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A hashmap implementation. I use this for storing the headers from the

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client.
This commit is contained in:
Robert James Kaes 2002-04-07 21:30:02 +00:00
parent 54f369a734
commit 5b3658b122
2 changed files with 491 additions and 0 deletions
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src/hashmap.c Normal file
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/* $Id: hashmap.c,v 1.1 2002-04-07 21:30:02 rjkaes Exp $
*
* A hashmap implementation. The keys are case-insensitive NULL terminated
* strings, and the data is arbitrary lumps of data. Copies of both the
* key and the data in the hashmap itself, so you must free the original
* key and data to avoid a memory leak. The hashmap returns a pointer
* to the data when a key is searched for, so take care in modifying the
* data as it's modifying the data stored in the hashmap. (In other words,
* don't try to free the data, or realloc the memory. :)
*
* Copyright (C) 2002 Robert James Kaes (rjkaes@flarenet.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <sys/types.h>
#include <inttypes.h>
#include <ctype.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "hashmap.h"
#include "vector.h"
/*
* These structures are the storage for the hashmap. Entries are stored in
* struct hashentry_s (the key, data, and length), and all the "buckets" are
* grouped together in hashmap_s. The hashmap_s.size member is for
* internal use. It stores the number of buckets the hashmap was created
* with.
*/
struct hashentry_s {
char *key;
void *data;
size_t len;
struct hashentry_s *prev, *next;
};
struct hashmap_s {
unsigned int size;
struct hashentry_s **maps;
};
/*
* A NULL terminated string is passed to this function and a "hash" value
* is produced within the range of [0 .. size) (In other words, 0 to one
* less than size.)
* The contents of the key are converted to lowercase, so this function
* is not case-sensitive.
*
* If any of the arguments are invalid a negative number is returned.
*/
static int
hashfunc(const char *key, unsigned int size)
{
uint32_t hash;
if (key == NULL)
return -EINVAL;
if (size == 0)
return -ERANGE;
for (hash = tolower(*key++); *key != '\0'; key++) {
uint32_t bit =
(hash & 1) ? (1 << (sizeof(uint32_t) - 1)) : 0;
hash >>= 1;
hash += tolower(*key) + bit;
}
/* Keep the hash within the table limits */
return hash % size;
}
/*
* Create a hashmap with the requested number of buckets. If "nbuckets" is
* not greater than zero a NULL is returned; otherwise, a _token_ to the
* hashmap is returned.
*
* NULLs are also returned if memory could not be allocated for hashmap.
*/
hashmap_t
hashmap_create(unsigned int nbuckets)
{
struct hashmap_s* ptr;
if (nbuckets == 0)
return NULL;
ptr = calloc(1, sizeof(struct hashmap_s));
if (!ptr)
return NULL;
ptr->size = nbuckets;
ptr->maps = calloc(nbuckets, sizeof(struct hashentry_s *));
if (!ptr->maps) {
free(ptr);
return NULL;
}
return ptr;
}
/*
* Follow the chain of hashentries and delete them (including the data and
* the key.)
*
* Returns: 0 if the function completed successfully
* negative number is returned if "entry" was NULL
*/
static inline int
delete_hashentries(struct hashentry_s* entry)
{
struct hashentry_s *nextptr;
struct hashentry_s *ptr;
if (entry == NULL)
return -EINVAL;
ptr = entry;
while (ptr) {
nextptr = ptr->next;
free(ptr->key);
free(ptr->data);
free(ptr);
ptr = nextptr;
}
return 0;
}
/*
* Deletes a hashmap. All the key/data pairs are also deleted.
*
* Returns: 0 on success
* negative if a NULL "map" was supplied
*/
int
hashmap_delete(hashmap_t map)
{
unsigned int i;
if (map == NULL)
return -EINVAL;
for (i = 0; i < map->size; i++) {
if (map->maps[i] != NULL)
delete_hashentries(map->maps[i]);
}
free(map);
return 0;
}
/*
* Inserts a NULL terminated string (as the key), plus any arbitrary "data"
* of "len" bytes. Both the key and the data are copied, so the original
* key/data must be freed to avoid a memory leak.
* The "data" must be non-NULL and "len" must be greater than zero. You
* cannot insert NULL data in association with the key.
*
* Returns: 0 on success
* negative number if there are errors
*/
int
hashmap_insert(hashmap_t map, const char *key,
const void *data, size_t len)
{
struct hashentry_s *ptr, *prevptr;
int hash;
char *key_copy;
void *data_copy;
if (map == NULL || key == NULL)
return -EINVAL;
if (!data || len < 1)
return -ERANGE;
hash = hashfunc(key, map->size);
if (hash < 0)
return hash;
ptr = map->maps[hash];
/*
* First make copies of the key and data in case there is a memory
* problem later.
*/
key_copy = strdup(key);
if (!key_copy)
return -ENOMEM;
if (data) {
data_copy = malloc(len);
if (!data_copy) {
free(key_copy);
return -ENOMEM;
}
memcpy(data_copy, data, len);
} else {
data_copy = NULL;
}
if (ptr) {
/* There is already an entry, so tack onto the end */
while (ptr) {
prevptr = ptr;
ptr = ptr->next;
}
ptr = calloc(1, sizeof(struct hashentry_s));
ptr->prev = prevptr;
prevptr->next = ptr;
} else {
ptr = map->maps[hash] = calloc(1, sizeof(struct hashentry_s));
}
if (!ptr) {
free(key_copy);
free(data_copy);
return -ENOMEM;
}
ptr->key = key_copy;
ptr->data = data_copy;
ptr->len = len;
return 0;
}
/*
* A pointer to data is returned based on a case-insensitive NULL terminated
* "key". If the "key" is not found, "data" is set to NULL. A NULL "data"
* argument indicates that the data associated with the key is to be ignored.
