2 * This implementation is based on code from uClibc-0.9.30.3 but was
3 * modified and extended for use within U-Boot.
5 * Copyright (C) 2010 Wolfgang Denk <wd@denx.de>
7 * Original license header:
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.
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.
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.
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
32 #ifdef USE_HOSTCC /* HOST build */
38 # define debug(fmt,args...) printf(fmt ,##args)
40 # define debug(fmt,args...)
43 #else /* U-Boot build */
45 # include <linux/string.h>
48 #ifndef CONFIG_ENV_MIN_ENTRIES /* minimum number of entries */
49 #define CONFIG_ENV_MIN_ENTRIES 64
51 #ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */
52 #define CONFIG_ENV_MAX_ENTRIES 512
58 * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
59 * [Knuth] The Art of Computer Programming, part 3 (6.4)
63 * The reentrant version has no static variables to maintain the state.
64 * Instead the interface of all functions is extended to take an argument
65 * which describes the current status.
67 typedef struct _ENTRY {
78 * For the used double hash method the table size has to be a prime. To
79 * correct the user given table size we need a prime test. This trivial
80 * algorithm is adequate because
81 * a) the code is (most probably) called a few times per program run and
82 * b) the number is small because the table must fit in the core
84 static int isprime(unsigned int number)
86 /* no even number will be passed */
89 while (div * div < number && number % div != 0)
92 return number % div != 0;
96 * Before using the hash table we must allocate memory for it.
97 * Test for an existing table are done. We allocate one element
98 * more as the found prime number says. This is done for more effective
99 * indexing as explained in the comment for the hsearch function.
100 * The contents of the table is zeroed, especially the field used
104 int hcreate_r(size_t nel, struct hsearch_data *htab)
106 /* Test for correct arguments. */
112 /* There is still another table active. Return with error. */
113 if (htab->table != NULL)
116 /* Change nel to the first prime number not smaller as nel. */
117 nel |= 1; /* make odd */
118 while (!isprime(nel))
124 /* allocate memory and zero out */
125 htab->table = (_ENTRY *) calloc(htab->size + 1, sizeof(_ENTRY));
126 if (htab->table == NULL)
129 /* everything went alright */
139 * After using the hash table it has to be destroyed. The used memory can
140 * be freed and the local static variable can be marked as not used.
143 void hdestroy_r(struct hsearch_data *htab)
147 /* Test for correct arguments. */
153 /* free used memory */
154 for (i = 1; i <= htab->size; ++i) {
155 if (htab->table[i].used > 0) {
156 ENTRY *ep = &htab->table[i].entry;
164 /* the sign for an existing table is an value != NULL in htable */
173 * This is the search function. It uses double hashing with open addressing.
174 * The argument item.key has to be a pointer to an zero terminated, most
175 * probably strings of chars. The function for generating a number of the
176 * strings is simple but fast. It can be replaced by a more complex function
177 * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
179 * We use an trick to speed up the lookup. The table is created by hcreate
180 * with one more element available. This enables us to use the index zero
181 * special. This index will never be used because we store the first hash
182 * index in the field used where zero means not used. Every other value
183 * means used. The used field can be used as a first fast comparison for
184 * equality of the stored and the parameter value. This helps to prevent
185 * unnecessary expensive calls of strcmp.
187 * This implementation differs from the standard library version of
188 * this function in a number of ways:
190 * - While the standard version does not make any assumptions about
191 * the type of the stored data objects at all, this implementation
192 * works with NUL terminated strings only.
193 * - Instead of storing just pointers to the original objects, we
194 * create local copies so the caller does not need to care about the
196 * - The standard implementation does not provide a way to update an
197 * existing entry. This version will create a new entry or update an
198 * existing one when both "action == ENTER" and "item.data != NULL".
199 * - Instead of returning 1 on success, we return the index into the
200 * internal hash table, which is also guaranteed to be positive.
201 * This allows us direct access to the found hash table slot for
202 * example for functions like hdelete().
205 int hmatch_r(const char *match, int last_idx, ENTRY ** retval,
206 struct hsearch_data *htab)
209 size_t key_len = strlen(match);
211 for (idx = last_idx + 1; idx < htab->size; ++idx) {
212 if (htab->table[idx].used > 0)
214 if (!strncmp(match, htab->table[idx].entry.key, key_len)) {
215 *retval = &htab->table[idx].entry;
225 int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval,
226 struct hsearch_data *htab)
230 unsigned int len = strlen(item.key);
232 unsigned int first_deleted = 0;
234 /* Compute an value for the given string. Perhaps use a better method. */
237 while (count-- > 0) {
239 hval += item.key[count];
243 * First hash function:
244 * simply take the modul but prevent zero.
