/* $NetBSD: binhash.c,v 1.2 2017/02/14 01:16:49 christos Exp $ */
/*++
/* NAME
/* binhash 3
/* SUMMARY
/* hash table manager
/* SYNOPSIS
/* #include <binhash.h>
/*
/* typedef struct {
/* .in +4
/* void *key;
/* ssize_t key_len;
/* void *value;
/* /* private fields... */
/* .in -4
/* } BINHASH_INFO;
/*
/* BINHASH *binhash_create(size)
/* ssize_t size;
/*
/* BINHASH_INFO *binhash_enter(table, key, key_len, value)
/* BINHASH *table;
/* const void *key;
/* ssize_t key_len;
/* void *value;
/*
/* char *binhash_find(table, key, key_len)
/* BINHASH *table;
/* const void *key;
/* ssize_t key_len;
/*
/* BINHASH_INFO *binhash_locate(table, key, key_len)
/* BINHASH *table;
/* const void *key;
/* ssize_t key_len;
/*
/* void binhash_delete(table, key, key_len, free_fn)
/* BINHASH *table;
/* const void *key;
/* ssize_t key_len;
/* void (*free_fn)(void *);
/*
/* void binhash_free(table, free_fn)
/* BINHASH *table;
/* void (*free_fn)(void *);
/*
/* void binhash_walk(table, action, ptr)
/* BINHASH *table;
/* void (*action)(BINHASH_INFO *info, void *ptr);
/* void *ptr;
/*
/* BINHASH_INFO **binhash_list(table)
/* BINHASH *table;
/* DESCRIPTION
/* This module maintains one or more hash tables. Each table entry
/* consists of a unique binary-valued lookup key and a generic
/* character-pointer value.
/* The tables are automatically resized when they fill up. When the
/* values to be remembered are not character pointers, proper casts
/* should be used or the code will not be portable.
/*
/* binhash_create() creates a table of the specified size and returns a
/* pointer to the result. The lookup keys are saved with mymemdup().
/*
/* binhash_enter() stores a (key, value) pair into the specified table
/* and returns a pointer to the resulting entry. The code does not
/* check if an entry with that key already exists: use binhash_locate()
/* for updating an existing entry. The key is copied; the value is not.
/*
/* binhash_find() returns the value that was stored under the given key,
/* or a null pointer if it was not found. In order to distinguish
/* a null value from a non-existent value, use binhash_locate().
/*
/* binhash_locate() returns a pointer to the entry that was stored
/* for the given key, or a null pointer if it was not found.
/*
/* binhash_delete() removes one entry that was stored under the given key.
/* If the free_fn argument is not a null pointer, the corresponding
/* function is called with as argument the value that was stored under
/* the key.
/*
/* binhash_free() destroys a hash table, including contents. If the free_fn
/* argument is not a null pointer, the corresponding function is called
/* for each table entry, with as argument the value that was stored
/* with the entry.
/*
/* binhash_walk() invokes the action function for each table entry, with
/* a pointer to the entry as its argument. The ptr argument is passed
/* on to the action function.
/*
/* binhash_list() returns a null-terminated list of pointers to
/* all elements in the named table. The list should be passed to
/* myfree().
/* RESTRICTIONS
/* A callback function should not modify the hash table that is
/* specified to its caller.
/* DIAGNOSTICS
/* The following conditions are reported and cause the program to
/* terminate immediately: memory allocation failure; an attempt
/* to delete a non-existent entry.
/* SEE ALSO
/* mymalloc(3) memory management wrapper
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* C library */
#include <sys_defs.h>
#include <string.h>
/* Local stuff */
#include "mymalloc.h"
#include "msg.h"
#include "binhash.h"
/* binhash_hash - hash a string */
static size_t binhash_hash(const void *key, ssize_t len, size_t size)
{
size_t h = 0;
size_t g;
/*
* From the "Dragon" book by Aho, Sethi and Ullman.
