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_MIN_ENTRIES /* minimum number of entries */ 49 #define CONFIG_ENV_MIN_ENTRIES 64 50 #endif 51 #ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */ 52 #define CONFIG_ENV_MAX_ENTRIES 512 53 #endif 54 55 #include "search.h" 56 57 /* 58 * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986 59 * [Knuth] The Art of Computer Programming, part 3 (6.4) 60 */ 61 62 /* 63 * The non-reentrant version use a global space for storing the hash table. 64 */ 65 static struct hsearch_data htab; 66 67 /* 68 * The reentrant version has no static variables to maintain the state. 69 * Instead the interface of all functions is extended to take an argument 70 * which describes the current status. 71 */ 72 typedef struct _ENTRY { 73 unsigned int used; 74 ENTRY entry; 75 } _ENTRY; 76 77 78 /* 79 * hcreate() 80 */ 81 82 /* 83 * For the used double hash method the table size has to be a prime. To 84 * correct the user given table size we need a prime test. This trivial 85 * algorithm is adequate because 86 * a) the code is (most probably) called a few times per program run and 87 * b) the number is small because the table must fit in the core 88 * */ 89 static int isprime(unsigned int number) 90 { 91 /* no even number will be passed */ 92 unsigned int div = 3; 93 94 while (div * div < number && number % div != 0) 95 div += 2; 96 97 return number % div != 0; 98 } 99 100 int hcreate(size_t nel) 101 { 102 return hcreate_r(nel, &htab); 103 } 104 105 /* 106 * Before using the hash table we must allocate memory for it. 107 * Test for an existing table are done. We allocate one element 108 * more as the found prime number says. This is done for more effective 109 * indexing as explained in the comment for the hsearch function. 110 * The contents of the table is zeroed, especially the field used 111 * becomes zero. 112 */ 113 int hcreate_r(size_t nel, struct hsearch_data *htab) 114 { 115 /* Test for correct arguments. */ 116 if (htab == NULL) { 117 __set_errno(EINVAL); 118 return 0; 119 } 120 121 /* There is still another table active. Return with error. */ 122 if (htab->table != NULL) 123 return 0; 124 125 /* Change nel to the first prime number not smaller as nel. */ 126 nel |= 1; /* make odd */ 127 while (!isprime(nel)) 128 nel += 2; 129 130 htab->size = nel; 131 htab->filled = 0; 132 133 /* allocate memory and zero out */ 134 htab->table = (_ENTRY *) calloc(htab->size + 1, sizeof(_ENTRY)); 135 if (htab->table == NULL) 136 return 0; 137 138 /* everything went alright */ 139 return 1; 140 } 141 142 143 /* 144 * hdestroy() 145 */ 146 void hdestroy(void) 147 { 148 hdestroy_r(&htab); 149 } 150 151 /* 152 * After using the hash table it has to be destroyed. The used memory can 153 * be freed and the local static variable can be marked as not used. 154 */ 155 void hdestroy_r(struct hsearch_data *htab) 156 { 157 int i; 158 159 /* Test for correct arguments. */ 160 if (htab == NULL) { 161 __set_errno(EINVAL); 162 return; 163 } 164 165 /* free used memory */ 166 for (i = 1; i <= htab->size; ++i) { 167 if (htab->table[i].used) { 168 ENTRY *ep = &htab->table[i].entry; 169 170 free(ep->key); 171 free(ep->data); 172 } 173 } 174 free(htab->table); 175 176 /* the sign for an existing table is an value != NULL in htable */ 177 htab->table = NULL; 178 } 179 180 /* 181 * hsearch() 182 */ 183 184 /* 185 * This is the search function. It uses double hashing with open addressing. 