A hashmap implementation. I use this for storing the headers from the
client.
This commit is contained in:
Robert James Kaes
parent
54f369a734
commit
5b3658b122
389
src/hashmap.c
Normal file
389
src/hashmap.c
Normal file
@ -0,0 +1,389 @@
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/* $Id: hashmap.c,v 1.1 2002-04-07 21:30:02 rjkaes Exp $
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*
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* A hashmap implementation. The keys are case-insensitive NULL terminated
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* strings, and the data is arbitrary lumps of data. Copies of both the
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* key and the data in the hashmap itself, so you must free the original
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* key and data to avoid a memory leak. The hashmap returns a pointer
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* to the data when a key is searched for, so take care in modifying the
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* data as it's modifying the data stored in the hashmap. (In other words,
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* don't try to free the data, or realloc the memory. :)
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*
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* Copyright (C) 2002 Robert James Kaes (rjkaes@flarenet.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <sys/types.h>
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#include <inttypes.h>
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#include <ctype.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include "hashmap.h"
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#include "vector.h"
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/*
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* These structures are the storage for the hashmap. Entries are stored in
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* struct hashentry_s (the key, data, and length), and all the "buckets" are
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* grouped together in hashmap_s. The hashmap_s.size member is for
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* internal use. It stores the number of buckets the hashmap was created
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* with.
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*/
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struct hashentry_s {
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char *key;
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void *data;
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size_t len;
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struct hashentry_s *prev, *next;
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};
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struct hashmap_s {
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unsigned int size;
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struct hashentry_s **maps;
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};
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/*
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* A NULL terminated string is passed to this function and a "hash" value
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* is produced within the range of [0 .. size) (In other words, 0 to one
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* less than size.)
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* The contents of the key are converted to lowercase, so this function
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* is not case-sensitive.
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*
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* If any of the arguments are invalid a negative number is returned.
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*/
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static int
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hashfunc(const char *key, unsigned int size)
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{
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uint32_t hash;
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if (key == NULL)
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return -EINVAL;
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if (size == 0)
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return -ERANGE;
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for (hash = tolower(*key++); *key != '\0'; key++) {
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uint32_t bit =
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(hash & 1) ? (1 << (sizeof(uint32_t) - 1)) : 0;
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hash >>= 1;
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hash += tolower(*key) + bit;
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}
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/* Keep the hash within the table limits */
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return hash % size;
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}
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/*
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* Create a hashmap with the requested number of buckets. If "nbuckets" is
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* not greater than zero a NULL is returned; otherwise, a _token_ to the
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* hashmap is returned.
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*
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* NULLs are also returned if memory could not be allocated for hashmap.
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*/
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hashmap_t
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hashmap_create(unsigned int nbuckets)
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{
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struct hashmap_s* ptr;
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if (nbuckets == 0)
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return NULL;
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ptr = calloc(1, sizeof(struct hashmap_s));
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if (!ptr)
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return NULL;
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ptr->size = nbuckets;
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ptr->maps = calloc(nbuckets, sizeof(struct hashentry_s *));
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if (!ptr->maps) {
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free(ptr);
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return NULL;
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}
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return ptr;
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}
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/*
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* Follow the chain of hashentries and delete them (including the data and
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* the key.)
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*
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* Returns: 0 if the function completed successfully
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* negative number is returned if "entry" was NULL
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*/
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static inline int
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delete_hashentries(struct hashentry_s* entry)
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{
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struct hashentry_s *nextptr;
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struct hashentry_s *ptr;
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if (entry == NULL)
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return -EINVAL;
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ptr = entry;
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while (ptr) {
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nextptr = ptr->next;
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free(ptr->key);
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free(ptr->data);
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free(ptr);
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ptr = nextptr;
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}
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return 0;
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}
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/*
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* Deletes a hashmap. All the key/data pairs are also deleted.
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*
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* Returns: 0 on success
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* negative if a NULL "map" was supplied
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*/
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int
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hashmap_delete(hashmap_t map)
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{
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unsigned int i;
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if (map == NULL)
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return -EINVAL;
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for (i = 0; i < map->size; i++) {
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if (map->maps[i] != NULL)
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delete_hashentries(map->maps[i]);
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}
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free(map);
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return 0;
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}
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/*
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* Inserts a NULL terminated string (as the key), plus any arbitrary "data"
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* of "len" bytes. Both the key and the data are copied, so the original
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* key/data must be freed to avoid a memory leak.
