1 // SPDX-License-Identifier: LGPL-2.1+
3 * This implementation is based on code from uClibc-0.9.30.3 but was
4 * modified and extended for use within U-Boot.
6 * Copyright (C) 2010-2013 Wolfgang Denk <wd@denx.de>
8 * Original license header:
10 * Copyright (C) 1993, 1995, 1996, 1997, 2002 Free Software Foundation, Inc.
11 * This file is part of the GNU C Library.
12 * Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1993.
18 #ifdef USE_HOSTCC /* HOST build */
25 # define debug(fmt,args...) printf(fmt ,##args)
27 # define debug(fmt,args...)
30 #else /* U-Boot build */
32 # include <linux/string.h>
33 # include <linux/ctype.h>
36 #ifndef CONFIG_ENV_MIN_ENTRIES /* minimum number of entries */
37 #define CONFIG_ENV_MIN_ENTRIES 64
39 #ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */
40 #define CONFIG_ENV_MAX_ENTRIES 512
44 #define USED_DELETED -1
46 #include <env_callback.h>
47 #include <env_flags.h>
52 * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
53 * [Knuth] The Art of Computer Programming, part 3 (6.4)
57 * The reentrant version has no static variables to maintain the state.
58 * Instead the interface of all functions is extended to take an argument
59 * which describes the current status.
62 typedef struct _ENTRY {
64 struct env_entry entry;
68 static void _hdelete(const char *key, struct hsearch_data *htab,
69 struct env_entry *ep, int idx);
76 * For the used double hash method the table size has to be a prime. To
77 * correct the user given table size we need a prime test. This trivial
78 * algorithm is adequate because
79 * a) the code is (most probably) called a few times per program run and
80 * b) the number is small because the table must fit in the core
82 static int isprime(unsigned int number)
84 /* no even number will be passed */
87 while (div * div < number && number % div != 0)
90 return number % div != 0;
94 * Before using the hash table we must allocate memory for it.
95 * Test for an existing table are done. We allocate one element
96 * more as the found prime number says. This is done for more effective
97 * indexing as explained in the comment for the hsearch function.
98 * The contents of the table is zeroed, especially the field used
102 int hcreate_r(size_t nel, struct hsearch_data *htab)
104 /* Test for correct arguments. */
110 /* There is still another table active. Return with error. */
111 if (htab->table != NULL)
114 /* Change nel to the first prime number not smaller as nel. */
115 nel |= 1; /* make odd */
116 while (!isprime(nel))
122 /* allocate memory and zero out */
123 htab->table = (_ENTRY *) calloc(htab->size + 1, sizeof(_ENTRY));
124 if (htab->table == NULL)
127 /* everything went alright */
137 * After using the hash table it has to be destroyed. The used memory can
138 * be freed and the local static variable can be marked as not used.
141 void hdestroy_r(struct hsearch_data *htab)
145 /* Test for correct arguments. */
151 /* free used memory */
152 for (i = 1; i <= htab->size; ++i) {
153 if (htab->table[i].used > 0) {
154 struct env_entry *ep = &htab->table[i].entry;
156 free((void *)ep->key);
162 /* the sign for an existing table is an value != NULL in htable */
171 * This is the search function. It uses double hashing with open addressing.
172 * The argument item.key has to be a pointer to an zero terminated, most
173 * probably strings of chars. The function for generating a number of the
174 * strings is simple but fast. It can be replaced by a more complex function
175 * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
177 * We use an trick to speed up the lookup. The table is created by hcreate
178 * with one more element available. This enables us to use the index zero
179 * special. This index will never be used because we store the first hash
180 * index in the field used where zero means not used. Every other value
181 * means used. The used field can be used as a first fast comparison for
182 * equality of the stored and the parameter value. This helps to prevent
183 * unnecessary expensive calls of strcmp.
185 * This implementation differs from the standard library version of
186 * this function in a number of ways:
188 * - While the standard version does not make any assumptions about
189 * the type of the stored data objects at all, this implementation
190 * works with NUL terminated strings only.
191 * - Instead of storing just pointers to the original objects, we
192 * create local copies so the caller does not need to care about the
194 * - The standard implementation does not provide a way to update an
195 * existing entry. This version will create a new entry or update an
196 * existing one when both "action == ENTER" and "item.data != NULL".
