sysdeps/generic/ldsodefs.h

   1 /* Run-time dynamic linker data structures for loaded ELF shared objects.
   2    Copyright (C) 1995-1999, 2000 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 #include <string.h>
  29
  30 #include <elf.h>
  31 #include <dlfcn.h>
  32 #include <link.h>
  33 #include <dl-lookupcfg.h>
  34
  35 __BEGIN_DECLS
  36
  37 /* We use this macro to refer to ELF types independent of the native wordsize.
  38    `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'.  */
  39 #define ELFW(type)      _ElfW (ELF, __ELF_NATIVE_CLASS, type)
  40
  41 /* All references to the value of l_info[DT_PLTGOT],
  42   l_info[DT_STRTAB], l_info[DT_SYMTAB], l_info[DT_RELA],
  43   l_info[DT_REL], l_info[DT_JMPREL], and l_info[VERSYMIDX (DT_VERSYM)]
  44   have to be accessed via the D_PTR macro.  The macro is needed since for
  45   most architectures the entry is already relocated - but for some not
  46   and we need to relocate at access time.  */
  47 #ifdef DL_RO_DYN_SECTION
  48 # define D_PTR(map,i) (map->i->d_un.d_ptr + map->l_addr)
  49 #else
  50 # define D_PTR(map,i) map->i->d_un.d_ptr
  51 #endif
  52
  53 /* On some platforms more information than just the address of the symbol
  54    is needed from the lookup functions.  In this case we return the whole
  55    link map.  */
  56 #ifdef DL_LOOKUP_RETURNS_MAP
  57 typedef struct link_map *lookup_t;
  58 # define LOOKUP_VALUE(map) map
  59 # define LOOKUP_VALUE_ADDRESS(map) (map ? map->l_addr : 0)
  60 #else
  61 typedef ElfW(Addr) lookup_t;
  62 # define LOOKUP_VALUE(map) map->l_addr
  63 # define LOOKUP_VALUE_ADDRESS(address) address
  64 #endif
  65
  66 /* on some architectures a pointer to a function is not just a pointer
  67    to the actual code of the function but rather an architecture
  68    specific descriptor. */
  69 #ifndef ELF_FUNCTION_PTR_IS_SPECIAL
  70 #define DL_SYMBOL_ADDRESS(map, ref) \
  71  (void *) (LOOKUP_VALUE_ADDRESS (map) + ref->st_value)
  72 #endif
  73
  74 /* For the version handling we need an array with only names and their
  75    hash values.  */
  76 struct r_found_version
  77   {
  78     const char *name;
  79     ElfW(Word) hash;
  80
  81     int hidden;
  82     const char *filename;
  83   };
  84
  85 /* We want to cache information about the searches for shared objects.  */
  86
  87 enum r_dir_status { unknown, nonexisting, existing };
  88
  89 struct r_search_path_elem
  90   {
  91     /* This link is only used in the `all_dirs' member of `r_search_path'.  */
  92     struct r_search_path_elem *next;
  93
  94     /* Strings saying where the definition came from.  */
  95     const char *what;
  96     const char *where;
  97
  98     /* Basename for this search path element.  The string must end with
  99        a slash character.  */
 100     const char *dirname;
 101     size_t dirnamelen;
 102
 103     enum r_dir_status status[0];
 104   };
 105
 106 struct r_strlenpair
 107   {
 108     const char *str;
 109     size_t len;
 110   };
 111
 112
 113 /* A data structure for a simple single linked list of strings.  */
 114 struct libname_list
 115   {
 116     const char *name;           /* Name requested (before search).  */
 117     struct libname_list *next;  /* Link to next name for this object.  */
 118   };
 119
 120
 121 /* Test whether given NAME matches any of the names of the given object.  */
 122 static __inline int
 123 __attribute__ ((unused))
 124 _dl_name_match_p (const char *__name, struct link_map *__map)
 125 {
 126   int __found = strcmp (__name, __map->l_name) == 0;
 127   struct libname_list *__runp = __map->l_libname;
 128
 129   while (! __found && __runp != NULL)
 130     if (strcmp (__name, __runp->name) == 0)
 131       __found = 1;
 132     else
 133       __runp = __runp->next;
 134
 135   return __found;
 136 }
 137
 138 /* Function used as argument for `_dl_receive_error' function.  The
 139    arguments are the error code, error string, and the objname the
 140    error occurred in.  */
 141 typedef void (*receiver_fct) (int, const char *, const char *);
 142 \f
 143 /* Internal functions of the run-time dynamic linker.
