1 /*
2 * libwebsockets - small server side websockets and web server implementation
3 *
4 * Copyright (C) 2010 - 2019 Andy Green <andy@warmcat.com>
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to
8 * deal in the Software without restriction, including without limitation the
9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10 * sell copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22 * IN THE SOFTWARE.
23 */
24
25 /** \defgroup ll linked-lists
26 * ##Linked list apis
27 *
28 * simple single and doubly-linked lists
29 */
30 ///@{
31
32 /**
33 * lws_start_foreach_ll(): linkedlist iterator helper start
34 *
35 * \param type: type of iteration, eg, struct xyz *
36 * \param it: iterator var name to create
37 * \param start: start of list
38 *
39 * This helper creates an iterator and starts a while (it) {
40 * loop. The iterator runs through the linked list starting at start and
41 * ends when it gets a NULL.
42 * The while loop should be terminated using lws_start_foreach_ll().
43 */
44 #define lws_start_foreach_ll(type, it, start)\
45 { \
46 type it = start; \
47 while (it) {
48
49 /**
50 * lws_end_foreach_ll(): linkedlist iterator helper end
51 *
52 * \param it: same iterator var name given when starting
53 * \param nxt: member name in the iterator pointing to next list element
54 *
55 * This helper is the partner for lws_start_foreach_ll() that ends the
56 * while loop.
57 */
58
59 #define lws_end_foreach_ll(it, nxt) \
60 it = it->nxt; \
61 } \
62 }
63
64 /**
65 * lws_start_foreach_ll_safe(): linkedlist iterator helper start safe against delete
66 *
67 * \param type: type of iteration, eg, struct xyz *
68 * \param it: iterator var name to create
69 * \param start: start of list
70 * \param nxt: member name in the iterator pointing to next list element
71 *
72 * This helper creates an iterator and starts a while (it) {
73 * loop. The iterator runs through the linked list starting at start and
74 * ends when it gets a NULL.
75 * The while loop should be terminated using lws_end_foreach_ll_safe().
76 * Performs storage of next increment for situations where iterator can become invalidated
77 * during iteration.
78 */
79 #define lws_start_foreach_ll_safe(type, it, start, nxt)\
80 { \
81 type it = start; \
82 while (it) { \
83 type next_##it = it->nxt;
84
85 /**
86 * lws_end_foreach_ll_safe(): linkedlist iterator helper end (pre increment storage)
87 *
88 * \param it: same iterator var name given when starting
89 *
90 * This helper is the partner for lws_start_foreach_ll_safe() that ends the
91 * while loop. It uses the precreated next_ variable already stored during
92 * start.
93 */
94
95 #define lws_end_foreach_ll_safe(it) \
96 it = next_##it; \
97 } \
98 }
99
100 /**
101 * lws_start_foreach_llp(): linkedlist pointer iterator helper start
102 *
103 * \param type: type of iteration, eg, struct xyz **
104 * \param it: iterator var name to create
105 * \param start: start of list
106 *
107 * This helper creates an iterator and starts a while (it) {
108 * loop. The iterator runs through the linked list starting at the
109 * address of start and ends when it gets a NULL.
110 * The while loop should be terminated using lws_start_foreach_llp().
111 *
112 * This helper variant iterates using a pointer to the previous linked-list
113 * element. That allows you to easily delete list members by rewriting the
114 * previous pointer to the element's next pointer.
115 */
116 #define lws_start_foreach_llp(type, it, start)\
117 { \
118 type it = &(start); \
119 while (*(it)) {
120
121 #define lws_start_foreach_llp_safe(type, it, start, nxt)\
122 { \
123 type it = &(start); \
124 type next; \
125 while (*(it)) { \
126 next = &((*(it))->nxt); \
127
128 /**
129 * lws_end_foreach_llp(): linkedlist pointer iterator helper end
130 *
131 * \param it: same iterator var name given when starting
132 * \param nxt: member name in the iterator pointing to next list element
133 *
134 * This helper is the partner for lws_start_foreach_llp() that ends the
135 * while loop.
136 */
137
138 #define lws_end_foreach_llp(it, nxt) \
139 it = &(*(it))->nxt; \
140 } \
141 }
142
143 #define lws_end_foreach_llp_safe(it) \
144 it = next; \
145 } \
146 }
147
148 #define lws_ll_fwd_insert(\
149 ___new_object, /* pointer to new object */ \
150 ___m_list, /* member for next list object ptr */ \
151 ___list_head /* list head */ \
152 ) {\
153 ___new_object->___m_list = ___list_head; \
154 ___list_head = ___new_object; \
155 }
156
157 #define lws_ll_fwd_remove(\
158 ___type, /* type of listed object */ \
159 ___m_list, /* member for next list object ptr */ \
160 ___target, /* object to remove from list */ \
161 ___list_head /* list head */ \
162 ) { \
163 lws_start_foreach_llp(___type **, ___ppss, ___list_head) { \
164 if (*___ppss == ___target) { \
165 *___ppss = ___target->___m_list; \
166 break; \
167 } \
168 } lws_end_foreach_llp(___ppss, ___m_list); \
169 }
170
171
172 /*
173 * doubly linked-list
174 */
175
176 /*
177 * lws_dll2_owner / lws_dll2 : more capable version of lws_dll. Differences:
178 *
179 * - there's an explicit lws_dll2_owner struct which holds head, tail and
180 * count of members.