197 * - Instead of returning 1 on success, we return the index into the
198 * internal hash table, which is also guaranteed to be positive.
199 * This allows us direct access to the found hash table slot for
200 * example for functions like hdelete().
203 int hmatch_r(const char *match, int last_idx, struct env_entry **retval,
204 struct hsearch_data *htab)
207 size_t key_len = strlen(match);
209 for (idx = last_idx + 1; idx < htab->size; ++idx) {
210 if (htab->table[idx].used <= 0)
212 if (!strncmp(match, htab->table[idx].entry.key, key_len)) {
213 *retval = &htab->table[idx].entry;
224 * Compare an existing entry with the desired key, and overwrite if the action
225 * is ENTER. This is simply a helper function for hsearch_r().
227 static inline int _compare_and_overwrite_entry(struct env_entry item,
228 ACTION action, struct env_entry **retval,
229 struct hsearch_data *htab, int flag, unsigned int hval,
232 if (htab->table[idx].used == hval
233 && strcmp(item.key, htab->table[idx].entry.key) == 0) {
234 /* Overwrite existing value? */
235 if ((action == ENTER) && (item.data != NULL)) {
236 /* check for permission */
237 if (htab->change_ok != NULL && htab->change_ok(
238 &htab->table[idx].entry, item.data,
239 env_op_overwrite, flag)) {
240 debug("change_ok() rejected setting variable "
241 "%s, skipping it!\n", item.key);
247 /* If there is a callback, call it */
248 if (htab->table[idx].entry.callback &&
249 htab->table[idx].entry.callback(item.key,
250 item.data, env_op_overwrite, flag)) {
251 debug("callback() rejected setting variable "
252 "%s, skipping it!\n", item.key);
258 free(htab->table[idx].entry.data);
259 htab->table[idx].entry.data = strdup(item.data);
260 if (!htab->table[idx].entry.data) {
266 /* return found entry */
267 *retval = &htab->table[idx].entry;
274 int hsearch_r(struct env_entry item, ACTION action, struct env_entry **retval,
275 struct hsearch_data *htab, int flag)
279 unsigned int len = strlen(item.key);
281 unsigned int first_deleted = 0;
284 /* Compute an value for the given string. Perhaps use a better method. */
287 while (count-- > 0) {
289 hval += item.key[count];
293 * First hash function:
294 * simply take the modul but prevent zero.
300 /* The first index tried. */
303 if (htab->table[idx].used) {
305 * Further action might be required according to the
310 if (htab->table[idx].used == USED_DELETED
314 ret = _compare_and_overwrite_entry(item, action, retval, htab,
320 * Second hash function:
321 * as suggested in [Knuth]
323 hval2 = 1 + hval % (htab->size - 2);
327 * Because SIZE is prime this guarantees to
328 * step through all available indices.
331 idx = htab->size + idx - hval2;
336 * If we visited all entries leave the loop
342 if (htab->table[idx].used == USED_DELETED
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 != USED_FREE);
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 /* This is a new entry, so look up a possible callback */
387 env_callback_init(&htab->table[idx].entry);
388 /* Also look for flags */
389 env_flags_init(&htab->table[idx].entry);
391 /* check for permission */
392 if (htab->change_ok != NULL && htab->change_ok(
393 &htab->table[idx].entry, item.data, env_op_create, flag)) {
394 debug("change_ok() rejected setting variable "
395 "%s, skipping it!\n", item.key);
396 _hdelete(item.key, htab, &htab->table[idx].entry, idx);
402 /* If there is a callback, call it */
403 if (htab->table[idx].entry.callback &&
404 htab->table[idx].entry.callback(item.key, item.data,
405 env_op_create, flag)) {
406 debug("callback() rejected setting variable "
407 "%s, skipping it!\n", item.key);
408 _hdelete(item.key, htab, &htab->table[idx].entry, idx);
414 /* return new entry */
415 *retval = &htab->table[idx].entry;
430 * The standard implementation of hsearch(3) does not provide any way
431 * to delete any entries from the hash table. We extend the code to
435 static void _hdelete(const char *key, struct hsearch_data *htab,
436 struct env_entry *ep, int idx)
438 /* free used entry */
439 debug("hdelete: DELETING key \"%s\"\n", key);
440 free((void *)ep->key);
444 htab->table[idx].used = USED_DELETED;
449 int hdelete_r(const char *key, struct hsearch_data *htab, int flag)
451 struct env_entry e, *ep;
454 debug("hdelete: DELETE key \"%s\"\n", key);
458 idx = hsearch_r(e, FIND, &ep, htab, 0);
461 return 0; /* not found */
464 /* Check for permission */
465 if (htab->change_ok != NULL &&
466 htab->change_ok(ep, NULL, env_op_delete, flag)) {
467 debug("change_ok() rejected deleting variable "
468 "%s, skipping it!\n", key);
473 /* If there is a callback, call it */
474 if (htab->table[idx].entry.callback &&
475 htab->table[idx].entry.callback(key, NULL, env_op_delete, flag)) {
476 debug("callback() rejected deleting variable "
477 "%s, skipping it!\n", key);
482 _hdelete(key, htab, ep, idx);
487 #if !(defined(CONFIG_SPL_BUILD) && !defined(CONFIG_SPL_SAVEENV))
493 * Export the data stored in the hash table in linearized form.
