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 */
39 # define debug(fmt,args...) printf(fmt ,##args)
41 # define debug(fmt,args...)
44 #else /* U-Boot build */
46 # include <linux/string.h>
47 # include <linux/ctype.h>
50 #ifndef CONFIG_ENV_MIN_ENTRIES /* minimum number of entries */
51 #define CONFIG_ENV_MIN_ENTRIES 64
53 #ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */
54 #define CONFIG_ENV_MAX_ENTRIES 512
60 * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
61 * [Knuth] The Art of Computer Programming, part 3 (6.4)
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.
69 typedef struct _ENTRY {
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
86 static int isprime(unsigned int number)
88 /* no even number will be passed */
91 while (div * div < number && number % div != 0)
94 return number % div != 0;
98 * Before using the hash table we must allocate memory for it.
99 * Test for an existing table are done. We allocate one element
100 * more as the found prime number says. This is done for more effective
101 * indexing as explained in the comment for the hsearch function.
102 * The contents of the table is zeroed, especially the field used
106 int hcreate_r(size_t nel, struct hsearch_data *htab)
108 /* Test for correct arguments. */
114 /* There is still another table active. Return with error. */
115 if (htab->table != NULL)
118 /* Change nel to the first prime number not smaller as nel. */
119 nel |= 1; /* make odd */
120 while (!isprime(nel))
126 /* allocate memory and zero out */
127 htab->table = (_ENTRY *) calloc(htab->size + 1, sizeof(_ENTRY));
128 if (htab->table == NULL)
131 /* everything went alright */
141 * After using the hash table it has to be destroyed. The used memory can
142 * be freed and the local static variable can be marked as not used.
145 void hdestroy_r(struct hsearch_data *htab, int do_apply)
149 /* Test for correct arguments. */
155 /* free used memory */
156 for (i = 1; i <= htab->size; ++i) {
157 if (htab->table[i].used > 0) {
158 ENTRY *ep = &htab->table[i].entry;
159 if (do_apply && htab->apply != NULL) {
160 /* deletion is always forced */
161 htab->apply(ep->key, ep->data, NULL, H_FORCE);
163 free((void *)ep->key);
169 /* the sign for an existing table is an value != NULL in htable */
178 * This is the search function. It uses double hashing with open addressing.
179 * The argument item.key has to be a pointer to an zero terminated, most
180 * probably strings of chars. The function for generating a number of the
181 * strings is simple but fast. It can be replaced by a more complex function
182 * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
184 * We use an trick to speed up the lookup. The table is created by hcreate
185 * with one more element available. This enables us to use the index zero
186 * special. This index will never be used because we store the first hash
187 * index in the field used where zero means not used. Every other value
188 * means used. The used field can be used as a first fast comparison for
189 * equality of the stored and the parameter value. This helps to prevent
190 * unnecessary expensive calls of strcmp.
192 * This implementation differs from the standard library version of
193 * this function in a number of ways:
195 * - While the standard version does not make any assumptions about
196 * the type of the stored data objects at all, this implementation
197 * works with NUL terminated strings only.
198 * - Instead of storing just pointers to the original objects, we
199 * create local copies so the caller does not need to care about the
201 * - The standard implementation does not provide a way to update an
202 * existing entry. This version will create a new entry or update an
203 * existing one when both "action == ENTER" and "item.data != NULL".
204 * - Instead of returning 1 on success, we return the index into the
205 * internal hash table, which is also guaranteed to be positive.
206 * This allows us direct access to the found hash table slot for
207 * example for functions like hdelete().
211 * hstrstr_r - return index to entry whose key and/or data contains match
213 int hstrstr_r(const char *match, int last_idx, ENTRY ** retval,
214 struct hsearch_data *htab)
218 for (idx = last_idx + 1; idx < htab->size; ++idx) {
219 if (htab->table[idx].used <= 0)
221 if (strstr(htab->table[idx].entry.key, match) ||
222 strstr(htab->table[idx].entry.data, match)) {
223 *retval = &htab->table[idx].entry;
233 int hmatch_r(const char *match, int last_idx, ENTRY ** retval,
234 struct hsearch_data *htab)
237 size_t key_len = strlen(match);
239 for (idx = last_idx + 1; idx < htab->size; ++idx) {
240 if (htab->table[idx].used <= 0)
242 if (!strncmp(match, htab->table[idx].entry.key, key_len)) {
243 *retval = &htab->table[idx].entry;
253 int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval,
254 struct hsearch_data *htab)
258 unsigned int len = strlen(item.key);
260 unsigned int first_deleted = 0;
262 /* Compute an value for the given string. Perhaps use a better method. */
265 while (count-- > 0) {
267 hval += item.key[count];
271 * First hash function:
272 * simply take the modul but prevent zero.
