1 /*
2 Copyright 2021 Northern.tech AS
3
4 This file is part of CFEngine 3 - written and maintained by Northern.tech AS.
5
6 This program is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; version 3.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
18
19 To the extent this program is licensed as part of the Enterprise
20 versions of CFEngine, the applicable Commercial Open Source License
21 (COSL) may apply to this file if you as a licensee so wish it. See
22 included file COSL.txt.
23 */
24
25 #include <alloc.h>
26 #include <refcount.h>
27 #include <misc_lib.h>
28 #include <platform.h>
29
RefCountNew(RefCount ** ref)30 void RefCountNew(RefCount **ref)
31 {
32 if (!ref)
33 {
34 return;
35 }
36 *ref = (RefCount *)xmalloc(sizeof(RefCount));
37 (*ref)->user_count = 0;
38 (*ref)->users = NULL;
39 (*ref)->last = NULL;
40 }
41
RefCountDestroy(RefCount ** ref)42 void RefCountDestroy(RefCount **ref)
43 {
44 if (ref && *ref)
45 {
46 // Destroying a refcount which has more than one user is a bug, but we let it
47 // pass in production code (memory leak).
48 assert((*ref)->user_count <= 1);
49 if ((*ref)->user_count > 1)
50 return;
51 if ((*ref)->users)
52 free((*ref)->users);
53 free(*ref);
54 *ref = NULL;
55 }
56 }
57
RefCountAttach(RefCount * ref,void * owner)58 void RefCountAttach(RefCount *ref, void *owner)
59 {
60 if (!ref || !owner)
61 {
62 ProgrammingError("Either refcount or owner is NULL (or both)");
63 }
64 ref->user_count++;
65 RefCountNode *node = (RefCountNode *)xmalloc(sizeof(RefCountNode));
66 node->next = NULL;
67 node->user = owner;
68 if (ref->last)
69 {
70 ref->last->next = node;
71 node->previous = ref->last;
72 }
73 else
74 {
75 ref->users = node;
76 node->previous = NULL;
77 }
78 ref->last = node;
79 }
80
RefCountDetach(RefCount * ref,void * owner)81 void RefCountDetach(RefCount *ref, void *owner)
82 {
83 if (!ref || !owner)
84 {
85 ProgrammingError("Either refcount or owner is NULL (or both)");
86 }
87 if (ref->user_count <= 1)
88 {
89 /*
90 * Semantics: If 1 that means that we are the only users, if 0 nobody is using it.
91 * In either case it is safe to destroy the refcount.
92 */
93 return;
94 }
95 RefCountNode *p = NULL;
96 int found = 0;
97 for (p = ref->users; p; p = p->next)
98 {
99 if (p->user == owner)
100 {
101 found = 1;
102 if (p->previous && p->next)
103 {
104 p->previous->next = p->next;
105 p->next->previous = p->previous;
106 }
107 else if (p->previous && !p->next)
108 {
109 // Last node
110 p->previous->next = NULL;
111 ref->last = p->previous;
112 }
113 else if (!p->previous && p->next)
114 {
115 // First node
116 ref->users = p->next;
117 p->next->previous = NULL;
118 }
119 else
120 {
121 // Only one node, we cannot detach from ourselves.
122 return;
123 }
124 free(p);
125 break;
126 }
127 }
128 if (!found)
129 {
130 ProgrammingError("The object is not attached to the RefCount object");
131 }
132 ref->user_count--;
133 }
134
RefCountIsShared(RefCount * ref)135 bool RefCountIsShared(RefCount *ref)
136 {
137 return ref && (ref->user_count > 1);
138 }
139
RefCountIsEqual(RefCount * a,RefCount * b)140 bool RefCountIsEqual(RefCount *a, RefCount *b)
141 {
142 return (a && b) && (a == b);
143 }
144