1 /* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
2 * Permission is hereby granted, free of charge, to any person obtaining a copy
3 * of this software and associated documentation files (the "Software"), to
4 * deal in the Software without restriction, including without limitation the
5 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
6 * sell copies of the Software, and to permit persons to whom the Software is
7 * furnished to do so, subject to the following conditions:
8 *
9 * The above copyright notice and this permission notice shall be included in
10 * all copies or substantial portions of the Software.
11 *
12 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
13 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
14 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
15 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
16 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
17 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
18 * IN THE SOFTWARE.
19 */
20
21 #include <assert.h>
22 #include <signal.h>
23
24 #include "uv.h"
25 #include "internal.h"
26 #include "handle-inl.h"
27 #include "req-inl.h"
28
29
30 RB_HEAD(uv_signal_tree_s, uv_signal_s);
31
32 static struct uv_signal_tree_s uv__signal_tree = RB_INITIALIZER(uv__signal_tree);
33 static CRITICAL_SECTION uv__signal_lock;
34
35 static BOOL WINAPI uv__signal_control_handler(DWORD type);
36
37 int uv__signal_start(uv_signal_t* handle,
38 uv_signal_cb signal_cb,
39 int signum,
40 int oneshot);
41
uv__signals_init(void)42 void uv__signals_init(void) {
43 InitializeCriticalSection(&uv__signal_lock);
44 if (!SetConsoleCtrlHandler(uv__signal_control_handler, TRUE))
45 abort();
46 }
47
48
uv__signal_cleanup(void)49 void uv__signal_cleanup(void) {
50 /* TODO(bnoordhuis) Undo effects of uv_signal_init()? */
51 }
52
53
uv__signal_compare(uv_signal_t * w1,uv_signal_t * w2)54 static int uv__signal_compare(uv_signal_t* w1, uv_signal_t* w2) {
55 /* Compare signums first so all watchers with the same signnum end up
56 * adjacent. */
57 if (w1->signum < w2->signum) return -1;
58 if (w1->signum > w2->signum) return 1;
59
60 /* Sort by loop pointer, so we can easily look up the first item after
61 * { .signum = x, .loop = NULL }. */
62 if ((uintptr_t) w1->loop < (uintptr_t) w2->loop) return -1;
63 if ((uintptr_t) w1->loop > (uintptr_t) w2->loop) return 1;
64
65 if ((uintptr_t) w1 < (uintptr_t) w2) return -1;
66 if ((uintptr_t) w1 > (uintptr_t) w2) return 1;
67
68 return 0;
69 }
70
71
RB_GENERATE_STATIC(uv_signal_tree_s,uv_signal_s,tree_entry,uv__signal_compare)72 RB_GENERATE_STATIC(uv_signal_tree_s, uv_signal_s, tree_entry, uv__signal_compare)
73
74
75 /*
76 * Dispatches signal {signum} to all active uv_signal_t watchers in all loops.
77 * Returns 1 if the signal was dispatched to any watcher, or 0 if there were
78 * no active signal watchers observing this signal.
79 */
80 int uv__signal_dispatch(int signum) {
81 uv_signal_t lookup;
82 uv_signal_t* handle;
83 int dispatched;
84
85 dispatched = 0;
86
87 EnterCriticalSection(&uv__signal_lock);
88
89 lookup.signum = signum;
90 lookup.loop = NULL;
91
92 for (handle = RB_NFIND(uv_signal_tree_s, &uv__signal_tree, &lookup);
93 handle != NULL && handle->signum == signum;
94 handle = RB_NEXT(uv_signal_tree_s, &uv__signal_tree, handle)) {
95 unsigned long previous = InterlockedExchange(
96 (volatile LONG*) &handle->pending_signum, signum);
97
98 if (handle->flags & UV_SIGNAL_ONE_SHOT_DISPATCHED)
99 continue;
100
101 if (!previous) {
102 POST_COMPLETION_FOR_REQ(handle->loop, &handle->signal_req);
103 }
104
105 dispatched = 1;
106 if (handle->flags & UV_SIGNAL_ONE_SHOT)
107 handle->flags |= UV_SIGNAL_ONE_SHOT_DISPATCHED;
108 }
109
110 LeaveCriticalSection(&uv__signal_lock);
111
112 return dispatched;
113 }
114
115
uv__signal_control_handler(DWORD type)116 static BOOL WINAPI uv__signal_control_handler(DWORD type) {
117 switch (type) {
118 case CTRL_C_EVENT:
119 return uv__signal_dispatch(SIGINT);
120
121 case CTRL_BREAK_EVENT:
122 return uv__signal_dispatch(SIGBREAK);
123
124 case CTRL_CLOSE_EVENT:
125 if (uv__signal_dispatch(SIGHUP)) {
126 /* Windows will terminate the process after the control handler
127 * returns. After that it will just terminate our process. Therefore
128 * block the signal handler so the main loop has some time to pick up
129 * the signal and do something for a few seconds. */
130 Sleep(INFINITE);
131 return TRUE;
132 }
133 return FALSE;
134
135 case CTRL_LOGOFF_EVENT:
136 case CTRL_SHUTDOWN_EVENT:
