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)
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;
160 free((void *)ep->key);
166 /* the sign for an existing table is an value != NULL in htable */
175 * This is the search function. It uses double hashing with open addressing.
176 * The argument item.key has to be a pointer to an zero terminated, most
177 * probably strings of chars. The function for generating a number of the
178 * strings is simple but fast. It can be replaced by a more complex function
179 * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
181 * We use an trick to speed up the lookup. The table is created by hcreate
182 * with one more element available. This enables us to use the index zero
183 * special. This index will never be used because we store the first hash
184 * index in the field used where zero means not used. Every other value
185 * means used. The used field can be used as a first fast comparison for
186 * equality of the stored and the parameter value. This helps to prevent
187 * unnecessary expensive calls of strcmp.
189 * This implementation differs from the standard library version of
190 * this function in a number of ways:
192 * - While the standard version does not make any assumptions about
193 * the type of the stored data objects at all, this implementation
194 * works with NUL terminated strings only.
195 * - Instead of storing just pointers to the original objects, we
196 * create local copies so the caller does not need to care about the
198 * - The standard implementation does not provide a way to update an
199 * existing entry. This version will create a new entry or update an
200 * existing one when both "action == ENTER" and "item.data != NULL".
201 * - Instead of returning 1 on success, we return the index into the
202 * internal hash table, which is also guaranteed to be positive.
203 * This allows us direct access to the found hash table slot for
204 * example for functions like hdelete().
208 * hstrstr_r - return index to entry whose key and/or data contains match
210 int hstrstr_r(const char *match, int last_idx, ENTRY ** retval,
211 struct hsearch_data *htab)
215 for (idx = last_idx + 1; idx < htab->size; ++idx) {
216 if (htab->table[idx].used <= 0)
218 if (strstr(htab->table[idx].entry.key, match) ||
219 strstr(htab->table[idx].entry.data, match)) {
220 *retval = &htab->table[idx].entry;
230 int hmatch_r(const char *match, int last_idx, ENTRY ** retval,
231 struct hsearch_data *htab)
234 size_t key_len = strlen(match);
236 for (idx = last_idx + 1; idx < htab->size; ++idx) {
237 if (htab->table[idx].used <= 0)
239 if (!strncmp(match, htab->table[idx].entry.key, key_len)) {
240 *retval = &htab->table[idx].entry;
251 * Compare an existing entry with the desired key, and overwrite if the action
252 * is ENTER. This is simply a helper function for hsearch_r().
254 static inline int _compare_and_overwrite_entry(ENTRY item, ACTION action,
255 ENTRY **retval, struct hsearch_data *htab, int flag,
256 unsigned int hval, unsigned int idx)
258 if (htab->table[idx].used == hval
259 && strcmp(item.key, htab->table[idx].entry.key) == 0) {
260 /* Overwrite existing value? */
261 if ((action == ENTER) && (item.data != NULL)) {
262 free(htab->table[idx].entry.data);
263 htab->table[idx].entry.data = strdup(item.data);
264 if (!htab->table[idx].entry.data) {
270 /* return found entry */
271 *retval = &htab->table[idx].entry;
278 int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval,
279 struct hsearch_data *htab, int flag)
283 unsigned int len = strlen(item.key);
285 unsigned int first_deleted = 0;
288 /* Compute an value for the given string. Perhaps use a better method. */
291 while (count-- > 0) {
293 hval += item.key[count];
297 * First hash function:
298 * simply take the modul but prevent zero.
304 /* The first index tried. */
307 if (htab->table[idx].used) {
309 * Further action might be required according to the
314 if (htab->table[idx].used == -1
318 ret = _compare_and_overwrite_entry(item, action, retval, htab,
324 * Second hash function:
325 * as suggested in [Knuth]
327 hval2 = 1 + hval % (htab->size - 2);
331 * Because SIZE is prime this guarantees to
332 * step through all available indices.
335 idx = htab->size + idx - hval2;
340 * If we visited all entries leave the loop
346 /* If entry is found use it. */
347 ret = _compare_and_overwrite_entry(item, action, retval,
348 htab, flag, hval, idx);
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 flag)
412 debug("hdelete: DELETE key \"%s\"\n", key);
416 idx = hsearch_r(e, FIND, &ep, htab, 0);
419 return 0; /* not found */
422 /* Check for permission */
423 if (htab->apply != NULL &&
424 htab->apply(ep->key, ep->data, NULL, flag)) {
429 /* free used ENTRY */
430 debug("hdelete: DELETING key \"%s\"\n", key);
431 free((void *)ep->key);
433 htab->table[idx].used = -1;
444 #ifndef CONFIG_SPL_BUILD
446 * Export the data stored in the hash table in linearized form.
