Add new, from scratch implementation of hsearch() et al that actually works.

Obtained from:	NetBSD
MFC after:	1 month

1 files changed, 184 insertions, 0 deletions

diff --git a/lib/libc/stdlib/hcreate.c b/lib/libc/stdlib/hcreate.c
new file mode 100644
index 0000000..ecc2431
--- /dev/null
+++ b/lib/libc/stdlib/hcreate.c
@@ -0,0 +1,184 @@
+/* $NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $ */
+/* $FreeBSD$ */
+
+/*
+ * Copyright (c) 2001 Christopher G. Demetriou
+ * 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 for the
+ *          NetBSD Project.  See http://www.netbsd.org/ for
+ *          information about NetBSD.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 THE AUTHOR 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.
+ * 
+ * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
+ */
+
+/*
+ * hcreate() / hsearch() / hdestroy()
+ *
+ * SysV/XPG4 hash table functions.
+ *
+ * Implementation done based on NetBSD manual page and Solaris manual page,
+ * plus my own personal experience about how they're supposed to work.
+ *
+ * I tried to look at Knuth (as cited by the Solaris manual page), but
+ * nobody had a copy in the office, so...
+ */
+
+#include <sys/cdefs.h>
+#if defined(LIBC_SCCS) && !defined(lint)
+__RCSID("$NetBSD: hcreate.c,v 1.2 2001/02/19 21:26:04 ross Exp $");
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+#include <sys/queue.h>
+#include <errno.h>
+#include <search.h>
+#include <stdlib.h>
+#include <string.h>
+#include "namespace.h"
+
+/*
+ * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit
+ * ptr machine) without adjusting MAX_BUCKETS_LG2 below.
+ */
+struct internal_entry {
+	SLIST_ENTRY(internal_entry) link;
+	ENTRY ent;
+};
+SLIST_HEAD(internal_head, internal_entry);
+
+#define	MIN_BUCKETS_LG2	4
+#define	MIN_BUCKETS	(1 << MIN_BUCKETS_LG2)
+
+/*
+ * max * sizeof internal_entry must fit into size_t.
+ * assumes internal_entry is <= 32 (2^5) bytes.
+ */
+#define	MAX_BUCKETS_LG2	(sizeof (size_t) * 8 - 1 - 5)
+#define	MAX_BUCKETS	((size_t)1 << MAX_BUCKETS_LG2)
+
+/* Default hash function, from db/hash/hash_func.c */
+extern u_int32_t (*__default_hash)(const void *, size_t);
+
+static struct internal_head *htable;
+static size_t htablesize;
+
+int
+hcreate(size_t nel)
+{
+	size_t idx;
+	unsigned int p2;
+
+	/* Make sure this this isn't called when a table already exists. */
+	if (htable != NULL) {
+		errno = EINVAL;
+		return 0;
+	}
+
+	/* If nel is too small, make it min sized. */
+	if (nel < MIN_BUCKETS)
+		nel = MIN_BUCKETS;
+
+	/* If it's too large, cap it. */
+	if (nel > MAX_BUCKETS)
+		nel = MAX_BUCKETS;
+
+	/* If it's is not a power of two in size, round up. */
+	if ((nel & (nel - 1)) != 0) {
+		for (p2 = 0; nel != 0; p2++)
+			nel >>= 1;
+		nel = 1 << p2;
+	}
+	
+	/* Allocate the table. */
+	htablesize = nel;
+	htable = malloc(htablesize * sizeof htable[0]);
+	if (htable == NULL) {
+		errno = ENOMEM;
+		return 0;
+	}
+
+	/* Initialize it. */
+	for (idx = 0; idx < htablesize; idx++)
+		SLIST_INIT(&htable[idx]);
+
+	return 1;
+}
+
+void
+hdestroy(void)
+{
+	struct internal_entry *ie;
+	size_t idx;
+
+	if (htable == NULL)
+		return;
+
+	for (idx = 0; idx < htablesize; idx++) {
+		while (!SLIST_EMPTY(&htable[idx])) {
+			ie = SLIST_FIRST(&htable[idx]);
+			SLIST_REMOVE_HEAD(&htable[idx], link);
+			free(ie->ent.key);
+			free(ie);
+		}
+	}
+	free(htable);
+	htable = NULL;
+}
+
+ENTRY *
+hsearch(ENTRY item, ACTION action)
+{
+	struct internal_head *head;
+	struct internal_entry *ie;
+	uint32_t hashval;
+	size_t len;
+
+	len = strlen(item.key);
+	hashval = (*__default_hash)(item.key, len);
+
+	head = &htable[hashval & (htablesize - 1)];
+	ie = SLIST_FIRST(head);
+	while (ie != NULL) {
+		if (strcmp(ie->ent.key, item.key) == 0)
+			break;
+		ie = SLIST_NEXT(ie, link);
+	}
+
+	if (ie != NULL)
+		return &ie->ent;
+	else if (action == FIND)
+		return NULL;
+
+	ie = malloc(sizeof *ie);
+	if (ie == NULL)
+		return NULL;
+	ie->ent.key = item.key;
+	ie->ent.data = item.data;
+
+	SLIST_INSERT_HEAD(head, ie, link);
+	return &ie->ent;
+}