]>
git.ipfire.org Git - people/ms/u-boot.git/blob - lib/hashtable.c
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
57 #include <env_callback.h>
61 * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
62 * [Knuth] The Art of Computer Programming, part 3 (6.4)
66 * The reentrant version has no static variables to maintain the state.
67 * Instead the interface of all functions is extended to take an argument
68 * which describes the current status.
71 typedef struct _ENTRY
{
77 static void _hdelete(const char *key
, struct hsearch_data
*htab
, ENTRY
*ep
,
85 * For the used double hash method the table size has to be a prime. To
86 * correct the user given table size we need a prime test. This trivial
87 * algorithm is adequate because
88 * a) the code is (most probably) called a few times per program run and
89 * b) the number is small because the table must fit in the core
91 static int isprime(unsigned int number
)
93 /* no even number will be passed */
96 while (div
* div
< number
&& number
% div
!= 0)
99 return number
% div
!= 0;
103 * Before using the hash table we must allocate memory for it.
104 * Test for an existing table are done. We allocate one element
105 * more as the found prime number says. This is done for more effective
106 * indexing as explained in the comment for the hsearch function.
107 * The contents of the table is zeroed, especially the field used
111 int hcreate_r(size_t nel
, struct hsearch_data
*htab
)
113 /* Test for correct arguments. */
119 /* There is still another table active. Return with error. */
120 if (htab
->table
!= NULL
)
123 /* Change nel to the first prime number not smaller as nel. */
124 nel
|= 1; /* make odd */
125 while (!isprime(nel
))
131 /* allocate memory and zero out */
132 htab
->table
= (_ENTRY
*) calloc(htab
->size
+ 1, sizeof(_ENTRY
));
133 if (htab
->table
== NULL
)
136 /* everything went alright */
146 * After using the hash table it has to be destroyed. The used memory can
147 * be freed and the local static variable can be marked as not used.
150 void hdestroy_r(struct hsearch_data
*htab
)
154 /* Test for correct arguments. */
160 /* free used memory */
161 for (i
= 1; i
<= htab
->size
; ++i
) {
162 if (htab
->table
[i
].used
> 0) {
163 ENTRY
*ep
= &htab
->table
[i
].entry
;
165 free((void *)ep
->key
);
171 /* the sign for an existing table is an value != NULL in htable */
180 * This is the search function. It uses double hashing with open addressing.
181 * The argument item.key has to be a pointer to an zero terminated, most
182 * probably strings of chars. The function for generating a number of the
183 * strings is simple but fast. It can be replaced by a more complex function
184 * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
186 * We use an trick to speed up the lookup. The table is created by hcreate
187 * with one more element available. This enables us to use the index zero
188 * special. This index will never be used because we store the first hash
189 * index in the field used where zero means not used. Every other value
190 * means used. The used field can be used as a first fast comparison for
191 * equality of the stored and the parameter value. This helps to prevent
192 * unnecessary expensive calls of strcmp.
194 * This implementation differs from the standard library version of
195 * this function in a number of ways:
197 * - While the standard version does not make any assumptions about
198 * the type of the stored data objects at all, this implementation
199 * works with NUL terminated strings only.
200 * - Instead of storing just pointers to the original objects, we
201 * create local copies so the caller does not need to care about the
203 * - The standard implementation does not provide a way to update an
204 * existing entry. This version will create a new entry or update an
205 * existing one when both "action == ENTER" and "item.data != NULL".
206 * - Instead of returning 1 on success, we return the index into the
207 * internal hash table, which is also guaranteed to be positive.
208 * This allows us direct access to the found hash table slot for
209 * example for functions like hdelete().