186 * The argument item.key has to be a pointer to an zero terminated, most 187 * probably strings of chars. The function for generating a number of the 188 * strings is simple but fast. It can be replaced by a more complex function 189 * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown. 190 * 191 * We use an trick to speed up the lookup. The table is created by hcreate 192 * with one more element available. This enables us to use the index zero 193 * special. This index will never be used because we store the first hash 194 * index in the field used where zero means not used. Every other value 195 * means used. The used field can be used as a first fast comparison for 196 * equality of the stored and the parameter value. This helps to prevent 197 * unnecessary expensive calls of strcmp. 198 * 199 * This implementation differs from the standard library version of 200 * this function in a number of ways: 201 * 202 * - While the standard version does not make any assumptions about 203 * the type of the stored data objects at all, this implementation 204 * works with NUL terminated strings only. 205 * - Instead of storing just pointers to the original objects, we 206 * create local copies so the caller does not need to care about the 207 * data any more. 208 * - The standard implementation does not provide a way to update an 209 * existing entry. This version will create a new entry or update an 210 * existing one when both "action == ENTER" and "item.data != NULL". 211 * - Instead of returning 1 on success, we return the index into the 212 * internal hash table, which is also guaranteed to be positive. 213 * This allows us direct access to the found hash table slot for 214 * example for functions like hdelete(). 215 */ 216 217 ENTRY *hsearch(ENTRY item, ACTION action) 218 { 219 ENTRY *result; 220 221 (void) hsearch_r(item, action, &result, &htab); 222 223 return result; 224 } 225 226 int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval, 227 struct hsearch_data *htab) 228 { 229 unsigned int hval; 230 unsigned int count; 231 unsigned int len = strlen(item.key); 232 unsigned int idx; 233 234 /* Compute an value for the given string. Perhaps use a better method. */ 235 hval = len; 236 count = len; 237 while (count-- > 0) { 238 hval <<= 4; 239 hval += item.key[count]; 240 } 241 242 /* 243 * First hash function: 244 * simply take the modul but prevent zero. 245 */ 246 hval %= htab->size; 247 if (hval == 0) 248 ++hval; 249 250 /* The first index tried. */ 251 idx = hval; 252 253 if (htab->table[idx].used) { 254 /* 255 * Further action might be required according to the 256 * action value. 257 */ 258 unsigned hval2; 259 260 if (htab->table[idx].used == hval 261 && strcmp(item.key, htab->table[idx].entry.key) == 0) { 262 /* Overwrite existing value? */ 263 if ((action == ENTER) && (item.data != NULL)) { 264 free(htab->table[idx].entry.data); 265 htab->table[idx].entry.data = 266 strdup(item.data); 267 if (!htab->table[idx].entry.data) { 268 __set_errno(ENOMEM); 269 *retval = NULL; 270 return 0; 271 } 272 } 273 /* return found entry */ 274 *retval = &htab->table[idx].entry; 275 return idx; 276 } 277 278 /* 279 * Second hash function: 280 * as suggested in [Knuth] 281 */ 282 hval2 = 1 + hval % (htab->size - 2); 283 284 do { 285 /* 286 * Because SIZE is prime this guarantees to 287 * step through all available indices. 288 */ 289 if (idx <= hval2) 290 idx = htab->size + idx - hval2; 291 else 292 idx -= hval2; 293 294 /* 295 * If we visited all entries leave the loop 296 * unsuccessfully. 297 */ 298 if (idx == hval) 299 break; 300 301 /* If entry is found use it. */ 302 if ((htab->table[idx].used == hval) 303 && strcmp(item.key, htab->table[idx].entry.key) == 0) { 304 /* Overwrite existing value? */ 305 if ((action == ENTER) && (item.data != NULL)) { 306 free(htab->table[idx].entry.data); 307 htab->table[idx].entry.data = 308 strdup(item.data); 309 if (!htab->table[idx].entry.data) { 310 __set_errno(ENOMEM); 311 *retval = NULL; 312 return 0; 313 } 314 } 315 /* return found entry */ 316 *retval = &htab->table[idx].entry; 317 return idx; 318 } 319 } 320 while (htab->table[idx].used); 321 } 322 323 /* An empty bucket has been found. */ 324 if (action == ENTER) { 325 /* 326 * If table is full and another entry should be 327 * entered return with error. 