1 /* 2 * This implementation is based on code from uClibc-0.9.30.3 but was 3 * modified and extended for use within U-Boot. 4 * 5 * Copyright (C) 2010 Wolfgang Denk <wd@denx.de> 6 * 7 * Original license header: 8 * 9 * Copyright (C) 1993, 1995, 1996, 1997, 2002 Free Software Foundation, Inc. 10 * This file is part of the GNU C Library. 11 * Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1993. 12 * 13 * The GNU C Library is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU Lesser General Public 15 * License as published by the Free Software Foundation; either 16 * version 2.1 of the License, or (at your option) any later version. 17 * 18 * The GNU C Library is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 * Lesser General Public License for more details. 22 * 23 * You should have received a copy of the GNU Lesser General Public 24 * License along with the GNU C Library; if not, write to the Free 25 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 26 * 02111-1307 USA. 27 */ 28 29 #include <errno.h> 30 #include <malloc.h> 31 32 #ifdef USE_HOSTCC /* HOST build */ 33 # include <string.h> 34 # include <assert.h> 35 36 # ifndef debug 37 # ifdef DEBUG 38 # define debug(fmt,args...) printf(fmt ,##args) 39 # else 40 # define debug(fmt,args...) 41 # endif 42 # endif 43 #else /* U-Boot build */ 44 # include <common.h> 45 # include <linux/string.h> 46 #endif 47 48 #ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */ 49 #define CONFIG_ENV_MAX_ENTRIES 512 50 #endif 51 52 #include "search.h" 53 54 /* 55 * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986 56 * [Knuth] The Art of Computer Programming, part 3 (6.4) 57 */ 58 59 /* 60 * The non-reentrant version use a global space for storing the hash table. 61 */ 62 static struct hsearch_data htab; 63 64 /* 65 * The reentrant version has no static variables to maintain the state. 66 * Instead the interface of all functions is extended to take an argument 67 * which describes the current status. 68 */ 69 typedef struct _ENTRY { 70 unsigned int used; 71 ENTRY entry; 72 } _ENTRY; 73 74 75 /* 76 * hcreate() 77 */ 78 79 /* 80 * For the used double hash method the table size has to be a prime. To 81 * correct the user given table size we need a prime test. This trivial 82 * algorithm is adequate because 83 * a) the code is (most probably) called a few times per program run and 84 * b) the number is small because the table must fit in the core 85 * */ 86 static int isprime(unsigned int number) 87 { 88 /* no even number will be passed */ 89 unsigned int div = 3; 90 91 while (div * div < number && number % div != 0) 92 div += 2; 93 94 return number % div != 0; 95 } 96 97 int hcreate(size_t nel) 98 { 99 return hcreate_r(nel, &htab); 100 } 101 102 /* 103 * Before using the hash table we must allocate memory for it. 104 * Test for an existing table are done. We allocate one element 105 * more as the found prime number says. This is done for more effective 106 * indexing as explained in the comment for the hsearch function. 107 * The contents of the table is zeroed, especially the field used 108 * becomes zero. 109 */ 110 int hcreate_r(size_t nel, struct hsearch_data *htab) 111 { 112 /* Test for correct arguments. */ 113 if (htab == NULL) { 114 __set_errno(EINVAL); 115 return 0; 116 } 117 118 /* There is still another table active. Return with error. */ 119 if (htab->table != NULL) 120 return 0; 121 122 /* Change nel to the first prime number not smaller as nel. */ 123 nel |= 1; /* make odd */ 124 while (!isprime(nel)) 125 nel += 2; 126 127 htab->size = nel; 128 htab->filled = 0; 129 130 /* allocate memory and zero out */ 131 htab->table = (_ENTRY *) calloc(htab->size + 1, sizeof(_ENTRY)); 132 if (htab->table == NULL) 133 return 0; 134 135 /* everything went alright */ 136 return 1; 137 } 138 139 140 /* 141 * hdestroy() 142 */ 143 void hdestroy(void) 144 { 145 hdestroy_r(&htab); 146 } 147 148 /* 149 * After using the hash table it has to be destroyed. The used memory can 150 * be freed and the local static variable can be marked as not