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      1 
      2 /* Author : Stephen Smalley, <sds (at) epoch.ncsc.mil> */
      3 
      4 /* FLASK */
      5 
      6 /*
      7  * Implementation of the double-ended queue type.
      8  */
      9 
     10 #include <stdlib.h>
     11 #include "queue.h"
     12 
     13 queue_t queue_create(void)
     14 {
     15 	queue_t q;
     16 
     17 	q = (queue_t) malloc(sizeof(struct queue_info));
     18 	if (q == NULL)
     19 		return NULL;
     20 
     21 	q->head = q->tail = NULL;
     22 
     23 	return q;
     24 }
     25 
     26 int queue_insert(queue_t q, queue_element_t e)
     27 {
     28 	queue_node_ptr_t newnode;
     29 
     30 	if (!q)
     31 		return -1;
     32 
     33 	newnode = (queue_node_ptr_t) malloc(sizeof(struct queue_node));
     34 	if (newnode == NULL)
     35 		return -1;
     36 
     37 	newnode->element = e;
     38 	newnode->next = NULL;
     39 
     40 	if (q->head == NULL) {
     41 		q->head = q->tail = newnode;
     42 	} else {
     43 		q->tail->next = newnode;
     44 		q->tail = newnode;
     45 	}
     46 
     47 	return 0;
     48 }
     49 
     50 int queue_push(queue_t q, queue_element_t e)
     51 {
     52 	queue_node_ptr_t newnode;
     53 
     54 	if (!q)
     55 		return -1;
     56 
     57 	newnode = (queue_node_ptr_t) malloc(sizeof(struct queue_node));
     58 	if (newnode == NULL)
     59 		return -1;
     60 
     61 	newnode->element = e;
     62 	newnode->next = NULL;
     63 
     64 	if (q->head == NULL) {
     65 		q->head = q->tail = newnode;
     66 	} else {
     67 		newnode->next = q->head;
     68 		q->head = newnode;
     69 	}
     70 
     71 	return 0;
     72 }
     73 
     74 queue_element_t queue_remove(queue_t q)
     75 {
     76 	queue_node_ptr_t node;
     77 	queue_element_t e;
     78 
     79 	if (!q)
     80 		return NULL;
     81 
     82 	if (q->head == NULL)
     83 		return NULL;
     84 
     85 	node = q->head;
     86 	q->head = q->head->next;
     87 	if (q->head == NULL)
     88 		q->tail = NULL;
     89 
     90 	e = node->element;
     91 	free(node);
     92 
     93 	return e;
     94 }
     95 
     96 queue_element_t queue_head(queue_t q)
     97 {
     98 	if (!q)
     99 		return NULL;
    100 
    101 	if (q->head == NULL)
    102 		return NULL;
    103 
    104 	return q->head->element;
    105 }
    106 
    107 void queue_destroy(queue_t q)
    108 {
    109 	queue_node_ptr_t p, temp;
    110 
    111 	if (!q)
    112 		return;
    113 
    114 	p = q->head;
    115 	while (p != NULL) {
    116 		temp = p;
    117 		p = p->next;
    118 		free(temp);
    119 	}
    120 
    121 	free(q);
    122 }
    123 
    124 int queue_map(queue_t q, int (*f) (queue_element_t, void *), void *vp)
    125 {
    126 	queue_node_ptr_t p;
    127 	int ret;
    128 
    129 	if (!q)
    130 		return 0;
    131 
    132 	p = q->head;
    133 	while (p != NULL) {
    134 		ret = f(p->element, vp);
    135 		if (ret)
    136 			return ret;
    137 		p = p->next;
    138 	}
    139 	return 0;
    140 }
    141 
    142 void queue_map_remove_on_error(queue_t q,
    143 			       int (*f) (queue_element_t, void *),
    144 			       void (*g) (queue_element_t, void *), void *vp)
    145 {
    146 	queue_node_ptr_t p, last, temp;
    147 	int ret;
    148 
    149 	if (!q)
    150 		return;
    151 
    152 	last = NULL;
    153 	p = q->head;
    154 	while (p != NULL) {
    155 		ret = f(p->element, vp);
    156 		if (ret) {
    157 			if (last) {
    158 				last->next = p->next;
    159 				if (last->next == NULL)
    160 					q->tail = last;
    161 			} else {
    162 				q->head = p->next;
    163 				if (q->head == NULL)
    164 					q->tail = NULL;
    165 			}
    166 
    167 			temp = p;
    168 			p = p->next;
    169 			g(temp->element, vp);
    170 			free(temp);
    171 		} else {
    172 			last = p;
    173 			p = p->next;
    174 		}
    175 	}
    176 
    177 	return;
    178 }
    179 
    180 /* FLASK */
    181