328 */ 329 if (htab->filled == htab->size) { 330 __set_errno(ENOMEM); 331 *retval = NULL; 332 return 0; 333 } 334 335 /* 336 * Create new entry; 337 * create copies of item.key and item.data 338 */ 339 htab->table[idx].used = hval; 340 htab->table[idx].entry.key = strdup(item.key); 341 htab->table[idx].entry.data = strdup(item.data); 342 if (!htab->table[idx].entry.key || 343 !htab->table[idx].entry.data) { 344 __set_errno(ENOMEM); 345 *retval = NULL; 346 return 0; 347 } 348 349 ++htab->filled; 350 351 /* return new entry */ 352 *retval = &htab->table[idx].entry; 353 return 1; 354 } 355 356 __set_errno(ESRCH); 357 *retval = NULL; 358 return 0; 359 } 360 361 362 /* 363 * hdelete() 364 */ 365 366 /* 367 * The standard implementation of hsearch(3) does not provide any way 368 * to delete any entries from the hash table. We extend the code to 369 * do that. 370 */ 371 372 int hdelete(const char *key) 373 { 374 return hdelete_r(key, &htab); 375 } 376 377 int hdelete_r(const char *key, struct hsearch_data *htab) 378 { 379 ENTRY e, *ep; 380 int idx; 381 382 debug("hdelete: DELETE key \"%s\"\n", key); 383 384 e.key = (char *)key; 385 386 if ((idx = hsearch_r(e, FIND, &ep, htab)) == 0) { 387 __set_errno(ESRCH); 388 return 0; /* not found */ 389 } 390 391 /* free used ENTRY */ 392 debug("hdelete: DELETING key \"%s\"\n", key); 393 394 free(ep->key); 395 free(ep->data); 396 htab->table[idx].used = 0; 397 398 --htab->filled; 399 400 return 1; 401 } 402 403 /* 404 * hexport() 405 */ 406 407 /* 408 * Export the data stored in the hash table in linearized form. 409 * 410 * Entries are exported as "name=value" strings, separated by an 411 * arbitrary (non-NUL, of course) separator character. This allows to 412 * use this function both when formatting the U-Boot environment for 413 * external storage (using '\0' as separator), but also when using it 414 * for the "printenv" command to print all variables, simply by using 415 * as '\n" as separator. This can also be used for new features like 416 * exporting the environment data as text file, including the option 417 * for later re-import. 418 * 419 * The entries in the result list will be sorted by ascending key 420 * values. 421 * 422 * If the separator character is different from NUL, then any 423 * separator characters and backslash characters in the values will 424 * be escaped by a preceeding backslash in output. This is needed for 425 * example to enable multi-line values, especially when the output 426 * shall later be parsed (for example, for re-import). 427 * 428 * There are several options how the result buffer is handled: 429 * 430 * *resp size 431 * ----------- 432 * NULL 0 A string of sufficient length will be allocated. 433 * NULL >0 A string of the size given will be 434 * allocated. An error will be returned if the size is 435 * not sufficient. Any unused bytes in the string will 436 * be '\0'-padded. 437 * !NULL 0 The user-supplied buffer will be used. No length 438 * checking will be performed, i. e. it is assumed that 439 * the buffer size will always be big enough. DANGEROUS. 440 * !NULL >0 The user-supplied buffer will be used. An error will 441 * be returned if the size is not sufficient. Any unused 442 * bytes in the string will be '\0'-padded. 