2 Unix SMB/CIFS implementation.
4 common events code for signal events
6 Copyright (C) Andrew Tridgell 2007
8 ** NOTE! The following LGPL license applies to the tevent
9 ** library. This does NOT imply that all of Samba is released
12 This library is free software; you can redistribute it and/or
13 modify it under the terms of the GNU Lesser General Public
14 License as published by the Free Software Foundation; either
15 version 3 of the License, or (at your option) any later version.
17 This library is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 Lesser General Public License for more details.
22 You should have received a copy of the GNU Lesser General Public
23 License along with this library; if not, see <http://www.gnu.org/licenses/>.
27 #include "system/filesys.h"
28 #include "system/wait.h"
30 #include "tevent_internal.h"
31 #include "tevent_util.h"
33 #define NUM_SIGNALS 64
35 /* maximum number of SA_SIGINFO signals to hold in the queue */
36 #define SA_INFO_QUEUE_COUNT 100
43 #define SIG_INCREMENT(s) (s).count++
44 #define SIG_SEEN(s, n) (s).seen += (n)
45 #define SIG_PENDING(s) ((s).seen != (s).count)
47 struct tevent_common_signal_list
{
48 struct tevent_common_signal_list
*prev
, *next
;
49 struct tevent_signal
*se
;
53 the poor design of signals means that this table must be static global
55 static struct sig_state
{
56 struct tevent_common_signal_list
*sig_handlers
[NUM_SIGNALS
+1];
57 struct sigaction
*oldact
[NUM_SIGNALS
+1];
58 struct sigcounter signal_count
[NUM_SIGNALS
+1];
59 struct sigcounter got_signal
;
62 /* with SA_SIGINFO we get quite a lot of info per signal */
63 siginfo_t
*sig_info
[NUM_SIGNALS
+1];
64 struct sigcounter sig_blocked
[NUM_SIGNALS
+1];
69 return number of sigcounter events not processed yet
71 static uint32_t sig_count(struct sigcounter s
)
73 if (s
.count
>= s
.seen
) {
74 return s
.count
- s
.seen
;
76 return 1 + (0xFFFFFFFF & ~(s
.seen
- s
.count
));
80 signal handler - redirects to registered signals
82 static void tevent_common_signal_handler(int signum
)
86 SIG_INCREMENT(sig_state
->signal_count
[signum
]);
87 SIG_INCREMENT(sig_state
->got_signal
);
88 /* doesn't matter if this pipe overflows */
89 res
= write(sig_state
->pipe_hack
[1], &c
, 1);
94 signal handler with SA_SIGINFO - redirects to registered signals
96 static void tevent_common_signal_handler_info(int signum
, siginfo_t
*info
,
99 uint32_t count
= sig_count(sig_state
->signal_count
[signum
]);
100 sig_state
->sig_info
[signum
][count
] = *info
;
102 tevent_common_signal_handler(signum
);
104 /* handle SA_SIGINFO */
105 if (count
+1 == SA_INFO_QUEUE_COUNT
) {
106 /* we've filled the info array - block this signal until
107 these ones are delivered */
110 sigaddset(&set
, signum
);
111 sigprocmask(SIG_BLOCK
, &set
, NULL
);
112 SIG_INCREMENT(sig_state
->sig_blocked
[signum
]);
117 static int tevent_common_signal_list_destructor(struct tevent_common_signal_list
*sl
)
119 DLIST_REMOVE(sig_state
->sig_handlers
[sl
->se
->signum
], sl
);
124 destroy a signal event
126 static int tevent_signal_destructor(struct tevent_signal
*se
)
128 struct tevent_common_signal_list
*sl
;
129 sl
= talloc_get_type(se
->additional_data
,
130 struct tevent_common_signal_list
);
133 DLIST_REMOVE(se
->event_ctx
->signal_events
, se
);
138 if (sig_state
->sig_handlers
[se
->signum
] == NULL
) {
139 /* restore old handler, if any */
140 sigaction(se
->signum
, sig_state
->oldact
[se
->signum
], NULL
);
141 sig_state
->oldact
[se
->signum
] = NULL
;
143 if (se
->sa_flags
& SA_SIGINFO
) {
144 talloc_free(sig_state
->sig_info
[se
->signum
]);
145 sig_state
->sig_info
[se
->signum
] = NULL
;
154 this is part of the pipe hack needed to avoid the signal race condition
156 static void signal_pipe_handler(struct tevent_context
*ev
, struct tevent_fd
*fde
,
157 uint16_t flags
, void *private)
