Add re-entrant versions of the hash functions based on the GNU api.

While testing this I found a conformance issue in hdestroy()
that will be fixed in a subsequent commit.

Obtained from:	NetBSD (hcreate.c, CVS Rev. 1.7)

include/search.h

@@ -1,8 +1,8 @@
 /*-
- * Written by J.T. Conklin <jtc@netbsd.org>
+ * Written by J.T. Conklin <jtc@NetBSD.org>
  * Public domain.
  *
- *	$NetBSD: search.h,v 1.12 1999/02/22 10:34:28 christos Exp $
+ *	$NetBSD: search.h,v 1.16 2005/02/03 04:39:32 perry Exp $
  * $FreeBSD$
  */
 
@@ -45,6 +45,15 @@ struct que_elem {
 };
 #endif
 
+#if __BSD_VISIBLE
+struct _ENTRY;
+struct hsearch_data {
+	struct _ENTRY *table;
+	size_t size;
+	size_t filled;
+};
+#endif
+
 __BEGIN_DECLS
 int	 hcreate(size_t);
 void	 hdestroy(void);
@@ -61,6 +70,13 @@ void	*tfind(const void *, void * const *,
 	    int (*)(const void *, const void *));
 void	*tsearch(const void *, void **, int (*)(const void *, const void *));
 void	 twalk(const void *, void (*)(const void *, VISIT, int));
+
+#if __BSD_VISIBLE
+int	 hcreate_r(size_t, struct hsearch_data *);
+void	 hdestroy_r(struct hsearch_data *);
+int	 hsearch_r(ENTRY, ACTION, ENTRY **, struct hsearch_data *);
+#endif
+
 __END_DECLS
 
 #endif /* !_SEARCH_H_ */

lib/libc/stdlib/Makefile.inc

@@ -35,6 +35,7 @@ MLINKS+=exit.3 _Exit.3
 MLINKS+=getenv.3 putenv.3 getenv.3 setenv.3 getenv.3 unsetenv.3
 MLINKS+=getopt_long.3 getopt_long_only.3
 MLINKS+=hcreate.3 hdestroy.3 hcreate.3 hsearch.3
+MLINKS+=hcreate.3 hcreate_r.3 hcreate.3 hdestroy_r.3 hcreate.3 hsearch_r.3
 MLINKS+=insque.3 remque.3
 MLINKS+=lsearch.3 lfind.3
 MLINKS+=ptsname.3 grantpt.3 ptsname.3 unlockpt.3

lib/libc/stdlib/Symbol.map

@@ -109,6 +109,9 @@ FBSD_1.4 {
 	heapsort_b;
 	mergesort_b;
 	qsort_b;
+	hcreate_r;
+	hdestroy_r;
+	hsearch_r;
 };
 
