]>
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
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.
70 typedef struct _ENTRY
{
76 static void _hdelete(const char *key
, struct hsearch_data
*htab
, ENTRY
*ep
,
84 * For the used double hash method the table size has to be a prime. To
85 * correct the user given table size we need a prime test. This trivial
86 * algorithm is adequate because
87 * a) the code is (most probably) called a few times per program run and
88 * b) the number is small because the table must fit in the core
90 static int isprime(unsigned int number
)
92 /* no even number will be passed */
95 while (div
* div
< number
&& number
% div
!= 0)
98 return number
% div
!= 0;
102 * Before using the hash table we must allocate memory for it.
103 * Test for an existing table are done. We allocate one element
104 * more as the found prime number says. This is done for more effective
105 * indexing as explained in the comment for the hsearch function.
106 * The contents of the table is zeroed, especially the field used
110 int hcreate_r(size_t nel
, struct hsearch_data
*htab
)
112 /* Test for correct arguments. */
118 /* There is still another table active. Return with error. */
119 if (htab
->table
!= NULL
)
122 /* Change nel to the first prime number not smaller as nel. */
123 nel
|= 1; /* make odd */
124 while (!isprime(nel
))
130 /* allocate memory and zero out */
131 htab
->table
= (_ENTRY
*) calloc(htab
->size
+ 1, sizeof(_ENTRY
));
132 if (htab
->table
== NULL
)
135 /* everything went alright */
145 * After using the hash table it has to be destroyed. The used memory can
146 * be freed and the local static variable can be marked as not used.
149 void hdestroy_r(struct hsearch_data
*htab
)
153 /* Test for correct arguments. */
159 /* free used memory */
160 for (i
= 1; i
<= htab
->size
; ++i
) {
161 if (htab
->table
[i
].used
> 0) {
162 ENTRY
*ep
= &htab
->table
[i
].entry
;
164 free((void *)ep
->key
);
170 /* the sign for an existing table is an value != NULL in htable */
179 * This is the search function. It uses double hashing with open addressing.
180 * The argument item.key has to be a pointer to an zero terminated, most
181 * probably strings of chars. The function for generating a number of the
182 * strings is simple but fast. It can be replaced by a more complex function
183 * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
185 * We use an trick to speed up the lookup. The table is created by hcreate
186 * with one more element available. This enables us to use the index zero
187 * special. This index will never be used because we store the first hash
188 * index in the field used where zero means not used. Every other value
189 * means used. The used field can be used as a first fast comparison for
190 * equality of the stored and the parameter value. This helps to prevent
191 * unnecessary expensive calls of strcmp.
193 * This implementation differs from the standard library version of
194 * this function in a number of ways:
196 * - While the standard version does not make any assumptions about
197 * the type of the stored data objects at all, this implementation
198 * works with NUL terminated strings only.
199 * - Instead of storing just pointers to the original objects, we
200 * create local copies so the caller does not need to care about the
202 * - The standard implementation does not provide a way to update an
203 * existing entry. This version will create a new entry or update an
204 * existing one when both "action == ENTER" and "item.data != NULL".
205 * - Instead of returning 1 on success, we return the index into the
206 * internal hash table, which is also guaranteed to be positive.
207 * This allows us direct access to the found hash table slot for
208 * example for functions like hdelete().
212 * hstrstr_r - return index to entry whose key and/or data contains match
214 int hstrstr_r(const char *match
, int last_idx
, ENTRY
** retval
,
215 struct hsearch_data
*htab
)
219 for (idx
= last_idx
+ 1; idx
< htab
->size
; ++idx
) {
220 if (htab
->table
[idx
].used
<= 0)
222 if (strstr(htab
->table
[idx
].entry
.key
, match
) ||
223 strstr(htab
->table
[idx
].entry
.data
, match
)) {
224 *retval
= &htab
->table
[idx
].entry
;
234 int hmatch_r(const char *match
, int last_idx
, ENTRY
** retval
,
235 struct hsearch_data
*htab
)
238 size_t key_len
= strlen(match
);
240 for (idx
= last_idx
+ 1; idx
< htab
->size
; ++idx
) {
241 if (htab
->table
[idx
].used
<= 0)
243 if (!strncmp(match
, htab
->table
[idx
].entry
.key
, key_len
)) {
244 *retval
= &htab
->table
[idx
].entry
;
255 * Compare an existing entry with the desired key, and overwrite if the action
256 * is ENTER. This is simply a helper function for hsearch_r().
