1 /* $OpenBSD: cmd-wait-for.c,v 1.22 2021/08/21 10:22:39 nicm Exp $ */
2
3 /*
4 * Copyright (c) 2013 Nicholas Marriott <nicholas.marriott@gmail.com>
5 * Copyright (c) 2013 Thiago de Arruda <tpadilha84@gmail.com>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
16 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
17 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 #include <sys/types.h>
21
22 #include <stdlib.h>
23 #include <string.h>
24
25 #include "tmux.h"
26
27 /*
28 * Block or wake a client on a named wait channel.
29 */
30
31 static enum cmd_retval cmd_wait_for_exec(struct cmd *, struct cmdq_item *);
32
33 const struct cmd_entry cmd_wait_for_entry = {
34 .name = "wait-for",
35 .alias = "wait",
36
37 .args = { "LSU", 1, 1, NULL },
38 .usage = "[-L|-S|-U] channel",
39
40 .flags = 0,
41 .exec = cmd_wait_for_exec
42 };
43
44 struct wait_item {
45 struct cmdq_item *item;
46 TAILQ_ENTRY(wait_item) entry;
47 };
48
49 struct wait_channel {
50 const char *name;
51 int locked;
52 int woken;
53
54 TAILQ_HEAD(, wait_item) waiters;
55 TAILQ_HEAD(, wait_item) lockers;
56
57 RB_ENTRY(wait_channel) entry;
58 };
59 RB_HEAD(wait_channels, wait_channel);
60 static struct wait_channels wait_channels = RB_INITIALIZER(wait_channels);
61
62 static int wait_channel_cmp(struct wait_channel *, struct wait_channel *);
63 RB_GENERATE_STATIC(wait_channels, wait_channel, entry, wait_channel_cmp);
64
65 static int
wait_channel_cmp(struct wait_channel * wc1,struct wait_channel * wc2)66 wait_channel_cmp(struct wait_channel *wc1, struct wait_channel *wc2)
67 {
68 return (strcmp(wc1->name, wc2->name));
69 }
70
71 static enum cmd_retval cmd_wait_for_signal(struct cmdq_item *, const char *,
72 struct wait_channel *);
73 static enum cmd_retval cmd_wait_for_wait(struct cmdq_item *, const char *,
74 struct wait_channel *);
75 static enum cmd_retval cmd_wait_for_lock(struct cmdq_item *, const char *,
76 struct wait_channel *);
77 static enum cmd_retval cmd_wait_for_unlock(struct cmdq_item *, const char *,
78 struct wait_channel *);
79
80 static struct wait_channel *cmd_wait_for_add(const char *);
81 static void cmd_wait_for_remove(struct wait_channel *);
82
83 static struct wait_channel *
cmd_wait_for_add(const char * name)84 cmd_wait_for_add(const char *name)
85 {
86 struct wait_channel *wc;
87
88 wc = xmalloc(sizeof *wc);
89 wc->name = xstrdup(name);
90
91 wc->locked = 0;
92 wc->woken = 0;
93
94 TAILQ_INIT(&wc->waiters);
95 TAILQ_INIT(&wc->lockers);
96
97 RB_INSERT(wait_channels, &wait_channels, wc);
98
99 log_debug("add wait channel %s", wc->name);
100
101 return (wc);
102 }
103
104 static void
cmd_wait_for_remove(struct wait_channel * wc)105 cmd_wait_for_remove(struct wait_channel *wc)
106 {
107 if (wc->locked)
108 return;
109 if (!TAILQ_EMPTY(&wc->waiters) || !wc->woken)
110 return;
111
112 log_debug("remove wait channel %s", wc->name);
113
114 RB_REMOVE(wait_channels, &wait_channels, wc);
115
116 free((void *)wc->name);
117 free(wc);
118 }
119
120 static enum cmd_retval
cmd_wait_for_exec(struct cmd * self,struct cmdq_item * item)121 cmd_wait_for_exec(struct cmd *self, struct cmdq_item *item)
122 {
123 struct args *args = cmd_get_args(self);
124 const char *name = args_string(args, 0);
125 struct wait_channel *wc, find;
126
127 find.name = name;
128 wc = RB_FIND(wait_channels, &wait_channels, &find);
129
130 if (args_has(args, 'S'))
131 return (cmd_wait_for_signal(item, name, wc));
132 if (args_has(args, 'L'))
133 return (cmd_wait_for_lock(item, name, wc));
134 if (args_has(args, 'U'))
