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

client.

1 files changed, 389 insertions, 0 deletions

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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;
+}