181 *
182 * - list members all hold a pointer to their owner. So user code does not
183 * have to track anything about exactly what lws_dll2_owner list the object
184 * is a member of.
185 *
186 * - you can use lws_dll unless you want the member count or the ability to
187 * not track exactly which list it's on.
188 *
189 * - layout is compatible with lws_dll (but lws_dll apis will not update the
190 * new stuff)
191 */
192
193
194 struct lws_dll2;
195 struct lws_dll2_owner;
196
197 typedef struct lws_dll2 {
198 struct lws_dll2 *prev;
199 struct lws_dll2 *next;
200 struct lws_dll2_owner *owner;
201 } lws_dll2_t;
202
203 typedef struct lws_dll2_owner {
204 struct lws_dll2 *tail;
205 struct lws_dll2 *head;
206
207 uint32_t count;
208 } lws_dll2_owner_t;
209
210 LWS_VISIBLE LWS_EXTERN int
211 lws_dll2_is_detached(const struct lws_dll2 *d);
212
213 static LWS_INLINE const struct lws_dll2_owner *
lws_dll2_owner(const struct lws_dll2 * d)214 lws_dll2_owner(const struct lws_dll2 *d) { return d->owner; }
215
216 static LWS_INLINE struct lws_dll2 *
lws_dll2_get_head(struct lws_dll2_owner * owner)217 lws_dll2_get_head(struct lws_dll2_owner *owner) { return owner->head; }
218
219 static LWS_INLINE struct lws_dll2 *
lws_dll2_get_tail(struct lws_dll2_owner * owner)220 lws_dll2_get_tail(struct lws_dll2_owner *owner) { return owner->tail; }
221
222 LWS_VISIBLE LWS_EXTERN void
223 lws_dll2_add_head(struct lws_dll2 *d, struct lws_dll2_owner *owner);
224
225 LWS_VISIBLE LWS_EXTERN void
226 lws_dll2_add_tail(struct lws_dll2 *d, struct lws_dll2_owner *owner);
227
228 LWS_VISIBLE LWS_EXTERN void
229 lws_dll2_remove(struct lws_dll2 *d);
230
231 typedef int (*lws_dll2_foreach_cb_t)(struct lws_dll2 *d, void *user);
232
233 LWS_VISIBLE LWS_EXTERN int
234 lws_dll2_foreach_safe(struct lws_dll2_owner *owner, void *user,
235 lws_dll2_foreach_cb_t cb);
236
237 LWS_VISIBLE LWS_EXTERN void
238 lws_dll2_clear(struct lws_dll2 *d);
239
240 LWS_VISIBLE LWS_EXTERN void
241 lws_dll2_owner_clear(struct lws_dll2_owner *d);
242
243 LWS_VISIBLE LWS_EXTERN void
244 lws_dll2_add_before(struct lws_dll2 *d, struct lws_dll2 *after);
245
246 LWS_VISIBLE LWS_EXTERN void
247 lws_dll2_add_sorted(lws_dll2_t *d, lws_dll2_owner_t *own,
248 int (*compare)(const lws_dll2_t *d, const lws_dll2_t *i));
249
250 LWS_VISIBLE LWS_EXTERN void
251 lws_dll2_add_sorted_priv(lws_dll2_t *d, lws_dll2_owner_t *own, void *priv,
252 int (*compare3)(void *priv, const lws_dll2_t *d,
253 const lws_dll2_t *i));
254
255 LWS_VISIBLE LWS_EXTERN void *
256 _lws_dll2_search_sz_pl(lws_dll2_owner_t *own, const char *name, size_t namelen,
257 size_t dll2_ofs, size_t ptr_ofs);
258
259 /*
260 * Searches objects in an owner list linearly and returns one with a given
261 * member C-string matching a supplied length-provided string if it exists, else
262 * NULL.
263 */
264
265 #define lws_dll2_search_sz_pl(own, name, namelen, type, membd2list, membptr) \
266 ((type *)_lws_dll2_search_sz_pl(own, name, namelen, \
267 offsetof(type, membd2list), \
268 offsetof(type, membptr)))
269
270 #if defined(_DEBUG)
271 void
272 lws_dll2_describe(struct lws_dll2_owner *owner, const char *desc);
273 #else
274 #define lws_dll2_describe(x, y)
275 #endif
276
277 /*
278 * these are safe against the current container object getting deleted,
279 * since the hold his next in a temp and go to that next. ___tmp is
280 * the temp.
281 */
282
283 #define lws_start_foreach_dll_safe(___type, ___it, ___tmp, ___start) \
284 { \
285 ___type ___it = ___start; \
286 while (___it) { \
287 ___type ___tmp = (___it)->next;
288
289 #define lws_end_foreach_dll_safe(___it, ___tmp) \
290 ___it = ___tmp; \
291 } \
292 }
293
294 #define lws_start_foreach_dll(___type, ___it, ___start) \
295 { \
296 ___type ___it = ___start; \
297 while (___it) {
298
299 #define lws_end_foreach_dll(___it) \
300 ___it = (___it)->next; \
301 } \
302 }
303
304 ///@}
305
306