| 1 | /* |
| 2 | * dlf.c |
| 3 | * |
| 4 | * $Id$ |
| 5 | * |
| 6 | * Dynamic Library Loader (mapping to SVR4) |
| 7 | * |
| 8 | * The iODBC driver manager. |
| 9 | * |
| 10 | * Copyright (C) 1995 by Ke Jin <kejin@empress.com> |
| 11 | * |
| 12 | * This library is free software; you can redistribute it and/or |
| 13 | * modify it under the terms of the GNU Library General Public |
| 14 | * License as published by the Free Software Foundation; either |
| 15 | * version 2 of the License, or (at your option) any later version. |
| 16 | * |
| 17 | * This library is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 20 | * Library General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU Library General Public |
| 23 | * License along with this library; if not, write to the Free |
| 24 | * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 25 | */ |
| 26 | |
| 27 | #include "dlf.h" |
| 28 | #include <errno.h> |
| 29 | |
| 30 | #ifdef DLDAPI_DEFINED |
| 31 | #undef DLDAPI_DEFINED |
| 32 | #endif |
| 33 | |
| 34 | #ifdef DLDAPI_SVR4_DLFCN |
| 35 | #define DLDAPI_DEFINED |
| 36 | static char sccsid[] = "@(#)dynamic load interface -- SVR4 dlfcn"; |
| 37 | #endif |
| 38 | |
| 39 | /********************************* |
| 40 | * |
| 41 | * HP/UX |
| 42 | * |
| 43 | *********************************/ |
| 44 | |
| 45 | #ifdef DLDAPI_HP_SHL |
| 46 | #define DLDAPI_DEFINED |
| 47 | #include <dl.h> |
| 48 | |
| 49 | static char sccsid[] = "@(#)dynamic load interface -- HP/UX dl(shl)"; |
| 50 | |
| 51 | void * |
| 52 | dlopen (char *path, int mode) |
| 53 | { |
| 54 | return (void *) shl_load ((char *) (path), BIND_DEFERRED, 0L); |
| 55 | } |
| 56 | |
| 57 | |
| 58 | void * |
| 59 | dlsym (void *hdll, char *sym) |
| 60 | { |
| 61 | void *symaddr = 0; |
| 62 | int ret; |
| 63 | |
| 64 | if (!hdll) |
| 65 | hdll = (void *) PROG_HANDLE; |
| 66 | |
| 67 | /* Remember, a driver may export calls as function pointers |
| 68 | * (i.e. with type TYPE_DATA) rather than as functions |
| 69 | * (i.e. with type TYPE_PROCEDURE). Thus, to be safe, we |
| 70 | * uses TYPE_UNDEFINED to cover all of them. |
| 71 | */ |
| 72 | ret = shl_findsym ((shl_t *) & hdll, sym, TYPE_UNDEFINED, &symaddr); |
| 73 | |
| 74 | if (ret == -1) |
| 75 | return 0; |
| 76 | |
| 77 | return symaddr; |
| 78 | } |
| 79 | |
| 80 | |
| 81 | char * |
| 82 | dlerror () |
| 83 | { |
| 84 | extern char *strerror (); |
| 85 | |
| 86 | return strerror (errno); |
| 87 | } |
| 88 | |
| 89 | |
| 90 | int |
| 91 | dlclose (void *hdll) |
| 92 | { |
| 93 | return shl_unload ((shl_t) hdll); |
| 94 | } |
| 95 | #endif /* end of HP/UX Seection */ |
| 96 | |
| 97 | |
| 98 | /********************************* |
| 99 | * |
| 100 | * IBM AIX |
| 101 | * |
| 102 | *********************************/ |
| 103 | |
| 104 | #ifdef DLDAPI_AIX_LOAD |
| 105 | #define DLDAPI_DEFINED |
| 106 | #include <sys/types.h> |
| 107 | #include <sys/ldr.h> |
| 108 | #include <sys/stat.h> |
| 109 | #include <nlist.h> |
| 110 | |
| 111 | /* |
| 112 | * Following id sting is a copyright mark. Removing(i.e. use the |
| 113 | * source code in this .c file without include it or make it not |
| 114 | * appear in the final object file of AIX platform) or modifing |