161 /* its non-blocking, doesn't matter if we read too much */
162 res
= read(sig_state
->pipe_hack
[0], c
, sizeof(c
));
167 return NULL on failure (memory allocation error)
169 struct tevent_signal
*tevent_common_add_signal(struct tevent_context
*ev
,
173 tevent_signal_handler_t handler
,
175 const char *handler_name
,
176 const char *location
)
178 struct tevent_signal
*se
;
179 struct tevent_common_signal_list
*sl
;
181 if (signum
>= NUM_SIGNALS
) {
186 /* the sig_state needs to be on a global context as it can last across
187 multiple event contexts */
188 if (sig_state
== NULL
) {
189 sig_state
= talloc_zero(talloc_autofree_context(), struct sig_state
);
190 if (sig_state
== NULL
) {
195 se
= talloc(mem_ctx
?mem_ctx
:ev
, struct tevent_signal
);
196 if (se
== NULL
) return NULL
;
200 se
->sa_flags
= sa_flags
;
201 se
->handler
= handler
;
202 se
->private_data
= private_data
;
203 se
->handler_name
= handler_name
;
204 se
->location
= location
;
205 se
->additional_data
= NULL
;
207 sl
= talloc(se
, struct tevent_common_signal_list
);
213 se
->additional_data
= sl
;
215 /* Ensure, no matter the destruction order, that we always have a handle on the global sig_state */
216 if (!talloc_reference(se
, sig_state
)) {
221 /* only install a signal handler if not already installed */
222 if (sig_state
->sig_handlers
[signum
] == NULL
) {
223 struct sigaction act
;
225 act
.sa_handler
= tevent_common_signal_handler
;
226 act
.sa_flags
= sa_flags
;
228 if (sa_flags
& SA_SIGINFO
) {
229 act
.sa_handler
= NULL
;
230 act
.sa_sigaction
= tevent_common_signal_handler_info
;
231 if (sig_state
->sig_info
[signum
] == NULL
) {
232 sig_state
->sig_info
[signum
] = talloc_array(sig_state
, siginfo_t
, SA_INFO_QUEUE_COUNT
);
233 if (sig_state
->sig_info
[signum
] == NULL
) {
240 sig_state
->oldact
[signum
] = talloc(sig_state
, struct sigaction
);
241 if (sig_state
->oldact
[signum
] == NULL
) {
245 if (sigaction(signum
, &act
, sig_state
->oldact
[signum
]) == -1) {
251 DLIST_ADD(se
->event_ctx
->signal_events
, se
);
252 DLIST_ADD(sig_state
->sig_handlers
[signum
], sl
);
254 talloc_set_destructor(se
, tevent_signal_destructor
);
255 talloc_set_destructor(sl
, tevent_common_signal_list_destructor
);
257 /* we need to setup the pipe hack handler if not already
259 if (ev
->pipe_fde
== NULL
) {
260 if (sig_state
->pipe_hack
[0] == 0 &&
261 sig_state
->pipe_hack
[1] == 0) {
262 if (pipe(sig_state
->pipe_hack
) == -1) {
266 ev_set_blocking(sig_state
->pipe_hack
[0], false);
267 ev_set_blocking(sig_state
->pipe_hack
[1], false);
269 ev
->pipe_fde
= tevent_add_fd(ev
, ev
, sig_state
->pipe_hack
[0],
270 TEVENT_FD_READ
, signal_pipe_handler
, NULL
);
282 check if a signal is pending
283 return != 0 if a signal was pending
285 int tevent_common_check_signal(struct tevent_context
*ev
)
289 if (!sig_state
|| !SIG_PENDING(sig_state
->got_signal
)) {
293 for (i
=0;i
<NUM_SIGNALS
+1;i
++) {
294 struct tevent_common_signal_list
*sl
, *next
;
295 struct sigcounter counter
= sig_state
->signal_count
[i
];
296 uint32_t count
= sig_count(counter
);
301 for (sl
=sig_state
->sig_handlers
[i
];sl
;sl
=next
) {
302 struct tevent_signal
*se
= sl
->se
;
305 if (se
->sa_flags
& SA_SIGINFO
) {
307 for (j
=0;j
<count
;j
++) {
308 /* note the use of the sig_info array as a
310 int ofs
= ((count
-1) + j
) % SA_INFO_QUEUE_COUNT
;
311 se
->handler(ev
, se
, i
, 1,
312 (void*)&sig_state
->sig_info
[i
][ofs
],
315 if (SIG_PENDING(sig_state
->sig_blocked
[i
])) {
316 /* we'd filled the queue, unblock the
321 SIG_SEEN(sig_state
->sig_blocked
[i
],
322 sig_count(sig_state
->sig_blocked
[i
]));
323 sigprocmask(SIG_UNBLOCK
, &set
, NULL
);
325 if (se
->sa_flags
& SA_RESETHAND
) {
331 se
->handler(ev
, se
, i
, count
, NULL
, se
->private_data
);
332 if (se
->sa_flags
& SA_RESETHAND
) {
336 SIG_SEEN(sig_state
->signal_count
[i
], count
);
337 SIG_SEEN(sig_state
->got_signal
, count
);