minix/usr.bin/grep/queue.c

   1 /*      $OpenBSD: queue.c,v 1.6 2011/07/08 01:20:24 tedu Exp $  */
   2
   3 /*-
   4  * Copyright (c) 1999 James Howard and Dag-Erling Coïdan Smørgrav
   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 <sys/param.h>
  35
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 #include "grep.h"
  40
  41 typedef struct queue {
  42         struct queue   *next;
  43         str_t           data;
  44 } queue_t;
  45
  46 static queue_t  *q_head, *q_tail;
  47 static int       count;
  48
  49 static queue_t  *dequeue(void);
  50
  51 void
  52 initqueue(void)
  53 {
  54         q_head = q_tail = NULL;
  55 }
  56
  57 static void
  58 free_item(queue_t *item)
  59 {
  60         free(item);
  61 }
  62
  63 void
  64 enqueue(str_t *x)
  65 {
  66         queue_t *item;
  67
  68         item = grep_malloc(sizeof *item + x->len);
  69         item->data.len = x->len;
  70         item->data.line_no = x->line_no;
  71         item->data.off = x->off;
  72         item->data.dat = (char *)item + sizeof *item;
  73         memcpy(item->data.dat, x->dat, x->len);
  74         item->data.file = x->file;
  75         item->next = NULL;
  76
  77         if (!q_head) {
  78                 q_head = q_tail = item;
  79         } else {
  80                 q_tail->next = item;
  81                 q_tail = item;
  82         }
  83
  84         if (++count > Bflag)
  85                 free_item(dequeue());
  86 }
  87
  88 static queue_t *
  89 dequeue(void)
  90 {
  91         queue_t *item;
  92
  93         if (q_head == NULL)
  94                 return NULL;
  95
  96         --count;
  97         item = q_head;
  98         q_head = item->next;
  99         if (q_head == NULL)
 100                 q_tail = NULL;
 101         return item;
 102 }
 103
 104 void
 105 printqueue(void)
 106 {
 107         queue_t *item;
 108
 109         while ((item = dequeue()) != NULL) {
 110                 printline(&item->data, '-', NULL);
 111                 free_item(item);
 112         }
 113 }
 114
 115 void
 116 clearqueue(void)
 117 {
 118         queue_t *item;
 119
 120         while ((item = dequeue()) != NULL)
 121                 free_item(item);
 122 }