213 * hstrstr_r - return index to entry whose key and/or data contains match
215 int hstrstr_r(const char *match
, int last_idx
, ENTRY
** retval
,
216 struct hsearch_data
*htab
)
220 for (idx
= last_idx
+ 1; idx
< htab
->size
; ++idx
) {
221 if (htab
->table
[idx
].used
<= 0)
223 if (strstr(htab
->table
[idx
].entry
.key
, match
) ||
224 strstr(htab
->table
[idx
].entry
.data
, match
)) {
225 *retval
= &htab
->table
[idx
].entry
;
235 int hmatch_r(const char *match
, int last_idx
, ENTRY
** retval
,
236 struct hsearch_data
*htab
)
239 size_t key_len
= strlen(match
);
241 for (idx
= last_idx
+ 1; idx
< htab
->size
; ++idx
) {
242 if (htab
->table
[idx
].used
<= 0)
244 if (!strncmp(match
, htab
->table
[idx
].entry
.key
, key_len
)) {
245 *retval
= &htab
->table
[idx
].entry
;
256 * Compare an existing entry with the desired key, and overwrite if the action
257 * is ENTER. This is simply a helper function for hsearch_r().
259 static inline int _compare_and_overwrite_entry(ENTRY item
, ACTION action
,
260 ENTRY
**retval
, struct hsearch_data
*htab
, int flag
,
261 unsigned int hval
, unsigned int idx
)
263 if (htab
->table
[idx
].used
== hval
264 && strcmp(item
.key
, htab
->table
[idx
].entry
.key
) == 0) {
265 /* Overwrite existing value? */
266 if ((action
== ENTER
) && (item
.data
!= NULL
)) {
267 /* check for permission */
268 if (htab
->change_ok
!= NULL
&& htab
->change_ok(
269 &htab
->table
[idx
].entry
, item
.data
,
270 env_op_overwrite
, flag
)) {
271 debug("change_ok() rejected setting variable "
272 "%s, skipping it!\n", item
.key
);
278 /* If there is a callback, call it */
279 if (htab
->table
[idx
].entry
.callback
&&
280 htab
->table
[idx
].entry
.callback(item
.key
,
281 item
.data
, env_op_overwrite
, flag
)) {
282 debug("callback() rejected setting variable "
283 "%s, skipping it!\n", item
.key
);
289 free(htab
->table
[idx
].entry
.data
);
290 htab
->table
[idx
].entry
.data
= strdup(item
.data
);
291 if (!htab
->table
[idx
].entry
.data
) {
297 /* return found entry */
298 *retval
= &htab
->table
[idx
].entry
;
305 int hsearch_r(ENTRY item
, ACTION action
, ENTRY
** retval
,
306 struct hsearch_data
*htab
, int flag
)
310 unsigned int len
= strlen(item
.key
);
312 unsigned int first_deleted
= 0;
315 /* Compute an value for the given string. Perhaps use a better method. */
318 while (count
-- > 0) {
320 hval
+= item
.key
[count
];
324 * First hash function:
325 * simply take the modul but prevent zero.
331 /* The first index tried. */
334 if (htab
->table
[idx
].used
) {
336 * Further action might be required according to the
341 if (htab
->table
[idx
].used
== -1
345 ret
= _compare_and_overwrite_entry(item
, action
, retval
, htab
,
351 * Second hash function:
352 * as suggested in [Knuth]
354 hval2
= 1 + hval
% (htab
->size
- 2);
358 * Because SIZE is prime this guarantees to
359 * step through all available indices.
362 idx
= htab
->size
+ idx
- hval2
;
367 * If we visited all entries leave the loop
373 /* If entry is found use it. */
374 ret
= _compare_and_overwrite_entry(item
, action
, retval
,
375 htab
, flag
, hval
, idx
);
379 while (htab
->table
[idx
].used
);
382 /* An empty bucket has been found. */
383 if (action
== ENTER
) {
385 * If table is full and another entry should be
386 * entered return with error.
