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 deccriptor 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 void _dl_map_object_deps (struct link_map *map,
 253                                  struct link_map **preloads,
 254                                  unsigned int npreloads, int trace_mode)
 255      internal_function;
 256
 257 /* Cache the locations of MAP's hash table.  */
 258 extern void _dl_setup_hash (struct link_map *map) internal_function;
 259
 260
 261 /* Open the shared object NAME, relocate it, and run its initializer if it
 262    hasn't already been run.  MODE is as for `dlopen' (see <dlfcn.h>).  If
 263    the object is already opened, returns its existing map.  */
 264 extern struct link_map *_dl_open (const char *name, int mode)
 265      internal_function;
 266
 267 /* Close an object previously opened by _dl_open.  */
 268 extern void _dl_close (struct link_map *map)
 269      internal_function;
 270
 271
 272 /* Search loaded objects' symbol tables for a definition of the symbol
 273    referred to by UNDEF.  *SYM is the symbol table entry containing the
 274    reference; it is replaced with the defining symbol, and the base load
 275    address of the defining object is returned.  SYMBOL_SCOPE is a
 276    null-terminated list of object scopes to search; each object's
 277    l_searchlist (i.e. the segment of the dependency tree starting at that
 278    object) is searched in turn.  REFERENCE_NAME should name the object
 279    containing the reference; it is used in error messages.
 280    RELOC_TYPE is a machine-dependent reloc type, which is passed to
 281    the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
 282    symbols can be chosen.  */
 283 extern ElfW(Addr) _dl_lookup_symbol (const char *undef,
 284                                      const ElfW(Sym) **sym,
 285                                      struct r_scope_elem *symbol_scope[],
 286                                      const char *reference_name,
 287                                      int reloc_type)
 288      internal_function;
 289
 290 /* Lookup versioned symbol.  */
 291 extern ElfW(Addr) _dl_lookup_versioned_symbol (const char *undef,
 292                                                const ElfW(Sym) **sym,
 293                                                struct r_scope_elem *symbol_scope[],
 294                                                const char *reference_name,
 295                                                const struct r_found_version *version,
 296                                                int reloc_type)
 297      internal_function;
 298
 299 /* For handling RTLD_NEXT we must be able to skip shared objects.  */
 300 extern ElfW(Addr) _dl_lookup_symbol_skip (const char *undef,
 301                                           const ElfW(Sym) **sym,
 302                                           struct r_scope_elem *symbol_scope[],
 303                                           const char *reference_name,
 304                                           struct link_map *skip_this)
 305      internal_function;
 306
 307 /* For handling RTLD_NEXT with versioned symbols we must be able to
 308    skip shared objects.  */
 309 extern ElfW(Addr) _dl_lookup_versioned_symbol_skip (const char *undef,
 310                                                     const ElfW(Sym) **sym,
 311                                                     struct r_scope_elem *symbol_scope[],
 312                                                     const char *reference_name,
 313                                                     const struct r_found_version *version,
 314                                                     struct link_map *skip_this)
 315      internal_function;
 316
 317 /* Locate shared object containing the given address.  */
 318 extern int _dl_addr (const void *address, Dl_info *info)
 319      internal_function;
 320
 321 /* Look up symbol NAME in MAP's scope and return its run-time address.  */
 322 extern ElfW(Addr) _dl_symbol_value (struct link_map *map, const char *name)
 323      internal_function;
 324
 325
 326 /* Structure describing the dynamic linker itself.  */
 327 extern struct link_map _dl_rtld_map;
 328 /* And a pointer to the map for the main map.  */
 329 extern struct link_map *_dl_loaded;
 330 /* Array representing global scope.  */
 331 extern struct r_scope_elem *_dl_global_scope[2];
 332 /* Direct pointer to the searchlist of the main object.  */
 333 extern struct r_scope_elem *_dl_main_searchlist;
 334
 335 /* Allocate a `struct link_map' for a new object being loaded,
 336    and enter it into the _dl_main_map list.  */
 337 extern struct link_map *_dl_new_object (char *realname, const char *libname,
 338                                         int type, struct link_map *loader)
 339      internal_function;
 340
 341 /* Relocate the given object (if it hasn't already been).