 FBSDprivate_1.0 {

lib/libc/stdlib/hcreate.3

@@ -28,11 +28,16 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 6, 2008
+.Dd July 21, 2014
 .Dt HCREATE 3
 .Os
 .Sh NAME
-.Nm hcreate , hdestroy , hsearch
+.Nm hcreate ,
+.Nm hcreate_r ,
+.Nm hdestroy ,
+.Nm hdestroy_r ,
+.Nm hsearch ,
+.Nm hsearch_r
 .Nd manage hash search table
 .Sh LIBRARY
 .Lb libc
@@ -40,16 +45,25 @@
 .In search.h
 .Ft int
 .Fn hcreate "size_t nel"
+.Ft int
+.Fn hcreate_r "size_t nel" "struct hsearch_data *table"
 .Ft void
-.Fn hdestroy void
+.Fn hdestroy "void"
+.Ft void
+.Fn hdestroy_r "struct hsearch_data *table"
 .Ft ENTRY *
 .Fn hsearch "ENTRY item" "ACTION action"
+.Ft int
+.Fn hsearch_r "ENTRY item" "ACTION action" "ENTRY ** itemp" "struct hsearch_data *table"
 .Sh DESCRIPTION
 The
 .Fn hcreate ,
+.Fn hcreate_r ,
 .Fn hdestroy ,
+.Fn hdestroy_r
+.Fn hsearch ,
 and
-.Fn hsearch
+.Fn hsearch_r
 functions manage hash search tables.
 .Pp
 The
@@ -90,7 +104,7 @@ argument is a structure of type
 .Vt ENTRY
 (defined in the
 .In search.h
-header) containing two pointers:
+header) that contains two pointers:
 .Fa item.key
 points to the comparison key (a
 .Vt "char *" ) ,
@@ -136,21 +150,50 @@ is
 and
 .Fn hdestroy
 is called.
+.Pp
+The
+.Fn hcreate_r ,
+.Fn hdestroy_r ,
+and
+.Fn hsearch_r
+functions are re-entrant versions of the above functions that can
+operate on a table supplied by the user.
+The
+.Fn hsearch_r
+function returns
+.Dv 0
+if the action is
+.Dv ENTER
+and the element cannot be created,
+.Dv 1
+otherwise.
+If the element exists or can be created, it will be placed in
+.Fa itemp ,
+otherwise
+.Fa itemp
+will be set to
+.Dv NULL .
 .Sh RETURN VALUES
 The
 .Fn hcreate
-function returns 0 if the table creation failed and the global variable
+and
+.Fn hcreate_r
+functions return 0 if the table creation failed and the global variable
 .Va errno
 is set to indicate the error;
 otherwise, a non-zero value is returned.
 .Pp
 The
 .Fn hdestroy
-function does not return a value.
+and
+.Fn hdestroy_r
+functions return no value.
 .Pp
 The
 .Fn hsearch
-function returns a
+and
+.Fn hsearch_r
+functions return a
 .Dv NULL
 pointer if either the
 .Fa action
@@ -223,15 +266,31 @@ main(void)
 .Sh ERRORS
 The
 .Fn hcreate
-and
+.Fn hcreate_r ,
 .Fn hsearch
-functions may fail if:
+and
+.Fn hsearch_r
+functions will fail if:
 .Bl -tag -width Er
 .It Bq Er ENOMEM
-Insufficient storage space is available.
+Insufficient memory is available.
 .It Bq Er EINVAL
 A table already exists.
 .El
+.Pp
+The
+.Fn hsearch
+and
+.Fn hsearch_r
+functions will also fail if the action is
+.Dv SEARCH
+and the element is not found:
+.Bl -tag -width Er
+.It Bq Er ESRCH
+The
+.Fa item
+given is not found.
+.El
 .Sh SEE ALSO
 .Xr bsearch 3 ,
 .Xr lsearch 3 ,
@@ -254,5 +313,15 @@ and
 .Fn hsearch
 functions first appeared in
 .At V .
+The
+.Fn hcreate_r ,
+.Fn hdestroy_r
+and
+.Fn hsearch_r
+functions are
+.Tn GNU
+extensions.
 .Sh BUGS
-The interface permits the use of only one hash table at a time.
+The original,
+.Pf non- Tn GNU
+interface permits the use of only one hash table at a time.

lib/libc/stdlib/hcreate.c

@@ -1,4 +1,4 @@
-/* $NetBSD: hcreate.c,v 1.6 2008/07/21 12:05:43 lukem Exp $ */
+/* $NetBSD: hcreate.c,v 1.7 2011/09/14 23:33:51 christos Exp $ */
 
 /*
  * Copyright (c) 2001 Christopher G. Demetriou
@@ -49,7 +49,7 @@
 #include <sys/cdefs.h>
 #if 0
 #if defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: hcreate.c,v 1.6 2008/07/21 12:05:43 lukem Exp $");
+__RCSID("$NetBSD: hcreate.c,v 1.7 2011/09/14 23:33:51 christos Exp $");
 #endif /* LIBC_SCCS and not lint */
 #endif
 __FBSDID("$FreeBSD$");
@@ -84,20 +84,27 @@ SLIST_HEAD(internal_head, internal_entry);
 /* 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;
+static struct hsearch_data htable;
 
 int
 hcreate(size_t nel)
 {
-	size_t idx;
-	unsigned int p2;
 