388 if (htab
->filled
== htab
->size
) {
396 * create copies of item.key and item.data
401 htab
->table
[idx
].used
= hval
;
402 htab
->table
[idx
].entry
.key
= strdup(item
.key
);
403 htab
->table
[idx
].entry
.data
= strdup(item
.data
);
404 if (!htab
->table
[idx
].entry
.key
||
405 !htab
->table
[idx
].entry
.data
) {
413 /* This is a new entry, so look up a possible callback */
414 env_callback_init(&htab
->table
[idx
].entry
);
416 /* check for permission */
417 if (htab
->change_ok
!= NULL
&& htab
->change_ok(
418 &htab
->table
[idx
].entry
, item
.data
, env_op_create
, flag
)) {
419 debug("change_ok() rejected setting variable "
420 "%s, skipping it!\n", item
.key
);
421 _hdelete(item
.key
, htab
, &htab
->table
[idx
].entry
, idx
);
427 /* If there is a callback, call it */
428 if (htab
->table
[idx
].entry
.callback
&&
429 htab
->table
[idx
].entry
.callback(item
.key
, item
.data
,
430 env_op_create
, flag
)) {
431 debug("callback() rejected setting variable "
432 "%s, skipping it!\n", item
.key
);
433 _hdelete(item
.key
, htab
, &htab
->table
[idx
].entry
, idx
);
439 /* return new entry */
440 *retval
= &htab
->table
[idx
].entry
;
455 * The standard implementation of hsearch(3) does not provide any way
456 * to delete any entries from the hash table. We extend the code to
460 static void _hdelete(const char *key
, struct hsearch_data
*htab
, ENTRY
*ep
,
463 /* free used ENTRY */
464 debug("hdelete: DELETING key \"%s\"\n", key
);
465 free((void *)ep
->key
);
468 htab
->table
[idx
].used
= -1;
473 int hdelete_r(const char *key
, struct hsearch_data
*htab
, int flag
)
478 debug("hdelete: DELETE key \"%s\"\n", key
);
482 idx
= hsearch_r(e
, FIND
, &ep
, htab
, 0);
485 return 0; /* not found */
488 /* Check for permission */
489 if (htab
->change_ok
!= NULL
&&
490 htab
->change_ok(ep
, NULL
, env_op_delete
, flag
)) {
491 debug("change_ok() rejected deleting variable "
492 "%s, skipping it!\n", key
);
497 /* If there is a callback, call it */
498 if (htab
->table
[idx
].entry
.callback
&&
499 htab
->table
[idx
].entry
.callback(key
, NULL
, env_op_delete
, flag
)) {
500 debug("callback() rejected deleting variable "
501 "%s, skipping it!\n", key
);
506 _hdelete(key
, htab
, ep
, idx
);
515 #ifndef CONFIG_SPL_BUILD
517 * Export the data stored in the hash table in linearized form.
519 * Entries are exported as "name=value" strings, separated by an
520 * arbitrary (non-NUL, of course) separator character. This allows to
521 * use this function both when formatting the U-Boot environment for
522 * external storage (using '\0' as separator), but also when using it
523 * for the "printenv" command to print all variables, simply by using
524 * as '\n" as separator. This can also be used for new features like
525 * exporting the environment data as text file, including the option
526 * for later re-import.
528 * The entries in the result list will be sorted by ascending key
531 * If the separator character is different from NUL, then any
532 * separator characters and backslash characters in the values will
533 * be escaped by a preceeding backslash in output. This is needed for
534 * example to enable multi-line values, especially when the output
535 * shall later be parsed (for example, for re-import).
537 * There are several options how the result buffer is handled:
541 * NULL 0 A string of sufficient length will be allocated.
542 * NULL >0 A string of the size given will be
543 * allocated. An error will be returned if the size is
544 * not sufficient. Any unused bytes in the string will
546 * !NULL 0 The user-supplied buffer will be used. No length
547 * checking will be performed, i. e. it is assumed that
548 * the buffer size will always be big enough. DANGEROUS.
549 * !NULL >0 The user-supplied buffer will be used. An error will
550 * be returned if the size is not sufficient. Any unused
551 * bytes in the string will be '\0'-padded.
554 static int cmpkey(const void *p1
, const void *p2
)
556 ENTRY
*e1
= *(ENTRY
**) p1
;
557 ENTRY
*e2
= *(ENTRY
**) p2
;
559 return (strcmp(e1
->key
, e2
->key
));
562 ssize_t
hexport_r(struct hsearch_data
*htab
, const char sep
, int flag
,
563 char **resp
, size_t size
,
564 int argc
, char * const argv
[])
566 ENTRY
*list
[htab
->size
];
571 /* Test for correct arguments. */
572 if ((resp
== NULL
) || (htab
== NULL
)) {
577 debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, "
578 "size = %zu\n", htab
, htab
->size
, htab
->filled
, size
);
581 * search used entries,
582 * save addresses and compute total length
584 for (i
= 1, n
= 0, totlen
= 0; i
<= htab
->size
; ++i
) {
586 if (htab
->table
[i
].used
> 0) {
587 ENTRY
*ep
= &htab
->table
[i
].entry
;
590 for (arg
= 0; arg
< argc
; ++arg
) {
591 if (strcmp(argv
[arg
], ep
->key
) == 0) {
596 if ((argc
> 0) && (found
== 0))
599 if ((flag
& H_HIDE_DOT
) && ep
->key
[0] == '.')