258 static inline int _compare_and_overwrite_entry(ENTRY item
, ACTION action
,
259 ENTRY
**retval
, struct hsearch_data
*htab
, int flag
,
260 unsigned int hval
, unsigned int idx
)
262 if (htab
->table
[idx
].used
== hval
263 && strcmp(item
.key
, htab
->table
[idx
].entry
.key
) == 0) {
264 /* Overwrite existing value? */
265 if ((action
== ENTER
) && (item
.data
!= NULL
)) {
266 /* check for permission */
267 if (htab
->change_ok
!= NULL
&& htab
->change_ok(
268 &htab
->table
[idx
].entry
, item
.data
,
269 env_op_overwrite
, flag
)) {
270 debug("change_ok() rejected setting variable "
271 "%s, skipping it!\n", item
.key
);
277 free(htab
->table
[idx
].entry
.data
);
278 htab
->table
[idx
].entry
.data
= strdup(item
.data
);
279 if (!htab
->table
[idx
].entry
.data
) {
285 /* return found entry */
286 *retval
= &htab
->table
[idx
].entry
;
293 int hsearch_r(ENTRY item
, ACTION action
, ENTRY
** retval
,
294 struct hsearch_data
*htab
, int flag
)
298 unsigned int len
= strlen(item
.key
);
300 unsigned int first_deleted
= 0;
303 /* Compute an value for the given string. Perhaps use a better method. */
306 while (count
-- > 0) {
308 hval
+= item
.key
[count
];
312 * First hash function:
313 * simply take the modul but prevent zero.
319 /* The first index tried. */
322 if (htab
->table
[idx
].used
) {
324 * Further action might be required according to the
329 if (htab
->table
[idx
].used
== -1
333 ret
= _compare_and_overwrite_entry(item
, action
, retval
, htab
,
339 * Second hash function:
340 * as suggested in [Knuth]
342 hval2
= 1 + hval
% (htab
->size
- 2);
346 * Because SIZE is prime this guarantees to
347 * step through all available indices.
350 idx
= htab
->size
+ idx
- hval2
;
355 * If we visited all entries leave the loop
361 /* If entry is found use it. */
362 ret
= _compare_and_overwrite_entry(item
, action
, retval
,
363 htab
, flag
, hval
, idx
);
367 while (htab
->table
[idx
].used
);
370 /* An empty bucket has been found. */
371 if (action
== ENTER
) {
373 * If table is full and another entry should be
374 * entered return with error.
376 if (htab
->filled
== htab
->size
) {
384 * create copies of item.key and item.data
389 htab
->table
[idx
].used
= hval
;
390 htab
->table
[idx
].entry
.key
= strdup(item
.key
);
391 htab
->table
[idx
].entry
.data
= strdup(item
.data
);
392 if (!htab
->table
[idx
].entry
.key
||
393 !htab
->table
[idx
].entry
.data
) {
401 /* check for permission */
402 if (htab
->change_ok
!= NULL
&& htab
->change_ok(
403 &htab
->table
[idx
].entry
, item
.data
, env_op_create
, flag
)) {
404 debug("change_ok() rejected setting variable "
405 "%s, skipping it!\n", item
.key
);
406 _hdelete(item
.key
, htab
, &htab
->table
[idx
].entry
, idx
);
412 /* return new entry */
413 *retval
= &htab
->table
[idx
].entry
;
428 * The standard implementation of hsearch(3) does not provide any way
429 * to delete any entries from the hash table. We extend the code to
433 static void _hdelete(const char *key
, struct hsearch_data
*htab
, ENTRY
*ep
,
436 /* free used ENTRY */
437 debug("hdelete: DELETING key \"%s\"\n", key
);
438 free((void *)ep
->key
);
440 htab
->table
[idx
].used
= -1;
445 int hdelete_r(const char *key
, struct hsearch_data
*htab
, int flag
)
450 debug("hdelete: DELETE key \"%s\"\n", key
);
454 idx
= hsearch_r(e
, FIND
, &ep
, htab
, 0);
457 return 0; /* not found */
460 /* Check for permission */
461 if (htab
->change_ok
!= NULL
&&
462 htab
->change_ok(ep
, NULL
, env_op_delete
, flag
)) {
463 debug("change_ok() rejected deleting variable "
464 "%s, skipping it!\n", key
);
469 _hdelete(key
, htab
, ep
, idx
);
478 #ifndef CONFIG_SPL_BUILD
480 * Export the data stored in the hash table in linearized form.
482 * Entries are exported as "name=value" strings, separated by an
483 * arbitrary (non-NUL, of course) separator character. This allows to
484 * use this function both when formatting the U-Boot environment for
485 * external storage (using '\0' as separator), but also when using it
486 * for the "printenv" command to print all variables, simply by using
487 * as '\n" as separator. This can also be used for new features like
488 * exporting the environment data as text file, including the option
489 * for later re-import.
491 * The entries in the result list will be sorted by ascending key
494 * If the separator character is different from NUL, then any
495 * separator characters and backslash characters in the values will
496 * be escaped by a preceeding backslash in output. This is needed for
497 * example to enable multi-line values, especially when the output
498 * shall later be parsed (for example, for re-import).
