1 /* Run-time dynamic linker data structures for loaded ELF shared objects.
2 Copyright (C) 1995, 1996, 1997, 1998, 1999 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
;
130 /* Filename of the output file. */
131 extern const char *_dl_profile_output
;
133 /* If nonzero the appropriate debug information is printed. */
134 extern int _dl_debug_libs
;
135 extern int _dl_debug_impcalls
;
136 extern int _dl_debug_bindings
;
137 extern int _dl_debug_symbols
;
138 extern int _dl_debug_versions
;
139 extern int _dl_debug_reloc
;
140 extern int _dl_debug_files
;
142 /* Expect cache ID. */
143 extern int _dl_correct_cache_id
;
145 /* Mask for hardware capabilities that are available. */
146 extern unsigned long int _dl_hwcap
;
148 /* Mask for important hardware capabilities we honour. */
149 extern unsigned long int _dl_hwcap_mask
;
151 /* File descriptor to write debug messages to. */
152 extern int _dl_debug_fd
;
154 /* Names of shared object for which the RPATH should be ignored. */
155 extern const char *_dl_inhibit_rpath
;
157 /* OS-dependent function to open the zero-fill device. */
158 extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
160 /* OS-dependent function to write a message on the specified
161 descriptor FD. All arguments are `const char *'; args until a null
162 pointer are concatenated to form the message to print. */
163 extern void _dl_sysdep_output (int fd
, const char *string
, ...);
165 /* OS-dependent function to write a debug message on the specified
166 descriptor for this. All arguments are `const char *'; args until
167 a null pointer are concatenated to form the message to print. If
168 NEW_LINE is nonzero it is assumed that the message starts on a new
170 extern void _dl_debug_message (int new_line
, const char *string
, ...);
172 /* OS-dependent function to write a message on the standard output.
173 All arguments are `const char *'; args until a null pointer
174 are concatenated to form the message to print. */
175 #define _dl_sysdep_message(string, args...) \
176 _dl_sysdep_output (STDOUT_FILENO, string, ##args)
178 /* OS-dependent function to write a message on the standard error.
179 All arguments are `const char *'; args until a null pointer
180 are concatenated to form the message to print. */
181 #define _dl_sysdep_error(string, args...) \
182 _dl_sysdep_output (STDERR_FILENO, string, ##args)
184 /* OS-dependent function to give a fatal error message and exit
185 when the dynamic linker fails before the program is fully linked.
186 All arguments are `const char *'; args until a null pointer
187 are concatenated to form the message to print. */
188 #define _dl_sysdep_fatal(string, args...) \
191 _dl_sysdep_output (STDERR_FILENO, string, ##args); \
196 /* Nonzero if the program should be "secure" (i.e. it's setuid or somesuch).
197 This tells the dynamic linker to ignore environment variables. */
198 extern int _dl_secure
;
200 /* This function is called by all the internal dynamic linker functions
201 when they encounter an error. ERRCODE is either an `errno' code or
202 zero; OBJECT is the name of the problematical shared object, or null if
203 it is a general problem; ERRSTRING is a string describing the specific
205 extern void _dl_signal_error (int errcode
,
207 const char *errstring
)
209 __attribute__ ((__noreturn__
));
211 /* Like _dl_signal_error, but may return when called in the context of
212 _dl_receive_error. */
213 extern void _dl_signal_cerror (int errcode
,
215 const char *errstring
)
218 /* Call OPERATE, catching errors from `dl_signal_error'. If there is no
219 error, *ERRSTRING is set to null. If there is an error, *ERRSTRING is
220 set to a string constructed from the strings passed to _dl_signal_error,
221 and the error code passed is the return value. ERRSTRING if nonzero
222 points to a malloc'ed string which the caller has to free after use.
223 ARGS is passed as argument to OPERATE. */
224 extern int _dl_catch_error (char **errstring
,
225 void (*operate
) (void *),
229 /* Call OPERATE, receiving errors from `dl_signal_cerror'. Unlike
230 `_dl_catch_error' the operation is resumed after the OPERATE
232 ARGS is passed as argument to OPERATE. */
233 extern void _dl_receive_error (receiver_fct fct
, void (*operate
) (void *),
238 /* Helper function for <dlfcn.h> functions. Runs the OPERATE function via
239 _dl_catch_error. Returns zero for success, nonzero for failure; and
240 arranges for `dlerror' to return the error details.