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* The "data" must be non-NULL and "len" must be greater than zero. You
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* cannot insert NULL data in association with the key.
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*
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* Returns: 0 on success
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* negative number if there are errors
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*/
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int
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hashmap_insert(hashmap_t map, const char *key,
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const void *data, size_t len)
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{
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struct hashentry_s *ptr, *prevptr;
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int hash;
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char *key_copy;
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void *data_copy;
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if (map == NULL || key == NULL)
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return -EINVAL;
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if (!data || len < 1)
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return -ERANGE;
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hash = hashfunc(key, map->size);
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if (hash < 0)
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return hash;
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ptr = map->maps[hash];
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/*
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* First make copies of the key and data in case there is a memory
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* problem later.
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*/
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key_copy = strdup(key);
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if (!key_copy)
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return -ENOMEM;
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if (data) {
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data_copy = malloc(len);
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if (!data_copy) {
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free(key_copy);
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return -ENOMEM;
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}
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memcpy(data_copy, data, len);
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} else {
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data_copy = NULL;
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}
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if (ptr) {
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/* There is already an entry, so tack onto the end */
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while (ptr) {
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prevptr = ptr;
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ptr = ptr->next;
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}
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ptr = calloc(1, sizeof(struct hashentry_s));
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ptr->prev = prevptr;
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prevptr->next = ptr;
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} else {
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ptr = map->maps[hash] = calloc(1, sizeof(struct hashentry_s));
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}
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if (!ptr) {
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free(key_copy);
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free(data_copy);
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return -ENOMEM;
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}
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ptr->key = key_copy;
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ptr->data = data_copy;
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ptr->len = len;
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return 0;
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}
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/*
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* A pointer to data is returned based on a case-insensitive NULL terminated
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* "key". If the "key" is not found, "data" is set to NULL. A NULL "data"
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* argument indicates that the data associated with the key is to be ignored.
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*
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* Returns: negative upon an error
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* zero if no key is found
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* length of data if key is found.
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*/
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ssize_t
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hashmap_search(hashmap_t map, const char *key, void **data)
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{
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int hash;
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struct hashentry_s* ptr;
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if (map == NULL || key == NULL)
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return -EINVAL;
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hash = hashfunc(key, map->size);
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if (hash < 0)
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return hash;
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ptr = map->maps[hash];
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/* Okay, there is an entry here, now see if it's the one we want */
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while (ptr) {
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if (strcasecmp(ptr->key, key) == 0) {
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/* Found it, return a pointer to the data */
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if (data)
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*data = ptr->data;
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return ptr->len;
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}
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/* This entry didn't contain the key; move to the next one */
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ptr = ptr->next;
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}
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/* The key was not found, so return NULL */
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if (data)
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*data = NULL;
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return 0;
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}
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/*
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* Produce a vector of all the keys in the hashmap.
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*
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* Returns: NULL upon error
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* a valid vector_t if everything is fine
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*/
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vector_t
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hashmap_keys(hashmap_t map)
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{
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vector_t vector;
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unsigned int i;
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struct hashentry_s *ptr;
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if (!map)
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return NULL;
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vector = vector_create();
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if (!vector)
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return NULL;
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/*
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* Iterate through all the entries and add the keys to the
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* vector.
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*/
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for (i = 0; i < map->size; i++) {
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ptr = map->maps[i];
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while (ptr) {
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if (vector_insert(vector, ptr->key, strlen(ptr->key) + 1) < 0) {
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/* There's a problem, so delete the vector */
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vector_delete(vector);
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return NULL;
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}
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ptr = ptr->next;
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}
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}
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return vector;
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}
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/*
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* Go through the hashmap and remove the particular key.
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* NOTE: This _will_ invalidate any vectors which might have been created
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* by the hashmap_keys() function.