used. 151 */ 152 void hdestroy_r(struct hsearch_data *htab) 153 { 154 int i; 155 156 /* Test for correct arguments. */ 157 if (htab == NULL) { 158 __set_errno(EINVAL); 159 return; 160 } 161 162 /* free used memory */ 163 for (i = 1; i <= htab->size; ++i) { 164 if (htab->table[i].used) { 165 ENTRY *ep = &htab->table[i].entry; 166 167 free(ep->key); 168 free(ep->data); 169 } 170 } 171 free(htab->table); 172 173 /* the sign for an existing table is an value != NULL in htable */ 174 htab->table = NULL; 175 } 176 177 /* 178 * hsearch() 179 */ 180 181 /* 182 * This is the search function. It uses double hashing with open addressing. 183 * The argument item.key has to be a pointer to an zero terminated, most 184 * probably strings of chars. The function for generating a number of the 185 * strings is simple but fast. It can be replaced by a more complex function 186 * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown. 187 * 188 * We use an trick to speed up the lookup. The table is created by hcreate 189 * with one more element available. This enables us to use the index zero 190 * special. This index will never be used because we store the first hash 191 * index in the field used where zero means not used. Every other value 192 * means used. The used field can be used as a first fast comparison for 193 * equality of the stored and the parameter value. This helps to prevent 194 * unnecessary expensive calls of strcmp. 195 * 196 * This implementation differs from the standard library version of 197 * this function in a number of ways: 198 * 199 * - While the standard version does not make any assumptions about 200 * the type of the stored data objects at all, this implementation 201 * works with NUL terminated strings only. 202 * - Instead of storing just pointers to the original objects, we 203 * create local copies so the caller does not need to care about the 204 * data any more. 205 * - The standard implementation does not provide a way to update an 206 * existing entry. This version will create a new entry or update an 207 * existing one when both "action == ENTER" and "item.data != NULL". 208 * - Instead of returning 1 on success, we return the index into the 209 * internal hash table, which is also guaranteed to be positive. 210 * This allows us direct access to the found hash table slot for 211 * example for functions like hdelete(). 212 */ 213 214 ENTRY *hsearch(ENTRY item, ACTION action) 215 { 216 ENTRY *result; 217 218 (void) hsearch_r(item, action, &result, &htab); 219 220 return result; 221 } 222 223 int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval, 224 struct hsearch_data *htab) 225 { 226 unsigned int hval; 227 unsigned int count; 228 unsigned int len = strlen(item.key); 229 unsigned int idx; 230 231 /* Compute an value for the given string. Perhaps use a better method. */ 232 hval = len; 233 count = len; 234 while (count-- > 0) { 235 hval <<= 4; 236 hval += item.key[count]; 237 } 238 239 /* 240 * First hash function: 241 * simply take the modul but prevent zero. 242 */ 243 hval %= htab->size; 244 if (hval == 0) 245 ++hval; 246 247 /* The first index tried. */ 248 idx = hval; 249 250 if (htab->table[idx].used) { 251 /* 252 * Further action might be required according to the 253 * action value. 254 */ 255 unsigned hval2; 256 257 if (htab->table[idx].used == hval 258 && strcmp(item.key, htab->table[idx].entry.key) == 0) { 259 /* Overwrite existing value? */ 260 if ((action == ENTER) && (item.data != NULL)) { 261 free(htab->table[idx].entry.data); 262 htab->table[idx].entry.data = 263 strdup(item.data); 264 if (!htab->table[idx].entry.data) { 265 __set_errno(ENOMEM); 266 *retval = NULL; 267 return 0; 268 } 269 } 270 /* return found entry */ 271 *retval = &htab->table[idx].entry; 272 return idx; 273 } 274 275 /* 276 * Second hash function: 277 * as suggested in [Knuth] 278 */ 279 hval2 = 1 + hval % (htab->size - 2); 280 281 do { 282 /* 283 * Because SIZE is prime this guarantees to 284 * step through all available indices. 