278 /* The first index tried. */
281 if (htab->table[idx].used) {
283 * Further action might be required according to the
288 if (htab->table[idx].used == -1
292 if (htab->table[idx].used == hval
293 && strcmp(item.key, htab->table[idx].entry.key) == 0) {
294 /* Overwrite existing value? */
295 if ((action == ENTER) && (item.data != NULL)) {
296 free(htab->table[idx].entry.data);
297 htab->table[idx].entry.data =
299 if (!htab->table[idx].entry.data) {
305 /* return found entry */
306 *retval = &htab->table[idx].entry;
311 * Second hash function:
312 * as suggested in [Knuth]
314 hval2 = 1 + hval % (htab->size - 2);
318 * Because SIZE is prime this guarantees to
319 * step through all available indices.
322 idx = htab->size + idx - hval2;
327 * If we visited all entries leave the loop
333 /* If entry is found use it. */
334 if ((htab->table[idx].used == hval)
335 && strcmp(item.key, htab->table[idx].entry.key) == 0) {
336 /* Overwrite existing value? */
337 if ((action == ENTER) && (item.data != NULL)) {
338 free(htab->table[idx].entry.data);
339 htab->table[idx].entry.data =
341 if (!htab->table[idx].entry.data) {
347 /* return found entry */
348 *retval = &htab->table[idx].entry;
352 while (htab->table[idx].used);
355 /* An empty bucket has been found. */
356 if (action == ENTER) {
358 * If table is full and another entry should be
359 * entered return with error.
361 if (htab->filled == htab->size) {
369 * create copies of item.key and item.data
374 htab->table[idx].used = hval;
375 htab->table[idx].entry.key = strdup(item.key);
376 htab->table[idx].entry.data = strdup(item.data);
377 if (!htab->table[idx].entry.key ||
378 !htab->table[idx].entry.data) {
386 /* return new entry */
387 *retval = &htab->table[idx].entry;
402 * The standard implementation of hsearch(3) does not provide any way
403 * to delete any entries from the hash table. We extend the code to
407 int hdelete_r(const char *key, struct hsearch_data *htab, int do_apply)
412 debug("hdelete: DELETE key \"%s\"\n", key);
416 if ((idx = hsearch_r(e, FIND, &ep, htab)) == 0) {
418 return 0; /* not found */
421 /* free used ENTRY */
422 debug("hdelete: DELETING key \"%s\"\n", key);
423 if (do_apply && htab->apply != NULL)
424 htab->apply(ep->key, ep->data, NULL, H_FORCE);
425 free((void *)ep->key);
427 htab->table[idx].used = -1;
439 * Export the data stored in the hash table in linearized form.
441 * Entries are exported as "name=value" strings, separated by an
442 * arbitrary (non-NUL, of course) separator character. This allows to
443 * use this function both when formatting the U-Boot environment for
444 * external storage (using '\0' as separator), but also when using it
445 * for the "printenv" command to print all variables, simply by using
446 * as '\n" as separator. This can also be used for new features like
447 * exporting the environment data as text file, including the option
448 * for later re-import.
450 * The entries in the result list will be sorted by ascending key
453 * If the separator character is different from NUL, then any
454 * separator characters and backslash characters in the values will
455 * be escaped by a preceeding backslash in output. This is needed for
456 * example to enable multi-line values, especially when the output
457 * shall later be parsed (for example, for re-import).
459 * There are several options how the result buffer is handled:
463 * NULL 0 A string of sufficient length will be allocated.
464 * NULL >0 A string of the size given will be
465 * allocated. An error will be returned if the size is
466 * not sufficient. Any unused bytes in the string will
468 * !NULL 0 The user-supplied buffer will be used. No length
469 * checking will be performed, i. e. it is assumed that
470 * the buffer size will always be big enough. DANGEROUS.
471 * !NULL >0 The user-supplied buffer will be used. An error will
472 * be returned if the size is not sufficient. Any unused
473 * bytes in the string will be '\0'-padded.
