]>
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) 2010-2013 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 * SPDX-License-Identifier: LGPL-2.1+
19 #ifdef USE_HOSTCC /* HOST build */
26 # define debug(fmt,args...) printf(fmt ,##args)
28 # define debug(fmt,args...)
31 #else /* U-Boot build */
33 # include <linux/string.h>
34 # include <linux/ctype.h>
37 #ifndef CONFIG_ENV_MIN_ENTRIES /* minimum number of entries */
38 #define CONFIG_ENV_MIN_ENTRIES 64
40 #ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */
41 #define CONFIG_ENV_MAX_ENTRIES 512
44 #include <env_callback.h>
45 #include <env_flags.h>
50 * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
51 * [Knuth] The Art of Computer Programming, part 3 (6.4)
55 * The reentrant version has no static variables to maintain the state.
56 * Instead the interface of all functions is extended to take an argument
57 * which describes the current status.
60 typedef struct _ENTRY
{
66 static void _hdelete(const char *key
, struct hsearch_data
*htab
, ENTRY
*ep
,
74 * For the used double hash method the table size has to be a prime. To
75 * correct the user given table size we need a prime test. This trivial
76 * algorithm is adequate because
77 * a) the code is (most probably) called a few times per program run and
78 * b) the number is small because the table must fit in the core
80 static int isprime(unsigned int number
)
82 /* no even number will be passed */
85 while (div
* div
< number
&& number
% div
!= 0)
88 return number
% div
!= 0;
92 * Before using the hash table we must allocate memory for it.
93 * Test for an existing table are done. We allocate one element
94 * more as the found prime number says. This is done for more effective
95 * indexing as explained in the comment for the hsearch function.
96 * The contents of the table is zeroed, especially the field used
100 int hcreate_r(size_t nel
, struct hsearch_data
*htab
)
102 /* Test for correct arguments. */
108 /* There is still another table active. Return with error. */
109 if (htab
->table
!= NULL
)
112 /* Change nel to the first prime number not smaller as nel. */
113 nel
|= 1; /* make odd */
114 while (!isprime(nel
))
120 /* allocate memory and zero out */
121 htab
->table
= (_ENTRY
*) calloc(htab
->size
+ 1, sizeof(_ENTRY
));
122 if (htab
->table
== NULL
)
125 /* everything went alright */
135 * After using the hash table it has to be destroyed. The used memory can
136 * be freed and the local static variable can be marked as not used.
139 void hdestroy_r(struct hsearch_data
*htab
)
143 /* Test for correct arguments. */
149 /* free used memory */
150 for (i
= 1; i
<= htab
->size
; ++i
) {
151 if (htab
->table
[i
].used
> 0) {
152 ENTRY
*ep
= &htab
->table
[i
].entry
;
154 free((void *)ep
->key
);
160 /* the sign for an existing table is an value != NULL in htable */
169 * This is the search function. It uses double hashing with open addressing.
170 * The argument item.key has to be a pointer to an zero terminated, most
171 * probably strings of chars. The function for generating a number of the
172 * strings is simple but fast. It can be replaced by a more complex function
173 * like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
175 * We use an trick to speed up the lookup. The table is created by hcreate
176 * with one more element available. This enables us to use the index zero
177 * special. This index will never be used because we store the first hash
178 * index in the field used where zero means not used. Every other value
179 * means used. The used field can be used as a first fast comparison for
180 * equality of the stored and the parameter value. This helps to prevent
181 * unnecessary expensive calls of strcmp.
183 * This implementation differs from the standard library version of
184 * this function in a number of ways:
186 * - While the standard version does not make any assumptions about
187 * the type of the stored data objects at all, this implementation
188 * works with NUL terminated strings only.
189 * - Instead of storing just pointers to the original objects, we
190 * create local copies so the caller does not need to care about the
192 * - The standard implementation does not provide a way to update an
193 * existing entry. This version will create a new entry or update an
194 * existing one when both "action == ENTER" and "item.data != NULL".
195 * - Instead of returning 1 on success, we return the index into the
196 * internal hash table, which is also guaranteed to be positive.
197 * This allows us direct access to the found hash table slot for
198 * example for functions like hdelete().
201 int hmatch_r(const char *match
, int last_idx
, ENTRY
** retval
,
202 struct hsearch_data
*htab
)
205 size_t key_len
= strlen(match
);
207 for (idx
= last_idx
+ 1; idx
< htab
->size
; ++idx
) {
208 if (htab
->table
[idx
].used
<= 0)
210 if (!strncmp(match
, htab
->table
[idx
].entry
.key
, key_len
)) {
211 *retval
= &htab
->table
[idx
].entry
;
222 * Compare an existing entry with the desired key, and overwrite if the action
223 * is ENTER. This is simply a helper function for hsearch_r().