| 115 | * it without permission from original author(kejin@empress.com) |
| 116 | * are copyright violation. |
| 117 | */ |
| 118 | static char sccsid[] |
| 119 | = "@(#)dynamic load interface, Copyright(c) 1995 by Ke Jin"; |
| 120 | |
| 121 | #ifndef HTAB_SIZE |
| 122 | #define HTAB_SIZE 256 |
| 123 | #endif |
| 124 | |
| 125 | #define FACTOR 0.618039887 /* i.e. (sqrt(5) - 1)/2 */ |
| 126 | |
| 127 | #ifndef ENTRY_SYM |
| 128 | #define ENTRY_SYM ".__start" /* default entry point for aix */ |
| 129 | #endif |
| 130 | |
| 131 | typedef struct slot_s |
| 132 | { |
| 133 | char *sym; |
| 134 | long fdesc[3]; /* 12 bytes function descriptor */ |
| 135 | struct slot_s *next; |
| 136 | } |
| 137 | slot_t; |
| 138 | |
| 139 | /* Note: on AIX, a function pointer actually points to a |
| 140 | * function descriptor, a 12 bytes data. The first 4 bytes |
| 141 | * is the virtual address of the function. The next 4 bytes |
| 142 | * is the virtual address of TOC (Table of Contents) of the |
| 143 | * object module the function belong to. The last 4 bytes |
| 144 | * are always 0 for C and Fortran functions. Every object |
| 145 | * module has an entry point (which can be specified at link |
| 146 | * time by -e ld option). iODBC driver manager requires ODBC |
| 147 | * driver shared library always use the default entry point |
| 148 | * (so you shouldn't use -e ld option when creating a driver |
| 149 | * share library). load() returns the function descriptor of |
| 150 | * a module's entry point. From which we can calculate function |
| 151 | * descriptors of other functions in the same module by using |
| 152 | * the fact that the load() doesn't change the relative |
| 153 | * offset of functions to their module entry point(i.e the |
| 154 | * offset in memory loaded by load() will be as same as in |
| 155 | * the module library file). |
| 156 | */ |
| 157 | |
| 158 | typedef slot_t *hent_t; |
| 159 | typedef struct nlist nlist_t; |
| 160 | typedef struct stat stat_t; |
| 161 | |
| 162 | typedef struct obj |
| 163 | { |
| 164 | int dev; /* device id */ |
| 165 | int ino; /* inode number */ |
| 166 | char *path; /* file name */ |
| 167 | int (*pentry) (); /* entry point of this share library */ |
| 168 | int refn; /* number of reference */ |
| 169 | hent_t htab[HTAB_SIZE]; |
| 170 | struct obj * next; |
| 171 | } |
| 172 | obj_t; |
| 173 | |
| 174 | static char *errmsg = 0; |
| 175 | |
| 176 | static void |
| 177 | init_htab (hent_t * ht) |
| 178 | /* initate a hashing table */ |
| 179 | { |
| 180 | int i; |
| 181 | |
| 182 | for (i = 0; i < HTAB_SIZE; i++) |
| 183 | ht[i] = (slot_t *) 0; |
| 184 | |
| 185 | return; |
| 186 | } |
| 187 | |
| 188 | |
| 189 | static void |
| 190 | clean_htab (hent_t * ht) |
| 191 | /* free all slots */ |
| 192 | { |
| 193 | int i; |
| 194 | slot_t *ent; |
| 195 | slot_t *tent; |
| 196 | |
| 197 | for (i = 0; i < HTAB_SIZE; i++) |
| 198 | { |
| 199 | for (ent = ht[i]; ent;) |
| 200 | { |
| 201 | tent = ent->next; |
| 202 | |
| 203 | free (ent->sym); |
| 204 | free (ent); |
| 205 | |
| 206 | ent = tent; |
| 207 | } |
| 208 | |
| 209 | ht[i] = 0; |
| 210 | } |
| 211 | |
| 212 | return; |
| 213 | } |
| 214 | |
| 215 | |
| 216 | static int |
| 217 | hash (char *sym) |
| 218 | { |
| 219 | int a, key; |
