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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 12:06:34 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 12:06:34 +0000 |
commit | 5e61585d76ae77fd5e9e96ebabb57afa4d74880d (patch) | |
tree | 2b467823aaeebc7ef8bc9e3cabe8074eaef1666d /src/util/htable.c | |
parent | Initial commit. (diff) | |
download | postfix-5e61585d76ae77fd5e9e96ebabb57afa4d74880d.tar.xz postfix-5e61585d76ae77fd5e9e96ebabb57afa4d74880d.zip |
Adding upstream version 3.5.24.upstream/3.5.24upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/util/htable.c')
-rw-r--r-- | src/util/htable.c | 421 |
1 files changed, 421 insertions, 0 deletions
diff --git a/src/util/htable.c b/src/util/htable.c new file mode 100644 index 0000000..48838e5 --- /dev/null +++ b/src/util/htable.c @@ -0,0 +1,421 @@ +/*++ +/* NAME +/* htable 3 +/* SUMMARY +/* hash table manager +/* SYNOPSIS +/* #include <htable.h> +/* +/* typedef struct { +/* .in +4 +/* char *key; +/* void *value; +/* /* private fields... */ +/* .in -4 +/* } HTABLE_INFO; +/* +/* HTABLE *htable_create(size) +/* int size; +/* +/* HTABLE_INFO *htable_enter(table, key, value) +/* HTABLE *table; +/* const char *key; +/* void *value; +/* +/* char *htable_find(table, key) +/* HTABLE *table; +/* const char *key; +/* +/* HTABLE_INFO *htable_locate(table, key) +/* HTABLE *table; +/* const char *key; +/* +/* void htable_delete(table, key, free_fn) +/* HTABLE *table; +/* const char *key; +/* void (*free_fn)(void *); +/* +/* void htable_free(table, free_fn) +/* HTABLE *table; +/* void (*free_fn)(void *); +/* +/* void htable_walk(table, action, ptr) +/* HTABLE *table; +/* void (*action)(HTABLE_INFO *, void *ptr); +/* void *ptr; +/* +/* HTABLE_INFO **htable_list(table) +/* HTABLE *table; +/* +/* HTABLE_INFO *htable_sequence(table, how) +/* HTABLE *table; +/* int how; +/* DESCRIPTION +/* This module maintains one or more hash tables. Each table entry +/* consists of a unique string-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. +/* +/* htable_create() creates a table of the specified size and returns a +/* pointer to the result. The lookup keys are saved with mystrdup(). +/* htable_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 htable_locate() +/* for updating an existing entry. +/* +/* htable_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 htable_locate(). +/* +/* htable_locate() returns a pointer to the entry that was stored +/* for the given key, or a null pointer if it was not found. +/* +/* htable_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 non-zero value stored under +/* the key. +/* +/* htable_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 non-zero value stored +/* with the entry. +/* +/* htable_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. +/* +/* htable_list() returns a null-terminated list of pointers to +/* all elements in the named table. The list should be passed to +/* myfree(). +/* +/* htable_sequence() returns the first or next element depending +/* on the value of the "how" argument. Specify HTABLE_SEQ_FIRST +/* to start a new sequence, HTABLE_SEQ_NEXT to continue, and +/* HTABLE_SEQ_STOP to terminate a sequence early. The caller +/* must not delete an element before it is visited. +/* 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 "htable.h" + +/* htable_hash - hash a string */ + +static size_t htable_hash(const char *s, size_t size) +{ + size_t h = 0; + size_t g; + + /* + * From the "Dragon" book by Aho, Sethi and Ullman. + */ + + while (*s) { + h = (h << 4U) + *(unsigned const char *) s++; + if ((g = (h & 0xf0000000)) != 0) { + h ^= (g >> 24U); + h ^= g; + } + } + return (h % size); +} + +/* htable_link - insert element into table */ + +#define htable_link(table, element) { \ + HTABLE_INFO **_h = table->data + htable_hash(element->key, table->size);\ + element->prev = 0; \ + if ((element->next = *_h) != 0) \ + (*_h)->prev = element; \ + *_h = element; \ + table->used++; \ +} + +/* htable_size - allocate and initialize hash table */ + +static void htable_size(HTABLE *table, size_t size) +{ + HTABLE_INFO **h; + + size |= 1; + + table->data = h = (HTABLE_INFO **) mymalloc(size * sizeof(HTABLE_INFO *)); + table->size = size; + table->used = 0; + + while (size-- > 0) + *h++ = 0; +} + +/* htable_create - create initial hash table */ + +HTABLE *htable_create(ssize_t size) +{ + HTABLE *table; + + table = (HTABLE *) mymalloc(sizeof(HTABLE)); + htable_size(table, size < 13 ? 