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*
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* Remove: negative upon error
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* 0 if the key was not found
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* 1 if the entry was deleted
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*/
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ssize_t
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hashmap_remove(hashmap_t map, const char *key)
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{
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int hash;
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struct hashentry_s* ptr;
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if (map == NULL || key == NULL)
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return -EINVAL;
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hash = hashfunc(key, map->size);
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if (hash < 0)
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return hash;
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ptr = map->maps[hash];
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while (ptr) {
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if (strcasecmp(ptr->key, key) == 0) {
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/*
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* Found the data, now need to remove everything
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* and update the hashmap.
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*/
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struct hashentry_s* prevptr = ptr->prev;
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if (prevptr) {
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prevptr->next = ptr->next;
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if (ptr->next)
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ptr->next->prev = prevptr;
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} else {
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map->maps[hash] = ptr->next;
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ptr->prev = NULL;
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}
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free(ptr->key);
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free(ptr->data);
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free(ptr);
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return 1;
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}
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/* This entry didn't contain the key; move to the next one */
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ptr = ptr->next;
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}
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/* The key was not found, so return 0 */
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return 0;
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}
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102
src/hashmap.h
Normal file
102
src/hashmap.h
Normal file
@ -0,0 +1,102 @@
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/* $Id: hashmap.h,v 1.1 2002-04-07 21:30:02 rjkaes Exp $
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*
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* A hashmap implementation. The keys are case-insensitive NULL terminated
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* strings, and the data is arbitrary lumps of data. Copies of both the
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* key and the data in the hashmap itself, so you must free the original
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* key and data to avoid a memory leak. The hashmap returns a pointer
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* to the data when a key is searched for, so take care in modifying the
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* data as it's modifying the data stored in the hashmap. (In other words,
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* don't try to free the data, or realloc the memory. :)
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*
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* Copyright (C) 2002 Robert James Kaes (rjkaes@flarenet.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef _HASHMAP_H
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#define _HASHMAP_H
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#include "vector.h"
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/* Allow the use in C++ code. */
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#if defined(__cplusplus)
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extern "C" {
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#endif
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/*
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* We're using a typedef here to "hide" the implementation details of the
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* hash map. Sure, it's a pointer, but the struct is hidden in the C file.
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* So, just use the hashmap_t like it's a cookie. :)
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*/
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typedef struct hashmap_s* hashmap_t;
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/*
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* hashmap_create() takes one argument, which is the number of buckets to
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* use internally. hashmap_delete() is self explanatory.
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*/
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extern hashmap_t hashmap_create(unsigned int nbuckets);
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extern int hashmap_delete(hashmap_t map);
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/*
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* When the you insert a key/data pair into the hashmap it will the key
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* and data are duplicated, so you must free your copy if it was created
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* on the heap. The key must be a NULL terminated string. "data" must be
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* non-NULL and length must be greater than zero.
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*
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* Returns: negative on error
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* 0 upon successful insert
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*/
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extern int hashmap_insert(hashmap_t map, const char *key,
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const void *data, size_t len);
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/*
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* If a valid key is found in the hash map you will get a pointer to the
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* data stored in the hash map. In other words, you have the power to change
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* the data a key is associated with, but do it responsibly since the
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* library doesn't take any steps to prevent you from messing up the hash
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* map. Don't try to realloc or free the data though; doing so will break
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* the hashmap. If you are only interested in whether the key is present
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* or not, supply a NULL for the "data" argument.
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*
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* Returns: negative on error
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* zero if the key was not found
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* positive (length of data) if key is found
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*/
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extern ssize_t hashmap_search(hashmap_t map, const char *key, void **data);
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/*
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* Produce a vector of all the keys in the hashmap.
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*
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* Returns: NULL upon error
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* a valid vector_t if everything is fine
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*/
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extern vector_t hashmap_keys(hashmap_t map);
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/*
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* Go through the hashmap and remove the particular key.
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* NOTE: This _will_ invalidate any vectors which might have been created
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* by the hashmap_keys() function.
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*
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* Remove: negative upon error
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* 0 if the key was not found
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* 1 if the entry was deleted
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*/
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extern ssize_t hashmap_remove(hashmap_t map, const char *key);
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#if defined(__cplusplus)
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}
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#endif /* C++ */
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#endif /* _HASHMAP_H */
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