structure. */
366 extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase);
368 /* Initialize the basic data structure for the search paths. */
369 extern void _dl_init_paths (const char *library_path);
371 /* Gather the information needed to install the profiling tables and start
373 extern void _dl_start_profile (struct link_map *map, const char *output_dir);
375 /* The actual functions used to keep book on the calls. */
376 extern void _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc);
379 /* Show the members of the auxiliary array passed up from the kernel. */
380 extern void _dl_show_auxv (void);
382 /* Return all environment variables starting with `LD_', one after the
384 extern char *_dl_next_ld_env_entry (char ***position);
388 #endif /* ldsodefs.h */