443 */ 444 445 ssize_t hexport(const char sep, char **resp, size_t size) 446 { 447 return hexport_r(&htab, sep, resp, size); 448 } 449 450 static int cmpkey(const void *p1, const void *p2) 451 { 452 ENTRY *e1 = *(ENTRY **) p1; 453 ENTRY *e2 = *(ENTRY **) p2; 454 455 return (strcmp(e1->key, e2->key)); 456 } 457 458 ssize_t hexport_r(struct hsearch_data *htab, const char sep, 459 char **resp, size_t size) 460 { 461 ENTRY *list[htab->size]; 462 char *res, *p; 463 size_t totlen; 464 int i, n; 465 466 /* Test for correct arguments. */ 467 if ((resp == NULL) || (htab == NULL)) { 468 __set_errno(EINVAL); 469 return (-1); 470 } 471 472 debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, size = %d\n", 473 htab, htab->size, htab->filled, size); 474 /* 475 * Pass 1: 476 * search used entries, 477 * save addresses and compute total length 478 */ 479 for (i = 1, n = 0, totlen = 0; i <= htab->size; ++i) { 480 481 if (htab->table[i].used) { 482 ENTRY *ep = &htab->table[i].entry; 483 484 list[n++] = ep; 485 486 totlen += strlen(ep->key) + 2; 487 488 if (sep == '\0') { 489 totlen += strlen(ep->data); 490 } else { /* check if escapes are needed */ 491 char *s = ep->data; 492 493 while (*s) { 494 ++totlen; 495 /* add room for needed escape chars */ 496 if ((*s == sep) || (*s == '\\')) 497 ++totlen; 498 ++s; 499 } 500 } 501 totlen += 2; /* for '=' and 'sep' char */ 502 } 503 } 504 505 #ifdef DEBUG 506 /* Pass 1a: print unsorted list */ 507 printf("Unsorted: n=%d\n", n); 508 for (i = 0; i < n; ++i) { 509 printf("\t%3d: %p ==> %-10s => %s\n", 510 i, list[i], list[i]->key, list[i]->data); 511 } 512 #endif 513 514 /* Sort list by keys */ 515 qsort(list, n, sizeof(ENTRY *), cmpkey); 516 517 /* Check if the user supplied buffer size is sufficient */ 518 if (size) { 519 if (size < totlen + 1) { /* provided buffer too small */ 520 debug("### buffer too small: %d, but need %d\n", 521 size, totlen + 1); 522 __set_errno(ENOMEM); 523 return (-1); 524 } 525 } else { 526 size = totlen + 1; 527 } 528 529 /* Check if the user provided a buffer */ 530 if (*resp) { 531 /* yes; clear it */ 532 res = *resp; 533 memset(res, '\0', size); 534 } else { 535 /* no, allocate and clear one */ 536 *resp = res = calloc(1, size); 537 if (res == NULL) { 538 __set_errno(ENOMEM); 539 return (-1); 540 } 541 } 542 /* 543 * Pass 2: 544 * export sorted list of result data 545 */ 546 for (i = 0, p = res; i < n; ++i) { 547 char *s; 548 549 s = list[i]->key; 550 while (*s) 551 *p++ = *s++; 552 *p++ = '='; 553 554 s = list[i]->data; 555 556 while (*s) { 557 if ((*s == sep) || (*s == '\\')) 558 *p++ = '\\'; /* escape */ 559 *p++ = *s++; 560 } 561 *p++ = sep; 562 } 563 *p = '\0'; /* terminate result */ 564 565 return size; 566 } 567 568 569 /* 570 * himport() 571 */ 572 573 /* 574 * Import linearized data into hash table. 575 * 576 * This is the inverse function to hexport(): it takes a linear list 577 * of "name=value" pairs and creates hash table entries from it. 578 * 579 * Entries without "value", i. e. consisting of only "name" or 580 * "name=", will cause this entry to be deleted from the hash table. 581 * 582 * The "flag" argument can be used to control the behaviour: when the 583 * H_NOCLEAR bit is set, then an existing hash table will kept, i. e. 584 * new data will be added to an existing hash table; otherwise, old 585 * data will be discarded and a new hash table will be created. 586 * 587 * The separator character for the "name=value" pairs can be selected, 588 * so we both support importing from externally stored environment 589 * data (separated by NUL characters) and from plain text files 590 * (entries separated by newline characters). 591 * 592 * To allow for nicely formatted text input, leading white space 593 * (sequences of SPACE and TAB chars) is ignored, and entries starting 594 * (after removal of any leading white space) with a '#' character are 595 * considered comments and ignored. 596 * 597 * [NOTE: this means that a variable name cannot start with a '#' 598 * character.] 599 * 600 * When using a non-NUL separator character, backslash is used as 601 * escape character in the value part, allowing for example for 602 * multi-line values. 603 * 604 * In theory, arbitrary separator characters can be used, but only 605 * '\0' and '\n' have really been tested. 