495 * Entries are exported as "name=value" strings, separated by an
496 * arbitrary (non-NUL, of course) separator character. This allows to
497 * use this function both when formatting the U-Boot environment for
498 * external storage (using '\0' as separator), but also when using it
499 * for the "printenv" command to print all variables, simply by using
500 * as '\n" as separator. This can also be used for new features like
501 * exporting the environment data as text file, including the option
502 * for later re-import.
504 * The entries in the result list will be sorted by ascending key
507 * If the separator character is different from NUL, then any
508 * separator characters and backslash characters in the values will
509 * be escaped by a preceding backslash in output. This is needed for
510 * example to enable multi-line values, especially when the output
511 * shall later be parsed (for example, for re-import).
513 * There are several options how the result buffer is handled:
517 * NULL 0 A string of sufficient length will be allocated.
518 * NULL >0 A string of the size given will be
519 * allocated. An error will be returned if the size is
520 * not sufficient. Any unused bytes in the string will
522 * !NULL 0 The user-supplied buffer will be used. No length
523 * checking will be performed, i. e. it is assumed that
524 * the buffer size will always be big enough. DANGEROUS.
525 * !NULL >0 The user-supplied buffer will be used. An error will
526 * be returned if the size is not sufficient. Any unused
527 * bytes in the string will be '\0'-padded.
530 static int cmpkey(const void *p1, const void *p2)
532 struct env_entry *e1 = *(struct env_entry **)p1;
533 struct env_entry *e2 = *(struct env_entry **)p2;
535 return (strcmp(e1->key, e2->key));
538 static int match_string(int flag, const char *str, const char *pat, void *priv)
540 switch (flag & H_MATCH_METHOD) {
542 if (strcmp(str, pat) == 0)
546 if (strstr(str, pat))
552 struct slre *slrep = (struct slre *)priv;
554 if (slre_match(slrep, str, strlen(str), NULL))
560 printf("## ERROR: unsupported match method: 0x%02x\n",
561 flag & H_MATCH_METHOD);
567 static int match_entry(struct env_entry *ep, int flag, int argc,
573 for (arg = 0; arg < argc; ++arg) {
577 if (slre_compile(&slre, argv[arg]) == 0) {
578 printf("Error compiling regex: %s\n", slre.err_str);
582 priv = (void *)&slre;
584 if (flag & H_MATCH_KEY) {
585 if (match_string(flag, ep->key, argv[arg], priv))
588 if (flag & H_MATCH_DATA) {
589 if (match_string(flag, ep->data, argv[arg], priv))
596 ssize_t hexport_r(struct hsearch_data *htab, const char sep, int flag,
597 char **resp, size_t size,
598 int argc, char * const argv[])
600 struct env_entry *list[htab->size];
605 /* Test for correct arguments. */
606 if ((resp == NULL) || (htab == NULL)) {
611 debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, size = %lu\n",
612 htab, htab->size, htab->filled, (ulong)size);
615 * search used entries,
616 * save addresses and compute total length
618 for (i = 1, n = 0, totlen = 0; i <= htab->size; ++i) {
620 if (htab->table[i].used > 0) {
621 struct env_entry *ep = &htab->table[i].entry;
622 int found = match_entry(ep, flag, argc, argv);
624 if ((argc > 0) && (found == 0))
627 if ((flag & H_HIDE_DOT) && ep->key[0] == '.')