225 static inline int _compare_and_overwrite_entry(ENTRY item
, ACTION action
,
226 ENTRY
**retval
, struct hsearch_data
*htab
, int flag
,
227 unsigned int hval
, unsigned int idx
)
229 if (htab
->table
[idx
].used
== hval
230 && strcmp(item
.key
, htab
->table
[idx
].entry
.key
) == 0) {
231 /* Overwrite existing value? */
232 if ((action
== ENTER
) && (item
.data
!= NULL
)) {
233 /* check for permission */
234 if (htab
->change_ok
!= NULL
&& htab
->change_ok(
235 &htab
->table
[idx
].entry
, item
.data
,
236 env_op_overwrite
, flag
)) {
237 debug("change_ok() rejected setting variable "
238 "%s, skipping it!\n", item
.key
);
244 /* If there is a callback, call it */
245 if (htab
->table
[idx
].entry
.callback
&&
246 htab
->table
[idx
].entry
.callback(item
.key
,
247 item
.data
, env_op_overwrite
, flag
)) {
248 debug("callback() rejected setting variable "
249 "%s, skipping it!\n", item
.key
);
255 free(htab
->table
[idx
].entry
.data
);
256 htab
->table
[idx
].entry
.data
= strdup(item
.data
);
257 if (!htab
->table
[idx
].entry
.data
) {
263 /* return found entry */
264 *retval
= &htab
->table
[idx
].entry
;
271 int hsearch_r(ENTRY item
, ACTION action
, ENTRY
** retval
,
272 struct hsearch_data
*htab
, int flag
)
276 unsigned int len
= strlen(item
.key
);
278 unsigned int first_deleted
= 0;
281 /* Compute an value for the given string. Perhaps use a better method. */
284 while (count
-- > 0) {
286 hval
+= item
.key
[count
];
290 * First hash function:
291 * simply take the modul but prevent zero.
297 /* The first index tried. */
300 if (htab
->table
[idx
].used
) {
302 * Further action might be required according to the
307 if (htab
->table
[idx
].used
== -1
311 ret
= _compare_and_overwrite_entry(item
, action
, retval
, htab
,
317 * Second hash function:
318 * as suggested in [Knuth]
320 hval2
= 1 + hval
% (htab
->size
- 2);
324 * Because SIZE is prime this guarantees to
325 * step through all available indices.
328 idx
= htab
->size
+ idx
- hval2
;
333 * If we visited all entries leave the loop
339 /* If entry is found use it. */
340 ret
= _compare_and_overwrite_entry(item
, action
, retval
,
341 htab
, flag
, hval
, idx
);
345 while (htab
->table
[idx
].used
);
348 /* An empty bucket has been found. */
349 if (action
== ENTER
) {
351 * If table is full and another entry should be
352 * entered return with error.
354 if (htab
->filled
== htab
->size
) {
362 * create copies of item.key and item.data
367 htab
->table
[idx
].used
= hval
;
368 htab
->table
[idx
].entry
.key
= strdup(item
.key
);
369 htab
->table
[idx
].entry
.data
= strdup(item
.data
);
370 if (!htab
->table
[idx
].entry
.key
||
371 !htab
->table
[idx
].entry
.data
) {
379 /* This is a new entry, so look up a possible callback */
380 env_callback_init(&htab
->table
[idx
].entry
);
381 /* Also look for flags */
382 env_flags_init(&htab
->table
[idx
].entry
);
384 /* check for permission */
385 if (htab
->change_ok
!= NULL
&& htab
->change_ok(
386 &htab
->table
[idx
].entry
, item
.data
, env_op_create
, flag
)) {
387 debug("change_ok() rejected setting variable "
388 "%s, skipping it!\n", item
.key
);
389 _hdelete(item
.key
, htab
, &htab
->table
[idx
].entry
, idx
);
395 /* If there is a callback, call it */
396 if (htab
->table
[idx
].entry
.callback
&&
397 htab
->table
[idx
].entry
.callback(item
.key
, item
.data
,
398 env_op_create
, flag
)) {
399 debug("callback() rejected setting variable "
400 "%s, skipping it!\n", item
.key
);
401 _hdelete(item
.key
, htab
, &htab
->table
[idx
].entry
, idx
);
407 /* return new entry */
408 *retval
= &htab
->table
[idx
].entry
;
423 * The standard implementation of hsearch(3) does not provide any way
424 * to delete any entries from the hash table. We extend the code to
428 static void _hdelete(const char *key
, struct hsearch_data
*htab
, ENTRY
*ep
,
431 /* free used ENTRY */
432 debug("hdelete: DELETING key \"%s\"\n", key
);
433 free((void *)ep
->key
);
437 htab
->table
[idx
].used
= -1;
442 int hdelete_r(const char *key
, struct hsearch_data
*htab
, int flag
)
