[people/ms/u-boot.git] / lib / hashtable.c

/*
 * 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 */
}
Commit	Line	Data
a6826fbc WD	1	/*
	2	* This implementation is based on code from uClibc-0.9.30.3 but was
	3	* modified and extended for use within U-Boot.
	4	*
	5	* Copyright (C) 2010 Wolfgang Denk <wd@denx.de>
	6	*
	7	* Original license header:
	8	*
	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.
	12	*
	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.
	17	*
	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.
	22	*
	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
	26	* 02111-1307 USA.
	27	*/
	28
	29	#include <errno.h>
	30	#include <malloc.h>
	31
	32	#ifdef USE_HOSTCC /* HOST build */
	33	# include <string.h>
	34	# include <assert.h>
	35
	36	# ifndef debug
	37	# ifdef DEBUG
	38	# define debug(fmt,args...) printf(fmt ,##args)
	39	# else
	40	# define debug(fmt,args...)
	41	# endif
	42	# endif
	43	#else /* U-Boot build */
	44	# include <common.h>
	45	# include <linux/string.h>
	46	#endif
	47
fc5fc76b AB	48	#ifndef CONFIG_ENV_MIN_ENTRIES /* minimum number of entries */
	49	#define CONFIG_ENV_MIN_ENTRIES 64
	50	#endif
ea882baf WD	51	#ifndef CONFIG_ENV_MAX_ENTRIES /* maximum number of entries */
	52	#define CONFIG_ENV_MAX_ENTRIES 512
	53	#endif
	54
a6826fbc WD	55	#include "search.h"
	56
	57	/*
	58	* [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
071bc923	59	* [Knuth] The Art of Computer Programming, part 3 (6.4)
a6826fbc WD	60	*/
a6826fbc WD	61
a6826fbc WD	62	/*
	63	* The reentrant version has no static variables to maintain the state.
	64	* Instead the interface of all functions is extended to take an argument
	65	* which describes the current status.
	66	*/
	67	typedef struct _ENTRY {
	68	unsigned int used;
	69	ENTRY entry;
	70	} _ENTRY;
	71
	72
	73	/*
	74	* hcreate()
	75	*/
	76
	77	/*
	78	* For the used double hash method the table size has to be a prime. To
	79	* correct the user given table size we need a prime test. This trivial
	80	* algorithm is adequate because
	81	* a) the code is (most probably) called a few times per program run and
	82	* b) the number is small because the table must fit in the core
	83	* */
	84	static int isprime(unsigned int number)
	85	{
	86	/* no even number will be passed */
	87	unsigned int div = 3;
	88
	89	while (div * div < number && number % div != 0)
	90	div += 2;
	91
	92	return number % div != 0;
	93	}
	94
a6826fbc WD	95	/*
	96	* Before using the hash table we must allocate memory for it.
	97	* Test for an existing table are done. We allocate one element
	98	* more as the found prime number says. This is done for more effective
	99	* indexing as explained in the comment for the hsearch function.
	100	* The contents of the table is zeroed, especially the field used
	101	* becomes zero.
	102	*/
2eb1573f	103
a6826fbc WD	104	int hcreate_r(size_t nel, struct hsearch_data *htab)
	105	{
	106	/* Test for correct arguments. */
	107	if (htab == NULL) {
	108	__set_errno(EINVAL);
	109	return 0;
	110	}
	111
	112	/* There is still another table active. Return with error. */
	113	if (htab->table != NULL)
	114	return 0;
	115
	116	/* Change nel to the first prime number not smaller as nel. */
	117	nel \|= 1; /* make odd */
	118	while (!isprime(nel))
	119	nel += 2;
	120
	121	htab->size = nel;
	122	htab->filled = 0;
	123
	124	/* allocate memory and zero out */
	125	htab->table = (_ENTRY *) calloc(htab->size + 1, sizeof(_ENTRY));
	126	if (htab->table == NULL)
	127	return 0;
	128
	129	/* everything went alright */
	130	return 1;
	131	}
	132
	133
	134	/*
	135	* hdestroy()
	136	*/
a6826fbc WD	137
	138	/*
	139	* After using the hash table it has to be destroyed. The used memory can
	140	* be freed and the local static variable can be marked as not used.