*/
while (len-- > 0) {
h = (h << 4U) + *(unsigned const char *) key++;
if ((g = (h & 0xf0000000)) != 0) {
h ^= (g >> 24U);
h ^= g;
}
}
return (h % size);
}
/* binhash_link - insert element into table */
#define binhash_link(table, elm) { \
BINHASH_INFO **_h = table->data + binhash_hash(elm->key, elm->key_len, table->size);\
elm->prev = 0; \
if ((elm->next = *_h) != 0) \
(*_h)->prev = elm; \
*_h = elm; \
table->used++; \
}
/* binhash_size - allocate and initialize hash table */
static void binhash_size(BINHASH *table, size_t size)
{
BINHASH_INFO **h;
size |= 1;
table->data = h = (BINHASH_INFO **) mymalloc(size * sizeof(BINHASH_INFO *));
table->size = size;
table->used = 0;
while (size-- > 0)
*h++ = 0;
}
/* binhash_create - create initial hash table */
BINHASH *binhash_create(ssize_t size)
{
BINHASH *table;
table = (BINHASH *) mymalloc(sizeof(BINHASH));
binhash_size(table, size < 13 ? 13 : size);
return (table);
}
/* binhash_grow - extend existing table */
static void binhash_grow(BINHASH *table)
{
BINHASH_INFO *ht;
BINHASH_INFO *next;
ssize_t old_size = table->size;
BINHASH_INFO **h = table->data;
BINHASH_INFO **old_entries = h;
binhash_size(table, 2 * old_size);
while (old_size-- > 0) {
for (ht = *h++; ht; ht = next) {
next = ht->next;
binhash_link(table, ht);
}
}
myfree((void *) old_entries);
}
/* binhash_enter - enter (key, value) pair */
BINHASH_INFO *binhash_enter(BINHASH *table, const void *key, ssize_t key_len, void *value)
{
BINHASH_INFO *ht;
if (table->used >= table->size)
binhash_grow(table);
ht = (BINHASH_INFO *) mymalloc(sizeof(BINHASH_INFO));
ht->key = mymemdup(key, key_len);
ht->key_len = key_len;
ht->value = value;
binhash_link(table, ht);
return (ht);
}
/* binhash_find - lookup value */
void *binhash_find(BINHASH *table, const void *key, ssize_t key_len)
{
BINHASH_INFO *ht;
#define KEY_EQ(x,y,l) (((unsigned char *) x)[0] == ((unsigned char *) y)[0] && memcmp(x,y,l) == 0)
if (table != 0)
for (ht = table->data[binhash_hash(key, key_len, table->size)]; ht; ht = ht->next)
if (key_len == ht->key_len && KEY_EQ(key, ht->key, key_len))
return (ht->value);
return (0);
}
/* binhash_locate - lookup entry */
BINHASH_INFO *binhash_locate(BINHASH *table, const void *key, ssize_t key_len)
{
BINHASH_INFO *ht;
if (table != 0)
for (ht = table->data[binhash_hash(key, key_len, table->size)]; ht; ht = ht->next)
if (key_len == ht->key_len && KEY_EQ(key, ht->key, key_len))
return (ht);
return (0);
}
/* binhash_delete - delete one entry */
void binhash_delete(BINHASH *table, const void *key, ssize_t key_len, void (*free_fn) (void *))
{
if (table != 0) {
BINHASH_INFO *ht;
BINHASH_INFO **h = table->data + binhash_hash(key, key_len, table->size);
for (ht = *h; ht; ht = ht->next) {
if (key_len == ht->key_len && KEY_EQ(key, ht->key, key_len)) {
if (ht->next)
ht->next->prev = ht->prev;
if (ht->prev)
ht->prev->next = ht->next;
else
*h = ht->next;
table->used--;
myfree(ht->key);
if (free_fn)
(*free_fn) (ht->value);
myfree((void *) ht);
return;
}
}
msg_panic("binhash_delete: unknown_key: \"%s\"", (char *) key);
}
}
/* binhash_free - destroy hash table */
void binhash_free(BINHASH *table, void (*free_fn) (void *))
{
if (table != 0) {
ssize_t i = table->size;
BINHASH_INFO *ht;
BINHASH_INFO *next;
BINHASH_INFO **h = table->data;
while (i-- > 0) {
for (ht = *h++; ht; ht = next) {
next = ht->next;
myfree(ht->key);
if (free_fn)
(*free_fn) (ht->value);
myfree((void *) ht);
}
}
myfree((void *) table->data);
table->data = 0;
myfree((void *) table);
}
}
/* binhash_walk - iterate over hash table */
void binhash_walk(BINHASH *table, void (*action) (BINHASH_INFO *, void *),
void *ptr) {
if (table != 0) {
ssize_t i = table->size;
BINHASH_INFO **h = table->data;
BINHASH_INFO *ht;
while (i-- > 0)
for (ht = *h++; ht; ht = ht->next)
(*action) (ht, ptr);
}
}
/* binhash_list - list all table members */
BINHASH_INFO **binhash_list(table)
BINHASH *table;
{
BINHASH_INFO **list;
BINHASH_INFO *member;
ssize_t count = 0;
ssize_t i;
if (table != 0) {
list = (BINHASH_INFO **) mymalloc(sizeof(*list) * (table->used + 1));
for (i = 0; i < table->size; i++)
for (member = table->data[i]; member != 0; member = member->next)
list[count++] = member;
} else {
list = (BINHASH_INFO **) mymalloc(sizeof(*list));
}
list[count] = 0;
return (list);
}