447 debug("hdelete: DELETE key \"%s\"\n", key
);
451 idx
= hsearch_r(e
, FIND
, &ep
, htab
, 0);
454 return 0; /* not found */
457 /* Check for permission */
458 if (htab
->change_ok
!= NULL
&&
459 htab
->change_ok(ep
, NULL
, env_op_delete
, flag
)) {
460 debug("change_ok() rejected deleting variable "
461 "%s, skipping it!\n", key
);
466 /* If there is a callback, call it */
467 if (htab
->table
[idx
].entry
.callback
&&
468 htab
->table
[idx
].entry
.callback(key
, NULL
, env_op_delete
, flag
)) {
469 debug("callback() rejected deleting variable "
470 "%s, skipping it!\n", key
);
475 _hdelete(key
, htab
, ep
, idx
);
484 #ifndef CONFIG_SPL_BUILD
486 * Export the data stored in the hash table in linearized form.
488 * Entries are exported as "name=value" strings, separated by an
489 * arbitrary (non-NUL, of course) separator character. This allows to
490 * use this function both when formatting the U-Boot environment for
491 * external storage (using '\0' as separator), but also when using it
492 * for the "printenv" command to print all variables, simply by using
493 * as '\n" as separator. This can also be used for new features like
494 * exporting the environment data as text file, including the option
495 * for later re-import.
497 * The entries in the result list will be sorted by ascending key
500 * If the separator character is different from NUL, then any
501 * separator characters and backslash characters in the values will
502 * be escaped by a preceeding backslash in output. This is needed for
503 * example to enable multi-line values, especially when the output
504 * shall later be parsed (for example, for re-import).
506 * There are several options how the result buffer is handled:
510 * NULL 0 A string of sufficient length will be allocated.
511 * NULL >0 A string of the size given will be
512 * allocated. An error will be returned if the size is
513 * not sufficient. Any unused bytes in the string will
515 * !NULL 0 The user-supplied buffer will be used. No length
516 * checking will be performed, i. e. it is assumed that
517 * the buffer size will always be big enough. DANGEROUS.
518 * !NULL >0 The user-supplied buffer will be used. An error will
519 * be returned if the size is not sufficient. Any unused
520 * bytes in the string will be '\0'-padded.
523 static int cmpkey(const void *p1
, const void *p2
)
525 ENTRY
*e1
= *(ENTRY
**) p1
;
526 ENTRY
*e2
= *(ENTRY
**) p2
;
528 return (strcmp(e1
->key
, e2
->key
));
531 static int match_string(int flag
, const char *str
, const char *pat
, void *priv
)
533 switch (flag
& H_MATCH_METHOD
) {
535 if (strcmp(str
, pat
) == 0)
539 if (strstr(str
, pat
))
545 struct slre
*slrep
= (struct slre
*)priv
;
546 struct cap caps
[slrep
->num_caps
+ 2];
548 if (slre_match(slrep
, str
, strlen(str
), caps
))
554 printf("## ERROR: unsupported match method: 0x%02x\n",
555 flag
& H_MATCH_METHOD
);
561 static int match_entry(ENTRY
*ep
, int flag
,
562 int argc
, char * const argv
[])
567 for (arg
= 0; arg
< argc
; ++arg
) {
571 if (slre_compile(&slre
, argv
[arg
]) == 0) {
572 printf("Error compiling regex: %s\n", slre
.err_str
);
576 priv
= (void *)&slre
;
578 if (flag
& H_MATCH_KEY
) {
579 if (match_string(flag
, ep
->key
, argv
[arg
], priv
))
582 if (flag
& H_MATCH_DATA
) {
583 if (match_string(flag
, ep
->data
, argv
[arg
], priv
))
590 ssize_t
hexport_r(struct hsearch_data
*htab
, const char sep
, int flag
,
591 char **resp
, size_t size
,
592 int argc
, char * const argv
[])
594 ENTRY
*list
[htab
->size
];
599 /* Test for correct arguments. */
600 if ((resp
== NULL
) || (htab
== NULL
)) {
605 debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, "
606 "size = %zu\n", htab
, htab
->size
, htab
->filled
, size
);
609 * search used entries,
610 * save addresses and compute total length
612 for (i
= 1, n
= 0, totlen
= 0; i
<= htab
->size
; ++i
) {
614 if (htab
->table
[i
].used
> 0) {
615 ENTRY
*ep
= &htab
->table
[i
].entry
;
616 int found
= match_entry(ep
, flag
, argc
, argv
);
618 if ((argc
> 0) && (found
== 0))
621 if ((flag
& H_HIDE_DOT
) && ep
->key
[0] == '.')