	141	*/
2eb1573f	142
a6826fbc WD	143	void hdestroy_r(struct hsearch_data *htab)
	144	{
	145	int i;
	146
	147	/* Test for correct arguments. */
	148	if (htab == NULL) {
	149	__set_errno(EINVAL);
	150	return;
	151	}
	152
	153	/* free used memory */
	154	for (i = 1; i <= htab->size; ++i) {
	155	if (htab->table[i].used) {
	156	ENTRY *ep = &htab->table[i].entry;
	157
	158	free(ep->key);
	159	free(ep->data);
	160	}
	161	}
	162	free(htab->table);
	163
	164	/* the sign for an existing table is an value != NULL in htable */
	165	htab->table = NULL;
	166	}
	167
	168	/*
	169	* hsearch()
	170	*/
	171
	172	/*
	173	* This is the search function. It uses double hashing with open addressing.
	174	* The argument item.key has to be a pointer to an zero terminated, most
	175	* probably strings of chars. The function for generating a number of the
	176	* strings is simple but fast. It can be replaced by a more complex function
	177	* like ajw (see [Aho,Sethi,Ullman]) if the needs are shown.
	178	*
	179	* We use an trick to speed up the lookup. The table is created by hcreate
	180	* with one more element available. This enables us to use the index zero
	181	* special. This index will never be used because we store the first hash
	182	* index in the field used where zero means not used. Every other value
	183	* means used. The used field can be used as a first fast comparison for
	184	* equality of the stored and the parameter value. This helps to prevent
	185	* unnecessary expensive calls of strcmp.
	186	*
	187	* This implementation differs from the standard library version of
	188	* this function in a number of ways:
	189	*
	190	* - While the standard version does not make any assumptions about
	191	* the type of the stored data objects at all, this implementation
	192	* works with NUL terminated strings only.
	193	* - Instead of storing just pointers to the original objects, we
	194	* create local copies so the caller does not need to care about the
	195	* data any more.
	196	* - The standard implementation does not provide a way to update an
	197	* existing entry. This version will create a new entry or update an
	198	* existing one when both "action == ENTER" and "item.data != NULL".
	199	* - Instead of returning 1 on success, we return the index into the
	200	* internal hash table, which is also guaranteed to be positive.
	201	* This allows us direct access to the found hash table slot for
	202	* example for functions like hdelete().
	203	*/
	204
560d424b MF	205	int hmatch_r(const char match, int last_idx, ENTRY * retval,
	206	struct hsearch_data *htab)
	207	{
	208	unsigned int idx;
	209	size_t key_len = strlen(match);
	210
	211	for (idx = last_idx + 1; idx < htab->size; ++idx) {
	212	if (!htab->table[idx].used)
	213	continue;
	214	if (!strncmp(match, htab->table[idx].entry.key, key_len)) {
	215	*retval = &htab->table[idx].entry;
	216	return idx;
	217	}
	218	}
	219
	220	__set_errno(ESRCH);
	221	*retval = NULL;
	222	return 0;
	223	}
	224
a6826fbc WD	225	int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval,
	226	struct hsearch_data *htab)
	227	{
	228	unsigned int hval;
	229	unsigned int count;
	230	unsigned int len = strlen(item.key);
	231	unsigned int idx;
	232
	233	/* Compute an value for the given string. Perhaps use a better method. */
	234	hval = len;
	235	count = len;
	236	while (count-- > 0) {
	237	hval <<= 4;
	238	hval += item.key[count];
	239	}
	240
	241	/*
	242	* First hash function:
	243	* simply take the modul but prevent zero.
	244	*/
	245	hval %= htab->size;
	246	if (hval == 0)
	247	++hval;
	248
	249	/* The first index tried. */
	250	idx = hval;
	251
	252	if (htab->table[idx].used) {
	253	/*
071bc923	254	* Further action might be required according to the
a6826fbc WD	255	* action value.
