original openbsd grep (freegrep)

commands/grep/queue.c

@@ -0,0 +1,122 @@
+/*	$OpenBSD: queue.c,v 1.4 2003/06/25 05:31:11 deraadt Exp $	*/
+
+/*-
+ * Copyright (c) 1999 James Howard and Dag-Erling Coïdan Smørgrav
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 THE AUTHOR 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.
+ */
+
+/*
+ * A really poor man's queue.  It does only what it has to and gets out of
+ * Dodge.
+ */
+
+#include <sys/param.h>
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "grep.h"
+
+typedef struct queue {
+	struct queue   *next;
+	str_t		data;
+} queue_t;
+
+static queue_t	*q_head, *q_tail;
+static int	 count;
+
+static queue_t	*dequeue(void);
+
+void
+initqueue(void)
+{
+	q_head = q_tail = NULL;
+}
+
+static void
+free_item(queue_t *item)
+{
+	free(item);
+}
+
+void
+enqueue(str_t *x)
+{
+	queue_t	*item;
+
+	item = grep_malloc(sizeof *item + x->len);
+	item->data.len = x->len;
+	item->data.line_no = x->line_no;
+	item->data.off = x->off;
+	item->data.dat = (char *)item + sizeof *item;
+	memcpy(item->data.dat, x->dat, x->len);
+	item->data.file = x->file;
+	item->next = NULL;
+
+	if (!q_head) {
+		q_head = q_tail = item;
+	} else {
+		q_tail->next = item;
+		q_tail = item;
+	}
+
+	if (++count > Bflag)
+		free_item(dequeue());
+}
+
+static queue_t *
+dequeue(void)
+{
+	queue_t	*item;
+
+	if (q_head == NULL)
+		return NULL;
+
+	--count;
+	item = q_head;
+	q_head = item->next;
+	if (q_head == NULL)
+		q_tail = NULL;
+	return item;
+}
+
+void
+printqueue(void)
+{
+	queue_t *item;
+
+	while ((item = dequeue()) != NULL) {
+		printline(&item->data, '-');
+		free_item(item);
+	}
+}
+
+void
+clearqueue(void)
+{
+	queue_t	*item;
+
+	while ((item = dequeue()) != NULL)
+		free_item(item);
+}