241 ARGS is passed as argument to OPERATE. */
242 extern int _dlerror_run (void (*operate
) (void *), void *args
)
246 /* Open the shared object NAME and map in its segments.
247 LOADER's DT_RPATH is used in searching for NAME.
248 If the object is already opened, returns its existing map.
249 For preloaded shared objects PRELOADED is set to a non-zero
250 value to allow additional security checks. */
251 extern struct link_map
*_dl_map_object (struct link_map
*loader
,
252 const char *name
, int preloaded
,
253 int type
, int trace_mode
)
256 /* Call _dl_map_object on the dependencies of MAP, and set up
257 MAP->l_searchlist. PRELOADS points to a vector of NPRELOADS previously
258 loaded objects that will be inserted into MAP->l_searchlist after MAP
259 but before its dependencies. */
260 extern unsigned int _dl_map_object_deps (struct link_map
*map
,
261 struct link_map
**preloads
,
262 unsigned int npreloads
,
263 int trace_mode
, int global_scope
)
266 /* Cache the locations of MAP's hash table. */
267 extern void _dl_setup_hash (struct link_map
*map
) internal_function
;
270 /* Open the shared object NAME, relocate it, and run its initializer if it
271 hasn't already been run. MODE is as for `dlopen' (see <dlfcn.h>). If
272 the object is already opened, returns its existing map. */
273 extern struct link_map
*_dl_open (const char *name
, int mode
)
276 /* Close an object previously opened by _dl_open. */
277 extern void _dl_close (struct link_map
*map
)
281 /* Search loaded objects' symbol tables for a definition of the symbol
282 referred to by UNDEF. *SYM is the symbol table entry containing the
283 reference; it is replaced with the defining symbol, and the base load
284 address of the defining object is returned. SYMBOL_SCOPE is a
285 null-terminated list of object scopes to search; each object's
286 l_searchlist (i.e. the segment of the dependency tree starting at that
287 object) is searched in turn. REFERENCE_NAME should name the object
288 containing the reference; it is used in error messages.
289 RELOC_TYPE is a machine-dependent reloc type, which is passed to
290 the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
291 symbols can be chosen. */
292 extern ElfW(Addr
) _dl_lookup_symbol (const char *undef
,
293 const ElfW(Sym
) **sym
,
294 struct r_scope_elem
*symbol_scope
[],
295 const char *reference_name
,
299 /* Lookup versioned symbol. */
300 extern ElfW(Addr
) _dl_lookup_versioned_symbol (const char *undef
,
301 const ElfW(Sym
) **sym
,
302 struct r_scope_elem
*symbol_scope
[],
303 const char *reference_name
,
304 const struct r_found_version
*version
,
308 /* For handling RTLD_NEXT we must be able to skip shared objects. */
309 extern ElfW(Addr
) _dl_lookup_symbol_skip (const char *undef
,
310 const ElfW(Sym
) **sym
,
311 struct r_scope_elem
*symbol_scope
[],
312 const char *reference_name
,
313 struct link_map
*skip_this
)
316 /* For handling RTLD_NEXT with versioned symbols we must be able to
317 skip shared objects. */
318 extern ElfW(Addr
) _dl_lookup_versioned_symbol_skip (const char *undef
,
319 const ElfW(Sym
) **sym
,
320 struct r_scope_elem
*symbol_scope
[],
321 const char *reference_name
,
322 const struct r_found_version
*version
,
323 struct link_map
*skip_this
)
326 /* Locate shared object containing the given address. */
327 extern int _dl_addr (const void *address
, Dl_info
*info
)
330 /* Look up symbol NAME in MAP's scope and return its run-time address. */
331 extern ElfW(Addr
) _dl_symbol_value (struct link_map
*map
, const char *name
)
335 /* Structure describing the dynamic linker itself. */
336 extern struct link_map _dl_rtld_map
;
337 /* And a pointer to the map for the main map. */
338 extern struct link_map
*_dl_loaded
;
339 /* Array representing global scope. */
340 extern struct r_scope_elem
*_dl_global_scope
[2];
341 /* Direct pointer to the searchlist of the main object. */
342 extern struct r_scope_elem
*_dl_main_searchlist
;
343 /* Copy of the content of `_dl_main_searchlist'. */
344 extern struct r_scope_elem _dl_initial_searchlist
;
345 /* This is zero at program start to signal that the global scope map is
346 allocated by rtld. Later it keeps the size of the map. It might be
347 reset if in _dl_close if the last global object is removed. */
348 extern size_t _dl_global_scope_alloc
;
350 /* Allocate a `struct link_map' for a new object being loaded,
351 and enter it into the _dl_main_map list. */
352 extern struct link_map
*_dl_new_object (char *realname
, const char *libname
,
353 int type
, struct link_map
*loader
)
356 /* Relocate the given object (if it hasn't already been).