13 : size); + table->seq_bucket = table->seq_element = 0; + return (table); +} + +/* htable_grow - extend existing table */ + +static void htable_grow(HTABLE *table) +{ + HTABLE_INFO *ht; + HTABLE_INFO *next; + size_t old_size = table->size; + HTABLE_INFO **h = table->data; + HTABLE_INFO **old_entries = h; + + htable_size(table, 2 * old_size); + + while (old_size-- > 0) { + for (ht = *h++; ht; ht = next) { + next = ht->next; + htable_link(table, ht); + } + } + myfree((void *) old_entries); +} + +/* htable_enter - enter (key, value) pair */ + +HTABLE_INFO *htable_enter(HTABLE *table, const char *key, void *value) +{ + HTABLE_INFO *ht; + + if (table->used >= table->size) + htable_grow(table); + ht = (HTABLE_INFO *) mymalloc(sizeof(HTABLE_INFO)); + ht->key = mystrdup(key); + ht->value = value; + htable_link(table, ht); + return (ht); +} + +/* htable_find - lookup value */ + +void *htable_find(HTABLE *table, const char *key) +{ + HTABLE_INFO *ht; + +#define STREQ(x,y) (x == y || (x[0] == y[0] && strcmp(x,y) == 0)) + + if (table) + for (ht = table->data[htable_hash(key, table->size)]; ht; ht = ht->next) + if (STREQ(key, ht->key)) + return (ht->value); + return (0); +} + +/* htable_locate - lookup entry */ + +HTABLE_INFO *htable_locate(HTABLE *table, const char *key) +{ + HTABLE_INFO *ht; + +#define STREQ(x,y) (x == y || (x[0] == y[0] && strcmp(x,y) == 0)) + + if (table) + for (ht = table->data[htable_hash(key, table->size)]; ht; ht = ht->next) + if (STREQ(key, ht->key)) + return (ht); + return (0); +} + +/* htable_delete - delete one entry */ + +void htable_delete(HTABLE *table, const char *key, void (*free_fn) (void *)) +{ + if (table) { + HTABLE_INFO *ht; + HTABLE_INFO **h = table->data + htable_hash(key, table->size); + +#define STREQ(x,y) (x == y || (x[0] == y[0] && strcmp(x,y) == 0)) + + for (ht = *h; ht; ht = ht->next) { + if (STREQ(key, ht->key)) { + 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 && ht->value) + (*free_fn) (ht->value); + myfree((void *) ht); + return; + } + } + msg_panic("htable_delete: unknown_key: \"%s\"", key); + } +} + +/* htable_free - destroy hash table */ + +void htable_free(HTABLE *table, void (*free_fn) (void *)) +{ + if (table) { + ssize_t i = table->size; + HTABLE_INFO *ht; + HTABLE_INFO *next; + HTABLE_INFO **h = table->data; + + while (i-- > 0) { + for (ht = *h++; ht; ht = next) { + next = ht->next; + myfree(ht->key); + if (free_fn && ht->value) + (*free_fn) (ht->value); + myfree((void *) ht); + } + } + myfree((void *) table->data); + table->data = 0; + if (table->seq_bucket) + myfree((void *) table->seq_bucket); + table->seq_bucket = 0; + myfree((void *) table); + } +} + +/* htable_walk - iterate over hash table */ + +void htable_walk(HTABLE *table, void (*action) (HTABLE_INFO *, void *), + void *ptr) { + if (table) { + ssize_t i = table->size; + HTABLE_INFO **h = table->data; + HTABLE_INFO *ht; + + while (i-- > 0) + for (ht = *h++; ht; ht = ht->next) + (*action) (ht, ptr); + } +} + +/* htable_list - list all table members */ + +HTABLE_INFO **htable_list(HTABLE *table) +{ + HTABLE_INFO **list; + HTABLE_INFO *member; + ssize_t count = 0; + ssize_t i; + + if (table != 0) { + list = (HTABLE_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 = (HTABLE_INFO **) mymalloc(sizeof(*list)); + } + list[count] = 0; + return (list); +} + +/* htable_sequence - dict(3) compatibility iterator */ + +HTABLE_INFO *htable_sequence(HTABLE *table, int how) +{ + if (table == 0) + return (0); + + switch (how) { + case HTABLE_SEQ_FIRST: /* start new sequence */ + if (table->seq_bucket) + myfree((void *) table->seq_bucket); + table->seq_bucket = htable_list(table); + table->seq_element = table->seq_bucket; + return (*(table->seq_element)++); + case HTABLE_SEQ_NEXT: /* next element */ + if (table->seq_element && *table->seq_element) + return (*(table->seq_element)++); + /* FALLTHROUGH */ + default: /* terminate sequence */ + if (table->seq_bucket) { + myfree((void *) table->seq_bucket); + table->seq_bucket = table->seq_element = 0; + } + return (0); + } +} + +#ifdef TEST +#include <vstring_vstream.h> +#include <myrand.h> + +int main(int unused_argc, char **unused_argv) +{ + VSTRING *buf = vstring_alloc(10); + ssize_t count = 0; + HTABLE *hash; + HTABLE_INFO **ht_info; + HTABLE_INFO **ht; + HTABLE_INFO *info; + ssize_t i; + ssize_t r; + int op; + + /* + * Load a large number of strings and delete them in a random order. + */ + hash = htable_create(10); + while (vstring_get(buf, VSTREAM_IN) != VSTREAM_EOF) + htable_enter(hash, vstring_str(buf), CAST_INT_TO_VOID_PTR(count++)); + for (i = 0, op = HTABLE_SEQ_FIRST; htable_sequence(hash, op) != 0; + i++, op = HTABLE_SEQ_NEXT) + /* void */ ; + if (i != hash->used) + msg_panic("%ld entries found, but %lu entries exist", + (long) i, (unsigned long) hash->used); + ht_info = htable_list(hash); + for (i = 0; i < hash->used; i++) { + r = myrand() % hash->used; + info = ht_info[i]; + ht_info[i] = ht_info[r]; + ht_info[r] = info; + } + for (ht = ht_info; *ht; ht++) + htable_delete(hash, ht[0]->key, (void (*) (void *)) 0); + if (hash->used > 0) + msg_panic("%ld entries not deleted", (long) hash->used); + myfree((void *) ht_info); + htable_free(hash, (void (*) (void *)) 0); + vstring_free(buf); + return (0); +} + +#endif |