604 totlen
+= strlen(ep
->key
) + 2;
607 totlen
+= strlen(ep
->data
);
608 } else { /* check if escapes are needed */
613 /* add room for needed escape chars */
614 if ((*s
== sep
) || (*s
== '\\'))
619 totlen
+= 2; /* for '=' and 'sep' char */
624 /* Pass 1a: print unsorted list */
625 printf("Unsorted: n=%d\n", n
);
626 for (i
= 0; i
< n
; ++i
) {
627 printf("\t%3d: %p ==> %-10s => %s\n",
628 i
, list
[i
], list
[i
]->key
, list
[i
]->data
);
632 /* Sort list by keys */
633 qsort(list
, n
, sizeof(ENTRY
*), cmpkey
);
635 /* Check if the user supplied buffer size is sufficient */
637 if (size
< totlen
+ 1) { /* provided buffer too small */
638 printf("Env export buffer too small: %zu, "
639 "but need %zu\n", size
, totlen
+ 1);
647 /* Check if the user provided a buffer */
651 memset(res
, '\0', size
);
653 /* no, allocate and clear one */
654 *resp
= res
= calloc(1, size
);
662 * export sorted list of result data
664 for (i
= 0, p
= res
; i
< n
; ++i
) {
675 if ((*s
== sep
) || (*s
== '\\'))
676 *p
++ = '\\'; /* escape */
681 *p
= '\0'; /* terminate result */
693 * Check whether variable 'name' is amongst vars[],
694 * and remove all instances by setting the pointer to NULL
696 static int drop_var_from_set(const char *name
, int nvars
, char * vars
[])
701 /* No variables specified means process all of them */
705 for (i
= 0; i
< nvars
; i
++) {
708 /* If we found it, delete all of them */
709 if (!strcmp(name
, vars
[i
])) {
715 debug("Skipping non-listed variable %s\n", name
);
721 * Import linearized data into hash table.
723 * This is the inverse function to hexport(): it takes a linear list
724 * of "name=value" pairs and creates hash table entries from it.
726 * Entries without "value", i. e. consisting of only "name" or
727 * "name=", will cause this entry to be deleted from the hash table.
729 * The "flag" argument can be used to control the behaviour: when the
730 * H_NOCLEAR bit is set, then an existing hash table will kept, i. e.
731 * new data will be added to an existing hash table; otherwise, old
732 * data will be discarded and a new hash table will be created.
734 * The separator character for the "name=value" pairs can be selected,
735 * so we both support importing from externally stored environment
736 * data (separated by NUL characters) and from plain text files
737 * (entries separated by newline characters).
739 * To allow for nicely formatted text input, leading white space
740 * (sequences of SPACE and TAB chars) is ignored, and entries starting
741 * (after removal of any leading white space) with a '#' character are
742 * considered comments and ignored.
744 * [NOTE: this means that a variable name cannot start with a '#'
747 * When using a non-NUL separator character, backslash is used as
748 * escape character in the value part, allowing for example for
751 * In theory, arbitrary separator characters can be used, but only
752 * '\0' and '\n' have really been tested.