250 /* The first index tried. */
253 if (htab->table[idx].used) {
255 * Further action might be required according to the
260 if (htab->table[idx].used == -1
264 if (htab->table[idx].used == hval
265 && strcmp(item.key, htab->table[idx].entry.key) == 0) {
266 /* Overwrite existing value? */
267 if ((action == ENTER) && (item.data != NULL)) {
268 free(htab->table[idx].entry.data);
269 htab->table[idx].entry.data =
271 if (!htab->table[idx].entry.data) {
277 /* return found entry */
278 *retval = &htab->table[idx].entry;
283 * Second hash function:
284 * as suggested in [Knuth]
286 hval2 = 1 + hval % (htab->size - 2);
290 * Because SIZE is prime this guarantees to
291 * step through all available indices.
294 idx = htab->size + idx - hval2;
299 * If we visited all entries leave the loop
305 /* If entry is found use it. */
306 if ((htab->table[idx].used == hval)
307 && strcmp(item.key, htab->table[idx].entry.key) == 0) {
308 /* Overwrite existing value? */
309 if ((action == ENTER) && (item.data != NULL)) {
310 free(htab->table[idx].entry.data);
311 htab->table[idx].entry.data =
313 if (!htab->table[idx].entry.data) {
319 /* return found entry */
320 *retval = &htab->table[idx].entry;
324 while (htab->table[idx].used);
327 /* An empty bucket has been found. */
328 if (action == ENTER) {
330 * If table is full and another entry should be
331 * entered return with error.
333 if (htab->filled == htab->size) {
341 * create copies of item.key and item.data
346 htab->table[idx].used = hval;
347 htab->table[idx].entry.key = strdup(item.key);
348 htab->table[idx].entry.data = strdup(item.data);
349 if (!htab->table[idx].entry.key ||
350 !htab->table[idx].entry.data) {
358 /* return new entry */
359 *retval = &htab->table[idx].entry;
374 * The standard implementation of hsearch(3) does not provide any way
375 * to delete any entries from the hash table. We extend the code to
379 int hdelete_r(const char *key, struct hsearch_data *htab)
384 debug("hdelete: DELETE key \"%s\"\n", key);
388 if ((idx = hsearch_r(e, FIND, &ep, htab)) == 0) {
390 return 0; /* not found */
393 /* free used ENTRY */
394 debug("hdelete: DELETING key \"%s\"\n", key);
398 htab->table[idx].used = -1;
410 * Export the data stored in the hash table in linearized form.
412 * Entries are exported as "name=value" strings, separated by an
413 * arbitrary (non-NUL, of course) separator character. This allows to
414 * use this function both when formatting the U-Boot environment for
415 * external storage (using '\0' as separator), but also when using it
416 * for the "printenv" command to print all variables, simply by using
417 * as '\n" as separator. This can also be used for new features like
418 * exporting the environment data as text file, including the option
419 * for later re-import.
421 * The entries in the result list will be sorted by ascending key
424 * If the separator character is different from NUL, then any
425 * separator characters and backslash characters in the values will
426 * be escaped by a preceeding backslash in output. This is needed for
427 * example to enable multi-line values, especially when the output
428 * shall later be parsed (for example, for re-import).
430 * There are several options how the result buffer is handled:
434 * NULL 0 A string of sufficient length will be allocated.
435 * NULL >0 A string of the size given will be
436 * allocated. An error will be returned if the size is
437 * not sufficient. Any unused bytes in the string will
439 * !NULL 0 The user-supplied buffer will be used. No length
440 * checking will be performed, i. e. it is assumed that
441 * the buffer size will always be big enough. DANGEROUS.
442 * !NULL >0 The user-supplied buffer will be used. An error will
443 * be returned if the size is not sufficient. Any unused
444 * bytes in the string will be '\0'-padded.