448 * Entries are exported as "name=value" strings, separated by an
449 * arbitrary (non-NUL, of course) separator character. This allows to
450 * use this function both when formatting the U-Boot environment for
451 * external storage (using '\0' as separator), but also when using it
452 * for the "printenv" command to print all variables, simply by using
453 * as '\n" as separator. This can also be used for new features like
454 * exporting the environment data as text file, including the option
455 * for later re-import.
457 * The entries in the result list will be sorted by ascending key
460 * If the separator character is different from NUL, then any
461 * separator characters and backslash characters in the values will
462 * be escaped by a preceeding backslash in output. This is needed for
463 * example to enable multi-line values, especially when the output
464 * shall later be parsed (for example, for re-import).
466 * There are several options how the result buffer is handled:
470 * NULL 0 A string of sufficient length will be allocated.
471 * NULL >0 A string of the size given will be
472 * allocated. An error will be returned if the size is
473 * not sufficient. Any unused bytes in the string will
475 * !NULL 0 The user-supplied buffer will be used. No length
476 * checking will be performed, i. e. it is assumed that
477 * the buffer size will always be big enough. DANGEROUS.
478 * !NULL >0 The user-supplied buffer will be used. An error will
479 * be returned if the size is not sufficient. Any unused
480 * bytes in the string will be '\0'-padded.
483 static int cmpkey(const void *p1, const void *p2)
485 ENTRY *e1 = *(ENTRY **) p1;
486 ENTRY *e2 = *(ENTRY **) p2;
488 return (strcmp(e1->key, e2->key));
491 ssize_t hexport_r(struct hsearch_data *htab, const char sep,
492 char **resp, size_t size,
493 int argc, char * const argv[])
495 ENTRY *list[htab->size];
500 /* Test for correct arguments. */
501 if ((resp == NULL) || (htab == NULL)) {
506 debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, "
507 "size = %zu\n", htab, htab->size, htab->filled, size);
510 * search used entries,
511 * save addresses and compute total length
513 for (i = 1, n = 0, totlen = 0; i <= htab->size; ++i) {
515 if (htab->table[i].used > 0) {
516 ENTRY *ep = &htab->table[i].entry;
519 for (arg = 0; arg < argc; ++arg) {
520 if (strcmp(argv[arg], ep->key) == 0) {
525 if ((argc > 0) && (found == 0))
530 totlen += strlen(ep->key) + 2;
533 totlen += strlen(ep->data);
534 } else { /* check if escapes are needed */
539 /* add room for needed escape chars */
540 if ((*s == sep) || (*s == '\\'))
545 totlen += 2; /* for '=' and 'sep' char */
550 /* Pass 1a: print unsorted list */
551 printf("Unsorted: n=%d\n", n);
552 for (i = 0; i < n; ++i) {
553 printf("\t%3d: %p ==> %-10s => %s\n",
554 i, list[i], list[i]->key, list[i]->data);
558 /* Sort list by keys */
559 qsort(list, n, sizeof(ENTRY *), cmpkey);
561 /* Check if the user supplied buffer size is sufficient */
563 if (size < totlen + 1) { /* provided buffer too small */
564 printf("Env export buffer too small: %zu, "
565 "but need %zu\n", size, totlen + 1);
573 /* Check if the user provided a buffer */
577 memset(res, '\0', size);
579 /* no, allocate and clear one */
580 *resp = res = calloc(1, size);
588 * export sorted list of result data
590 for (i = 0, p = res; i < n; ++i) {
601 if ((*s == sep) || (*s == '\\'))
602 *p++ = '\\'; /* escape */
607 *p = '\0'; /* terminate result */
619 * Check whether variable 'name' is amongst vars[],
620 * and remove all instances by setting the pointer to NULL
622 static int drop_var_from_set(const char *name, int nvars, char * vars[])
627 /* No variables specified means process all of them */
631 for (i = 0; i < nvars; i++) {
634 /* If we found it, delete all of them */
635 if (!strcmp(name, vars[i])) {
641 debug("Skipping non-listed variable %s\n", name);
647 * Import linearized data into hash table.
649 * This is the inverse function to hexport(): it takes a linear list
650 * of "name=value" pairs and creates hash table entries from it.
652 * Entries without "value", i. e. consisting of only "name" or
653 * "name=", will cause this entry to be deleted from the hash table.
655 * The "flag" argument can be used to control the behaviour: when the
656 * H_NOCLEAR bit is set, then an existing hash table will kept, i. e.
657 * new data will be added to an existing hash table; otherwise, old
658 * data will be discarded and a new hash table will be created.
660 * The separator character for the "name=value" pairs can be selected,
661 * so we both support importing from externally stored environment
662 * data (separated by NUL characters) and from plain text files
663 * (entries separated by newline characters).
665 * To allow for nicely formatted text input, leading white space
666 * (sequences of SPACE and TAB chars) is ignored, and entries starting
667 * (after removal of any leading white space) with a '#' character are
668 * considered comments and ignored.
