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diff --git a/libihash/ihash.c b/libihash/ihash.c
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+/* Integer-keyed hash table functions.
+
+ Copyright (C) 1993, 1994, 1995 Free Software Foundation, Inc.
+
+ This file is part of the GNU Hurd.
+
+ Written by Michael I. Bushnell; revised by Miles Bader <miles@gnu>.
+
+ The GNU Hurd 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, or (at your option)
+ any later version.
+
+ The GNU Hurd 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 the GNU Hurd; see the file COPYING. If not, write to
+ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+#include <string.h>
+#include <stdlib.h>
+
+#include "ihash.h"
+
+/* ---------------------------------------------------------------- */
+
+/* When an entry in a hashtable's TAB array is HASH_EMPTY, that location is
+ available, and none of the other arrays are valid at that index. */
+#define HASH_EMPTY 0
+
+/* When an entry in a hashtable's TAB array is HASH_DEL, that location is
+ available, and none of the other arrays are valid at that index. The
+ difference from HASH_EMPTY is that searches continue though HASH_DEL and
+ stop at HASH_EMPTY. */
+#define HASH_DEL ((void *) -1)
+
+/* Returns an initial index in HT for the key ID, for search for an entry. */
+#define HASH(ht, id) ((id) % (ht)->size)
+/* Returns subsequent indices in HT for the key ID, given the previous one. */
+#define REHASH(ht, id, h) (((id) + (h)) % (ht)->size)
+
+/* ---------------------------------------------------------------- */
+
+static inline int
+index_empty(ihash_t ht, int index)
+{
+ return ht->tab[index] == HASH_EMPTY || ht->tab[index] == HASH_DEL;
+}
+
+static inline int
+index_valid(ihash_t ht, int index, int id)
+{
+ return !index_empty(ht, index) && ht->ids[index] == id;
+}
+
+/* Given a hash table HT, and a key ID, finds the index in the table of that
+ key. You must subsequently check to see whether the given index is valid
+ (with index_valid() or index_empty()). */
+static inline int
+find_index(ihash_t ht, int id)
+{
+ int h, firsth = -1;
+
+ for (h = HASH(ht, id);
+ ht->tab[h] != HASH_EMPTY && ht->ids[h] != id && h != firsth;
+ h = REHASH(ht, id, h))
+ if (firsth == -1)
+ firsth = h;
+
+ return h;
+}
+
+/* ---------------------------------------------------------------- */
+
+/* Create an integer hash table and return it in HT. If a memory allocation
+ error occurs, ENOMEM is returned, otherwise 0. */
+error_t
+ihash_create(ihash_t *ht)
+{
+ *ht = malloc(sizeof(struct ihash));
+ if (*ht == NULL)
+ return ENOMEM;
+ (*ht)->size = 0;
+ return 0;
+}
+
+/* Free HT and all resources it consumes. */
+void
+ihash_free(ihash_t ht)
+{
+ void (*cleanup)(void *value, void *arg) = ht->cleanup;
+
+ if (cleanup)
+ {
+ int i;
+ void *arg = ht->cleanup_arg;
+ for (i = 0; i < ht->size; i++)
+ if (!index_empty(ht, i))
+ (*cleanup)(ht->tab[i], arg);
+ }
+
+ if (ht->size > 0)
+ {
+ free(ht->tab);
+ free(ht->ids);
+ free(ht->locps);
+ }
+
+ free(ht);
+}
+
+/* Sets HT's element cleanup function to CLEANUP, and its second argument to
+ ARG. CLEANUP will be called on the value of any element to be
+ subsequently overwritten or deleted, with ARG as the second argument. */
+void
+ihash_set_cleanup(ihash_t ht,
+ void (*cleanup)(void *value, void *arg),
+ void *arg)
+{
+ ht->cleanup = cleanup;
+ ht->cleanup_arg = arg;
+}
+
+/* ---------------------------------------------------------------- */
+
+/* Add ITEM to the hash table HT under the key ID. LOCP is the address of a
+ pointer located in ITEM; If non-NULL, LOCP should point to a variable of
+ type void **, and will be filled with a pointer that may be used as an
+ argument to ihash_locp_remove(). The variable pointed to by LOCP may be
+ written to subsequently between this called and when the element is
