u-boot for Mediatek MT623x baseband processor
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uboot-mt623x/lib/hashtable.c

723 lines
18 KiB

/*
* This implementation is based on code from uClibc-0.9.30.3 but was
* modified and extended for use within U-Boot.
*
* Copyright (C) 2010 Wolfgang Denk <wd@denx.de>
*
* Original license header:
*
* Copyright (C) 1993, 1995, 1996, 1997, 2002 Free Software Foundation, Inc.
* This file is part of the GNU C Library.
* Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1993.
*
* The GNU C Library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* The GNU C Library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with the GNU C Library; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
* 02111-1307 USA.
*/
#include <errno.h>
#include <malloc.h>
#ifdef USE_HOSTCC /* HOST build */
# include <string.h>
# include <assert.h>
# ifndef debug
# ifdef DEBUG
# define debug(fmt,args...) printf(fmt ,##args)
# else
# define debug(fmt,args...)
# endif
# endif
#else /* U-Boot build */
# include <common.h>
# include <linux/string.h>
#endif
#ifndef CONFIG_ENV_MIN_ENTRIES /* minimum number of entries */
#define CONFIG_ENV_MIN_ENTRIES 64
#endif
#ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */
#define CONFIG_ENV_MAX_ENTRIES 512
#endif
#include "search.h"
/*
* [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
* [Knuth] The Art of Computer Programming, part 3 (6.4)
*/
/*
* The reentrant version has no static variables to maintain the state.
* Instead the interface of all functions is extended to take an argument
* which describes the current status.
*/
typedef struct _ENTRY {
unsigned int used;
ENTRY entry;
} _ENTRY;
/*
* hcreate()
*/
/*
* For the used double hash method the table size has to be a prime. To
* correct the user given table size we need a prime test. This trivial
* algorithm is adequate because
* a) the code is (most probably) called a few times per program run and
* b) the number is small because the table must fit in the core
* */
static int isprime(unsigned int number)
{
/* no even number will be passed */
unsigned int div = 3;
while (div * div < number && number % div != 0)
div += 2;
return number % div != 0;
}
/*
* Before using the hash table we must allocate memory for it.
* Test for an existing table are done. We allocate one element
* more as the found prime number says. This is done for more effective
* indexing as explained in the comment for the hsearch function.
* The contents of the table is zeroed, especially the field used
* becomes zero.
*/
int hcreate_r(size_t nel, struct hsearch_data *htab)
{
/* Test for correct arguments. */
if (htab == NULL) {
__set_errno(EINVAL);
return 0;
}
/* There is still another table active. Return with error. */
if (htab->table != NULL)
return 0;
/* Change nel to the first prime number not smaller as nel. */
nel |= 1; /* make odd */
while (!isprime(nel))
nel += 2;
htab->size = nel;
htab->filled = 0;
/* allocate memory and zero out */
htab->table = (_ENTRY *) calloc(htab->size + 1, sizeof(_ENTRY));
if (htab->table == NULL)
return 0;
/* everything went alright */
return 1;
}
/*
* hdestroy()
*/
/*
* After using the hash table it has to be destroyed. The used memory can
* be freed and the local static variable can be marked as not used.
*/
void hdestroy_r(struct hsearch_data *htab)
{
int i;
/* Test for correct arguments. */
if (htab == NULL) {
__set_errno(EINVAL);
return;
}
/* free used memory */
for (i = 1; i <= htab->size; ++i) {
if (htab->table[i].used) {
ENTRY *ep = &htab->table[i].entry;
free(ep->key);
free(ep->data);
}
}
free(htab->table);
/* the sign for an existing table is an value != NULL in htable */
htab->table = NULL;
}
/*
* hsearch()
*/
/*
* This is the search function. It uses double hashing with open addressing.
* The argument item.key has to be a pointer to an zero terminated, most
* probably strings of chars. The function for generating a number of the
* strings is simple but fast. It can be replaced by a more complex function
* like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
*
* We use an trick to speed up the lookup. The table is created by hcreate
* with one more element available. This enables us to use the index zero
* special. This index will never be used because we store the first hash
* index in the field used where zero means not used. Every other value
* means used. The used field can be used as a first fast comparison for
* equality of the stored and the parameter value. This helps to prevent
* unnecessary expensive calls of strcmp.
*
* This implementation differs from the standard library version of
* this function in a number of ways:
*
* - While the standard version does not make any assumptions about
* the type of the stored data objects at all, this implementation
* works with NUL terminated strings only.