626 totlen
+= strlen(ep
->key
) + 2;
629 totlen
+= strlen(ep
->data
);
630 } else { /* check if escapes are needed */
635 /* add room for needed escape chars */
636 if ((*s
== sep
) || (*s
== '\\'))
641 totlen
+= 2; /* for '=' and 'sep' char */
646 /* Pass 1a: print unsorted list */
647 printf("Unsorted: n=%d\n", n
);
648 for (i
= 0; i
< n
; ++i
) {
649 printf("\t%3d: %p ==> %-10s => %s\n",
650 i
, list
[i
], list
[i
]->key
, list
[i
]->data
);
654 /* Sort list by keys */
655 qsort(list
, n
, sizeof(ENTRY
*), cmpkey
);
657 /* Check if the user supplied buffer size is sufficient */
659 if (size
< totlen
+ 1) { /* provided buffer too small */
660 printf("Env export buffer too small: %zu, "
661 "but need %zu\n", size
, totlen
+ 1);
669 /* Check if the user provided a buffer */
673 memset(res
, '\0', size
);
675 /* no, allocate and clear one */
676 *resp
= res
= calloc(1, size
);
684 * export sorted list of result data
686 for (i
= 0, p
= res
; i
< n
; ++i
) {
697 if ((*s
== sep
) || (*s
== '\\'))
698 *p
++ = '\\'; /* escape */
703 *p
= '\0'; /* terminate result */
715 * Check whether variable 'name' is amongst vars[],
716 * and remove all instances by setting the pointer to NULL
718 static int drop_var_from_set(const char *name
, int nvars
, char * vars
[])
723 /* No variables specified means process all of them */
727 for (i
= 0; i
< nvars
; i
++) {
730 /* If we found it, delete all of them */
731 if (!strcmp(name
, vars
[i
])) {
737 debug("Skipping non-listed variable %s\n", name
);
743 * Import linearized data into hash table.
745 * This is the inverse function to hexport(): it takes a linear list
746 * of "name=value" pairs and creates hash table entries from it.
748 * Entries without "value", i. e. consisting of only "name" or
749 * "name=", will cause this entry to be deleted from the hash table.
751 * The "flag" argument can be used to control the behaviour: when the
752 * H_NOCLEAR bit is set, then an existing hash table will kept, i. e.
753 * new data will be added to an existing hash table; otherwise, old
754 * data will be discarded and a new hash table will be created.
756 * The separator character for the "name=value" pairs can be selected,
757 * so we both support importing from externally stored environment
758 * data (separated by NUL characters) and from plain text files
759 * (entries separated by newline characters).
761 * To allow for nicely formatted text input, leading white space
762 * (sequences of SPACE and TAB chars) is ignored, and entries starting
763 * (after removal of any leading white space) with a '#' character are
764 * considered comments and ignored.
766 * [NOTE: this means that a variable name cannot start with a '#'
769 * When using a non-NUL separator character, backslash is used as
770 * escape character in the value part, allowing for example for
773 * In theory, arbitrary separator characters can be used, but only
774 * '\0' and '\n' have really been tested.
777 int himport_r(struct hsearch_data
*htab
,
778 const char *env
, size_t size
, const char sep
, int flag
,
779 int crlf_is_lf
, int nvars
, char * const vars
[])
781 char *data
, *sp
, *dp
, *name
, *value
;
782 char *localvars
[nvars
];
785 /* Test for correct arguments. */
791 /* we allocate new space to make sure we can write to the array */
792 if ((data
= malloc(size
+ 1)) == NULL
) {
793 debug("himport_r: can't malloc %zu bytes\n", size
+ 1);
797 memcpy(data
, env
, size
);
801 /* make a local copy of the list of variables */
803 memcpy(localvars
, vars
, sizeof(vars
[0]) * nvars
);
805 if ((flag
& H_NOCLEAR
) == 0) {
806 /* Destroy old hash table if one exists */
807 debug("Destroy Hash Table: %p table = %p\n", htab
,
814 * Create new hash table (if needed). The computation of the hash
815 * table size is based on heuristics: in a sample of some 70+
816 * existing systems we found an average size of 39+ bytes per entry
817 * in the environment (for the whole key=value pair). Assuming a
818 * size of 8 per entry (= safety factor of ~5) should provide enough
819 * safety margin for any existing environment definitions and still
820 * allow for more than enough dynamic additions. Note that the
821 * "size" argument is supposed to give the maximum environment size
822 * (CONFIG_ENV_SIZE). This heuristics will result in
823 * unreasonably large numbers (and thus memory footprint) for
824 * big flash environments (>8,000 entries for 64 KB
825 * envrionment size), so we clip it to a reasonable value.