632 totlen += strlen(ep->key);
635 totlen += strlen(ep->data);
636 } else { /* check if escapes are needed */
641 /* add room for needed escape chars */
642 if ((*s == sep) || (*s == '\\'))
647 totlen += 2; /* for '=' and 'sep' char */
652 /* Pass 1a: print unsorted list */
653 printf("Unsorted: n=%d\n", n);
654 for (i = 0; i < n; ++i) {
655 printf("\t%3d: %p ==> %-10s => %s\n",
656 i, list[i], list[i]->key, list[i]->data);
660 /* Sort list by keys */
661 qsort(list, n, sizeof(struct env_entry *), cmpkey);
663 /* Check if the user supplied buffer size is sufficient */
665 if (size < totlen + 1) { /* provided buffer too small */
666 printf("Env export buffer too small: %lu, but need %lu\n",
667 (ulong)size, (ulong)totlen + 1);
675 /* Check if the user provided a buffer */
679 memset(res, '\0', size);
681 /* no, allocate and clear one */
682 *resp = res = calloc(1, size);
690 * export sorted list of result data
692 for (i = 0, p = res; i < n; ++i) {
703 if ((*s == sep) || (*s == '\\'))
704 *p++ = '\\'; /* escape */
709 *p = '\0'; /* terminate result */
721 * Check whether variable 'name' is amongst vars[],
722 * and remove all instances by setting the pointer to NULL
724 static int drop_var_from_set(const char *name, int nvars, char * vars[])
729 /* No variables specified means process all of them */
733 for (i = 0; i < nvars; i++) {
736 /* If we found it, delete all of them */
737 if (!strcmp(name, vars[i])) {
743 debug("Skipping non-listed variable %s\n", name);
749 * Import linearized data into hash table.
751 * This is the inverse function to hexport(): it takes a linear list
752 * of "name=value" pairs and creates hash table entries from it.
754 * Entries without "value", i. e. consisting of only "name" or
755 * "name=", will cause this entry to be deleted from the hash table.
757 * The "flag" argument can be used to control the behaviour: when the
758 * H_NOCLEAR bit is set, then an existing hash table will kept, i. e.
759 * new data will be added to an existing hash table; otherwise, if no
760 * vars are passed, old data will be discarded and a new hash table
761 * will be created. If vars are passed, passed vars that are not in
762 * the linear list of "name=value" pairs will be removed from the
763 * current hash table.
765 * The separator character for the "name=value" pairs can be selected,
766 * so we both support importing from externally stored environment
767 * data (separated by NUL characters) and from plain text files
768 * (entries separated by newline characters).
770 * To allow for nicely formatted text input, leading white space
771 * (sequences of SPACE and TAB chars) is ignored, and entries starting
772 * (after removal of any leading white space) with a '#' character are
773 * considered comments and ignored.
775 * [NOTE: this means that a variable name cannot start with a '#'
778 * When using a non-NUL separator character, backslash is used as
779 * escape character in the value part, allowing for example for
782 * In theory, arbitrary separator characters can be used, but only
783 * '\0' and '\n' have really been tested.
786 int himport_r(struct hsearch_data *htab,
787 const char *env, size_t size, const char sep, int flag,
788 int crlf_is_lf, int nvars, char * const vars[])
790 char *data, *sp, *dp, *name, *value;
791 char *localvars[nvars];
794 /* Test for correct arguments. */
800 /* we allocate new space to make sure we can write to the array */
801 if ((data = malloc(size + 1)) == NULL) {
802 debug("himport_r: can't malloc %lu bytes\n", (ulong)size + 1);
806 memcpy(data, env, size);
810 /* make a local copy of the list of variables */
812 memcpy(localvars, vars, sizeof(vars[0]) * nvars);
814 if ((flag & H_NOCLEAR) == 0 && !nvars) {
815 /* Destroy old hash table if one exists */
816 debug("Destroy Hash Table: %p table = %p\n", htab,
823 * Create new hash table (if needed). The computation of the hash
824 * table size is based on heuristics: in a sample of some 70+
825 * existing systems we found an average size of 39+ bytes per entry
826 * in the environment (for the whole key=value pair). Assuming a
827 * size of 8 per entry (= safety factor of ~5) should provide enough
828 * safety margin for any existing environment definitions and still
829 * allow for more than enough dynamic additions. Note that the
830 * "size" argument is supposed to give the maximum environment size
831 * (CONFIG_ENV_SIZE). This heuristics will result in
832 * unreasonably large numbers (and thus memory footprint) for
833 * big flash environments (>8,000 entries for 64 KB
834 * environment size), so we clip it to a reasonable value.