755 int himport_r(struct hsearch_data
*htab
,
756 const char *env
, size_t size
, const char sep
, int flag
,
757 int nvars
, char * const vars
[])
759 char *data
, *sp
, *dp
, *name
, *value
;
760 char *localvars
[nvars
];
763 /* Test for correct arguments. */
769 /* we allocate new space to make sure we can write to the array */
770 if ((data
= malloc(size
)) == NULL
) {
771 debug("himport_r: can't malloc %zu bytes\n", size
);
775 memcpy(data
, env
, size
);
778 /* make a local copy of the list of variables */
780 memcpy(localvars
, vars
, sizeof(vars
[0]) * nvars
);
782 if ((flag
& H_NOCLEAR
) == 0) {
783 /* Destroy old hash table if one exists */
784 debug("Destroy Hash Table: %p table = %p\n", htab
,
791 * Create new hash table (if needed). The computation of the hash
792 * table size is based on heuristics: in a sample of some 70+
793 * existing systems we found an average size of 39+ bytes per entry
794 * in the environment (for the whole key=value pair). Assuming a
795 * size of 8 per entry (= safety factor of ~5) should provide enough
796 * safety margin for any existing environment definitions and still
797 * allow for more than enough dynamic additions. Note that the
798 * "size" argument is supposed to give the maximum enviroment size
799 * (CONFIG_ENV_SIZE). This heuristics will result in
800 * unreasonably large numbers (and thus memory footprint) for
801 * big flash environments (>8,000 entries for 64 KB
802 * envrionment size), so we clip it to a reasonable value.
803 * On the other hand we need to add some more entries for free
804 * space when importing very small buffers. Both boundaries can
805 * be overwritten in the board config file if needed.
809 int nent
= CONFIG_ENV_MIN_ENTRIES
+ size
/ 8;
811 if (nent
> CONFIG_ENV_MAX_ENTRIES
)
812 nent
= CONFIG_ENV_MAX_ENTRIES
;
814 debug("Create Hash Table: N=%d\n", nent
);
816 if (hcreate_r(nent
, htab
) == 0) {
822 /* Parse environment; allow for '\0' and 'sep' as separators */
826 /* skip leading white space */
830 /* skip comment lines */
832 while (*dp
&& (*dp
!= sep
))
839 for (name
= dp
; *dp
!= '=' && *dp
&& *dp
!= sep
; ++dp
)
842 /* deal with "name" and "name=" entries (delete var) */
843 if (*dp
== '\0' || *(dp
+ 1) == '\0' ||
844 *dp
== sep
|| *(dp
+ 1) == sep
) {
847 *dp
++ = '\0'; /* terminate name */
849 debug("DELETE CANDIDATE: \"%s\"\n", name
);
850 if (!drop_var_from_set(name
, nvars
, localvars
))
853 if (hdelete_r(name
, htab
, flag
) == 0)
854 debug("DELETE ERROR ##############################\n");
858 *dp
++ = '\0'; /* terminate name */
860 /* parse value; deal with escapes */
861 for (value
= sp
= dp
; *dp
&& (*dp
!= sep
); ++dp
) {
862 if ((*dp
== '\\') && *(dp
+ 1))
866 *sp
++ = '\0'; /* terminate value */
869 /* Skip variables which are not supposed to be processed */
870 if (!drop_var_from_set(name
, nvars
, localvars
))
873 /* enter into hash table */
877 hsearch_r(e
, ENTER
, &rv
, htab
, flag
);
879 printf("himport_r: can't insert \"%s=%s\" into hash table\n",
882 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
883 htab
, htab
->filled
, htab
->size
,
885 } while ((dp
< data
+ size
) && *dp
); /* size check needed for text */
886 /* without '\0' termination */
887 debug("INSERT: free(data = %p)\n", data
);
890 /* process variables which were not considered */
891 for (i
= 0; i
< nvars
; i
++) {
892 if (localvars
[i
] == NULL
)
895 * All variables which were not deleted from the variable list
896 * were not present in the imported env
897 * This could mean two things:
898 * a) if the variable was present in current env, we delete it
899 * b) if the variable was not present in current env, we notify
902 if (hdelete_r(localvars
[i
], htab
, flag
) == 0)
903 printf("WARNING: '%s' neither in running nor in imported env!\n", localvars
[i
]);
905 printf("WARNING: '%s' not in imported env, deleting it!\n", localvars
[i
]);
908 debug("INSERT: done\n");
909 return 1; /* everything OK */
917 * Walk all of the entries in the hash, calling the callback for each one.
918 * this allows some generic operation to be performed on each element.
920 int hwalk_r(struct hsearch_data
*htab
, int (*callback
)(ENTRY
*))
925 for (i
= 1; i
<= htab
->size
; ++i
) {
926 if (htab
->table
[i
].used
> 0) {
927 retval
= callback(&htab
->table
[i
].entry
);