* - Instead of storing just pointers to the original objects, we
* create local copies so the caller does not need to care about the
* data any more.
* - The standard implementation does not provide a way to update an
* existing entry. This version will create a new entry or update an
* existing one when both "action == ENTER" and "item.data != NULL".
* - Instead of returning 1 on success, we return the index into the
* internal hash table, which is also guaranteed to be positive.
* This allows us direct access to the found hash table slot for
* example for functions like hdelete().
*/
int hmatch_r(const char *match, int last_idx, ENTRY ** retval,
struct hsearch_data *htab)
{
unsigned int idx;
size_t key_len = strlen(match);
for (idx = last_idx + 1; idx < htab->size; ++idx) {
if (!htab->table[idx].used)
continue;
if (!strncmp(match, htab->table[idx].entry.key, key_len)) {
*retval = &htab->table[idx].entry;
return idx;
}
}
__set_errno(ESRCH);
*retval = NULL;
return 0;
}
int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval,
struct hsearch_data *htab)
{
unsigned int hval;
unsigned int count;
unsigned int len = strlen(item.key);
unsigned int idx;
/* Compute an value for the given string. Perhaps use a better method. */
hval = len;
count = len;
while (count-- > 0) {
hval <<= 4;
hval += item.key[count];
}
/*
* First hash function:
* simply take the modul but prevent zero.
*/
hval %= htab->size;
if (hval == 0)
++hval;
/* The first index tried. */
idx = hval;
if (htab->table[idx].used) {
/*
* Further action might be required according to the
* action value.
*/
unsigned hval2;
if (htab->table[idx].used == hval
&& strcmp(item.key, htab->table[idx].entry.key) == 0) {
/* Overwrite existing value? */
if ((action == ENTER) && (item.data != NULL)) {
free(htab->table[idx].entry.data);
htab->table[idx].entry.data =
strdup(item.data);
if (!htab->table[idx].entry.data) {
__set_errno(ENOMEM);
*retval = NULL;
return 0;
}
}
/* return found entry */
*retval = &htab->table[idx].entry;
return idx;
}
/*
* Second hash function:
* as suggested in [Knuth]
*/
hval2 = 1 + hval % (htab->size - 2);
do {
/*
* Because SIZE is prime this guarantees to
* step through all available indices.
*/
if (idx <= hval2)
idx = htab->size + idx - hval2;
else
idx -= hval2;
/*
* If we visited all entries leave the loop
* unsuccessfully.
*/
if (idx == hval)
break;
/* If entry is found use it. */
if ((htab->table[idx].used == hval)
&& strcmp(item.key, htab->table[idx].entry.key) == 0) {
/* Overwrite existing value? */
if ((action == ENTER) && (item.data != NULL)) {
free(htab->table[idx].entry.data);
htab->table[idx].entry.data =
strdup(item.data);
if (!htab->table[idx].entry.data) {
__set_errno(ENOMEM);
*retval = NULL;
return 0;
}
}
/* return found entry */
*retval = &htab->table[idx].entry;
return idx;
}
}
while (htab->table[idx].used);
}
/* An empty bucket has been found. */
if (action == ENTER) {
/*
* If table is full and another entry should be
* entered return with error.
*/
if (htab->filled == htab->size) {
__set_errno(ENOMEM);
*retval = NULL;
return 0;
}
/*
* Create new entry;
* create copies of item.key and item.data
*/
htab->table[idx].used = hval;
htab->table[idx].entry.key = strdup(item.key);
htab->table[idx].entry.data = strdup(item.data);
if (!htab->table[idx].entry.key ||
!htab->table[idx].entry.data) {
__set_errno(ENOMEM);
*retval = NULL;
return 0;
}
++htab->filled;
/* return new entry */
*retval = &htab->table[idx].entry;
return 1;
}
__set_errno(ESRCH);
*retval = NULL;
return 0;
}
/*
* hdelete()
*/
/*
* The standard implementation of hsearch(3) does not provide any way
* to delete any entries from the hash table. We extend the code to
* do that.
*/
int hdelete_r(const char *key, struct hsearch_data *htab)
{
ENTRY e, *ep;
int idx;
debug("hdelete: DELETE key \"%s\"\n", key);
e.key = (char *)key;
if ((idx = hsearch_r(e, FIND, &ep, htab)) == 0) {
__set_errno(ESRCH);
return 0; /* not found */
}
/* free used ENTRY */
debug("hdelete: DELETING key \"%s\"\n", key);
free(ep->key);
free(ep->data);
htab->table[idx].used = 0;
--htab->filled;
return 1;
}
/*
* hexport()
*/
/*
* Export the data stored in the hash table in linearized form.