835 * On the other hand we need to add some more entries for free
836 * space when importing very small buffers. Both boundaries can
837 * be overwritten in the board config file if needed.
841 int nent = CONFIG_ENV_MIN_ENTRIES + size / 8;
843 if (nent > CONFIG_ENV_MAX_ENTRIES)
844 nent = CONFIG_ENV_MAX_ENTRIES;
846 debug("Create Hash Table: N=%d\n", nent);
848 if (hcreate_r(nent, htab) == 0) {
856 return 1; /* everything OK */
859 /* Remove Carriage Returns in front of Line Feeds */
860 unsigned ignored_crs = 0;
861 for(;dp < data + size && *dp; ++dp) {
863 dp < data + size - 1 && *(dp+1) == '\n')
866 *(dp-ignored_crs) = *dp;
871 /* Parse environment; allow for '\0' and 'sep' as separators */
873 struct env_entry e, *rv;
875 /* skip leading white space */
879 /* skip comment lines */
881 while (*dp && (*dp != sep))
888 for (name = dp; *dp != '=' && *dp && *dp != sep; ++dp)
891 /* deal with "name" and "name=" entries (delete var) */
892 if (*dp == '\0' || *(dp + 1) == '\0' ||
893 *dp == sep || *(dp + 1) == sep) {
896 *dp++ = '\0'; /* terminate name */
898 debug("DELETE CANDIDATE: \"%s\"\n", name);
899 if (!drop_var_from_set(name, nvars, localvars))
902 if (hdelete_r(name, htab, flag) == 0)
903 debug("DELETE ERROR ##############################\n");
907 *dp++ = '\0'; /* terminate name */
909 /* parse value; deal with escapes */
910 for (value = sp = dp; *dp && (*dp != sep); ++dp) {
911 if ((*dp == '\\') && *(dp + 1))
915 *sp++ = '\0'; /* terminate value */
919 debug("INSERT: unable to use an empty key\n");
925 /* Skip variables which are not supposed to be processed */
926 if (!drop_var_from_set(name, nvars, localvars))
929 /* enter into hash table */
933 hsearch_r(e, ENTER, &rv, htab, flag);
935 printf("himport_r: can't insert \"%s=%s\" into hash table\n",
938 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
939 htab, htab->filled, htab->size,
941 } while ((dp < data + size) && *dp); /* size check needed for text */
942 /* without '\0' termination */
943 debug("INSERT: free(data = %p)\n", data);
946 if (flag & H_NOCLEAR)
949 /* process variables which were not considered */
950 for (i = 0; i < nvars; i++) {
951 if (localvars[i] == NULL)
954 * All variables which were not deleted from the variable list
955 * were not present in the imported env
956 * This could mean two things:
957 * a) if the variable was present in current env, we delete it
958 * b) if the variable was not present in current env, we notify
961 if (hdelete_r(localvars[i], htab, flag) == 0)
962 printf("WARNING: '%s' neither in running nor in imported env!\n", localvars[i]);
964 printf("WARNING: '%s' not in imported env, deleting it!\n", localvars[i]);
968 debug("INSERT: done\n");
969 return 1; /* everything OK */
977 * Walk all of the entries in the hash, calling the callback for each one.
978 * this allows some generic operation to be performed on each element.
980 int hwalk_r(struct hsearch_data *htab, int (*callback)(struct env_entry *entry))
985 for (i = 1; i <= htab->size; ++i) {
986 if (htab->table[i].used > 0) {
987 retval = callback(&htab->table[i].entry);