| 1 | /* loader-preopen.c -- emulate dynamic linking using preloaded_symbols |
| 2 | |
| 3 | Copyright (C) 1998, 1999, 2000, 2004, 2006, |
| 4 | 2007, 2008 Free Software Foundation, Inc. |
| 5 | Written by Thomas Tanner, 1998 |
| 6 | |
| 7 | NOTE: The canonical source of this file is maintained with the |
| 8 | GNU Libtool package. Report bugs to bug-libtool@gnu.org. |
| 9 | |
| 10 | GNU Libltdl is free software; you can redistribute it and/or |
| 11 | modify it under the terms of the GNU Lesser General Public |
| 12 | License as published by the Free Software Foundation; either |
| 13 | version 2 of the License, or (at your option) any later version. |
| 14 | |
| 15 | As a special exception to the GNU Lesser General Public License, |
| 16 | if you distribute this file as part of a program or library that |
| 17 | is built using GNU Libtool, you may include this file under the |
| 18 | same distribution terms that you use for the rest of that program. |
| 19 | |
| 20 | GNU Libltdl is distributed in the hope that it will be useful, |
| 21 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 22 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 23 | GNU Lesser General Public License for more details. |
| 24 | |
| 25 | You should have received a copy of the GNU Lesser General Public |
| 26 | License along with GNU Libltdl; see the file COPYING.LIB. If not, a |
| 27 | copy can be downloaded from http://www.gnu.org/licenses/lgpl.html, |
| 28 | or obtained by writing to the Free Software Foundation, Inc., |
| 29 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| 30 | */ |
| 31 | |
| 32 | #include "lt__private.h" |
| 33 | #include "lt_dlloader.h" |
| 34 | |
| 35 | /* Use the preprocessor to rename non-static symbols to avoid namespace |
| 36 | collisions when the loader code is statically linked into libltdl. |
| 37 | Use the "<module_name>_LTX_" prefix so that the symbol addresses can |
| 38 | be fetched from the preloaded symbol list by lt_dlsym(): */ |
| 39 | #define get_vtable preopen_LTX_get_vtable |
| 40 | |
| 41 | LT_BEGIN_C_DECLS |
| 42 | LT_SCOPE lt_dlvtable *get_vtable (lt_user_data loader_data); |
| 43 | LT_END_C_DECLS |
| 44 | |
| 45 | |
| 46 | /* Boilerplate code to set up the vtable for hooking this loader into |
| 47 | libltdl's loader list: */ |
| 48 | static int vl_init (lt_user_data loader_data); |
| 49 | static int vl_exit (lt_user_data loader_data); |
| 50 | static lt_module vm_open (lt_user_data loader_data, const char *filename, |
| 51 | lt_dladvise advise); |
| 52 | static int vm_close (lt_user_data loader_data, lt_module module); |
| 53 | static void * vm_sym (lt_user_data loader_data, lt_module module, |
| 54 | const char *symbolname); |
| 55 | |
| 56 | static lt_dlvtable *vtable = 0; |
| 57 | |
| 58 | /* Return the vtable for this loader, only the name and sym_prefix |
| 59 | attributes (plus the virtual function implementations, obviously) |
| 60 | change between loaders. */ |
| 61 | lt_dlvtable * |
| 62 | get_vtable (lt_user_data loader_data) |
| 63 | { |
| 64 | if (!vtable) |
| 65 | { |
| 66 | vtable = (lt_dlvtable *) lt__zalloc (sizeof *vtable); |
| 67 | } |
| 68 | |
| 69 | if (vtable && !vtable->name) |
| 70 | { |
| 71 | vtable->name = "lt_preopen"; |
| 72 | vtable->sym_prefix = 0; |
| 73 | vtable->module_open = vm_open; |
| 74 | vtable->module_close = vm_close; |
| 75 | vtable->find_sym = vm_sym; |
| 76 | vtable->dlloader_init = vl_init; |
| 77 | vtable->dlloader_exit = vl_exit; |
| 78 | vtable->dlloader_data = loader_data; |
| 79 | vtable->priority = LT_DLLOADER_PREPEND; |
| 80 | } |
| 81 | |
| 82 | if (vtable && (vtable->dlloader_data != loader_data)) |
| 83 | { |
| 84 | LT__SETERROR (INIT_LOADER); |
| 85 | return 0; |
| 86 | } |
| 87 | |
| 88 | return vtable; |
| 89 | } |
| 90 | |
| 91 | |
| 92 | |
| 93 | /* --- IMPLEMENTATION --- */ |
| 94 | |
| 95 | |
| 96 | /* Wrapper type to chain together symbol lists of various origins. */ |
| 97 | typedef struct symlist_chain |
| 98 | { |
| 99 | struct symlist_chain *next; |
| 100 | const lt_dlsymlist *symlist; |