*
* Entries are exported as "name=value" strings, separated by an
* arbitrary (non-NUL, of course) separator character. This allows to
* use this function both when formatting the U-Boot environment for
* external storage (using '\0' as separator), but also when using it
* for the "printenv" command to print all variables, simply by using
* as '\n" as separator. This can also be used for new features like
* exporting the environment data as text file, including the option
* for later re-import.
*
* The entries in the result list will be sorted by ascending key
* values.
*
* If the separator character is different from NUL, then any
* separator characters and backslash characters in the values will
* be escaped by a preceeding backslash in output. This is needed for
* example to enable multi-line values, especially when the output
* shall later be parsed (for example, for re-import).
*
* There are several options how the result buffer is handled:
*
* *resp size
* -----------
* NULL 0 A string of sufficient length will be allocated.
* NULL >0 A string of the size given will be
* allocated. An error will be returned if the size is
* not sufficient. Any unused bytes in the string will
* be '\0'-padded.
* !NULL 0 The user-supplied buffer will be used. No length
* checking will be performed, i. e. it is assumed that
* the buffer size will always be big enough. DANGEROUS.
* !NULL >0 The user-supplied buffer will be used. An error will
* be returned if the size is not sufficient. Any unused
* bytes in the string will be '\0'-padded.
*/
static int cmpkey(const void *p1, const void *p2)
{
ENTRY *e1 = *(ENTRY **) p1;
ENTRY *e2 = *(ENTRY **) p2;
return (strcmp(e1->key, e2->key));
}
ssize_t hexport_r(struct hsearch_data *htab, const char sep,
char **resp, size_t size)
{
ENTRY *list[htab->size];
char *res, *p;
size_t totlen;
int i, n;
/* Test for correct arguments. */
if ((resp == NULL) || (htab == NULL)) {
__set_errno(EINVAL);
return (-1);
}
debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, size = %d\n",
htab, htab->size, htab->filled, size);
/*
* Pass 1:
* search used entries,
* save addresses and compute total length
*/
for (i = 1, n = 0, totlen = 0; i <= htab->size; ++i) {
if (htab->table[i].used) {
ENTRY *ep = &htab->table[i].entry;
list[n++] = ep;
totlen += strlen(ep->key) + 2;
if (sep == '\0') {
totlen += strlen(ep->data);
} else { /* check if escapes are needed */
char *s = ep->data;
while (*s) {
++totlen;
/* add room for needed escape chars */
if ((*s == sep) || (*s == '\\'))
++totlen;
++s;
}
}
totlen += 2; /* for '=' and 'sep' char */
}
}
#ifdef DEBUG
/* Pass 1a: print unsorted list */
printf("Unsorted: n=%d\n", n);
for (i = 0; i < n; ++i) {
printf("\t%3d: %p ==> %-10s => %s\n",
i, list[i], list[i]->key, list[i]->data);
}
#endif
/* Sort list by keys */
qsort(list, n, sizeof(ENTRY *), cmpkey);
/* Check if the user supplied buffer size is sufficient */
if (size) {
if (size < totlen + 1) { /* provided buffer too small */
debug("### buffer too small: %d, but need %d\n",
size, totlen + 1);
__set_errno(ENOMEM);
return (-1);
}
} else {
size = totlen + 1;
}
/* Check if the user provided a buffer */
if (*resp) {
/* yes; clear it */
res = *resp;
memset(res, '\0', size);
} else {
/* no, allocate and clear one */
*resp = res = calloc(1, size);
if (res == NULL) {
__set_errno(ENOMEM);
return (-1);
}
}
/*
* Pass 2:
* export sorted list of result data
*/
for (i = 0, p = res; i < n; ++i) {
char *s;
s = list[i]->key;
while (*s)
*p++ = *s++;
*p++ = '=';
s = list[i]->data;
while (*s) {
if ((*s == sep) || (*s == '\\'))
*p++ = '\\'; /* escape */
*p++ = *s++;
}
*p++ = sep;
}
*p = '\0'; /* terminate result */
return size;
}
/*
* himport()
*/
/*
* Import linearized data into hash table.
*
* This is the inverse function to hexport(): it takes a linear list
* of "name=value" pairs and creates hash table entries from it.
*
* Entries without "value", i. e. consisting of only "name" or
* "name=", will cause this entry to be deleted from the hash table.