 144    These can be accessed if you link again the dynamic linker
 145    as a shared library, as in `-lld' or `/lib/ld.so' explicitly;
 146    but are not normally of interest to user programs.
 147
 148    The `-ldl' library functions in <dlfcn.h> provide a simple
 149    user interface to run-time dynamic linking.  */
 150
 151
 152 /* Parameters passed to the dynamic linker.  */
 153 extern char **_dl_argv;
 154
 155 /* Cached value of `getpagesize ()'.  */
 156 extern size_t _dl_pagesize;
 157
 158 /* File descriptor referring to the zero-fill device.  */
 159 extern int _dl_zerofd;
 160
 161 /* Name of the shared object to be profiled (if any).  */
 162 extern const char *_dl_profile;
 163 /* Map of shared object to be profiled.  */
 164 extern struct link_map *_dl_profile_map;
 165 /* Filename of the output file.  */
 166 extern const char *_dl_profile_output;
 167
 168 /* If nonzero the appropriate debug information is printed.  */
 169 extern int _dl_debug_libs;
 170 extern int _dl_debug_impcalls;
 171 extern int _dl_debug_bindings;
 172 extern int _dl_debug_symbols;
 173 extern int _dl_debug_versions;
 174 extern int _dl_debug_reloc;
 175 extern int _dl_debug_files;
 176
 177 /* Expect cache ID.  */
 178 extern int _dl_correct_cache_id;
 179
 180 /* Mask for hardware capabilities that are available.  */
 181 extern unsigned long int _dl_hwcap;
 182
 183 /* Mask for important hardware capabilities we honour. */
 184 extern unsigned long int _dl_hwcap_mask;
 185
 186 /* File descriptor to write debug messages to.  */
 187 extern int _dl_debug_fd;
 188
 189 /* Names of shared object for which the RPATH should be ignored.  */
 190 extern const char *_dl_inhibit_rpath;
 191
 192 /* OS-dependent function to open the zero-fill device.  */
 193 extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
 194
 195 /* OS-dependent function to write a message on the specified
 196    descriptor FD.  All arguments are `const char *'; args until a null
 197    pointer are concatenated to form the message to print.  */
 198 extern void _dl_sysdep_output (int fd, const char *string, ...);
 199
 200 /* OS-dependent function to write a debug message on the specified
 201    descriptor for this.  All arguments are `const char *'; args until
 202    a null pointer are concatenated to form the message to print.  If
 203    NEW_LINE is nonzero it is assumed that the message starts on a new
 204    line.  */
 205 extern void _dl_debug_message (int new_line, const char *string, ...);
 206
 207 /* OS-dependent function to write a message on the standard output.
 208    All arguments are `const char *'; args until a null pointer
 209    are concatenated to form the message to print.  */
 210 #define _dl_sysdep_message(string, args...) \
 211   _dl_sysdep_output (STDOUT_FILENO, string, ##args)
 212
 213 /* OS-dependent function to write a message on the standard error.
 214    All arguments are `const char *'; args until a null pointer
 215    are concatenated to form the message to print.  */
 216 #define _dl_sysdep_error(string, args...) \
 217   _dl_sysdep_output (STDERR_FILENO, string, ##args)
 218
 219 /* OS-dependent function to give a fatal error message and exit
 220    when the dynamic linker fails before the program is fully linked.