+ deleted, so you can't stash its value elsewhere and hope to use the
+ stashed value with ihash_locp_remove(). If a memory allocation error
+ occurs, ENOMEM is returned, otherwise 0. */
+error_t
+ihash_add(ihash_t ht, int id, void *item, void ***locp)
+{
+ if (ht->size)
+ {
+ int h, firsth = -1;
+
+ /* Search for for an empty or deleted space. */
+ for (h = HASH(ht, id);
+ ht->tab[h] != HASH_EMPTY && ht->tab[h] != HASH_DEL && h != firsth;
+ h = REHASH(ht, id, h))
+ if (firsth == -1)
+ firsth = h;
+
+ if (index_empty(ht, h) || ht->ids[h] == id)
+ {
+ if (!index_empty(ht, h) && ht->cleanup)
+ ht->cleanup(ht->tab[h], ht->cleanup_arg);
+
+ ht->tab[h] = item;
+ ht->ids[h] = id;
+ ht->locps[h] = locp;
+
+ if (locp)
+ *locp = &ht->tab[h];
+
+ return 0;
+ }
+ }
+
+ {
+ int i;
+ void **entry;
+ int old_size = ht->size;
+ void **old_tab = ht->tab;
+ void ****old_locps = ht->locps;
+ int *old_ids = ht->ids;
+
+ ht->size = nextprime (2 * old_size);
+ ht->tab = malloc(ht->size * sizeof (void *));
+ ht->locps = malloc (ht->size * sizeof (void ***));
+ ht->ids = malloc (ht->size * sizeof (int));
+
+ if (ht->tab == NULL || ht->locps == NULL || ht->ids == NULL)
+ /* Memory allocation error; back out our changes and fail... */
+ {
+ if (ht->tab) free(ht->tab);
+ if (ht->locps) free(ht->locps);
+ if (ht->ids) free(ht->ids);
+
+ ht->size = old_size;
+ ht->tab = old_tab;
+ ht->locps = old_locps;
+ ht->ids = old_ids;
+
+ return ENOMEM;
+ }
+
+ for (i = ht->size, entry = ht->tab; i > 0; i--, entry++)
+ *entry = HASH_EMPTY;
+
+ /* We have to rehash this again? */
+ if (old_size > 0)
+ for (i = 0; i < old_size; i++)
+ if (old_tab[i] != HASH_EMPTY && old_tab[i] != HASH_DEL)
+ ihash_add(ht, old_ids[i], old_tab[i], old_locps[i]);
+
+ /* Finally add the new element! */
+ ihash_add(ht, id, item, locp);
+
+ if (old_size > 0)
+ {
+ free(old_tab);
+ free(old_locps);
+ free(old_ids);
+ }
+
+ return 0;
+ }
+}
+
+/* Find and return the item in hash table HT with key ID, or NULL if it
+ doesn't exist. */
+void *
+ihash_find (ihash_t ht, int id)
+{
+ if (ht->size == 0)
+ return 0;
+ else
+ {
+ int index = find_index(ht, id);
+ return index_valid(ht, index, id) ? ht->tab[index] : 0;
+ }
+}
+
+/* ---------------------------------------------------------------- */
+
+/* Call function FUN of one arg for each element of HT. FUN's only arg is a
+ pointer to the value stored in the hash table. If FUN ever returns
+ non-zero, then iteration stops and ihash_iterate returns that value,
+ otherwise it (eventually) returns 0. */
+error_t
+ihash_iterate(ihash_t ht, error_t (*fun)(void *))
+{
+ int i;
+ for (i = 0; i < ht->size; i++)
+ if (!index_empty(ht, i))
+ {
+ error_t err = fun(ht->tab[i]);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+
+/* Remove the entry at LOCP from the hashtable HT. LOCP is as returned from
+ an earlier call to ihash_add(). This call should be faster than
+ ihash_remove(). HT can be NULL, in which case the call still succeeds,
+ but no cleanup can be done. */
+void
+ihash_locp_remove(ihash_t ht, void **locp)
+{
+ void *tag = HASH_DEL;
+
+ if (ht != NULL)
+ {
+ int index = locp - ht->tab;
+ int next_index = REHASH(ht, ht->ids[index], index);
+
+ if (ht && ht->cleanup)
+ ht->cleanup(*locp, ht->cleanup_arg);
+
+ /* If the next position in this hash chain is empty, then we don't need
+ to use HASH_DEL (which only serves to prevent breaking the chain to
+ preserve lookups past this point). */
+ if (ht->tab[next_index] == HASH_EMPTY)
+ tag = HASH_EMPTY;
+ }
+
+ *locp = tag;
+}
+
+/* Remove the entry with a key of ID from HT. If anything was actually
+ removed, 1 is returned, otherwise (if there was no such element), 0. */
+int
+ihash_remove(ihash_t ht, int id)
+{
+ int index = find_index(ht, id);
+ if (index_valid(ht, index, id))
+ {
+ ihash_locp_remove(ht, &ht->tab[index]);
+ return 1;
+ }
+ else
+ return 0;
+}
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