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Diffstat (limited to 'libexec/revnetgroup/hash.c')
| -rw-r--r-- | libexec/revnetgroup/hash.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/libexec/revnetgroup/hash.c b/libexec/revnetgroup/hash.c new file mode 100644 index 000000000000..db8e95e3040c --- /dev/null +++ b/libexec/revnetgroup/hash.c @@ -0,0 +1,205 @@ +/*- + * SPDX-License-Identifier: BSD-4-Clause + * + * Copyright (c) 1995 + * Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by Bill Paul. + * 4. Neither the name of the author nor the names of any co-contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/types.h> +#include "hash.h" + +/* + * This hash function is stolen directly from the + * Berkeley DB package. It already exists inside libc, but + * it's declared static which prevents us from calling it + * from here. + */ +/* + * OZ's original sdbm hash + */ +u_int32_t +hash(const void *keyarg, size_t len) +{ + const u_char *key; + size_t loop; + u_int32_t h; + +#define HASHC h = *key++ + 65599 * h + + h = 0; + key = keyarg; + if (len > 0) { + loop = (len + 8 - 1) >> 3; + + switch (len & (8 - 1)) { + case 0: + do { + HASHC; + /* FALLTHROUGH */ + case 7: + HASHC; + /* FALLTHROUGH */ + case 6: + HASHC; + /* FALLTHROUGH */ + case 5: + HASHC; + /* FALLTHROUGH */ + case 4: + HASHC; + /* FALLTHROUGH */ + case 3: + HASHC; + /* FALLTHROUGH */ + case 2: + HASHC; + /* FALLTHROUGH */ + case 1: + HASHC; + } while (--loop); + } + } + return (h); +} + +/* + * Generate a hash value for a given key (character string). + * We mask off all but the lower 8 bits since our table array + * can only hold 256 elements. + */ +u_int32_t +hashkey(char *key) +{ + + if (key == NULL) + return (-1); + return(hash((void *)key, strlen(key)) & HASH_MASK); +} + +/* Find an entry in the hash table (may be hanging off a linked list). */ +char * +lookup(struct group_entry *table[], char *key) +{ + struct group_entry *cur; + + cur = table[hashkey(key)]; + + while (cur) { + if (!strcmp(cur->key, key)) + return(cur->data); + cur = cur->next; + } + + return(NULL); +} + +/* + * Store an entry in the main netgroup hash table. Here's how this + * works: the table can only be so big when we initialize it (TABLESIZE) + * but the number of netgroups in the /etc/netgroup file could easily be + * much larger than the table. Since our hash values are adjusted to + * never be greater than TABLESIZE too, this means it won't be long before + * we find ourselves with two keys that hash to the same value. + * + * One way to deal with this is to malloc(2) a second table and start + * doing indirection, but this is a pain in the butt and it's not worth + * going to all that trouble for a dinky little program like this. Instead, + * we turn each table entry into a linked list and simply link keys + * with the same hash value together at the same index location within + * the table. + * + * That's a lot of comment for such a small piece of code, isn't it. + */ +void +store(struct group_entry *table[], char *key, char *data) +{ + struct group_entry *new; + u_int32_t i; + + i = hashkey(key); + + new = (struct group_entry *)malloc(sizeof(struct group_entry)); + new->key = strdup(key); + new->data = strdup(data); + new->next = table[i]; + table[i] = new; + + return; +} + +/* + * Store a group member entry and/or update its grouplist. This is + * a bit more complicated than the previous function since we have to + * maintain not only the hash table of group members, each group member + * structure also has a linked list of groups hung off it. If handed + * a member name that we haven't encountered before, we have to do + * two things: add that member to the table (possibly hanging them + * off the end of a linked list, as above), and add a group name to + * the member's grouplist list. If we're handed a name that already has + * an entry in the table, then we just have to do one thing, which is + * to update its grouplist. + */ +void +mstore(struct member_entry *table[], char *key, char *data, char *domain) +{ + struct member_entry *cur, *new; + struct grouplist *tmp; + u_int32_t i; + + i = hashkey(key); + cur = table[i]; + + tmp = (struct grouplist *)malloc(sizeof(struct grouplist)); + tmp->groupname = strdup(data); + tmp->next = NULL; + + /* Check if all we have to do is insert a new groupname. */ + while (cur) { + if (!strcmp(cur->key, key)) { + tmp->next = cur->groups; + cur->groups = tmp; + return; + } + cur = cur->next; + } + + /* Didn't find a match -- add the whole mess to the table. */ + new = (struct member_entry *)malloc(sizeof(struct member_entry)); + new->key = strdup(key); + new->domain = domain ? strdup(domain) : "*"; + new->groups = tmp; + new->next = table[i]; + table[i] = new; + + return; +} |