 221    All arguments are `const char *'; args until a null pointer
 222    are concatenated to form the message to print.  */
 223 #define _dl_sysdep_fatal(string, args...) \
 224   do                                                                          \
 225     {                                                                         \
 226       _dl_sysdep_output (STDERR_FILENO, string, ##args);                      \
 227       _exit (127);                                                            \
 228     }                                                                         \
 229   while (1)
 230
 231 /* Nonzero if the program should be "secure" (i.e. it's setuid or somesuch).
 232    This tells the dynamic linker to ignore environment variables.  */
 233 extern int _dl_secure;
 234
 235 /* This function is called by all the internal dynamic linker functions
 236    when they encounter an error.  ERRCODE is either an `errno' code or
 237    zero; OBJECT is the name of the problematical shared object, or null if
 238    it is a general problem; ERRSTRING is a string describing the specific
 239    problem.  */
 240 extern void _dl_signal_error (int errcode,
 241                               const char *object,
 242                               const char *errstring)
 243      internal_function
 244      __attribute__ ((__noreturn__));
 245
 246 /* Like _dl_signal_error, but may return when called in the context of
 247    _dl_receive_error.  */
 248 extern void _dl_signal_cerror (int errcode,
 249                                const char *object,
 250                                const char *errstring)
 251      internal_function;
 252
 253 /* Call OPERATE, receiving errors from `dl_signal_cerror'.  Unlike
 254    `_dl_catch_error' the operation is resumed after the OPERATE
 255    function returns.
 256    ARGS is passed as argument to OPERATE.  */
 257 extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
 258                                void *args)
 259      internal_function;
 260
 261
 262 /* Open the shared object NAME and map in its segments.
 263    LOADER's DT_RPATH is used in searching for NAME.
 264    If the object is already opened, returns its existing map.
 265    For preloaded shared objects PRELOADED is set to a non-zero
 266    value to allow additional security checks.  */
 267 extern struct link_map *_dl_map_object (struct link_map *loader,
 268                                         const char *name, int preloaded,
 269                                         int type, int trace_mode)
 270      internal_function;
 271
 272 /* Call _dl_map_object on the dependencies of MAP, and set up
 273    MAP->l_searchlist.  PRELOADS points to a vector of NPRELOADS previously
 274    loaded objects that will be inserted into MAP->l_searchlist after MAP
 275    but before its dependencies.  */
 276 extern void _dl_map_object_deps (struct link_map *map,
 277                                  struct link_map **preloads,
 278                                  unsigned int npreloads, int trace_mode)
 279      internal_function;
 280
 281 /* Cache the locations of MAP's hash table.  */
 282 extern void _dl_setup_hash (struct link_map *map) internal_function;
 283
 284
 285 /* Search loaded objects' symbol tables for a definition of the symbol
 286    referred to by UNDEF.  *SYM is the symbol table entry containing the
 287    reference; it is replaced with the defining symbol, and the base load
 288    address of the defining object is returned.  SYMBOL_SCOPE is a
 289    null-terminated list of object scopes to search; each object's
 290    l_searchlist (i.e. the segment of the dependency tree starting at that
 291    object) is searched in turn.  REFERENCE_NAME should name the object
 292    containing the reference; it is used in error messages.