*
* The "flag" argument can be used to control the behaviour: when the
* H_NOCLEAR bit is set, then an existing hash table will kept, i. e.
* new data will be added to an existing hash table; otherwise, old
* data will be discarded and a new hash table will be created.
*
* The separator character for the "name=value" pairs can be selected,
* so we both support importing from externally stored environment
* data (separated by NUL characters) and from plain text files
* (entries separated by newline characters).
*
* To allow for nicely formatted text input, leading white space
* (sequences of SPACE and TAB chars) is ignored, and entries starting
* (after removal of any leading white space) with a '#' character are
* considered comments and ignored.
*
* [NOTE: this means that a variable name cannot start with a '#'
* character.]
*
* When using a non-NUL separator character, backslash is used as
* escape character in the value part, allowing for example for
* multi-line values.
*
* In theory, arbitrary separator characters can be used, but only
* '\0' and '\n' have really been tested.
*/
int himport_r(struct hsearch_data *htab,
const char *env, size_t size, const char sep, int flag)
{
char *data, *sp, *dp, *name, *value;
/* Test for correct arguments. */
if (htab == NULL) {
__set_errno(EINVAL);
return 0;
}
/* we allocate new space to make sure we can write to the array */
if ((data = malloc(size)) == NULL) {
debug("himport_r: can't malloc %d bytes\n", size);
__set_errno(ENOMEM);
return 0;
}
memcpy(data, env, size);
dp = data;
if ((flag & H_NOCLEAR) == 0) {
/* Destroy old hash table if one exists */
debug("Destroy Hash Table: %p table = %p\n", htab,
htab->table);
if (htab->table)
hdestroy_r(htab);
}
/*
* Create new hash table (if needed). The computation of the hash
* table size is based on heuristics: in a sample of some 70+
* existing systems we found an average size of 39+ bytes per entry
* in the environment (for the whole key=value pair). Assuming a
* size of 8 per entry (= safety factor of ~5) should provide enough
* safety margin for any existing environment definitions and still
* allow for more than enough dynamic additions. Note that the
* "size" argument is supposed to give the maximum enviroment size
* (CONFIG_ENV_SIZE). This heuristics will result in
* unreasonably large numbers (and thus memory footprint) for
* big flash environments (>8,000 entries for 64 KB
* envrionment size), so we clip it to a reasonable value.
* On the other hand we need to add some more entries for free
* space when importing very small buffers. Both boundaries can
* be overwritten in the board config file if needed.
*/
if (!htab->table) {
int nent = CONFIG_ENV_MIN_ENTRIES + size / 8;
if (nent > CONFIG_ENV_MAX_ENTRIES)
nent = CONFIG_ENV_MAX_ENTRIES;
debug("Create Hash Table: N=%d\n", nent);
if (hcreate_r(nent, htab) == 0) {
free(data);
return 0;
}
}
/* Parse environment; allow for '\0' and 'sep' as separators */
do {
ENTRY e, *rv;
/* skip leading white space */
while ((*dp == ' ') || (*dp == '\t'))
++dp;
/* skip comment lines */
if (*dp == '#') {
while (*dp && (*dp != sep))
++dp;
++dp;
continue;
}
/* parse name */
for (name = dp; *dp != '=' && *dp && *dp != sep; ++dp)
;
/* deal with "name" and "name=" entries (delete var) */
if (*dp == '\0' || *(dp + 1) == '\0' ||
*dp == sep || *(dp + 1) == sep) {
if (*dp == '=')
*dp++ = '\0';
*dp++ = '\0'; /* terminate name */
debug("DELETE CANDIDATE: \"%s\"\n", name);
if (hdelete_r(name, htab) == 0)
debug("DELETE ERROR ##############################\n");
continue;
}
*dp++ = '\0'; /* terminate name */
/* parse value; deal with escapes */
for (value = sp = dp; *dp && (*dp != sep); ++dp) {
if ((*dp == '\\') && *(dp + 1))
++dp;
*sp++ = *dp;
}
*sp++ = '\0'; /* terminate value */
++dp;
/* enter into hash table */
e.key = name;
e.data = value;
hsearch_r(e, ENTER, &rv, htab);
if (rv == NULL) {
printf("himport_r: can't insert \"%s=%s\" into hash table\n",
name, value);
return 0;
}
debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
htab, htab->filled, htab->size,
rv, name, value);
} while ((dp < data + size) && *dp); /* size check needed for text */
/* without '\0' termination */
debug("INSERT: free(data = %p)\n", data);
free(data);
debug("INSERT: done\n");
return 1; /* everything OK */
}