500 * There are several options how the result buffer is handled:
504 * NULL 0 A string of sufficient length will be allocated.
505 * NULL >0 A string of the size given will be
506 * allocated. An error will be returned if the size is
507 * not sufficient. Any unused bytes in the string will
509 * !NULL 0 The user-supplied buffer will be used. No length
510 * checking will be performed, i. e. it is assumed that
511 * the buffer size will always be big enough. DANGEROUS.
512 * !NULL >0 The user-supplied buffer will be used. An error will
513 * be returned if the size is not sufficient. Any unused
514 * bytes in the string will be '\0'-padded.
517 static int cmpkey(const void *p1
, const void *p2
)
519 ENTRY
*e1
= *(ENTRY
**) p1
;
520 ENTRY
*e2
= *(ENTRY
**) p2
;
522 return (strcmp(e1
->key
, e2
->key
));
525 ssize_t
hexport_r(struct hsearch_data
*htab
, const char sep
, int flag
,
526 char **resp
, size_t size
,
527 int argc
, char * const argv
[])
529 ENTRY
*list
[htab
->size
];
534 /* Test for correct arguments. */
535 if ((resp
== NULL
) || (htab
== NULL
)) {
540 debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, "
541 "size = %zu\n", htab
, htab
->size
, htab
->filled
, size
);
544 * search used entries,
545 * save addresses and compute total length
547 for (i
= 1, n
= 0, totlen
= 0; i
<= htab
->size
; ++i
) {
549 if (htab
->table
[i
].used
> 0) {
550 ENTRY
*ep
= &htab
->table
[i
].entry
;
553 for (arg
= 0; arg
< argc
; ++arg
) {
554 if (strcmp(argv
[arg
], ep
->key
) == 0) {
559 if ((argc
> 0) && (found
== 0))
562 if ((flag
& H_HIDE_DOT
) && ep
->key
[0] == '.')
567 totlen
+= strlen(ep
->key
) + 2;
570 totlen
+= strlen(ep
->data
);
571 } else { /* check if escapes are needed */
576 /* add room for needed escape chars */
577 if ((*s
== sep
) || (*s
== '\\'))
582 totlen
+= 2; /* for '=' and 'sep' char */
587 /* Pass 1a: print unsorted list */
588 printf("Unsorted: n=%d\n", n
);
589 for (i
= 0; i
< n
; ++i
) {
590 printf("\t%3d: %p ==> %-10s => %s\n",
591 i
, list
[i
], list
[i
]->key
, list
[i
]->data
);
595 /* Sort list by keys */
596 qsort(list
, n
, sizeof(ENTRY
*), cmpkey
);
598 /* Check if the user supplied buffer size is sufficient */
600 if (size
< totlen
+ 1) { /* provided buffer too small */
601 printf("Env export buffer too small: %zu, "
602 "but need %zu\n", size
, totlen
+ 1);
610 /* Check if the user provided a buffer */
614 memset(res
, '\0', size
);
616 /* no, allocate and clear one */
617 *resp
= res
= calloc(1, size
);
625 * export sorted list of result data
627 for (i
= 0, p
= res
; i
< n
; ++i
) {
638 if ((*s
== sep
) || (*s
== '\\'))
639 *p
++ = '\\'; /* escape */
644 *p
= '\0'; /* terminate result */
656 * Check whether variable 'name' is amongst vars[],
657 * and remove all instances by setting the pointer to NULL
659 static int drop_var_from_set(const char *name
, int nvars
, char * vars
[])
664 /* No variables specified means process all of them */
668 for (i
= 0; i
< nvars
; i
++) {
671 /* If we found it, delete all of them */
672 if (!strcmp(name
, vars
[i
])) {
678 debug("Skipping non-listed variable %s\n", name
);
684 * Import linearized data into hash table.
686 * This is the inverse function to hexport(): it takes a linear list
687 * of "name=value" pairs and creates hash table entries from it.
689 * Entries without "value", i. e. consisting of only "name" or
690 * "name=", will cause this entry to be deleted from the hash table.
692 * The "flag" argument can be used to control the behaviour: when the
693 * H_NOCLEAR bit is set, then an existing hash table will kept, i. e.
694 * new data will be added to an existing hash table; otherwise, old
695 * data will be discarded and a new hash table will be created.
697 * The separator character for the "name=value" pairs can be selected,
698 * so we both support importing from externally stored environment
699 * data (separated by NUL characters) and from plain text files
700 * (entries separated by newline characters).
702 * To allow for nicely formatted text input, leading white space
703 * (sequences of SPACE and TAB chars) is ignored, and entries starting
704 * (after removal of any leading white space) with a '#' character are
705 * considered comments and ignored.