| 220 | double f; |
| 221 | |
| 222 | if (!sym || !*sym) |
| 223 | return 0; |
| 224 | |
| 225 | for (key = *sym; *sym; sym++) |
| 226 | { |
| 227 | key += *sym; |
| 228 | a = key; |
| 229 | |
| 230 | key = (int) ((a << 8) + (key >> 8)); |
| 231 | key = (key > 0) ? key : -key; |
| 232 | } |
| 233 | |
| 234 | f = key * FACTOR; |
| 235 | a = (int) f; |
| 236 | |
| 237 | return (int) ((HTAB_SIZE - 1) * (f - a)); |
| 238 | } |
| 239 | |
| 240 | |
| 241 | static hent_t |
| 242 | search (hent_t * htab, char *sym) |
| 243 | /* search hashing table to find a matched slot */ |
| 244 | { |
| 245 | int key; |
| 246 | slot_t *ent; |
| 247 | |
| 248 | key = hash (sym); |
| 249 | |
| 250 | for (ent = htab[key]; ent; ent = ent->next) |
| 251 | { |
| 252 | if (!strcmp (ent->sym, sym)) |
| 253 | return ent; |
| 254 | } |
| 255 | |
| 256 | return 0; /* no match */ |
| 257 | } |
| 258 | |
| 259 | |
| 260 | static void |
| 261 | insert (hent_t * htab, slot_t * ent) |
| 262 | /* insert a new slot to hashing table */ |
| 263 | { |
| 264 | int key; |
| 265 | |
| 266 | key = hash (ent->sym); |
| 267 | |
| 268 | ent->next = htab[key]; |
| 269 | htab[key] = ent; |
| 270 | |
| 271 | return; |
| 272 | } |
| 273 | |
| 274 | |
| 275 | static slot_t * |
| 276 | slot_alloc (char *sym) |
| 277 | /* allocate a new slot with symbol */ |
| 278 | { |
| 279 | slot_t *ent; |
| 280 | |
| 281 | ent = (slot_t *) malloc (sizeof (slot_t)); |
| 282 | |
| 283 | ent->sym = (char *) malloc (strlen (sym) + 1); |
| 284 | |
| 285 | if (!ent->sym) |
| 286 | { |
| 287 | free (ent); |
| 288 | return 0; |
| 289 | } |
| 290 | |
| 291 | strcpy (ent->sym, sym); |
| 292 | |
| 293 | return ent; |
| 294 | } |
| 295 | |
| 296 | |
| 297 | static obj_t *obj_list = 0; |
| 298 | |
| 299 | void * |
| 300 | dlopen (char *file, int mode) |
| 301 | { |
| 302 | stat_t st; |
| 303 | obj_t *pobj; |
| 304 | char buf[1024]; |
| 305 | |
| 306 | if (!file || !*file) |
| 307 | { |
| 308 | errno = EINVAL; |
| 309 | return 0; |
| 310 | } |
| 311 | |
| 312 | errno = 0; |
| 313 | errmsg = 0; |
| 314 | |
| 315 | if (stat (file, &st)) |
| 316 | return 0; |
| 317 | |
| 318 | for (pobj = obj_list; pobj; pobj = pobj->next) |
| 319 | /* find a match object */ |
| 320 | { |
| 321 | if (pobj->ino == st.st_ino |
| 322 | && pobj->dev == st.st_dev) |
| 323 | { |
| 324 | /* found a match. increase its |
| 325 | * reference count and return |
| 326 | * its address */ |
| 327 | pobj->refn++; |
| 328 | return pobj; |
| 329 | } |
| 330 | } |
| 331 | |
| 332 | pobj = (obj_t *) malloc (sizeof (obj_t)); |
| 333 | |
| 334 | if (!pobj) |
| 335 | return 0; |
| 336 | |
| 337 | pobj->path = (char *) malloc (strlen (file) + 1); |
| 338 | |
| 339 | if (!pobj->path) |
| 340 | { |
| 341 | free (pobj); |
| 342 | return 0; |
| 343 | } |
| 344 | |
| 345 | strcpy (pobj->path, file); |
| 346 | |
| 347 | pobj->dev = st.st_dev; |
| 348 | pobj->ino = st.st_ino; |
| 349 | pobj->refn = 1; |
| 350 | |
| 351 | pobj->pentry = (int (*)()) load (file, 0, 0); |
| 352 | |
| 353 | if (!pobj->pentry) |
| 354 | { |
| 355 | free (pobj->path); |
| 356 | free (pobj); |
| 357 | return 0; |
| 358 | } |
| 359 | |
| 360 | init_htab (pobj->htab); |
| 361 | |
| 362 | pobj->next = obj_list; |
| 363 | obj_list = pobj; |