137 /* These signals are only sent to services. Services have their own
138 * notification mechanism, so there's no point in handling these. */
139
140 default:
141 /* We don't handle these. */
142 return FALSE;
143 }
144 }
145
146
uv_signal_init(uv_loop_t * loop,uv_signal_t * handle)147 int uv_signal_init(uv_loop_t* loop, uv_signal_t* handle) {
148 uv__handle_init(loop, (uv_handle_t*) handle, UV_SIGNAL);
149 handle->pending_signum = 0;
150 handle->signum = 0;
151 handle->signal_cb = NULL;
152
153 UV_REQ_INIT(&handle->signal_req, UV_SIGNAL_REQ);
154 handle->signal_req.data = handle;
155
156 return 0;
157 }
158
159
uv_signal_stop(uv_signal_t * handle)160 int uv_signal_stop(uv_signal_t* handle) {
161 uv_signal_t* removed_handle;
162
163 /* If the watcher wasn't started, this is a no-op. */
164 if (handle->signum == 0)
165 return 0;
166
167 EnterCriticalSection(&uv__signal_lock);
168
169 removed_handle = RB_REMOVE(uv_signal_tree_s, &uv__signal_tree, handle);
170 assert(removed_handle == handle);
171
172 LeaveCriticalSection(&uv__signal_lock);
173
174 handle->signum = 0;
175 uv__handle_stop(handle);
176
177 return 0;
178 }
179
180
uv_signal_start(uv_signal_t * handle,uv_signal_cb signal_cb,int signum)181 int uv_signal_start(uv_signal_t* handle, uv_signal_cb signal_cb, int signum) {
182 return uv__signal_start(handle, signal_cb, signum, 0);
183 }
184
185
uv_signal_start_oneshot(uv_signal_t * handle,uv_signal_cb signal_cb,int signum)186 int uv_signal_start_oneshot(uv_signal_t* handle,
187 uv_signal_cb signal_cb,
188 int signum) {
189 return uv__signal_start(handle, signal_cb, signum, 1);
190 }
191
192
uv__signal_start(uv_signal_t * handle,uv_signal_cb signal_cb,int signum,int oneshot)193 int uv__signal_start(uv_signal_t* handle,
194 uv_signal_cb signal_cb,
195 int signum,
196 int oneshot) {
197 /* Test for invalid signal values. */
198 if (signum <= 0 || signum >= NSIG)
199 return UV_EINVAL;
200
201 /* Short circuit: if the signal watcher is already watching {signum} don't go
202 * through the process of deregistering and registering the handler.
203 * Additionally, this avoids pending signals getting lost in the (small) time
204 * frame that handle->signum == 0. */
205 if (signum == handle->signum) {
206 handle->signal_cb = signal_cb;
207 return 0;
208 }
209
210 /* If the signal handler was already active, stop it first. */
211 if (handle->signum != 0) {
212 int r = uv_signal_stop(handle);
213 /* uv_signal_stop is infallible. */
214 assert(r == 0);
215 }
216
217 EnterCriticalSection(&uv__signal_lock);
218
219 handle->signum = signum;
220 if (oneshot)
221 handle->flags |= UV_SIGNAL_ONE_SHOT;
222
223 RB_INSERT(uv_signal_tree_s, &uv__signal_tree, handle);
224
225 LeaveCriticalSection(&uv__signal_lock);
226
227 handle->signal_cb = signal_cb;
228 uv__handle_start(handle);
229
230 return 0;
231 }
232
233
uv__process_signal_req(uv_loop_t * loop,uv_signal_t * handle,uv_req_t * req)234 void uv__process_signal_req(uv_loop_t* loop, uv_signal_t* handle,
235 uv_req_t* req) {
236 long dispatched_signum;
237
238 assert(handle->type == UV_SIGNAL);
239 assert(req->type == UV_SIGNAL_REQ);
240
241 dispatched_signum = InterlockedExchange(
242 (volatile LONG*) &handle->pending_signum, 0);
243 assert(dispatched_signum != 0);
244
245 /* Check if the pending signal equals the signum that we are watching for.
246 * These can get out of sync when the handler is stopped and restarted while
247 * the signal_req is pending. */
248 if (dispatched_signum == handle->signum)
249 handle->signal_cb(handle, dispatched_signum);
250
251 if (handle->flags & UV_SIGNAL_ONE_SHOT)
252 uv_signal_stop(handle);
253
254 if (handle->flags & UV_HANDLE_CLOSING) {
255 /* When it is closing, it must be stopped at this point. */
256 assert(handle->signum == 0);
257 uv__want_endgame(loop, (uv_handle_t*) handle);
258 }
259 }
260
261
uv__signal_close(uv_loop_t * loop,uv_signal_t * handle)262 void uv__signal_close(uv_loop_t* loop, uv_signal_t* handle) {
263 uv_signal_stop(handle);
264 uv__handle_closing(handle);
265
266 if (handle->pending_signum == 0) {
267 uv__want_endgame(loop, (uv_handle_t*) handle);
268 }
269 }
270
271
uv__signal_endgame(uv_loop_t * loop,uv_signal_t * handle)272 void uv__signal_endgame(uv_loop_t* loop, uv_signal_t* handle) {
273 assert(handle->flags & UV_HANDLE_CLOSING);
274 assert(!(handle->flags & UV_HANDLE_CLOSED));
275
276 assert(handle->signum == 0);
277 assert(handle->pending_signum == 0);
278
279 handle->flags |= UV_HANDLE_CLOSED;
280
281 uv__handle_close(handle);
282 }
283