447 static int cmpkey(const void *p1, const void *p2)
449 ENTRY *e1 = *(ENTRY **) p1;
450 ENTRY *e2 = *(ENTRY **) p2;
452 return (strcmp(e1->key, e2->key));
455 ssize_t hexport_r(struct hsearch_data *htab, const char sep,
456 char **resp, size_t size)
458 ENTRY *list[htab->size];
463 /* Test for correct arguments. */
464 if ((resp == NULL) || (htab == NULL)) {
469 debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, size = %d\n",
470 htab, htab->size, htab->filled, size);
473 * search used entries,
474 * save addresses and compute total length
476 for (i = 1, n = 0, totlen = 0; i <= htab->size; ++i) {
478 if (htab->table[i].used > 0) {
479 ENTRY *ep = &htab->table[i].entry;
483 totlen += strlen(ep->key) + 2;
486 totlen += strlen(ep->data);
487 } else { /* check if escapes are needed */
492 /* add room for needed escape chars */
493 if ((*s == sep) || (*s == '\\'))
498 totlen += 2; /* for '=' and 'sep' char */
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);
511 /* Sort list by keys */
512 qsort(list, n, sizeof(ENTRY *), cmpkey);
514 /* Check if the user supplied buffer size is sufficient */
516 if (size < totlen + 1) { /* provided buffer too small */
517 debug("### buffer too small: %d, but need %d\n",
526 /* Check if the user provided a buffer */
530 memset(res, '\0', size);
532 /* no, allocate and clear one */
533 *resp = res = calloc(1, size);
541 * export sorted list of result data
543 for (i = 0, p = res; i < n; ++i) {
554 if ((*s == sep) || (*s == '\\'))
555 *p++ = '\\'; /* escape */
560 *p = '\0'; /* terminate result */
571 * Import linearized data into hash table.
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.
576 * Entries without "value", i. e. consisting of only "name" or
577 * "name=", will cause this entry to be deleted from the hash table.
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.
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).
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.
594 * [NOTE: this means that a variable name cannot start with a '#'
597 * When using a non-NUL separator character, backslash is used as
598 * escape character in the value part, allowing for example for
601 * In theory, arbitrary separator characters can be used, but only
602 * '\0' and '\n' have really been tested.
605 int himport_r(struct hsearch_data *htab,
606 const char *env, size_t size, const char sep, int flag)
608 char *data, *sp, *dp, *name, *value;
610 /* Test for correct arguments. */
616 /* we allocate new space to make sure we can write to the array */
617 if ((data = malloc(size)) == NULL) {
618 debug("himport_r: can't malloc %d bytes\n", size);
622 memcpy(data, env, size);
625 if ((flag & H_NOCLEAR) == 0) {
626 /* Destroy old hash table if one exists */
627 debug("Destroy Hash Table: %p table = %p\n", htab,
634 * Create new hash table (if needed). The computation of the hash
635 * table size is based on heuristics: in a sample of some 70+
636 * existing systems we found an average size of 39+ bytes per entry
637 * in the environment (for the whole key=value pair). Assuming a
638 * size of 8 per entry (= safety factor of ~5) should provide enough
639 * safety margin for any existing environment definitions and still
640 * allow for more than enough dynamic additions. Note that the
641 * "size" argument is supposed to give the maximum enviroment size
642 * (CONFIG_ENV_SIZE). This heuristics will result in
643 * unreasonably large numbers (and thus memory footprint) for
644 * big flash environments (>8,000 entries for 64 KB
645 * envrionment size), so we clip it to a reasonable value.
646 * On the other hand we need to add some more entries for free
647 * space when importing very small buffers. Both boundaries can
648 * be overwritten in the board config file if needed.
652 int nent = CONFIG_ENV_MIN_ENTRIES + size / 8;
654 if (nent > CONFIG_ENV_MAX_ENTRIES)
655 nent = CONFIG_ENV_MAX_ENTRIES;
657 debug("Create Hash Table: N=%d\n", nent);
659 if (hcreate_r(nent, htab) == 0) {
665 /* Parse environment; allow for '\0' and 'sep' as separators */
669 /* skip leading white space */
670 while ((*dp == ' ') || (*dp == '\t'))
673 /* skip comment lines */
675 while (*dp && (*dp != sep))
682 for (name = dp; *dp != '=' && *dp && *dp != sep; ++dp)
685 /* deal with "name" and "name=" entries (delete var) */
686 if (*dp == '\0' || *(dp + 1) == '\0' ||
687 *dp == sep || *(dp + 1) == sep) {
690 *dp++ = '\0'; /* terminate name */
692 debug("DELETE CANDIDATE: \"%s\"\n", name);
694 if (hdelete_r(name, htab) == 0)
695 debug("DELETE ERROR ##############################\n");
699 *dp++ = '\0'; /* terminate name */
701 /* parse value; deal with escapes */
702 for (value = sp = dp; *dp && (*dp != sep); ++dp) {
703 if ((*dp == '\\') && *(dp + 1))
707 *sp++ = '\0'; /* terminate value */
710 /* enter into hash table */
714 hsearch_r(e, ENTER, &rv, htab);
716 printf("himport_r: can't insert \"%s=%s\" into hash table\n",
721 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
722 htab, htab->filled, htab->size,
724 } while ((dp < data + size) && *dp); /* size check needed for text */
725 /* without '\0' termination */
726 debug("INSERT: free(data = %p)\n", data);
729 debug("INSERT: done\n");
730 return 1; /* everything OK */