476 static int cmpkey(const void *p1, const void *p2)
478 ENTRY *e1 = *(ENTRY **) p1;
479 ENTRY *e2 = *(ENTRY **) p2;
481 return (strcmp(e1->key, e2->key));
484 ssize_t hexport_r(struct hsearch_data *htab, const char sep,
485 char **resp, size_t size,
486 int argc, char * const argv[])
488 ENTRY *list[htab->size];
493 /* Test for correct arguments. */
494 if ((resp == NULL) || (htab == NULL)) {
499 debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, "
500 "size = %zu\n", htab, htab->size, htab->filled, size);
503 * search used entries,
504 * save addresses and compute total length
506 for (i = 1, n = 0, totlen = 0; i <= htab->size; ++i) {
508 if (htab->table[i].used > 0) {
509 ENTRY *ep = &htab->table[i].entry;
512 for (arg = 0; arg < argc; ++arg) {
513 if (strcmp(argv[arg], ep->key) == 0) {
518 if ((argc > 0) && (found == 0))
523 totlen += strlen(ep->key) + 2;
526 totlen += strlen(ep->data);
527 } else { /* check if escapes are needed */
532 /* add room for needed escape chars */
533 if ((*s == sep) || (*s == '\\'))
538 totlen += 2; /* for '=' and 'sep' char */
543 /* Pass 1a: print unsorted list */
544 printf("Unsorted: n=%d\n", n);
545 for (i = 0; i < n; ++i) {
546 printf("\t%3d: %p ==> %-10s => %s\n",
547 i, list[i], list[i]->key, list[i]->data);
551 /* Sort list by keys */
552 qsort(list, n, sizeof(ENTRY *), cmpkey);
554 /* Check if the user supplied buffer size is sufficient */
556 if (size < totlen + 1) { /* provided buffer too small */
557 printf("Env export buffer too small: %zu, "
558 "but need %zu\n", size, totlen + 1);
566 /* Check if the user provided a buffer */
570 memset(res, '\0', size);
572 /* no, allocate and clear one */
573 *resp = res = calloc(1, size);
581 * export sorted list of result data
583 for (i = 0, p = res; i < n; ++i) {
594 if ((*s == sep) || (*s == '\\'))
595 *p++ = '\\'; /* escape */
600 *p = '\0'; /* terminate result */
611 * Check whether variable 'name' is amongst vars[],
612 * and remove all instances by setting the pointer to NULL
614 static int drop_var_from_set(const char *name, int nvars, char * vars[])
619 /* No variables specified means process all of them */
623 for (i = 0; i < nvars; i++) {
626 /* If we found it, delete all of them */
627 if (!strcmp(name, vars[i])) {
633 debug("Skipping non-listed variable %s\n", name);
639 * Import linearized data into hash table.
641 * This is the inverse function to hexport(): it takes a linear list
642 * of "name=value" pairs and creates hash table entries from it.
644 * Entries without "value", i. e. consisting of only "name" or
645 * "name=", will cause this entry to be deleted from the hash table.
647 * The "flag" argument can be used to control the behaviour: when the
648 * H_NOCLEAR bit is set, then an existing hash table will kept, i. e.
649 * new data will be added to an existing hash table; otherwise, old
650 * data will be discarded and a new hash table will be created.
652 * The separator character for the "name=value" pairs can be selected,
653 * so we both support importing from externally stored environment
654 * data (separated by NUL characters) and from plain text files
655 * (entries separated by newline characters).
657 * To allow for nicely formatted text input, leading white space
658 * (sequences of SPACE and TAB chars) is ignored, and entries starting
659 * (after removal of any leading white space) with a '#' character are
660 * considered comments and ignored.
662 * [NOTE: this means that a variable name cannot start with a '#'
665 * When using a non-NUL separator character, backslash is used as
666 * escape character in the value part, allowing for example for
669 * In theory, arbitrary separator characters can be used, but only
670 * '\0' and '\n' have really been tested.