 	/* Make sure this is not called when a table already exists. */
-	if (htable != NULL) {
+	if (htable.table != NULL) {
 		errno = EINVAL;
 		return 0;
 	}
+	return hcreate_r(nel, &htable);
+}
+
+int
+hcreate_r(size_t nel, struct hsearch_data *head)
+{
+	struct internal_head *table;
+	size_t idx;
+	unsigned int p2;
+	void *p;
 
 	/* If nel is too small, make it min sized. */
 	if (nel < MIN_BUCKETS)
@@ -115,71 +122,103 @@ hcreate(size_t nel)
 	}
 	
 	/* Allocate the table. */
-	htablesize = nel;
-	htable = malloc(htablesize * sizeof htable[0]);
-	if (htable == NULL) {
+	head->size = nel;
+	head->filled = 0;
+	p = malloc(nel * sizeof table[0]);
+	if (p == NULL) {
 		errno = ENOMEM;
 		return 0;
 	}
+	head->table = p;
+	table = p;
 
 	/* Initialize it. */
-	for (idx = 0; idx < htablesize; idx++)
-		SLIST_INIT(&htable[idx]);
+	for (idx = 0; idx < nel; idx++)
+		SLIST_INIT(&table[idx]);
 
 	return 1;
 }
 
 void
 hdestroy(void)
+{
+	hdestroy_r(&htable);
+}
+
+void
+hdestroy_r(struct hsearch_data *head)
 {
 	struct internal_entry *ie;
 	size_t idx;
+	void *p;
+	struct internal_head *table;
 
-	if (htable == NULL)
+	if (head == NULL)
 		return;
 
-	for (idx = 0; idx < htablesize; idx++) {
-		while (!SLIST_EMPTY(&htable[idx])) {
-			ie = SLIST_FIRST(&htable[idx]);
-			SLIST_REMOVE_HEAD(&htable[idx], link);
+	p = head->table;
+	head->table = NULL;
+	table = p;
+
+	for (idx = 0; idx < head->size; idx++) {
+		while (!SLIST_EMPTY(&table[idx])) {
+			ie = SLIST_FIRST(&table[idx]);
+			SLIST_REMOVE_HEAD(&table[idx], link);
 			free(ie->ent.key);
 			free(ie);
 		}
 	}
-	free(htable);
-	htable = NULL;
+	free(table);
 }
 
 ENTRY *
 hsearch(ENTRY item, ACTION action)
 {
-	struct internal_head *head;
+	ENTRY *ep;
+	(void)hsearch_r(item, action, &ep, &htable);
+	return ep;
+}
+
+int
+hsearch_r(ENTRY item, ACTION action, ENTRY **itemp, struct hsearch_data *head)
+{
+	struct internal_head *table, *chain;
 	struct internal_entry *ie;
 	uint32_t hashval;
 	size_t len;
+	void *p;
+
+	p = head->table;
+	table = p;
 
 	len = strlen(item.key);
 	hashval = (*__default_hash)(item.key, len);
 
-	head = &htable[hashval & (htablesize - 1)];
-	ie = SLIST_FIRST(head);
+	chain = &table[hashval & (head->size - 1)];
+	ie = SLIST_FIRST(chain);
 	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;
+	if (ie != NULL) {
+		*itemp = &ie->ent;
+		return 1;
+	} else if (action == FIND) {
+		*itemp = NULL;
+		errno = ESRCH;
+		return 1;
+	}
 
 	ie = malloc(sizeof *ie);
 	if (ie == NULL)
-		return NULL;
+		return 0;
 	ie->ent.key = item.key;
 	ie->ent.data = item.data;
 
-	SLIST_INSERT_HEAD(head, ie, link);
-	return &ie->ent;
+	SLIST_INSERT_HEAD(chain, ie, link);
+	*itemp = &ie->ent;
+	head->filled++;
+	return 1;
 }