blob: 7ac3dddda693897f2a08cfda4ea682e943ab3e39 [file] [log] [blame]
Wolfgang Denka6826fb2010-06-20 13:17:12 +02001/*
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
Andreas Bießmannfc5fc762010-10-01 22:51:02 +020048#ifndef CONFIG_ENV_MIN_ENTRIES /* minimum number of entries */
49#define CONFIG_ENV_MIN_ENTRIES 64
50#endif
Wolfgang Denkea882ba2010-06-20 23:33:59 +020051#ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */
52#define CONFIG_ENV_MAX_ENTRIES 512
53#endif
54
Wolfgang Denka6826fb2010-06-20 13:17:12 +020055#include "search.h"
56
57/*
58 * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
Wolfgang Denk071bc922010-10-27 22:48:30 +020059 * [Knuth] The Art of Computer Programming, part 3 (6.4)
Wolfgang Denka6826fb2010-06-20 13:17:12 +020060 */
61
62/*
63 * The non-reentrant version use a global space for storing the hash table.
64 */
65static 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 */
72typedef 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 * */
89static 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
100int 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 */
113int 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 */
146void 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 */
155void 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
217ENTRY *hsearch(ENTRY item, ACTION action)
218{
219 ENTRY *result;
220
221 (void) hsearch_r(item, action, &result, &htab);
222
223 return result;
224}
225
226int 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 /*
Wolfgang Denk071bc922010-10-27 22:48:30 +0200255 * Further action might be required according to the
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200256 * 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 /*
Wolfgang Denk071bc922010-10-27 22:48:30 +0200286 * Because SIZE is prime this guarantees to
287 * step through all available indices.
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200288 */
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 /*
Wolfgang Denk071bc922010-10-27 22:48:30 +0200326 * If table is full and another entry should be
327 * entered return with error.
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200328 */
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
372int hdelete(const char *key)
373{
374 return hdelete_r(key, &htab);
375}
376
377int 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
445ssize_t hexport(const char sep, char **resp, size_t size)
446{
447 return hexport_r(&htab, sep, resp, size);
448}
449
450static 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
458ssize_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
608int himport(const char *env, size_t size, const char sep, int flag)
609{
610 return himport_r(&htab, env, size, sep, flag);
611}
612
613int 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
Wolfgang Denkea882ba2010-06-20 23:33:59 +0200646 * size of 8 per entry (= safety factor of ~5) should provide enough
647 * safety margin for any existing environment definitions and still
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200648 * allow for more than enough dynamic additions. Note that the
649 * "size" argument is supposed to give the maximum enviroment size
Wolfgang Denkea882ba2010-06-20 23:33:59 +0200650 * (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
Andreas Bießmannfc5fc762010-10-01 22:51:02 +0200653 * 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.
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200657 */
658
659 if (!htab->table) {
Andreas Bießmannfc5fc762010-10-01 22:51:02 +0200660 int nent = CONFIG_ENV_MIN_ENTRIES + size / 8;
Wolfgang Denkea882ba2010-06-20 23:33:59 +0200661
662 if (nent > CONFIG_ENV_MAX_ENTRIES)
663 nent = CONFIG_ENV_MAX_ENTRIES;
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200664
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) {
Wolfgang Denkea882ba2010-06-20 23:33:59 +0200724 printf("himport_r: can't insert \"%s=%s\" into hash table\n",
725 name, value);
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200726 return 0;
727 }
728
Wolfgang Denkea882ba2010-06-20 23:33:59 +0200729 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
730 htab, htab->filled, htab->size,
731 rv, name, value);
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200732 } while ((dp < data + size) && *dp); /* size check needed for text */
733 /* without '\0' termination */
Wolfgang Denkea882ba2010-06-20 23:33:59 +0200734 debug("INSERT: free(data = %p)\n", data);
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200735 free(data);
736
Wolfgang Denkea882ba2010-06-20 23:33:59 +0200737 debug("INSERT: done\n");
Wolfgang Denka6826fb2010-06-20 13:17:12 +0200738 return 1; /* everything OK */
739}