285 */ 286 if (idx <= hval2) 287 idx = htab->size + idx - hval2; 288 else 289 idx -= hval2; 290 291 /* 292 * If we visited all entries leave the loop 293 * unsuccessfully. 294 */ 295 if (idx == hval) 296 break; 297 298 /* If entry is found use it. */ 299 if ((htab->table[idx].used == hval) 300 && strcmp(item.key, htab->table[idx].entry.key) == 0) { 301 /* Overwrite existing value? */ 302 if ((action == ENTER) && (item.data != NULL)) { 303 free(htab->table[idx].entry.data); 304 htab->table[idx].entry.data = 305 strdup(item.data); 306 if (!htab->table[idx].entry.data) { 307 __set_errno(ENOMEM); 308 *retval = NULL; 309 return 0; 310 } 311 } 312 /* return found entry */ 313 *retval = &htab->table[idx].entry; 314 return idx; 315 } 316 } 317 while (htab->table[idx].used); 318 } 319 320 /* An empty bucket has been found. */ 321 if (action == ENTER) { 322 /* 323 * If table is full and another entry should be 324 * entered return with error. 325 */ 326 if (htab->filled == htab->size) { 327 __set_errno(ENOMEM); 328 *retval = NULL; 329 return 0; 330 } 331 332 /* 333 * Create new entry; 334 * create copies of item.key and item.data 335 */ 336 htab->table[idx].used = hval; 337 htab->table[idx].entry.key = strdup(item.key); 338 htab->table[idx].entry.data = strdup(item.data); 339 if (!htab->table[idx].entry.key || 340 !htab->table[idx].entry.data) { 341 __set_errno(ENOMEM); 342 *retval = NULL; 343 return 0; 344 } 345 346 ++htab->filled; 347 348 /* return new entry */ 349 *retval = &htab->table[idx].entry; 350 return 1; 351 } 352 353 __set_errno(ESRCH); 354 *retval = NULL; 355 return 0; 356 } 357 358 359 /* 360 * hdelete() 361 */ 362 363 /* 364 * The standard implementation of hsearch(3) does not provide any way 365 * to delete any entries from the hash table. We extend the code to 366 * do that. 367 */ 368 369 int hdelete(const char *key) 370 { 371 return hdelete_r(key, &htab); 372 } 373 374 int hdelete_r(const char *key, struct hsearch_data *htab) 375 { 376 ENTRY e, *ep; 377 int idx; 378 379 debug("hdelete: DELETE key \"%s\"\n", key); 380 381 e.key = (char *)key; 382 383 if ((idx = hsearch_r(e, FIND, &ep, htab)) == 0) { 384 __set_errno(ESRCH); 385 return 0; /* not found */ 386 } 387 388 /* free used ENTRY */ 389 debug("hdelete: DELETING key \"%s\"\n", key); 390 391 free(ep->key); 392 free(ep->data); 393 htab->table[idx].used = 0; 394 395 --htab->filled; 396 397 return 1; 398 } 399 400 /* 401 * hexport() 402 */ 403 404 /* 405 * Export the data stored in the hash table in linearized form. 406 * 407 * Entries are exported as "name=value" strings, separated by an 408 * arbitrary (non-NUL, of course) separator character. This allows to 409 * use this function both when formatting the U-Boot environment for 410 * external storage (using '\0' as separator), but also when using it 411 * for the "printenv" command to print all variables, simply by using 412 * as '\n" as separator. This can also be used for new features like 413 * exporting the environment data as text file, including the option 414 * for later re-import. 415 * 416 * The entries in the result list will be sorted by ascending key 417 * values. 418 * 419 * If the separator character is different from NUL, then any 420 * separator characters and backslash characters in the values will 421 * be escaped by a preceeding backslash in output. This is needed for 422 * example to enable multi-line values, especially when the output 423 * shall later be parsed (for example, for re-import). 424 * 425 * There are several options how the result buffer is handled: 426 * 427 * *resp size 428 * ----------- 429 * NULL 0 A string of sufficient length will be allocated. 430 * NULL >0 A string of the size given will be 431 * allocated. An error will be returned if the size is 432 * not sufficient. Any unused bytes in the string will 433 * be '\0'-padded. 434 * !NULL 0 The user-supplied buffer will be used. No length 435 * checking will be performed, i. e. it is assumed that 436 * the buffer size will always be big enough. DANGEROUS. 