 342    SCOPE is passed to _dl_lookup_symbol in symbol lookups.
 343    If LAZY is nonzero, don't relocate its PLT.  */
 344 extern void _dl_relocate_object (struct link_map *map,
 345                                  struct r_scope_elem *scope[],
 346                                  int lazy, int consider_profiling);
 347
 348 /* Check the version dependencies of all objects available through
 349    MAP.  If VERBOSE print some more diagnostics.  */
 350 extern int _dl_check_all_versions (struct link_map *map, int verbose)
 351      internal_function;
 352
 353 /* Check the version dependencies for MAP.  If VERBOSE print some more
 354    diagnostics.  */
 355 extern int _dl_check_map_versions (struct link_map *map, int verbose)
 356      internal_function;
 357
 358 /* Return the address of the next initializer function for SCOPE or one of
 359    its dependencies that has not yet been run.  When there are no more
 360    initializers to be run, this returns zero.  The functions are returned
 361    in the order they should be called.  */
 362 extern ElfW(Addr) _dl_init_next (struct r_scope_elem *scope) internal_function;
 363
 364 /* Call the finalizer functions of all shared objects whose
 365    initializer functions have completed.  */
 366 extern void _dl_fini (void) internal_function;
 367
 368 /* The dynamic linker calls this function before and having changing
 369    any shared object mappings.  The `r_state' member of `struct r_debug'
 370    says what change is taking place.  This function's address is
 371    the value of the `r_brk' member.  */
 372 extern void _dl_debug_state (void);
 373
 374 /* Initialize `struct r_debug' if it has not already been done.  The
 375    argument is the run-time load address of the dynamic linker, to be put
 376    in the `r_ldbase' member.  Returns the address of the structure.  */
 377 extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase)
 378      internal_function;
 379
 380 /* Initialize the basic data structure for the search paths.  */
 381 extern void _dl_init_paths (const char *library_path) internal_function;
 382
 383 /* Gather the information needed to install the profiling tables and start
 384    the timers.  */
 385 extern void _dl_start_profile (struct link_map *map, const char *output_dir)
 386      internal_function;
 387
 388 /* The actual functions used to keep book on the calls.  */
 389 extern void _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc);
 390
 391 /* This function is simply a wrapper around the _dl_mcount function
 392    which does not require a FROMPC parameter since this is the
 393    calling function.  */
 394 extern void _dl_mcount_wrapper (ElfW(Addr) selfpc);
 395
 396
 397 /* Show the members of the auxiliary array passed up from the kernel.  */
 398 extern void _dl_show_auxv (void) internal_function;
 399
 400 /* Return all environment variables starting with `LD_', one after the
 401    other.  */
 402 extern char *_dl_next_ld_env_entry (char ***position) internal_function;
 403
 404 /* Return an array with the names of the important hardware capabilities.  */
 405 extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,
 406                                                         size_t paltform_len,
 407                                                         size_t *sz,
 408                                                         size_t *max_capstrlen)
 409      internal_function;
 410
 411
 412 /* When we do profiling we have the problem that uses of `dlopen'ed
 413    objects don't use the PLT but instead use a pointer to the function.
 414    We still want to have profiling data and in these cases we must do
 415    the work of calling `_dl_mcount' ourself.  The following macros
 416    helps do it.  */
 417 #define _CALL_DL_FCT(fctp, args) \
 418   ({ if (_dl_profile_map != NULL)                                             \
 419        _dl_mcount_wrapper ((ElfW(Addr)) fctp);                                \
 420      (*fctp) args;                                                            \
 421   })
 422
 423 __END_DECLS
 424
 425 #endif /* ldsodefs.h */