826 * On the other hand we need to add some more entries for free
827 * space when importing very small buffers. Both boundaries can
828 * be overwritten in the board config file if needed.
832 int nent
= CONFIG_ENV_MIN_ENTRIES
+ size
/ 8;
834 if (nent
> CONFIG_ENV_MAX_ENTRIES
)
835 nent
= CONFIG_ENV_MAX_ENTRIES
;
837 debug("Create Hash Table: N=%d\n", nent
);
839 if (hcreate_r(nent
, htab
) == 0) {
847 return 1; /* everything OK */
850 /* Remove Carriage Returns in front of Line Feeds */
851 unsigned ignored_crs
= 0;
852 for(;dp
< data
+ size
&& *dp
; ++dp
) {
854 dp
< data
+ size
- 1 && *(dp
+1) == '\n')
857 *(dp
-ignored_crs
) = *dp
;
862 /* Parse environment; allow for '\0' and 'sep' as separators */
866 /* skip leading white space */
870 /* skip comment lines */
872 while (*dp
&& (*dp
!= sep
))
879 for (name
= dp
; *dp
!= '=' && *dp
&& *dp
!= sep
; ++dp
)
882 /* deal with "name" and "name=" entries (delete var) */
883 if (*dp
== '\0' || *(dp
+ 1) == '\0' ||
884 *dp
== sep
|| *(dp
+ 1) == sep
) {
887 *dp
++ = '\0'; /* terminate name */
889 debug("DELETE CANDIDATE: \"%s\"\n", name
);
890 if (!drop_var_from_set(name
, nvars
, localvars
))
893 if (hdelete_r(name
, htab
, flag
) == 0)
894 debug("DELETE ERROR ##############################\n");
898 *dp
++ = '\0'; /* terminate name */
900 /* parse value; deal with escapes */
901 for (value
= sp
= dp
; *dp
&& (*dp
!= sep
); ++dp
) {
902 if ((*dp
== '\\') && *(dp
+ 1))
906 *sp
++ = '\0'; /* terminate value */
910 debug("INSERT: unable to use an empty key\n");
916 /* Skip variables which are not supposed to be processed */
917 if (!drop_var_from_set(name
, nvars
, localvars
))
920 /* enter into hash table */
924 hsearch_r(e
, ENTER
, &rv
, htab
, flag
);
926 printf("himport_r: can't insert \"%s=%s\" into hash table\n",
929 debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
930 htab
, htab
->filled
, htab
->size
,
932 } while ((dp
< data
+ size
) && *dp
); /* size check needed for text */
933 /* without '\0' termination */
934 debug("INSERT: free(data = %p)\n", data
);
937 /* process variables which were not considered */
938 for (i
= 0; i
< nvars
; i
++) {
939 if (localvars
[i
] == NULL
)
942 * All variables which were not deleted from the variable list
943 * were not present in the imported env
944 * This could mean two things:
945 * a) if the variable was present in current env, we delete it
946 * b) if the variable was not present in current env, we notify
949 if (hdelete_r(localvars
[i
], htab
, flag
) == 0)
950 printf("WARNING: '%s' neither in running nor in imported env!\n", localvars
[i
]);
952 printf("WARNING: '%s' not in imported env, deleting it!\n", localvars
[i
]);
955 debug("INSERT: done\n");
956 return 1; /* everything OK */
964 * Walk all of the entries in the hash, calling the callback for each one.
965 * this allows some generic operation to be performed on each element.
967 int hwalk_r(struct hsearch_data
*htab
, int (*callback
)(ENTRY
*))
972 for (i
= 1; i
<= htab
->size
; ++i
) {
973 if (htab
->table
[i
].used
> 0) {
974 retval
= callback(&htab
->table
[i
].entry
);