 293    RELOC_TYPE is a machine-dependent reloc type, which is passed to
 294    the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
 295    symbols can be chosen.  */
 296 extern lookup_t _dl_lookup_symbol (const char *undef,
 297                                    struct link_map *undef_map,
 298                                    const ElfW(Sym) **sym,
 299                                    struct r_scope_elem *symbol_scope[],
 300                                    int reloc_type)
 301      internal_function;
 302
 303 /* Lookup versioned symbol.  */
 304 extern lookup_t _dl_lookup_versioned_symbol (const char *undef,
 305                                              struct link_map *undef_map,
 306                                              const ElfW(Sym) **sym,
 307                                              struct r_scope_elem *symbol_scope[],
 308                                              const struct r_found_version *version,
 309                                              int reloc_type)
 310      internal_function;
 311
 312 /* For handling RTLD_NEXT we must be able to skip shared objects.  */
 313 extern lookup_t _dl_lookup_symbol_skip (const char *undef,
 314                                         struct link_map *undef_map,
 315                                         const ElfW(Sym) **sym,
 316                                         struct r_scope_elem *symbol_scope[],
 317                                         struct link_map *skip_this)
 318      internal_function;
 319
 320 /* For handling RTLD_NEXT with versioned symbols we must be able to
 321    skip shared objects.  */
 322 extern lookup_t _dl_lookup_versioned_symbol_skip (const char *undef,
 323                                                   struct link_map *undef_map,
 324                                                   const ElfW(Sym) **sym,
 325                                                   struct r_scope_elem *symbol_scope[],
 326                                                   const struct r_found_version *version,
 327                                                   struct link_map *skip_this)
 328      internal_function;
 329
 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)
 332      internal_function;
 333
 334
 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;
 349
 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)
 354      internal_function;
 355
 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);
 362
 363 /* Call _dl_signal_error with a message about an unhandled reloc type.
 364    TYPE is the result of ELFW(R_TYPE) (r_info), i.e. an R_<CPU>_* value.
 365    PLT is nonzero if this was a PLT reloc; it just affects the message.  */
 366 extern void _dl_reloc_bad_type (struct link_map *map,
 367                                 uint_fast8_t type, int plt)
 368      internal_function;
 369
 370 /* Check the version dependencies of all objects available through
 371    MAP.  If VERBOSE print some more diagnostics.  */
 372 extern int _dl_check_all_versions (struct link_map *map, int verbose,
 373                                    int trace_mode)
 374      internal_function;
 375
 376 /* Check the version dependencies for MAP.  If VERBOSE print some more
 377    diagnostics.  */
 378 extern int _dl_check_map_versions (struct link_map *map, int verbose,
 379                                    int trace_mode)
 380      internal_function;
 381
 382 /* Initialize the object in SCOPE by calling the constructors with
 383    ARGC, ARGV, and ENV as the parameters.  */
 384 extern void _dl_init (struct link_map *main_map, int argc, char **argv,
 385                       char **env) internal_function;
 386
 387 /* Call the finalizer functions of all shared objects whose
 388    initializer functions have completed.  */
 389 extern void _dl_fini (void) internal_function;
 390
 391 /* The dynamic linker calls this function before and having changing
 392    any shared object mappings.  The `r_state' member of `struct r_debug'
 393    says what change is taking place.  This function's address is
 394    the value of the `r_brk' member.  */
 395 extern void _dl_debug_state (void);
 396
 397 /* Initialize `struct r_debug' if it has not already been done.  The
 398    argument is the run-time load address of the dynamic linker, to be put
 399    in the `r_ldbase' member.  Returns the address of the structure.  */
 400 extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase)
 401      internal_function;
 402
 403 /* Initialize the basic data structure for the search paths.  */
 404 extern void _dl_init_paths (const char *library_path) internal_function;
 405
 406 /* Gather the information needed to install the profiling tables and start
 407    the timers.  */
 408 extern void _dl_start_profile (struct link_map *map, const char *output_dir)
 409      internal_function;
 410
 411 /* The actual functions used to keep book on the calls.  */
 412 extern void _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc);
 413
 414 /* This function is simply a wrapper around the _dl_mcount function
 415    which does not require a FROMPC parameter since this is the
 416    calling function.  */
 417 extern void _dl_mcount_wrapper (void *selfpc);
 418
 419 /* Show the members of the auxiliary array passed up from the kernel.  */
 420 extern void _dl_show_auxv (void) internal_function;
 421
 422 /* Return all environment variables starting with `LD_', one after the
 423    other.  */
 424 extern char *_dl_next_ld_env_entry (char ***position) internal_function;
 425
 426 /* Return an array with the names of the important hardware capabilities.  */
 427 extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,
 428                                                         size_t paltform_len,
 429                                                         size_t *sz,
 430                                                         size_t *max_capstrlen)
 431      internal_function;
 432
 433 __END_DECLS
 434
 435 #endif /* ldsodefs.h */