elf/ldsodefs.h

   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.
   4
   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.
   9
  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.
  14
  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.  */
  19
  20 #ifndef _LDSODEFS_H
  21 #define _LDSODEFS_H     1
  22
  23 #include <features.h>
  24
  25 #define __need_size_t
  26 #define __need_NULL
  27 #include <stddef.h>
  28
  29 #include <elf.h>
  30 #include <dlfcn.h>
  31 #include <link.h>
  32
  33 __BEGIN_DECLS
  34
  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)
  38
  39 /* For the version handling we need an array with only names and their
  40    hash values.  */
  41 struct r_found_version
  42   {
  43     const char *name;
  44     ElfW(Word) hash;
  45
  46     int hidden;
  47     const char *filename;
  48   };
  49
  50 /* We want to cache information about the searches for shared objects.  */
  51
  52 enum r_dir_status { unknown, nonexisting, existing };
  53
  54 struct r_search_path_elem
  55   {
  56     /* This link is only used in the `all_dirs' member of `r_search_path'.  */
  57     struct r_search_path_elem *next;
  58
  59     /* Strings saying where the definition came from.  */
  60     const char *what;
  61     const char *where;
  62
  63     /* Basename for this search path element.  The string must end with
  64        a slash character.  */
  65     const char *dirname;
  66     size_t dirnamelen;
  67
  68     enum r_dir_status status[0];
  69   };
  70
  71 struct r_strlenpair
  72   {
  73     const char *str;
  74     size_t len;
  75   };
  76
  77
  78 /* A data structure for a simple single linked list of strings.  */
  79 struct libname_list
  80   {
  81     const char *name;           /* Name requested (before search).  */
  82     struct libname_list *next;  /* Link to next name for this object.  */
  83   };
  84
  85
  86 /* Test whether given NAME matches any of the names of the given object.  */
  87 static __inline int
  88 __attribute__ ((unused))
  89 _dl_name_match_p (const char *__name, struct link_map *__map)
  90 {
  91   int __found = strcmp (__name, __map->l_name) == 0;
  92   struct libname_list *__runp = __map->l_libname;
  93
  94   while (! __found && __runp != NULL)
  95     if (strcmp (__name, __runp->name) == 0)
  96       __found = 1;
  97     else
  98       __runp = __runp->next;
  99
 100   return __found;
 101 }
 102
 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 *);
 107 \f
 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.
 112
 113    The `-ldl' library functions in <dlfcn.h> provide a simple
 114    user interface to run-time dynamic linking.  */
 115
 116
 117 /* Parameters passed to the dynamic linker.  */
 118 extern char **_dl_argv;
 119
 120 /* Cached value of `getpagesize ()'.  */
 121 extern size_t _dl_pagesize;
 122
 123 /* File descriptor referring to the zero-fill device.  */
 124 extern int _dl_zerofd;
 125
 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;
 132
 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;
 141
 142 /* Expect cache ID.  */
 143 extern int _dl_correct_cache_id;
 144
 145 /* Mask for hardware capabilities that are available.  */
 146 extern unsigned long int _dl_hwcap;
 147
 148 /* Mask for important hardware capabilities we honour. */
 149 extern unsigned long int _dl_hwcap_mask;
 150
 151 /* File descriptor to write debug messages to.  */
 152 extern int _dl_debug_fd;
 153
 154 /* Names of shared object for which the RPATH should be ignored.  */
 155 extern const char *_dl_inhibit_rpath;
 156
 157 /* OS-dependent function to open the zero-fill device.  */
 158 extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
 159
 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, ...);
 164
 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
 169    line.  */
 170 extern void _dl_debug_message (int new_line, const char *string, ...);
 171
 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)
 177
 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)
 183
 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...) \
 189   do                                                                          \
 190     {                                                                         \
 191       _dl_sysdep_output (STDERR_FILENO, string, ##args);                      \
 192       _exit (127);                                                            \
 193     }                                                                         \
 194   while (1)
 195
 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;
 199
 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
 204    problem.  */
 205 extern void _dl_signal_error (int errcode,
 206                               const char *object,
 207                               const char *errstring)
 208      internal_function;
 209
 210 /* Call OPERATE, catching errors from `dl_signal_error'.  If there is no
 211    error, *ERRSTRING is set to null.  If there is an error, *ERRSTRING is
 212    set to a string constructed from the strings passed to _dl_signal_error,
 213    and the error code passed is the return value.  ERRSTRING if nonzero
 214    points to a malloc'ed string which the caller has to free after use.
 215    ARGS is passed as argument to OPERATE.  */
 216 extern int _dl_catch_error (char **errstring,
 217                             void (*operate) (void *),
 218                             void *args)
 219      internal_function;
 220
 221 /* Call OPERATE, receiving errors from `dl_signal_error'.  Unlike
 222    `_dl_catch_error' the operation is resumed after the OPERATE
 223    function returns.