606 */ 607 608 int himport(const char *env, size_t size, const char sep, int flag) 609 { 610 return himport_r(&htab, env, size, sep, flag); 611 } 612 613 int himport_r(struct hsearch_data *htab, 614 const char *env, size_t size, const char sep, int flag) 615 { 616 char *data, *sp, *dp, *name, *value; 617 618 /* Test for correct arguments. */ 619 if (htab == NULL) { 620 __set_errno(EINVAL); 621 return 0; 622 } 623 624 /* we allocate new space to make sure we can write to the array */ 625 if ((data = malloc(size)) == NULL) { 626 debug("himport_r: can't malloc %d bytes\n", size); 627 __set_errno(ENOMEM); 628 return 0; 629 } 630 memcpy(data, env, size); 631 dp = data; 632 633 if ((flag & H_NOCLEAR) == 0) { 634 /* Destroy old hash table if one exists */ 635 debug("Destroy Hash Table: %p table = %p\n", htab, 636 htab->table); 637 if (htab->table) 638 hdestroy_r(htab); 639 } 640 641 /* 642 * Create new hash table (if needed). The computation of the hash 643 * table size is based on heuristics: in a sample of some 70+ 644 * existing systems we found an average size of 39+ bytes per entry 645 * in the environment (for the whole key=value pair). Assuming a 646 * size of 8 per entry (= safety factor of ~5) should provide enough 647 * safety margin for any existing environment definitions and still 648 * allow for more than enough dynamic additions. Note that the 649 * "size" argument is supposed to give the maximum enviroment size 650 * (CONFIG_ENV_SIZE). This heuristics will result in 651 * unreasonably large numbers (and thus memory footprint) for 652 * big flash environments (>8,000 entries for 64 KB 653 * envrionment size), so we clip it to a reasonable value. 654 * On the other hand we need to add some more entries for free 655 * space when importing very small buffers. Both boundaries can 656 * be overwritten in the board config file if needed. 657 */ 658 659 if (!htab->table) { 660 int nent = CONFIG_ENV_MIN_ENTRIES + size / 8; 661 662 if (nent > CONFIG_ENV_MAX_ENTRIES) 663 nent = CONFIG_ENV_MAX_ENTRIES; 664 665 debug("Create Hash Table: N=%d\n", nent); 666 667 if (hcreate_r(nent, htab) == 0) { 668 free(data); 669 return 0; 670 } 671 } 672 673 /* Parse environment; allow for '\0' and 'sep' as separators */ 674 do { 675 ENTRY e, *rv; 676 677 /* skip leading white space */ 678 while ((*dp == ' ') || (*dp == '\t')) 679 ++dp; 680 681 /* skip comment lines */ 682 if (*dp == '#') { 683 while (*dp && (*dp != sep)) 684 ++dp; 685 ++dp; 686 continue; 687 } 688 689 /* parse name */ 690 for (name = dp; *dp != '=' && *dp && *dp != sep; ++dp) 691 ; 692 693 /* deal with "name" and "name=" entries (delete var) */ 694 if (*dp == '\0' || *(dp + 1) == '\0' || 695 *dp == sep || *(dp + 1) == sep) { 696 if (*dp == '=') 697 *dp++ = '\0'; 698 *dp++ = '\0'; /* terminate name */ 699 700 debug("DELETE CANDIDATE: \"%s\"\n", name); 701 702 if (hdelete_r(name, htab) == 0) 703 debug("DELETE ERROR ##############################\n"); 704 705 continue; 706 } 707 *dp++ = '\0'; /* terminate name */ 708 709 /* parse value; deal with escapes */ 710 for (value = sp = dp; *dp && (*dp != sep); ++dp) { 711 if ((*dp == '\\') && *(dp + 1)) 712 ++dp; 713 *sp++ = *dp; 714 } 715 *sp++ = '\0'; /* terminate value */ 716 ++dp; 717 718 /* enter into hash table */ 719 e.key = name; 720 e.data = value; 721 722 hsearch_r(e, ENTER, &rv, htab); 723 if (rv == NULL) { 724 printf("himport_r: can't insert \"%s=%s\" into hash table\n", 725 name, value); 726 return 0; 727 } 728 729 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n", 730 htab, htab->filled, htab->size, 731 rv, name, value); 732 } while ((dp < data + size) && *dp); /* size check needed for text */ 733 /* without '\0' termination */ 734 debug("INSERT: free(data = %p)\n", data); 735 free(data); 736 737 debug("INSERT: done\n"); 738 return 1; /* everything OK */ 739 } 740