437 * !NULL >0 The user-supplied buffer will be used. An error will 438 * be returned if the size is not sufficient. Any unused 439 * bytes in the string will be '\0'-padded. 440 */ 441 442 ssize_t hexport(const char sep, char **resp, size_t size) 443 { 444 return hexport_r(&htab, sep, resp, size); 445 } 446 447 static int cmpkey(const void *p1, const void *p2) 448 { 449 ENTRY *e1 = *(ENTRY **) p1; 450 ENTRY *e2 = *(ENTRY **) p2; 451 452 return (strcmp(e1->key, e2->key)); 453 } 454 455 ssize_t hexport_r(struct hsearch_data *htab, const char sep, 456 char **resp, size_t size) 457 { 458 ENTRY *list[htab->size]; 459 char *res, *p; 460 size_t totlen; 461 int i, n; 462 463 /* Test for correct arguments. */ 464 if ((resp == NULL) || (htab == NULL)) { 465 __set_errno(EINVAL); 466 return (-1); 467 } 468 469 debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, size = %d\n", 470 htab, htab->size, htab->filled, size); 471 /* 472 * Pass 1: 473 * search used entries, 474 * save addresses and compute total length 475 */ 476 for (i = 1, n = 0, totlen = 0; i <= htab->size; ++i) { 477 478 if (htab->table[i].used) { 479 ENTRY *ep = &htab->table[i].entry; 480 481 list[n++] = ep; 482 483 totlen += strlen(ep->key) + 2; 484 485 if (sep == '\0') { 486 totlen += strlen(ep->data); 487 } else { /* check if escapes are needed */ 488 char *s = ep->data; 489 490 while (*s) { 491 ++totlen; 492 /* add room for needed escape chars */ 493 if ((*s == sep) || (*s == '\\')) 494 ++totlen; 495 ++s; 496 } 497 } 498 totlen += 2; /* for '=' and 'sep' char */ 499 } 500 } 501 502 #ifdef DEBUG 503 /* Pass 1a: print unsorted list */ 504 printf("Unsorted: n=%d\n", n); 505 for (i = 0; i < n; ++i) { 506 printf("\t%3d: %p ==> %-10s => %s\n", 507 i, list[i], list[i]->key, list[i]->data); 508 } 509 #endif 510 511 /* Sort list by keys */ 512 qsort(list, n, sizeof(ENTRY *), cmpkey); 513 514 /* Check if the user supplied buffer size is sufficient */ 515 if (size) { 516 if (size < totlen + 1) { /* provided buffer too small */ 517 debug("### buffer too small: %d, but need %d\n", 518 size, totlen + 1); 519 __set_errno(ENOMEM); 520 return (-1); 521 } 522 } else { 523 size = totlen + 1; 524 } 525 526 /* Check if the user provided a buffer */ 527 if (*resp) { 528 /* yes; clear it */ 529 res = *resp; 530 memset(res, '\0', size); 531 } else { 532 /* no, allocate and clear one */ 533 *resp = res = calloc(1, size); 534 if (res == NULL) { 535 __set_errno(ENOMEM); 536 return (-1); 537 } 538 } 539 /* 540 * Pass 2: 541 * export sorted list of result data 542 */ 543 for (i = 0, p = res; i < n; ++i) { 544 char *s; 545 546 s = list[i]->key; 547 while (*s) 548 *p++ = *s++; 549 *p++ = '='; 550 551 s = list[i]->data; 552 553 while (*s) { 554 if ((*s == sep) || (*s == '\\')) 555 *p++ = '\\'; /* escape */ 556 *p++ = *s++; 557 } 558 *p++ = sep; 559 } 560 *p = '\0'; /* terminate result */ 561 562 return size; 563 } 564 565 566 /* 567 * himport() 568 */ 569 570 /* 571 * Import linearized data into hash table. 572 * 573 * This is the inverse function to hexport(): it takes a linear list 574 * of "name=value" pairs and creates hash table entries from it. 575 * 576 * Entries without "value", i. e. consisting of only "name" or 577 * "name=", will cause this entry to be deleted from the hash table. 578 * 579 * The "flag" argument can be used to control the behaviour: when the 580 * H_NOCLEAR bit is set, then an existing hash table will kept, i. e. 581 * new data will be added to an existing hash table; otherwise, old 582 * data will be discarded and a new hash table will be created. 583 * 584 * The separator character for the "name=value" pairs can be selected, 585 * so we both support importing from externally stored environment 586 * data (separated by NUL characters) and from plain text files 587 * (entries separated by newline characters). 588 * 589 * To allow for nicely formatted text input, leading white space 590 * (sequences of SPACE and TAB chars) is ignored, and entries starting 591 * (after removal of any leading white space) with a '#' character are 592 * considered comments and ignored. 