670 * [NOTE: this means that a variable name cannot start with a '#'
673 * When using a non-NUL separator character, backslash is used as
674 * escape character in the value part, allowing for example for
677 * In theory, arbitrary separator characters can be used, but only
678 * '\0' and '\n' have really been tested.
681 int himport_r(struct hsearch_data *htab,
682 const char *env, size_t size, const char sep, int flag,
683 int nvars, char * const vars[])
685 char *data, *sp, *dp, *name, *value;
686 char *localvars[nvars];
689 /* Test for correct arguments. */
695 /* we allocate new space to make sure we can write to the array */
696 if ((data = malloc(size)) == NULL) {
697 debug("himport_r: can't malloc %zu bytes\n", size);
701 memcpy(data, env, size);
704 /* make a local copy of the list of variables */
706 memcpy(localvars, vars, sizeof(vars[0]) * nvars);
708 if ((flag & H_NOCLEAR) == 0) {
709 /* Destroy old hash table if one exists */
710 debug("Destroy Hash Table: %p table = %p\n", htab,
717 * Create new hash table (if needed). The computation of the hash
718 * table size is based on heuristics: in a sample of some 70+
719 * existing systems we found an average size of 39+ bytes per entry
720 * in the environment (for the whole key=value pair). Assuming a
721 * size of 8 per entry (= safety factor of ~5) should provide enough
722 * safety margin for any existing environment definitions and still
723 * allow for more than enough dynamic additions. Note that the
724 * "size" argument is supposed to give the maximum enviroment size
725 * (CONFIG_ENV_SIZE). This heuristics will result in
726 * unreasonably large numbers (and thus memory footprint) for
727 * big flash environments (>8,000 entries for 64 KB
728 * envrionment size), so we clip it to a reasonable value.
729 * On the other hand we need to add some more entries for free
730 * space when importing very small buffers. Both boundaries can
731 * be overwritten in the board config file if needed.
735 int nent = CONFIG_ENV_MIN_ENTRIES + size / 8;
737 if (nent > CONFIG_ENV_MAX_ENTRIES)
738 nent = CONFIG_ENV_MAX_ENTRIES;
740 debug("Create Hash Table: N=%d\n", nent);
742 if (hcreate_r(nent, htab) == 0) {
748 /* Parse environment; allow for '\0' and 'sep' as separators */
752 /* skip leading white space */
756 /* skip comment lines */
758 while (*dp && (*dp != sep))
765 for (name = dp; *dp != '=' && *dp && *dp != sep; ++dp)
768 /* deal with "name" and "name=" entries (delete var) */
769 if (*dp == '\0' || *(dp + 1) == '\0' ||
770 *dp == sep || *(dp + 1) == sep) {
773 *dp++ = '\0'; /* terminate name */
775 debug("DELETE CANDIDATE: \"%s\"\n", name);
776 if (!drop_var_from_set(name, nvars, localvars))
779 if (hdelete_r(name, htab, flag) == 0)
780 debug("DELETE ERROR ##############################\n");
784 *dp++ = '\0'; /* terminate name */
786 /* parse value; deal with escapes */
787 for (value = sp = dp; *dp && (*dp != sep); ++dp) {
788 if ((*dp == '\\') && *(dp + 1))
792 *sp++ = '\0'; /* terminate value */
795 /* Skip variables which are not supposed to be processed */
796 if (!drop_var_from_set(name, nvars, localvars))
799 /* enter into hash table */
803 /* if there is an apply function, check what it has to say */
804 if (htab->apply != NULL) {
805 debug("searching before calling cb function"
808 * Search for variable in existing env, so to pass
809 * its previous value to the apply callback
811 hsearch_r(e, FIND, &rv, htab, 0);
812 debug("previous value was %s\n", rv ? rv->data : "");
813 if (htab->apply(name, rv ? rv->data : NULL,
815 debug("callback function refused to set"
816 " variable %s, skipping it!\n", name);
821 hsearch_r(e, ENTER, &rv, htab, flag);
823 printf("himport_r: can't insert \"%s=%s\" into hash table\n",
828 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
829 htab, htab->filled, htab->size,
831 } while ((dp < data + size) && *dp); /* size check needed for text */
832 /* without '\0' termination */
833 debug("INSERT: free(data = %p)\n", data);
836 /* process variables which were not considered */
837 for (i = 0; i < nvars; i++) {
838 if (localvars[i] == NULL)
841 * All variables which were not deleted from the variable list
842 * were not present in the imported env
843 * This could mean two things:
844 * a) if the variable was present in current env, we delete it
845 * b) if the variable was not present in current env, we notify
848 if (hdelete_r(localvars[i], htab, flag) == 0)
849 printf("WARNING: '%s' neither in running nor in imported env!\n", localvars[i]);
851 printf("WARNING: '%s' not in imported env, deleting it!\n", localvars[i]);
854 debug("INSERT: done\n");
855 return 1; /* everything OK */