	256	*/
	257	unsigned hval2;
	258
	259	if (htab->table[idx].used == hval
	260	&& strcmp(item.key, htab->table[idx].entry.key) == 0) {
	261	/* Overwrite existing value? */
	262	if ((action == ENTER) && (item.data != NULL)) {
	263	free(htab->table[idx].entry.data);
	264	htab->table[idx].entry.data =
	265	strdup(item.data);
	266	if (!htab->table[idx].entry.data) {
	267	__set_errno(ENOMEM);
	268	*retval = NULL;
	269	return 0;
	270	}
	271	}
	272	/* return found entry */
	273	*retval = &htab->table[idx].entry;
	274	return idx;
	275	}
	276
	277	/*
	278	* Second hash function:
	279	* as suggested in [Knuth]
	280	*/
	281	hval2 = 1 + hval % (htab->size - 2);
	282
	283	do {
	284	/*
071bc923 WD	285	* Because SIZE is prime this guarantees to
071bc923 WD	286	* step through all available indices.
a6826fbc WD	287	*/
	288	if (idx <= hval2)
	289	idx = htab->size + idx - hval2;
	290	else
	291	idx -= hval2;
	292
	293	/*
	294	* If we visited all entries leave the loop
	295	* unsuccessfully.
	296	*/
	297	if (idx == hval)
	298	break;
	299
	300	/* If entry is found use it. */
	301	if ((htab->table[idx].used == hval)
	302	&& strcmp(item.key, htab->table[idx].entry.key) == 0) {
	303	/* Overwrite existing value? */
	304	if ((action == ENTER) && (item.data != NULL)) {
	305	free(htab->table[idx].entry.data);
	306	htab->table[idx].entry.data =
	307	strdup(item.data);
	308	if (!htab->table[idx].entry.data) {
	309	__set_errno(ENOMEM);
	310	*retval = NULL;
	311	return 0;
	312	}
	313	}
	314	/* return found entry */
	315	*retval = &htab->table[idx].entry;
	316	return idx;
	317	}
	318	}
	319	while (htab->table[idx].used);
	320	}
	321
	322	/* An empty bucket has been found. */
	323	if (action == ENTER) {
	324	/*
071bc923 WD	325	* If table is full and another entry should be
071bc923 WD	326	* entered return with error.
a6826fbc WD	327	*/
	328	if (htab->filled == htab->size) {
	329	__set_errno(ENOMEM);
	330	*retval = NULL;
	331	return 0;
	332	}
	333
	334	/*
	335	* Create new entry;
	336	* create copies of item.key and item.data
	337	*/
	338	htab->table[idx].used = hval;
	339	htab->table[idx].entry.key = strdup(item.key);
	340	htab->table[idx].entry.data = strdup(item.data);
	341	if (!htab->table[idx].entry.key \|\|
	342	!htab->table[idx].entry.data) {
	343	__set_errno(ENOMEM);
	344	*retval = NULL;
	345	return 0;
	346	}
	347
	348	++htab->filled;
	349
	350	/* return new entry */
	351	*retval = &htab->table[idx].entry;
	352	return 1;
	353	}
	354
	355	__set_errno(ESRCH);
	356	*retval = NULL;
	357	return 0;
	358	}
	359
	360
	361	/*
	362	* hdelete()
	363	*/
	364
	365	/*
	366	* The standard implementation of hsearch(3) does not provide any way
	367	* to delete any entries from the hash table. We extend the code to
	368	* do that.
	369	*/
	370
a6826fbc WD	371	int hdelete_r(const char key, struct hsearch_data htab)
	372	{
	373	ENTRY e, *ep;
	374	int idx;
	375
	376	debug("hdelete: DELETE key \"%s\"\n", key);
	377
	378	e.key = (char *)key;
	379
	380	if ((idx = hsearch_r(e, FIND, &ep, htab)) == 0) {
	381	__set_errno(ESRCH);
	382	return 0; /* not found */
	383	}
	384
	385	/* free used ENTRY */
	386	debug("hdelete: DELETING key \"%s\"\n", key);
	387
	388	free(ep->key);
	389	free(ep->data);
	390	htab->table[idx].used = 0;
	391
	392	--htab->filled;
	393
	394	return 1;
	395	}
	396
	397	/*
	398	* hexport()
	399	*/
	400
	401	/*
	402	* Export the data stored in the hash table in linearized form.