| 364 | |
| 365 | return pobj; |
| 366 | } |
| 367 | |
| 368 | |
| 369 | int |
| 370 | dlclose (void *hobj) |
| 371 | { |
| 372 | obj_t *pobj = (obj_t *) hobj; |
| 373 | obj_t *tpobj; |
| 374 | int match = 0; |
| 375 | |
| 376 | if (!hobj) |
| 377 | { |
| 378 | errno = EINVAL; |
| 379 | return -1; |
| 380 | } |
| 381 | |
| 382 | errno = 0; |
| 383 | errmsg = 0; |
| 384 | |
| 385 | if (pobj == obj_list) |
| 386 | { |
| 387 | pobj->refn--; |
| 388 | |
| 389 | if (pobj->refn) |
| 390 | return 0; |
| 391 | |
| 392 | match = 1; |
| 393 | obj_list = pobj->next; |
| 394 | } |
| 395 | |
| 396 | for (tpobj = obj_list; !match && tpobj; tpobj = tpobj->next) |
| 397 | { |
| 398 | if (tpobj->next == pobj) |
| 399 | { |
| 400 | pobj->refn--; |
| 401 | |
| 402 | if (pobj->refn) |
| 403 | return 0; |
| 404 | |
| 405 | match = 1; |
| 406 | tpobj->next = pobj->next; |
| 407 | } |
| 408 | } |
| 409 | |
| 410 | if (match) |
| 411 | { |
| 412 | unload ((void *) (pobj->pentry)); |
| 413 | clean_htab (pobj->htab); |
| 414 | free (pobj->path); |
| 415 | free (pobj); |
| 416 | } |
| 417 | |
| 418 | return 0; |
| 419 | } |
| 420 | |
| 421 | |
| 422 | char * |
| 423 | dlerror () |
| 424 | { |
| 425 | extern char *sys_errlist[]; |
| 426 | |
| 427 | if (!errmsg || !errmsg[0]) |
| 428 | { |
| 429 | if (errno >= 0) |
| 430 | return sys_errlist[errno]; |
| 431 | |
| 432 | return ""; |
| 433 | } |
| 434 | |
| 435 | return errmsg; |
| 436 | } |
| 437 | |
| 438 | |
| 439 | void * |
| 440 | dlsym (void *hdl, char *sym) |
| 441 | { |
| 442 | nlist_t nl[3]; |
| 443 | obj_t *pobj = (obj_t *) hdl; |
| 444 | slot_t *ent; |
| 445 | int (*fp) (); |
| 446 | long lbuf[3]; |
| 447 | |
| 448 | if (!hdl || !(pobj->htab) || !sym || !*sym) |
| 449 | { |
| 450 | errno = EINVAL; |
| 451 | return 0; |
| 452 | } |
| 453 | |
| 454 | errno = 0; |
| 455 | errmsg = 0; |
| 456 | |
| 457 | ent = search (pobj->htab, sym); |
| 458 | |
| 459 | if (ent) |
| 460 | return ent->fdesc; |
| 461 | |
| 462 | #define n_name _n._n_name |
| 463 | |
| 464 | nl[0].n_name = ENTRY_SYM; |
| 465 | nl[1].n_name = sym; |
| 466 | nl[2].n_name = 0; |
| 467 | |
| 468 | /* There is a potential problem here. If application |
| 469 | * did not pass a full path name, and changed the |
| 470 | * working directory after the load(), then nlist() |
| 471 | * will be unable to open the original shared library |
| 472 | * file to resolve the symbols. there are 3 ways to working |
| 473 | * round this: 1. convert to full pathname in driver |
| 474 | * manager. 2. applications always pass driver's full |
| 475 | * path name. 3. if driver itself don't support |
| 476 | * SQLGetFunctions(), call it with SQL_ALL_FUNCTIONS |
| 477 | * as flag immidately after SQLConnect(), SQLDriverConnect() |
| 478 | * and SQLBrowseConnect() to force the driver manager |
| 479 | * resolving all will be used symbols. |
| 480 | */ |
| 481 | if (nlist (pobj->path, nl) == -1) |
| 482 | return 0; |
| 483 | |
| 484 | if (!nl[0].n_type && !nl[0].n_value) |
| 485 | { |
| 486 | errmsg = "can't locate module entry symbol"; |
| 487 | return 0; |
| 488 | } |
| 489 | |
| 490 | /* Note: On AIX 3.x if the object library is not |
| 491 | * built with -g compiling option, .n_type field |
| 492 | * is always 0. While on 4.x it will be 32. |