*
* Returns: negative upon an error
* zero if no key is found
* length of data if key is found.
*/
ssize_t
hashmap_search(hashmap_t map, const char *key, void **data)
{
int hash;
struct hashentry_s* ptr;
if (map == NULL || key == NULL)
return -EINVAL;
hash = hashfunc(key, map->size);
if (hash < 0)
return hash;
ptr = map->maps[hash];
/* Okay, there is an entry here, now see if it's the one we want */
while (ptr) {
if (strcasecmp(ptr->key, key) == 0) {
/* Found it, return a pointer to the data */
if (data)
*data = ptr->data;
return ptr->len;
}
/* This entry didn't contain the key; move to the next one */
ptr = ptr->next;
}
/* The key was not found, so return NULL */
if (data)
*data = NULL;
return 0;
}
/*
* Produce a vector of all the keys in the hashmap.
*
* Returns: NULL upon error
* a valid vector_t if everything is fine
*/
vector_t
hashmap_keys(hashmap_t map)
{
vector_t vector;
unsigned int i;
struct hashentry_s *ptr;
if (!map)
return NULL;
vector = vector_create();
if (!vector)
return NULL;
/*
* Iterate through all the entries and add the keys to the
* vector.
*/
for (i = 0; i < map->size; i++) {
ptr = map->maps[i];
while (ptr) {
if (vector_insert(vector, ptr->key, strlen(ptr->key) + 1) < 0) {
/* There's a problem, so delete the vector */
vector_delete(vector);
return NULL;
}
ptr = ptr->next;
}
}
return vector;
}
/*
* Go through the hashmap and remove the particular key.
* NOTE: This _will_ invalidate any vectors which might have been created
* by the hashmap_keys() function.
*
* Remove: negative upon error
* 0 if the key was not found
* 1 if the entry was deleted
*/
ssize_t
hashmap_remove(hashmap_t map, const char *key)
{
int hash;
struct hashentry_s* ptr;
if (map == NULL || key == NULL)
return -EINVAL;
hash = hashfunc(key, map->size);
if (hash < 0)
return hash;
ptr = map->maps[hash];
while (ptr) {
if (strcasecmp(ptr->key, key) == 0) {
/*
* Found the data, now need to remove everything
* and update the hashmap.
*/
struct hashentry_s* prevptr = ptr->prev;
if (prevptr) {
prevptr->next = ptr->next;
if (ptr->next)
ptr->next->prev = prevptr;
} else {
map->maps[hash] = ptr->next;
ptr->prev = NULL;
}
free(ptr->key);
free(ptr->data);
free(ptr);
return 1;
}
/* This entry didn't contain the key; move to the next one */
ptr = ptr->next;
}
/* The key was not found, so return 0 */
return 0;
}

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/* $Id: hashmap.h,v 1.1 2002-04-07 21:30:02 rjkaes Exp $
*
* A hashmap implementation. The keys are case-insensitive NULL terminated
* strings, and the data is arbitrary lumps of data. Copies of both the
* key and the data in the hashmap itself, so you must free the original
* key and data to avoid a memory leak. The hashmap returns a pointer
* to the data when a key is searched for, so take care in modifying the
* data as it's modifying the data stored in the hashmap. (In other words,
* don't try to free the data, or realloc the memory. :)
*
* Copyright (C) 2002 Robert James Kaes (rjkaes@flarenet.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _HASHMAP_H
#define _HASHMAP_H
#include "vector.h"
/* Allow the use in C++ code. */
#if defined(__cplusplus)
extern "C" {
#endif
/*
* We're using a typedef here to "hide" the implementation details of the
* hash map. Sure, it's a pointer, but the struct is hidden in the C file.
* So, just use the hashmap_t like it's a cookie. :)
*/
typedef struct hashmap_s* hashmap_t;
/*
* hashmap_create() takes one argument, which is the number of buckets to
* use internally. hashmap_delete() is self explanatory.
*/
extern hashmap_t hashmap_create(unsigned int nbuckets);
extern int hashmap_delete(hashmap_t map);
/*
* When the you insert a key/data pair into the hashmap it will the key
* and data are duplicated, so you must free your copy if it was created
* on the heap. The key must be a NULL terminated string. "data" must be
* non-NULL and length must be greater than zero.
*
* Returns: negative on error
* 0 upon successful insert
*/
extern int hashmap_insert(hashmap_t map, const char *key,
const void *data, size_t len);
/*
* If a valid key is found in the hash map you will get a pointer to the
* data stored in the hash map. In other words, you have the power to change
* the data a key is associated with, but do it responsibly since the
* library doesn't take any steps to prevent you from messing up the hash
* map. Don't try to realloc or free the data though; doing so will break
* the hashmap. If you are only interested in whether the key is present
* or not, supply a NULL for the "data" argument.
*
* Returns: negative on error
* zero if the key was not found
* positive (length of data) if key is found
*/
extern ssize_t hashmap_search(hashmap_t map, const char *key, void **data);
/*
* Produce a vector of all the keys in the hashmap.
*
* Returns: NULL upon error
* a valid vector_t if everything is fine
*/
extern vector_t hashmap_keys(hashmap_t map);
/*
* Go through the hashmap and remove the particular key.
* NOTE: This _will_ invalidate any vectors which might have been created
* by the hashmap_keys() function.
*
* Remove: negative upon error
* 0 if the key was not found
* 1 if the entry was deleted
*/
extern ssize_t hashmap_remove(hashmap_t map, const char *key);
#if defined(__cplusplus)
}
#endif /* C++ */
#endif /* _HASHMAP_H */