| 101 | } symlist_chain; |
| 102 | |
| 103 | |
| 104 | static int add_symlist (const lt_dlsymlist *symlist); |
| 105 | static int free_symlists (void); |
| 106 | |
| 107 | /* The start of the symbol lists chain. */ |
| 108 | static symlist_chain *preloaded_symlists = 0; |
| 109 | |
| 110 | /* A symbol list preloaded before lt_init() was called. */ |
| 111 | static const lt_dlsymlist *default_preloaded_symbols = 0; |
| 112 | |
| 113 | |
| 114 | /* A function called through the vtable to initialise this loader. */ |
| 115 | static int |
| 116 | vl_init (lt_user_data LT__UNUSED loader_data) |
| 117 | { |
| 118 | int errors = 0; |
| 119 | |
| 120 | preloaded_symlists = 0; |
| 121 | if (default_preloaded_symbols) |
| 122 | { |
| 123 | errors = lt_dlpreload (default_preloaded_symbols); |
| 124 | } |
| 125 | |
| 126 | return errors; |
| 127 | } |
| 128 | |
| 129 | |
| 130 | /* A function called through the vtable when this loader is no |
| 131 | longer needed by the application. */ |
| 132 | static int |
| 133 | vl_exit (lt_user_data LT__UNUSED loader_data) |
| 134 | { |
| 135 | vtable = NULL; |
| 136 | free_symlists (); |
| 137 | return 0; |
| 138 | } |
| 139 | |
| 140 | |
| 141 | /* A function called through the vtable to open a module with this |
| 142 | loader. Returns an opaque representation of the newly opened |
| 143 | module for processing with this loader's other vtable functions. */ |
| 144 | static lt_module |
| 145 | vm_open (lt_user_data LT__UNUSED loader_data, const char *filename, |
| 146 | lt_dladvise LT__UNUSED advise) |
| 147 | { |
| 148 | symlist_chain *lists; |
| 149 | lt_module module = 0; |
| 150 | |
| 151 | if (!preloaded_symlists) |
| 152 | { |
| 153 | LT__SETERROR (NO_SYMBOLS); |
| 154 | goto done; |
| 155 | } |
| 156 | |
| 157 | /* Can't use NULL as the reflective symbol header, as NULL is |
| 158 | used to mark the end of the entire symbol list. Self-dlpreopened |
| 159 | symbols follow this magic number, chosen to be an unlikely |
| 160 | clash with a real module name. */ |
| 161 | if (!filename) |
| 162 | { |
| 163 | filename = "@PROGRAM@"; |
| 164 | } |
| 165 | |
| 166 | for (lists = preloaded_symlists; lists; lists = lists->next) |
| 167 | { |
| 168 | const lt_dlsymlist *symbol; |
| 169 | for (symbol= lists->symlist; symbol->name; ++symbol) |
| 170 | { |
| 171 | if (!symbol->address && streq (symbol->name, filename)) |
| 172 | { |
| 173 | /* If the next symbol's name and address is 0, it means |
| 174 | the module just contains the originator and no symbols. |
| 175 | In this case we pretend that we never saw the module and |
| 176 | hope that some other loader will be able to load the module |
| 177 | and have access to its symbols */ |
| 178 | const lt_dlsymlist *next_symbol = symbol +1; |
| 179 | if (next_symbol->address && next_symbol->name) |
| 180 | { |
| 181 | module = (lt_module) lists->symlist; |
| 182 | goto done; |
| 183 | } |
| 184 | } |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | LT__SETERROR (FILE_NOT_FOUND); |
| 189 | |
| 190 | done: |
| 191 | return module; |
| 192 | } |
| 193 | |
| 194 | |
| 195 | /* A function called through the vtable when a particular module |
| 196 | should be unloaded. */ |
| 197 | static int |
| 198 | vm_close (lt_user_data LT__UNUSED loader_data, lt_module LT__UNUSED module) |
| 199 | { |
| 200 | /* Just to silence gcc -Wall */ |
| 201 | module = 0; |
| 202 | return 0; |
| 203 | } |
| 204 | |
| 205 | |
| 206 | /* A function called through the vtable to get the address of |
| 207 | a symbol loaded from a particular module. */ |
| 208 | static void * |
| 209 | vm_sym (lt_user_data LT__UNUSED loader_data, lt_module module, const char *name) |
| 210 | { |
| 211 | lt_dlsymlist *symbol = (lt_dlsymlist*) module; |
| 212 | |
| 213 | symbol +=2; /* Skip header (originator then libname). */ |
| 214 | |
| 215 | while (symbol->name) |
| 216 | { |
| 217 | if (streq (symbol->name, name)) |
| 218 | { |
| 219 | return symbol->address; |
| 220 | } |
| 221 | |
| 222 | ++symbol; |
| 223 | } |
| 224 | |
| 225 | LT__SETERROR (SYMBOL_NOT_FOUND); |