 224    ARGS is passed as argument to OPERATE.  */
 225 extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
 226                                void *args)
 227      internal_function;
 228
 229
 230 /* Helper function for <dlfcn.h> functions.  Runs the OPERATE function via
 231    _dl_catch_error.  Returns zero for success, nonzero for failure; and
 232    arranges for `dlerror' to return the error details.
 233    ARGS is passed as argument to OPERATE.  */
 234 extern int _dlerror_run (void (*operate) (void *), void *args)
 235      internal_function;
 236
 237
 238 /* Open the shared object NAME and map in its segments.
 239    LOADER's DT_RPATH is used in searching for NAME.
 240    If the object is already opened, returns its existing map.
 241    For preloaded shared objects PRELOADED is set to a non-zero
 242    value to allow additional security checks.  */
 243 extern struct link_map *_dl_map_object (struct link_map *loader,
 244                                         const char *name, int preloaded,
 245                                         int type, int trace_mode)
 246      internal_function;
 247
 248 /* Call _dl_map_object on the dependencies of MAP, and set up
 249    MAP->l_searchlist.  PRELOADS points to a vector of NPRELOADS previously
 250    loaded objects that will be inserted into MAP->l_searchlist after MAP
 251    but before its dependencies.  */
 252 extern unsigned int _dl_map_object_deps (struct link_map *map,
 253                                          struct link_map **preloads,
 254                                          unsigned int npreloads,
 255                                          int trace_mode, int global_scope)
 256      internal_function;
 257
 258 /* Cache the locations of MAP's hash table.  */
 259 extern void _dl_setup_hash (struct link_map *map) internal_function;
 260
 261
 262 /* Open the shared object NAME, relocate it, and run its initializer if it
 263    hasn't already been run.  MODE is as for `dlopen' (see <dlfcn.h>).  If
 264    the object is already opened, returns its existing map.  */
 265 extern struct link_map *_dl_open (const char *name, int mode)
 266      internal_function;
 267
 268 /* Close an object previously opened by _dl_open.  */
 269 extern void _dl_close (struct link_map *map)
 270      internal_function;
 271
 272
 273 /* Search loaded objects' symbol tables for a definition of the symbol
 274    referred to by UNDEF.  *SYM is the symbol table entry containing the
 275    reference; it is replaced with the defining symbol, and the base load
 276    address of the defining object is returned.  SYMBOL_SCOPE is a
 277    null-terminated list of object scopes to search; each object's
 278    l_searchlist (i.e. the segment of the dependency tree starting at that
 279    object) is searched in turn.  REFERENCE_NAME should name the object
 280    containing the reference; it is used in error messages.
 281    RELOC_TYPE is a machine-dependent reloc type, which is passed to
 282    the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
 283    symbols can be chosen.  */
 284 extern ElfW(Addr) _dl_lookup_symbol (const char *undef,
 285                                      const ElfW(Sym) **sym,
 286                                      struct r_scope_elem *symbol_scope[],
 287                                      const char *reference_name,
 288                                      int reloc_type)
 289      internal_function;
 290
 291 /* Lookup versioned symbol.  */
 292 extern ElfW(Addr) _dl_lookup_versioned_symbol (const char *undef,
 293                                                const ElfW(Sym) **sym,
 294                                                struct r_scope_elem *symbol_scope[],
 295                                                const char *reference_name,
 296                                                const struct r_found_version *version,
 297                                                int reloc_type)
 298      internal_function;
 299
 300 /* For handling RTLD_NEXT we must be able to skip shared objects.  */
 301 extern ElfW(Addr) _dl_lookup_symbol_skip (const char *undef,
 302                                           const ElfW(Sym) **sym,
 303                                           struct r_scope_elem *symbol_scope[],
 304                                           const char *reference_name,
 305                                           struct link_map *skip_this)
 306      internal_function;
 307
 308 /* For handling RTLD_NEXT with versioned symbols we must be able to
 309    skip shared objects.  */
 310 extern ElfW(Addr) _dl_lookup_versioned_symbol_skip (const char *undef,
 311                                                     const ElfW(Sym) **sym,
 312                                                     struct r_scope_elem *symbol_scope[],
 313                                                     const char *reference_name,
 314                                                     const struct r_found_version *version,
 315                                                     struct link_map *skip_this)
 316      internal_function;
 317
 318 /* Locate shared object containing the given address.  */
 319 extern int _dl_addr (const void *address, Dl_info *info)
 320      internal_function;
 321
 322 /* Look up symbol NAME in MAP's scope and return its run-time address.  */
 323 extern ElfW(Addr) _dl_symbol_value (struct link_map *map, const char *name)
 324      internal_function;
 325
 326
 327 /* Structure describing the dynamic linker itself.  */
 328 extern struct link_map _dl_rtld_map;
 329 /* And a pointer to the map for the main map.  */
 330 extern struct link_map *_dl_loaded;
 331 /* Array representing global scope.  */
 332 extern struct r_scope_elem *_dl_global_scope[2];
 333 /* Direct pointer to the searchlist of the main object.  */
 334 extern struct r_scope_elem *_dl_main_searchlist;
 335 /* Copy of the content of `_dl_main_searchlist'.  */
 336 extern struct r_scope_elem _dl_initial_searchlist;
 337 /* This is zero at program start to signal that the global scope map is
 338    allocated by rtld.  Later it keeps the size of the map.  It might be
 339    reset if in _dl_close if the last global object is removed.  */
 340 extern size_t _dl_global_scope_alloc;
 341
 342 /* Allocate a `struct link_map' for a new object being loaded,
 343    and enter it into the _dl_main_map list.  */
 344 extern struct link_map *_dl_new_object (char *realname, const char *libname,
 345                                         int type, struct link_map *loader)
 346      internal_function;
 347
 348 /* Relocate the given object (if it hasn't already been).