	403	*
	404	* Entries are exported as "name=value" strings, separated by an
	405	* arbitrary (non-NUL, of course) separator character. This allows to
	406	* use this function both when formatting the U-Boot environment for
	407	* external storage (using '\0' as separator), but also when using it
	408	* for the "printenv" command to print all variables, simply by using
	409	* as '\n" as separator. This can also be used for new features like
	410	* exporting the environment data as text file, including the option
	411	* for later re-import.
	412	*
	413	* The entries in the result list will be sorted by ascending key
	414	* values.
	415	*
	416	* If the separator character is different from NUL, then any
	417	* separator characters and backslash characters in the values will
	418	* be escaped by a preceeding backslash in output. This is needed for
	419	* example to enable multi-line values, especially when the output
	420	* shall later be parsed (for example, for re-import).
	421	*
	422	* There are several options how the result buffer is handled:
	423	*
	424	* *resp size
	425	* -----------
	426	* NULL 0 A string of sufficient length will be allocated.
	427	* NULL >0 A string of the size given will be
	428	* allocated. An error will be returned if the size is
	429	* not sufficient. Any unused bytes in the string will
	430	* be '\0'-padded.
	431	* !NULL 0 The user-supplied buffer will be used. No length
	432	* checking will be performed, i. e. it is assumed that
	433	* the buffer size will always be big enough. DANGEROUS.
	434	* !NULL >0 The user-supplied buffer will be used. An error will
435	* be returned if the size is not sufficient. Any unused
436	* bytes in the string will be '\0'-padded.
437	*/
438
a6826fbc WD	439	static int cmpkey(const void p1, const void p2)
	440	{
	441	ENTRY e1 = (ENTRY **) p1;
	442	ENTRY e2 = (ENTRY **) p2;
	443
	444	return (strcmp(e1->key, e2->key));
	445	}
	446
	447	ssize_t hexport_r(struct hsearch_data *htab, const char sep,
	448	char **resp, size_t size)
	449	{
	450	ENTRY *list[htab->size];
	451	char res, p;
	452	size_t totlen;
	453	int i, n;
	454
	455	/* Test for correct arguments. */
	456	if ((resp == NULL) \|\| (htab == NULL)) {
	457	__set_errno(EINVAL);
	458	return (-1);
	459	}
	460
	461	debug("EXPORT table = %p, htab.size = %d, htab.filled = %d, size = %d\n",
	462	htab, htab->size, htab->filled, size);
	463	/*
	464	* Pass 1:
	465	* search used entries,
	466	* save addresses and compute total length
	467	*/
	468	for (i = 1, n = 0, totlen = 0; i <= htab->size; ++i) {
	469
	470	if (htab->table[i].used) {
	471	ENTRY *ep = &htab->table[i].entry;
	472
	473	list[n++] = ep;
	474
	475	totlen += strlen(ep->key) + 2;
	476
	477	if (sep == '\0') {
	478	totlen += strlen(ep->data);
	479	} else { /* check if escapes are needed */
	480	char *s = ep->data;
	481
	482	while (*s) {
	483	++totlen;
	484	/* add room for needed escape chars */
	485	if ((s == sep) \|\| (s == '\\'))
	486	++totlen;
	487	++s;
	488	}
	489	}
	490	totlen += 2; /* for '=' and 'sep' char */
	491	}
	492	}
	493
	494	#ifdef DEBUG
	495	/* Pass 1a: print unsorted list */
	496	printf("Unsorted: n=%d\n", n);
	497	for (i = 0; i < n; ++i) {
	498	printf("\t%3d: %p ==> %-10s => %s\n",
	499	i, list[i], list[i]->key, list[i]->data);
	500	}
	501	#endif
	502
503	/* Sort list by keys */
504	qsort(list, n, sizeof(ENTRY *), cmpkey);
505
506	/* Check if the user supplied buffer size is sufficient */
507	if (size) {
508	if (size < totlen + 1) { /* provided buffer too small */
509	debug("### buffer too small: %d, but need %d\n",
510	size, totlen + 1);
511	__set_errno(ENOMEM);
512	return (-1);
513	}
514	} else {
515	size = totlen + 1;
516	}
517
518	/* Check if the user provided a buffer */
519	if (*resp) {
520	/* yes; clear it */
521	res = *resp;
522	memset(res, '\0', size);