593 * 594 * [NOTE: this means that a variable name cannot start with a '#' 595 * character.] 596 * 597 * When using a non-NUL separator character, backslash is used as 598 * escape character in the value part, allowing for example for 599 * multi-line values. 600 * 601 * In theory, arbitrary separator characters can be used, but only 602 * '\0' and '\n' have really been tested. 603 */ 604 605 int himport(const char *env, size_t size, const char sep, int flag) 606 { 607 return himport_r(&htab, env, size, sep, flag); 608 } 609 610 int himport_r(struct hsearch_data *htab, 611 const char *env, size_t size, const char sep, int flag) 612 { 613 char *data, *sp, *dp, *name, *value; 614 615 /* Test for correct arguments. */ 616 if (htab == NULL) { 617 __set_errno(EINVAL); 618 return 0; 619 } 620 621 /* we allocate new space to make sure we can write to the array */ 622 if ((data = malloc(size)) == NULL) { 623 debug("himport_r: can't malloc %d bytes\n", size); 624 __set_errno(ENOMEM); 625 return 0; 626 } 627 memcpy(data, env, size); 628 dp = data; 629 630 if ((flag & H_NOCLEAR) == 0) { 631 /* Destroy old hash table if one exists */ 632 debug("Destroy Hash Table: %p table = %p\n", htab, 633 htab->table); 634 if (htab->table) 635 hdestroy_r(htab); 636 } 637 638 /* 639 * Create new hash table (if needed). The computation of the hash 640 * table size is based on heuristics: in a sample of some 70+ 641 * existing systems we found an average size of 39+ bytes per entry 642 * in the environment (for the whole key=value pair). Assuming a 643 * size of 8 per entry (= safety factor of ~5) should provide enough 644 * safety margin for any existing environment definitions and still 645 * allow for more than enough dynamic additions. Note that the 646 * "size" argument is supposed to give the maximum enviroment size 647 * (CONFIG_ENV_SIZE). This heuristics will result in 648 * unreasonably large numbers (and thus memory footprint) for 649 * big flash environments (>8,000 entries for 64 KB 650 * envrionment size), so we clip it to a reasonable value 651 * (which can be overwritten in the board config file if 652 * needed). 653 */ 654 655 if (!htab->table) { 656 int nent = size / 8; 657 658 if (nent > CONFIG_ENV_MAX_ENTRIES) 659 nent = CONFIG_ENV_MAX_ENTRIES; 660 661 debug("Create Hash Table: N=%d\n", nent); 662 663 if (hcreate_r(nent, htab) == 0) { 664 free(data); 665 return 0; 666 } 667 } 668 669 /* Parse environment; allow for '\0' and 'sep' as separators */ 670 do { 671 ENTRY e, *rv; 672 673 /* skip leading white space */ 674 while ((*dp == ' ') || (*dp == '\t')) 675 ++dp; 676 677 /* skip comment lines */ 678 if (*dp == '#') { 679 while (*dp && (*dp != sep)) 680 ++dp; 681 ++dp; 682 continue; 683 } 684 685 /* parse name */ 686 for (name = dp; *dp != '=' && *dp && *dp != sep; ++dp) 687 ; 688 689 /* deal with "name" and "name=" entries (delete var) */ 690 if (*dp == '\0' || *(dp + 1) == '\0' || 691 *dp == sep || *(dp + 1) == sep) { 692 if (*dp == '=') 693 *dp++ = '\0'; 694 *dp++ = '\0'; /* terminate name */ 695 696 debug("DELETE CANDIDATE: \"%s\"\n", name); 697 698 if (hdelete_r(name, htab) == 0) 699 debug("DELETE ERROR ##############################\n"); 700 701 continue; 702 } 703 *dp++ = '\0'; /* terminate name */ 704 705 /* parse value; deal with escapes */ 706 for (value = sp = dp; *dp && (*dp != sep); ++dp) { 707 if ((*dp == '\\') && *(dp + 1)) 708 ++dp; 709 *sp++ = *dp; 710 } 711 *sp++ = '\0'; /* terminate value */ 712 ++dp; 713 714 /* enter into hash table */ 715 e.key = name; 716 e.data = value; 717 718 hsearch_r(e, ENTER, &rv, htab); 719 if (rv == NULL) { 720 printf("himport_r: can't insert \"%s=%s\" into hash table\n", 721 name, value); 722 return 0; 723 } 724 725 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n", 726 htab, htab->filled, htab->size, 727 rv, name, value); 728 } while ((dp < data + size) && *dp); /* size check needed for text */ 729 /* without '\0' termination */ 730 debug("INSERT: free(data = %p)\n", data); 731 free(data); 732 733 debug("INSERT: done\n"); 734 return 1; /* everything OK */ 735 } 736