| 493 | * On AIX 4.x, if the symbol is a entry point, |
| 494 | * n_value will be 0. However, one thing is for sure |
| 495 | * that if a symbol is not existance in the file, |
| 496 | * both .n_type and .n_value would be 0. |
| 497 | */ |
| 498 | |
| 499 | if (!nl[1].n_type && !nl[1].n_value) |
| 500 | { |
| 501 | errmsg = "symbol not existance in this module"; |
| 502 | return 0; |
| 503 | } |
| 504 | |
| 505 | ent = slot_alloc (sym); |
| 506 | |
| 507 | if (!ent) |
| 508 | return 0; |
| 509 | |
| 510 | /* catch it with a slot in the hashing table */ |
| 511 | insert (pobj->htab, ent); |
| 512 | |
| 513 | memcpy (ent->fdesc, pobj->pentry, sizeof (ent->fdesc)); |
| 514 | |
| 515 | /* now ent->fdesc[0] is the virtual address of entry point |
| 516 | * and ent->fdesc[1] is the TOC of the module |
| 517 | */ |
| 518 | |
| 519 | /* let's calculate the virtual address of the symbol |
| 520 | * by adding a relative offset getting from the module |
| 521 | * file symbol table, i.e |
| 522 | * |
| 523 | * functin virtual address = entry point virtual address + |
| 524 | * + ( function offset in file - entry point offset in file ) |
| 525 | */ |
| 526 | |
| 527 | (ent->fdesc)[0] = (ent->fdesc)[0] + |
| 528 | (nl[1].n_value - nl[0].n_value); |
| 529 | |
| 530 | /* return the function descriptor */ |
| 531 | return ent->fdesc; |
| 532 | } |
| 533 | #endif /* end of IBM AIX Section */ |
| 534 | |
| 535 | |
| 536 | /********************************* |
| 537 | * |
| 538 | * Windows 3.x, 95, NT |
| 539 | * |
| 540 | *********************************/ |
| 541 | |
| 542 | #ifdef DLDAPI_WINDOWS |
| 543 | #define DLDAPI_DEFINED |
| 544 | #include <windows.h> |
| 545 | |
| 546 | void FAR * |
| 547 | dlopen (char FAR * dll, int mode) |
| 548 | { |
| 549 | HINSTANCE hint; |
| 550 | |
| 551 | if (dll == NULL) |
| 552 | { |
| 553 | return GetWindowWord (NULL, GWW_HINSTANCE); |
| 554 | } |
| 555 | |
| 556 | hint = LoadLibrary (dll); |
| 557 | |
| 558 | if (hint < HINSTANCE_ERROR) |
| 559 | { |
| 560 | return NULL; |
| 561 | } |
| 562 | |
| 563 | return (void FAR *) hint; |
| 564 | } |
| 565 | |
| 566 | |
| 567 | void FAR * |
| 568 | dlsym (void FAR * hdll, char FAR * sym) |
| 569 | { |
| 570 | return (void FAR *) GetProcAddress (hdll, sym); |
| 571 | } |
| 572 | |
| 573 | |
| 574 | char FAR * |
| 575 | dlerror () |
| 576 | { |
| 577 | return 0L; /* unimplemented yet */ |
| 578 | } |
| 579 | |
| 580 | |
| 581 | int |
| 582 | dlclose (void FAR * hdll) |
| 583 | { |
| 584 | FreeLibrary ((HINSTANCE) hdll); |
| 585 | } |
| 586 | #endif /* end of Windows family */ |
| 587 | |
| 588 | |
| 589 | /*********************************** |
| 590 | * |
| 591 | * other platforms |
| 592 | * |
| 593 | ***********************************/ |
| 594 | |
| 595 | #ifdef DLDAPI_OS2 |
| 596 | #define DLDAPI_DEFINED |
| 597 | /* |
| 598 | * DosLoadModule(), DosQueryProcAddress(), DosFreeModule(), ... |
| 599 | */ |
| 600 | #endif |
| 601 | |
| 602 | #ifdef DLDAPI_MAC |
| 603 | #define DLDAPI_DEFINED |
| 604 | #endif |
| 605 | |
| 606 | #ifdef DLDAPI_NEXT |
| 607 | #define DLDAPI_DEFINED |
| 608 | #endif |
| 609 | |
| 610 | #ifndef DLDAPI_DEFINED |
| 611 | #error "dynamic load editor undefined" |
| 612 | #endif |