523	} else {
524	/* no, allocate and clear one */
525	*resp = res = calloc(1, size);
526	if (res == NULL) {
527	__set_errno(ENOMEM);
528	return (-1);
529	}
530	}
531	/*
532	* Pass 2:
533	* export sorted list of result data
534	*/
535	for (i = 0, p = res; i < n; ++i) {
536	char *s;
537
538	s = list[i]->key;
539	while (*s)
540	p++ = s++;
541	*p++ = '=';
542
543	s = list[i]->data;
544
545	while (*s) {
546	if ((s == sep) \|\| (s == '\\'))
547	p++ = '\\'; / escape */
548	p++ = s++;
549	}
550	*p++ = sep;
551	}
552	p = '\0'; / terminate result */
553
554	return size;
555	}
556
557
558	/*
559	* himport()
560	*/
561
562	/*
563	* Import linearized data into hash table.
564	*
565	* This is the inverse function to hexport(): it takes a linear list
566	* of "name=value" pairs and creates hash table entries from it.
567	*
568	* Entries without "value", i. e. consisting of only "name" or
569	* "name=", will cause this entry to be deleted from the hash table.
570	*
571	* The "flag" argument can be used to control the behaviour: when the
572	* H_NOCLEAR bit is set, then an existing hash table will kept, i. e.
573	* new data will be added to an existing hash table; otherwise, old
574	* data will be discarded and a new hash table will be created.
575	*
576	* The separator character for the "name=value" pairs can be selected,
577	* so we both support importing from externally stored environment
578	* data (separated by NUL characters) and from plain text files
579	* (entries separated by newline characters).
580	*
581	* To allow for nicely formatted text input, leading white space
582	* (sequences of SPACE and TAB chars) is ignored, and entries starting
583	* (after removal of any leading white space) with a '#' character are
584	* considered comments and ignored.
585	*
586	* [NOTE: this means that a variable name cannot start with a '#'
587	* character.]
588	*
589	* When using a non-NUL separator character, backslash is used as
590	* escape character in the value part, allowing for example for
591	* multi-line values.
592	*
593	* In theory, arbitrary separator characters can be used, but only
594	* '\0' and '\n' have really been tested.
595	*/
596
a6826fbc WD	597	int himport_r(struct hsearch_data *htab,
	598	const char *env, size_t size, const char sep, int flag)
	599	{
	600	char data, sp, dp, name, *value;
	601
	602	/* Test for correct arguments. */
	603	if (htab == NULL) {
	604	__set_errno(EINVAL);
	605	return 0;
	606	}
	607
	608	/* we allocate new space to make sure we can write to the array */
	609	if ((data = malloc(size)) == NULL) {
	610	debug("himport_r: can't malloc %d bytes\n", size);
	611	__set_errno(ENOMEM);
	612	return 0;
	613	}
	614	memcpy(data, env, size);
	615	dp = data;
	616
	617	if ((flag & H_NOCLEAR) == 0) {
	618	/* Destroy old hash table if one exists */
	619	debug("Destroy Hash Table: %p table = %p\n", htab,
	620	htab->table);
	621	if (htab->table)
	622	hdestroy_r(htab);
	623	}
	624
	625	/*
	626	* Create new hash table (if needed). The computation of the hash
	627	* table size is based on heuristics: in a sample of some 70+
	628	* existing systems we found an average size of 39+ bytes per entry
	629	* in the environment (for the whole key=value pair). Assuming a
ea882baf WD	630	* size of 8 per entry (= safety factor of ~5) should provide enough
ea882baf WD	631	* safety margin for any existing environment definitions and still
a6826fbc WD	632	* allow for more than enough dynamic additions. Note that the
a6826fbc WD	633	* "size" argument is supposed to give the maximum enviroment size
ea882baf WD	634	* (CONFIG_ENV_SIZE). This heuristics will result in
	635	* unreasonably large numbers (and thus memory footprint) for
	636	* big flash environments (>8,000 entries for 64 KB
fc5fc76b AB	637	* envrionment size), so we clip it to a reasonable value.