707 * [NOTE: this means that a variable name cannot start with a '#'
710 * When using a non-NUL separator character, backslash is used as
711 * escape character in the value part, allowing for example for
714 * In theory, arbitrary separator characters can be used, but only
715 * '\0' and '\n' have really been tested.
718 int himport_r(struct hsearch_data
*htab
,
719 const char *env
, size_t size
, const char sep
, int flag
,
720 int nvars
, char * const vars
[])
722 char *data
, *sp
, *dp
, *name
, *value
;
723 char *localvars
[nvars
];
726 /* Test for correct arguments. */
732 /* we allocate new space to make sure we can write to the array */
733 if ((data
= malloc(size
)) == NULL
) {
734 debug("himport_r: can't malloc %zu bytes\n", size
);
738 memcpy(data
, env
, size
);
741 /* make a local copy of the list of variables */
743 memcpy(localvars
, vars
, sizeof(vars
[0]) * nvars
);
745 if ((flag
& H_NOCLEAR
) == 0) {
746 /* Destroy old hash table if one exists */
747 debug("Destroy Hash Table: %p table = %p\n", htab
,
754 * Create new hash table (if needed). The computation of the hash
755 * table size is based on heuristics: in a sample of some 70+
756 * existing systems we found an average size of 39+ bytes per entry
757 * in the environment (for the whole key=value pair). Assuming a
758 * size of 8 per entry (= safety factor of ~5) should provide enough
759 * safety margin for any existing environment definitions and still
760 * allow for more than enough dynamic additions. Note that the
761 * "size" argument is supposed to give the maximum enviroment size
762 * (CONFIG_ENV_SIZE). This heuristics will result in
763 * unreasonably large numbers (and thus memory footprint) for
764 * big flash environments (>8,000 entries for 64 KB
765 * envrionment size), so we clip it to a reasonable value.
766 * On the other hand we need to add some more entries for free
767 * space when importing very small buffers. Both boundaries can
768 * be overwritten in the board config file if needed.
772 int nent
= CONFIG_ENV_MIN_ENTRIES
+ size
/ 8;
774 if (nent
> CONFIG_ENV_MAX_ENTRIES
)
775 nent
= CONFIG_ENV_MAX_ENTRIES
;
777 debug("Create Hash Table: N=%d\n", nent
);
779 if (hcreate_r(nent
, htab
) == 0) {
785 /* Parse environment; allow for '\0' and 'sep' as separators */
789 /* skip leading white space */
793 /* skip comment lines */
795 while (*dp
&& (*dp
!= sep
))
802 for (name
= dp
; *dp
!= '=' && *dp
&& *dp
!= sep
; ++dp
)
805 /* deal with "name" and "name=" entries (delete var) */
806 if (*dp
== '\0' || *(dp
+ 1) == '\0' ||
807 *dp
== sep
|| *(dp
+ 1) == sep
) {
810 *dp
++ = '\0'; /* terminate name */
812 debug("DELETE CANDIDATE: \"%s\"\n", name
);
813 if (!drop_var_from_set(name
, nvars
, localvars
))
816 if (hdelete_r(name
, htab
, flag
) == 0)
817 debug("DELETE ERROR ##############################\n");
821 *dp
++ = '\0'; /* terminate name */
823 /* parse value; deal with escapes */
824 for (value
= sp
= dp
; *dp
&& (*dp
!= sep
); ++dp
) {
825 if ((*dp
== '\\') && *(dp
+ 1))
829 *sp
++ = '\0'; /* terminate value */
832 /* Skip variables which are not supposed to be processed */
833 if (!drop_var_from_set(name
, nvars
, localvars
))
836 /* enter into hash table */
840 hsearch_r(e
, ENTER
, &rv
, htab
, flag
);
842 printf("himport_r: can't insert \"%s=%s\" into hash table\n",
847 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
848 htab
, htab
->filled
, htab
->size
,
850 } while ((dp
< data
+ size
) && *dp
); /* size check needed for text */
851 /* without '\0' termination */
852 debug("INSERT: free(data = %p)\n", data
);
855 /* process variables which were not considered */
856 for (i
= 0; i
< nvars
; i
++) {
857 if (localvars
[i
] == NULL
)
860 * All variables which were not deleted from the variable list
861 * were not present in the imported env
862 * This could mean two things:
863 * a) if the variable was present in current env, we delete it
864 * b) if the variable was not present in current env, we notify
867 if (hdelete_r(localvars
[i
], htab
, flag
) == 0)
868 printf("WARNING: '%s' neither in running nor in imported env!\n", localvars
[i
]);
870 printf("WARNING: '%s' not in imported env, deleting it!\n", localvars
[i
]);
873 debug("INSERT: done\n");
874 return 1; /* everything OK */