135 return (cmd_wait_for_unlock(item, name, wc));
136 return (cmd_wait_for_wait(item, name, wc));
137 }
138
139 static enum cmd_retval
cmd_wait_for_signal(__unused struct cmdq_item * item,const char * name,struct wait_channel * wc)140 cmd_wait_for_signal(__unused struct cmdq_item *item, const char *name,
141 struct wait_channel *wc)
142 {
143 struct wait_item *wi, *wi1;
144
145 if (wc == NULL)
146 wc = cmd_wait_for_add(name);
147
148 if (TAILQ_EMPTY(&wc->waiters) && !wc->woken) {
149 log_debug("signal wait channel %s, no waiters", wc->name);
150 wc->woken = 1;
151 return (CMD_RETURN_NORMAL);
152 }
153 log_debug("signal wait channel %s, with waiters", wc->name);
154
155 TAILQ_FOREACH_SAFE(wi, &wc->waiters, entry, wi1) {
156 cmdq_continue(wi->item);
157
158 TAILQ_REMOVE(&wc->waiters, wi, entry);
159 free(wi);
160 }
161
162 cmd_wait_for_remove(wc);
163 return (CMD_RETURN_NORMAL);
164 }
165
166 static enum cmd_retval
cmd_wait_for_wait(struct cmdq_item * item,const char * name,struct wait_channel * wc)167 cmd_wait_for_wait(struct cmdq_item *item, const char *name,
168 struct wait_channel *wc)
169 {
170 struct client *c = cmdq_get_client(item);
171 struct wait_item *wi;
172
173 if (c == NULL) {
174 cmdq_error(item, "not able to wait");
175 return (CMD_RETURN_ERROR);
176 }
177
178 if (wc == NULL)
179 wc = cmd_wait_for_add(name);
180
181 if (wc->woken) {
182 log_debug("wait channel %s already woken (%p)", wc->name, c);
183 cmd_wait_for_remove(wc);
184 return (CMD_RETURN_NORMAL);
185 }
186 log_debug("wait channel %s not woken (%p)", wc->name, c);
187
188 wi = xcalloc(1, sizeof *wi);
189 wi->item = item;
190 TAILQ_INSERT_TAIL(&wc->waiters, wi, entry);
191
192 return (CMD_RETURN_WAIT);
193 }
194
195 static enum cmd_retval
cmd_wait_for_lock(struct cmdq_item * item,const char * name,struct wait_channel * wc)196 cmd_wait_for_lock(struct cmdq_item *item, const char *name,
197 struct wait_channel *wc)
198 {
199 struct wait_item *wi;
200
201 if (cmdq_get_client(item) == NULL) {
202 cmdq_error(item, "not able to lock");
203 return (CMD_RETURN_ERROR);
204 }
205
206 if (wc == NULL)
207 wc = cmd_wait_for_add(name);
208
209 if (wc->locked) {
210 wi = xcalloc(1, sizeof *wi);
211 wi->item = item;
212 TAILQ_INSERT_TAIL(&wc->lockers, wi, entry);
213 return (CMD_RETURN_WAIT);
214 }
215 wc->locked = 1;
216
217 return (CMD_RETURN_NORMAL);
218 }
219
220 static enum cmd_retval
cmd_wait_for_unlock(struct cmdq_item * item,const char * name,struct wait_channel * wc)221 cmd_wait_for_unlock(struct cmdq_item *item, const char *name,
222 struct wait_channel *wc)
223 {
224 struct wait_item *wi;
225
226 if (wc == NULL || !wc->locked) {
227 cmdq_error(item, "channel %s not locked", name);
228 return (CMD_RETURN_ERROR);
229 }
230
231 if ((wi = TAILQ_FIRST(&wc->lockers)) != NULL) {
232 cmdq_continue(wi->item);
233 TAILQ_REMOVE(&wc->lockers, wi, entry);
234 free(wi);
235 } else {
236 wc->locked = 0;
237 cmd_wait_for_remove(wc);
238 }
239
240 return (CMD_RETURN_NORMAL);
241 }
242
243 void
cmd_wait_for_flush(void)244 cmd_wait_for_flush(void)
245 {
246 struct wait_channel *wc, *wc1;
247 struct wait_item *wi, *wi1;
248
249 RB_FOREACH_SAFE(wc, wait_channels, &wait_channels, wc1) {
250 TAILQ_FOREACH_SAFE(wi, &wc->waiters, entry, wi1) {
251 cmdq_continue(wi->item);
252 TAILQ_REMOVE(&wc->waiters, wi, entry);
253 free(wi);
254 }
255 wc->woken = 1;
256 TAILQ_FOREACH_SAFE(wi, &wc->lockers, entry, wi1) {
257 cmdq_continue(wi->item);
258 TAILQ_REMOVE(&wc->lockers, wi, entry);
259 free(wi);
260 }
261 wc->locked = 0;
262 cmd_wait_for_remove(wc);
263 }
264 }
265