	638	* On the other hand we need to add some more entries for free
	639	* space when importing very small buffers. Both boundaries can
	640	* be overwritten in the board config file if needed.
a6826fbc WD	641	*/
	642
	643	if (!htab->table) {
fc5fc76b	644	int nent = CONFIG_ENV_MIN_ENTRIES + size / 8;
ea882baf WD	645
	646	if (nent > CONFIG_ENV_MAX_ENTRIES)
	647	nent = CONFIG_ENV_MAX_ENTRIES;
a6826fbc WD	648
	649	debug("Create Hash Table: N=%d\n", nent);
	650
	651	if (hcreate_r(nent, htab) == 0) {
	652	free(data);
	653	return 0;
	654	}
	655	}
	656
	657	/* Parse environment; allow for '\0' and 'sep' as separators */
	658	do {
	659	ENTRY e, *rv;
	660
	661	/* skip leading white space */
	662	while ((dp == ' ') \|\| (dp == '\t'))
	663	++dp;
	664
	665	/* skip comment lines */
	666	if (*dp == '#') {
	667	while (dp && (dp != sep))
	668	++dp;
	669	++dp;
	670	continue;
	671	}
	672
	673	/* parse name */
	674	for (name = dp; dp != '=' && dp && *dp != sep; ++dp)
	675	;
	676
	677	/* deal with "name" and "name=" entries (delete var) */
	678	if (dp == '\0' \|\| (dp + 1) == '\0' \|\|
	679	dp == sep \|\| (dp + 1) == sep) {
	680	if (*dp == '=')
	681	*dp++ = '\0';
	682	dp++ = '\0'; / terminate name */
	683
	684	debug("DELETE CANDIDATE: \"%s\"\n", name);
	685
	686	if (hdelete_r(name, htab) == 0)
	687	debug("DELETE ERROR ##############################\n");
	688
	689	continue;
	690	}
	691	dp++ = '\0'; / terminate name */
	692
	693	/* parse value; deal with escapes */
	694	for (value = sp = dp; dp && (dp != sep); ++dp) {
	695	if ((dp == '\\') && (dp + 1))
	696	++dp;
	697	sp++ = dp;
	698	}
	699	sp++ = '\0'; / terminate value */
	700	++dp;
	701
	702	/* enter into hash table */
	703	e.key = name;
	704	e.data = value;
	705
	706	hsearch_r(e, ENTER, &rv, htab);
	707	if (rv == NULL) {
ea882baf WD	708	printf("himport_r: can't insert \"%s=%s\" into hash table\n",
ea882baf WD	709	name, value);
a6826fbc WD	710	return 0;
	711	}
	712
ea882baf WD	713	debug("INSERT: table %p, filled %d/%d rv %p ==> name=\"%s\" value=\"%s\"\n",
	714	htab, htab->filled, htab->size,
	715	rv, name, value);
a6826fbc WD	716	} while ((dp < data + size) && dp); / size check needed for text */
a6826fbc WD	717	/* without '\0' termination */
ea882baf	718	debug("INSERT: free(data = %p)\n", data);
a6826fbc WD	719	free(data);
a6826fbc WD	720
ea882baf	721	debug("INSERT: done\n");
a6826fbc WD	722	return 1; /* everything OK */
a6826fbc WD	723	}