673 int himport_r(struct hsearch_data *htab,
674 const char *env, size_t size, const char sep, int flag,
675 int nvars, char * const vars[], int do_apply)
677 char *data, *sp, *dp, *name, *value;
678 char *localvars[nvars];
681 /* Test for correct arguments. */
687 /* we allocate new space to make sure we can write to the array */
688 if ((data = malloc(size)) == NULL) {
689 debug("himport_r: can't malloc %zu bytes\n", size);
693 memcpy(data, env, size);
696 /* make a local copy of the list of variables */
698 memcpy(localvars, vars, sizeof(vars[0]) * nvars);
700 if ((flag & H_NOCLEAR) == 0) {
701 /* Destroy old hash table if one exists */
702 debug("Destroy Hash Table: %p table = %p\n", htab,
705 hdestroy_r(htab, do_apply);
709 * Create new hash table (if needed). The computation of the hash
710 * table size is based on heuristics: in a sample of some 70+
711 * existing systems we found an average size of 39+ bytes per entry
712 * in the environment (for the whole key=value pair). Assuming a
713 * size of 8 per entry (= safety factor of ~5) should provide enough
714 * safety margin for any existing environment definitions and still
715 * allow for more than enough dynamic additions. Note that the
716 * "size" argument is supposed to give the maximum enviroment size
717 * (CONFIG_ENV_SIZE). This heuristics will result in
718 * unreasonably large numbers (and thus memory footprint) for
719 * big flash environments (>8,000 entries for 64 KB
720 * envrionment size), so we clip it to a reasonable value.
721 * On the other hand we need to add some more entries for free
722 * space when importing very small buffers. Both boundaries can
723 * be overwritten in the board config file if needed.
727 int nent = CONFIG_ENV_MIN_ENTRIES + size / 8;
729 if (nent > CONFIG_ENV_MAX_ENTRIES)
730 nent = CONFIG_ENV_MAX_ENTRIES;
732 debug("Create Hash Table: N=%d\n", nent);
734 if (hcreate_r(nent, htab) == 0) {
740 /* Parse environment; allow for '\0' and 'sep' as separators */
744 /* skip leading white space */
748 /* skip comment lines */
750 while (*dp && (*dp != sep))
757 for (name = dp; *dp != '=' && *dp && *dp != sep; ++dp)
760 /* deal with "name" and "name=" entries (delete var) */
761 if (*dp == '\0' || *(dp + 1) == '\0' ||
762 *dp == sep || *(dp + 1) == sep) {
765 *dp++ = '\0'; /* terminate name */
767 debug("DELETE CANDIDATE: \"%s\"\n", name);
768 if (!drop_var_from_set(name, nvars, localvars))
771 if (hdelete_r(name, htab, do_apply) == 0)
772 debug("DELETE ERROR ##############################\n");
776 *dp++ = '\0'; /* terminate name */
778 /* parse value; deal with escapes */
779 for (value = sp = dp; *dp && (*dp != sep); ++dp) {
780 if ((*dp == '\\') && *(dp + 1))
784 *sp++ = '\0'; /* terminate value */
787 /* Skip variables which are not supposed to be processed */
788 if (!drop_var_from_set(name, nvars, localvars))
791 /* enter into hash table */
795 /* if there is an apply function, check what it has to say */
796 if (do_apply && htab->apply != NULL) {
797 debug("searching before calling cb function"
800 * Search for variable in existing env, so to pass
801 * its previous value to the apply callback
803 hsearch_r(e, FIND, &rv, htab);
804 debug("previous value was %s\n", rv ? rv->data : "");
805 if (htab->apply(name, rv ? rv->data : NULL,
807 debug("callback function refused to set"
808 " variable %s, skipping it!\n", name);
813 hsearch_r(e, ENTER, &rv, htab);
815 printf("himport_r: can't insert \"%s=%s\" into hash table\n",
820 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
821 htab, htab->filled, htab->size,
823 } while ((dp < data + size) && *dp); /* size check needed for text */
824 /* without '\0' termination */
825 debug("INSERT: free(data = %p)\n", data);
828 /* process variables which were not considered */
829 for (i = 0; i < nvars; i++) {
830 if (localvars[i] == NULL)
833 * All variables which were not deleted from the variable list
834 * were not present in the imported env
835 * This could mean two things:
836 * a) if the variable was present in current env, we delete it
837 * b) if the variable was not present in current env, we notify
840 if (hdelete_r(localvars[i], htab, do_apply) == 0)
841 printf("WARNING: '%s' neither in running nor in imported env!\n", localvars[i]);
843 printf("WARNING: '%s' not in imported env, deleting it!\n", localvars[i]);
846 debug("INSERT: done\n");
847 return 1; /* everything OK */