| 226 | |
| 227 | return 0; |
| 228 | } |
| 229 | |
| 230 | |
| 231 | |
| 232 | /* --- HELPER FUNCTIONS --- */ |
| 233 | |
| 234 | |
| 235 | /* The symbol lists themselves are not allocated from the heap, but |
| 236 | we can unhook them and free up the chain of links between them. */ |
| 237 | static int |
| 238 | free_symlists (void) |
| 239 | { |
| 240 | symlist_chain *lists; |
| 241 | |
| 242 | lists = preloaded_symlists; |
| 243 | while (lists) |
| 244 | { |
| 245 | symlist_chain *next = lists->next; |
| 246 | FREE (lists); |
| 247 | lists = next; |
| 248 | } |
| 249 | preloaded_symlists = 0; |
| 250 | |
| 251 | return 0; |
| 252 | } |
| 253 | |
| 254 | /* Add a new symbol list to the global chain. */ |
| 255 | static int |
| 256 | add_symlist (const lt_dlsymlist *symlist) |
| 257 | { |
| 258 | symlist_chain *lists; |
| 259 | int errors = 0; |
| 260 | |
| 261 | /* Search for duplicate entries: */ |
| 262 | for (lists = preloaded_symlists; |
| 263 | lists && lists->symlist != symlist; lists = lists->next) |
| 264 | /*NOWORK*/; |
| 265 | |
| 266 | /* Don't add the same list twice: */ |
| 267 | if (!lists) |
| 268 | { |
| 269 | symlist_chain *tmp = (symlist_chain *) lt__zalloc (sizeof *tmp); |
| 270 | |
| 271 | if (tmp) |
| 272 | { |
| 273 | tmp->symlist = symlist; |
| 274 | tmp->next = preloaded_symlists; |
| 275 | preloaded_symlists = tmp; |
| 276 | } |
| 277 | else |
| 278 | { |
| 279 | ++errors; |
| 280 | } |
| 281 | } |
| 282 | |
| 283 | return errors; |
| 284 | } |
| 285 | |
| 286 | |
| 287 | |
| 288 | /* --- PRELOADING API CALL IMPLEMENTATIONS --- */ |
| 289 | |
| 290 | |
| 291 | /* Save a default symbol list for later. */ |
| 292 | int |
| 293 | lt_dlpreload_default (const lt_dlsymlist *preloaded) |
| 294 | { |
| 295 | default_preloaded_symbols = preloaded; |
| 296 | return 0; |
| 297 | } |
| 298 | |
| 299 | |
| 300 | /* Add a symbol list to the global chain, or with a NULL argument, |
| 301 | revert to just the default list. */ |
| 302 | int |
| 303 | lt_dlpreload (const lt_dlsymlist *preloaded) |
| 304 | { |
| 305 | int errors = 0; |
| 306 | |
| 307 | if (preloaded) |
| 308 | { |
| 309 | errors = add_symlist (preloaded); |
| 310 | } |
| 311 | else |
| 312 | { |
| 313 | free_symlists(); |
| 314 | |
| 315 | if (default_preloaded_symbols) |
| 316 | { |
| 317 | errors = lt_dlpreload (default_preloaded_symbols); |
| 318 | } |
| 319 | } |
| 320 | |
| 321 | return errors; |
| 322 | } |
| 323 | |
| 324 | |
| 325 | /* Open all the preloaded modules from the named originator, executing |
| 326 | a callback for each one. If ORIGINATOR is NULL, then call FUNC for |
| 327 | each preloaded module from the program itself. */ |
| 328 | int |
| 329 | lt_dlpreload_open (const char *originator, lt_dlpreload_callback_func *func) |
| 330 | { |
| 331 | symlist_chain *list; |
| 332 | int errors = 0; |
| 333 | int found = 0; |
| 334 | |
| 335 | /* For each symlist in the chain... */ |
| 336 | for (list = preloaded_symlists; list; list = list->next) |
| 337 | { |
| 338 | /* ...that was preloaded by the requesting ORIGINATOR... */ |
| 339 | if ((originator && streq (list->symlist->name, originator)) |
| 340 | || (!originator && streq (list->symlist->name, "@PROGRAM@"))) |
| 341 | { |
| 342 | const lt_dlsymlist *symbol; |
| 343 | unsigned int idx = 0; |
| 344 | |
| 345 | ++found; |
| 346 | |
| 347 | /* ...load the symbols per source compilation unit: |
| 348 | (we preincrement the index to skip over the originator entry) */ |
| 349 | while ((symbol = &list->symlist[++idx])->name != 0) |
| 350 | { |
| 351 | if ((symbol->address == 0) |
| 352 | && (strneq (symbol->name, "@PROGRAM@"))) |
| 353 | { |
| 354 | lt_dlhandle handle = lt_dlopen (symbol->name); |
| 355 | if (handle == 0) |
| 356 | { |
| 357 | ++errors; |
| 358 | } |
| 359 | else |
| 360 | { |
| 361 | errors += (*func) (handle); |
| 362 | } |
| 363 | } |
| 364 | } |
| 365 | } |
| 366 | } |
| 367 | |
| 368 | if (!found) |
| 369 | { |
| 370 | LT__SETERROR(CANNOT_OPEN); |
| 371 | ++errors; |
| 372 | } |
| 373 | |
| 374 | return errors; |
| 375 | } |