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1/* $OpenBSD: queue.c,v 1.7 2015/01/16 06:40:08 deraadt Exp $ */
2
3/*-
4 * Copyright (c) 1999 James Howard and Dag-Erling Co�dan Sm�rgrav
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29/*
30 * A really poor man's queue. It does only what it has to and gets out of
31 * Dodge.
32 */
33
34#include <stdlib.h>
35#include <string.h>
36
37#include "grep.h"
38
39typedef struct queue {
40 struct queue *next;
41 str_t data;
42} queue_t;
43
44static queue_t *q_head, *q_tail;
45static int count;
46
47static queue_t *dequeue(void);
48
49void
50initqueue(void)
51{
52 q_head = q_tail = NULL;
53}
54
55static void
56free_item(queue_t *item)
57{
58 free(item);
59}
60
61void
62enqueue(str_t *x)
63{
64 queue_t *item;
65
66 item = grep_malloc(sizeof *item + x->len);
67 item->data.len = x->len;
68 item->data.line_no = x->line_no;
69 item->data.off = x->off;
70 item->data.dat = (char *)item + sizeof *item;
71 memcpy(item->data.dat, x->dat, x->len);
72 item->data.file = x->file;
73 item->next = NULL;
74
75 if (!q_head) {
76 q_head = q_tail = item;
77 } else {
78 q_tail->next = item;
79 q_tail = item;
80 }
81
82 if (++count > Bflag)
83 free_item(dequeue());
84}
85
86static queue_t *
87dequeue(void)
88{
89 queue_t *item;
90
91 if (q_head == NULL)
92 return NULL;
93
94 --count;
95 item = q_head;
96 q_head = item->next;
97 if (q_head == NULL)
98 q_tail = NULL;
99 return item;
100}
101
102void
103printqueue(void)
104{
105 queue_t *item;
106
107 while ((item = dequeue()) != NULL) {
108 printline(&item->data, '-', NULL);
109 free_item(item);
110 }
111}
112
113void
114clearqueue(void)
115{
116 queue_t *item;
117
118 while ((item = dequeue()) != NULL)
119 free_item(item);
120}