 349    SCOPE is passed to _dl_lookup_symbol in symbol lookups.
 350    If LAZY is nonzero, don't relocate its PLT.  */
 351 extern void _dl_relocate_object (struct link_map *map,
 352                                  struct r_scope_elem *scope[],
 353                                  int lazy, int consider_profiling);
 354
 355 /* Check the version dependencies of all objects available through
 356    MAP.  If VERBOSE print some more diagnostics.  */
 357 extern int _dl_check_all_versions (struct link_map *map, int verbose)
 358      internal_function;
 359
 360 /* Check the version dependencies for MAP.  If VERBOSE print some more
 361    diagnostics.  */
 362 extern int _dl_check_map_versions (struct link_map *map, int verbose)
 363      internal_function;
 364
 365 /* Return the address of the next initializer function for SCOPE or one of
 366    its dependencies that has not yet been run.  When there are no more
 367    initializers to be run, this returns zero.  The functions are returned
 368    in the order they should be called.  */
 369 extern ElfW(Addr) _dl_init_next (struct r_scope_elem *scope) internal_function;
 370
 371 /* Call the finalizer functions of all shared objects whose
 372    initializer functions have completed.  */
 373 extern void _dl_fini (void) internal_function;
 374
 375 /* The dynamic linker calls this function before and having changing
 376    any shared object mappings.  The `r_state' member of `struct r_debug'
 377    says what change is taking place.  This function's address is
 378    the value of the `r_brk' member.  */
 379 extern void _dl_debug_state (void);
 380
 381 /* Initialize `struct r_debug' if it has not already been done.  The
 382    argument is the run-time load address of the dynamic linker, to be put
 383    in the `r_ldbase' member.  Returns the address of the structure.  */
 384 extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase)
 385      internal_function;
 386
 387 /* Initialize the basic data structure for the search paths.  */
 388 extern void _dl_init_paths (const char *library_path) internal_function;
 389
 390 /* Gather the information needed to install the profiling tables and start
 391    the timers.  */
 392 extern void _dl_start_profile (struct link_map *map, const char *output_dir)
 393      internal_function;
 394
 395 /* The actual functions used to keep book on the calls.  */
 396 extern void _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc);
 397
 398 /* This function is simply a wrapper around the _dl_mcount function
 399    which does not require a FROMPC parameter since this is the
 400    calling function.  */
 401 extern void _dl_mcount_wrapper (ElfW(Addr) selfpc);
 402
 403
 404 /* Show the members of the auxiliary array passed up from the kernel.  */
 405 extern void _dl_show_auxv (void) internal_function;
 406
 407 /* Return all environment variables starting with `LD_', one after the
 408    other.  */
 409 extern char *_dl_next_ld_env_entry (char ***position) internal_function;
 410
 411 /* Return an array with the names of the important hardware capabilities.  */
 412 extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,
 413                                                         size_t paltform_len,
 414                                                         size_t *sz,
 415                                                         size_t *max_capstrlen)
 416      internal_function;
 417
 418
 419 /* When we do profiling we have the problem that uses of `dlopen'ed
 420    objects don't use the PLT but instead use a pointer to the function.
 421    We still want to have profiling data and in these cases we must do
 422    the work of calling `_dl_mcount' ourself.  The following macros
 423    helps do it.  */
 424 #define _CALL_DL_FCT(fctp, args) \
 425   ({ if (_dl_profile_map != NULL)                                             \
 426        _dl_mcount_wrapper ((ElfW(Addr)) fctp);                                \
 427      (*fctp) args;                                                            \
 428   })
 429
 430 __END_DECLS
 431
 432 #endif /* ldsodefs.h */