357 SCOPE is passed to _dl_lookup_symbol in symbol lookups.
358 If LAZY is nonzero, don't relocate its PLT. */
359 extern void _dl_relocate_object (struct link_map
*map
,
360 struct r_scope_elem
*scope
[],
361 int lazy
, int consider_profiling
);
363 /* Check the version dependencies of all objects available through
364 MAP. If VERBOSE print some more diagnostics. */
365 extern int _dl_check_all_versions (struct link_map
*map
, int verbose
)
368 /* Check the version dependencies for MAP. If VERBOSE print some more
370 extern int _dl_check_map_versions (struct link_map
*map
, int verbose
)
373 /* Return the address of the next initializer function for SCOPE or one of
374 its dependencies that has not yet been run. When there are no more
375 initializers to be run, this returns zero. The functions are returned
376 in the order they should be called. */
377 extern ElfW(Addr
) _dl_init_next (struct r_scope_elem
*scope
) internal_function
;
379 /* Call the finalizer functions of all shared objects whose
380 initializer functions have completed. */
381 extern void _dl_fini (void) internal_function
;
383 /* The dynamic linker calls this function before and having changing
384 any shared object mappings. The `r_state' member of `struct r_debug'
385 says what change is taking place. This function's address is
386 the value of the `r_brk' member. */
387 extern void _dl_debug_state (void);
389 /* Initialize `struct r_debug' if it has not already been done. The
390 argument is the run-time load address of the dynamic linker, to be put
391 in the `r_ldbase' member. Returns the address of the structure. */
392 extern struct r_debug
*_dl_debug_initialize (ElfW(Addr
) ldbase
)
395 /* Initialize the basic data structure for the search paths. */
396 extern void _dl_init_paths (const char *library_path
) internal_function
;
398 /* Gather the information needed to install the profiling tables and start
400 extern void _dl_start_profile (struct link_map
*map
, const char *output_dir
)
403 /* The actual functions used to keep book on the calls. */
404 extern void _dl_mcount (ElfW(Addr
) frompc
, ElfW(Addr
) selfpc
);
406 /* This function is simply a wrapper around the _dl_mcount function
407 which does not require a FROMPC parameter since this is the
409 extern void _dl_mcount_wrapper (ElfW(Addr
) selfpc
);
412 /* Show the members of the auxiliary array passed up from the kernel. */
413 extern void _dl_show_auxv (void) internal_function
;
415 /* Return all environment variables starting with `LD_', one after the
417 extern char *_dl_next_ld_env_entry (char ***position
) internal_function
;
419 /* Return an array with the names of the important hardware capabilities. */
420 extern const struct r_strlenpair
*_dl_important_hwcaps (const char *platform
,
423 size_t *max_capstrlen
)
427 /* When we do profiling we have the problem that uses of `dlopen'ed
428 objects don't use the PLT but instead use a pointer to the function.
429 We still want to have profiling data and in these cases we must do
430 the work of calling `_dl_mcount' ourself. The following macros
432 #define _CALL_DL_FCT(fctp, args) \
433 ({ if (_dl_profile_map != NULL) \
434 _dl_mcount_wrapper ((ElfW(Addr)) fctp); \
440 #endif /* ldsodefs.h */