1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
*
* This file is part of LVM2.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License v.2.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "lib.h"
/*
* Initialise a list before use.
* The list head's next and previous pointers point back to itself.
*/
void list_init(struct list *head)
{
head->n = head->p = head;
}
/*
* Insert an element before 'head'.
* If 'head' is the list head, this adds an element to the end of the list.
*/
void list_add(struct list *head, struct list *elem)
{
assert(head->n);
elem->n = head;
elem->p = head->p;
head->p->n = elem;
head->p = elem;
}
/*
* Insert an element after 'head'.
* If 'head' is the list head, this adds an element to the front of the list.
*/
void list_add_h(struct list *head, struct list *elem)
{
assert(head->n);
elem->n = head->n;
elem->p = head;
head->n->p = elem;
head->n = elem;
}
/*
* Delete an element from its list.
* Note that this doesn't change the element itself - it may still be safe
* to follow its pointers.
*/
void list_del(struct list *elem)
{
elem->n->p = elem->p;
elem->p->n = elem->n;
}
/*
* Is the list empty?
*/
int list_empty(struct list *head)
{
return head->n == head;
}
/*
* Is this the first element of the list?
*/
int list_start(struct list *head, struct list *elem)
{
return elem->p == head;
}
/*
* Is this the last element of the list?
*/
int list_end(struct list *head, struct list *elem)
{
return elem->n == head;
}
/*
* Return first element of the list or NULL if empty
*/
struct list *list_first(struct list *head)
{
return (list_empty(head) ? NULL : head->n);
}
/*
* Return last element of the list or NULL if empty
*/
struct list *list_last(struct list *head)
{
return (list_empty(head) ? NULL : head->p);
}
/*
* Return the previous element of the list, or NULL if we've reached the start.
*/
struct list *list_prev(struct list *head, struct list *elem)
{
return (list_start(head, elem) ? NULL : elem->p);
}
/*
* Return the next element of the list, or NULL if we've reached the end.
*/
struct list *list_next(struct list *head, struct list *elem)
{
return (list_end(head, elem) ? NULL : elem->n);
}
/*
* Return the number of elements in a list by walking it.
*/
unsigned int list_size(const struct list *head)
{
unsigned int s = 0;
const struct list *v;
list_iterate(v, head)
s++;
return s;
}
|
