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30 .Dd September 14, 2012
35 .Nd "signal generation information"
39 A process may request signal information when it is catching a signal.
40 The information specifies why the system generated that signal.
41 To request signal information in a signal handler, the user can set
48 otherwise the user can use
52 to get signal information.
53 In either case, the system returns the information in a structure of type
55 which includes the following information:
56 .Bl -column ".Vt union signal" ".Va si_overrun"
57 .It Sy "Type Member Description"
58 .It Vt int Ta Va si_signo Ta
60 .It Vt int Ta Va si_errno Ta
62 .It Vt int Ta Va si_code Ta
64 .It Vt union sigval Ta Va si_value Ta
66 .It Vt pid_t Ta Va si_pid Ta
68 .It Vt uid_t Ta Va si_uid Ta
69 sending process's real user ID
70 .It Vt void Ta Va *si_addr Ta
71 address of faulting instruction
72 .It Vt int Ta Va si_status Ta
74 .It Vt long Ta Va si_band Ta
77 .It Vt int Ta Va si_trapno Ta
79 .It Vt int Ta Va si_timerid Ta
82 .It Vt int Ta Va si_overrun Ta
85 .It Vt int Ta Va si_mqd Ta
92 member contains the signal number.
96 member contains an error number defined in the file
101 member contains a code which describes the cause of the signal.
102 The macros specified in the
104 column of the following table are defined
107 that are signal-specific or non-signal-specific reasons why the signal was
109 .Bl -column ".Dv SIGPOLL" ".Dv CLD_CONTINUED"
110 .It Sy "Signal Code Reason"
111 .It Dv SIGILL Ta Dv ILL_ILLOPC Ta
113 .It Ta Dv ILL_ILLOPN Ta
115 .It Ta Dv ILL_ILLADR Ta
116 illegal addressing mode
117 .It Ta Dv ILL_ILLTRP Ta
119 .It Ta Dv ILL_PRVOPC Ta
120 illegal privileged opcode
121 .It Ta Dv ILL_PRVREG Ta
122 illegal privileged register
123 .It Ta Dv ILL_COPROC Ta
125 .It Ta Dv ILL_BADSTK Ta
127 .It Dv SIGFPE Ta Dv FPE_INTDIV Ta
128 integer divide by zero
129 .It Ta Dv FPE_INTOVF Ta
131 .It Ta Dv FPE_FLTDIV Ta
132 floating-point divide by zero
133 .It Ta Dv FPE_FLTOVF Ta
134 floating-point overflow
135 .It Ta Dv FPE_FLTUND Ta
136 floating-point underflow
137 .It Ta Dv FPE_FLTRES Ta
138 floating-point inexact result
139 .It Ta Dv FPE_FLTINV Ta
140 invalid floating-point operation
141 .It Ta Dv FPE_FLTSUB Ta
142 subscript out of range
143 .It Dv SIGSEGV Ta Dv SEGV_MAPERR Ta
144 address not mapped to object
145 .It Ta Dv SEGV_ACCERR Ta
146 invalid permissions for mapped object
147 .It Dv SIGBUS Ta Dv BUS_ADRALN Ta
148 invalid address alignment
149 .It Ta Dv BUS_ADRERR Ta
150 nonexistent physical address
151 .It Ta Dv BUS_OBJERR Ta
152 object-specific hardware error
153 .It Dv SIGTRAP Ta Dv TRAP_BRKPT Ta
155 .It Ta Dv TRAP_TRACE Ta
157 .It Ta Dv TRAP_DTRACE Ta
159 .It Dv SIGCHLD Ta Dv CLD_EXITED Ta
161 .It Ta Dv CLD_KILLED Ta
162 child has terminated abnormally and did not create a core file
163 .It Ta Dv CLD_DUMPED Ta
164 child has terminated abnormally and created a core file
165 .It Ta Dv CLD_TRAPPED Ta
166 traced child has trapped
167 .It Ta Dv CLD_STOPPED Ta
169 .It Ta Dv CLD_CONTINUED Ta
170 stopped child has continued
171 .It Dv SIGPOLL Ta Dv POLL_IN Ta
173 .It Ta Dv POLL_OUT Ta
174 output buffers available
175 .It Ta Dv POLL_MSG Ta
176 input message available
177 .It Ta Dv POLL_ERR Ta
179 .It Ta Dv POLL_PRI Ta
180 high priority input available
181 .It Ta Dv POLL_HUP Ta
183 .It Any Ta Dv SI_NOINFO Ta
186 member is meaningful; the value of all other members is unspecified.
190 .It Ta Dv SI_QUEUE Ta
193 .It Ta Dv SI_TIMER Ta
194 signal generated by expiration of a timer set by
196 .It Ta Dv SI_ASYNCIO Ta
197 signal generated by completion of an asynchronous I/O request
198 .It Ta Dv SI_MESGQ Ta
199 signal generated by arrival of a message on an empty message queue
200 .It Ta Dv SI_KERNEL Ta
201 signal generated by miscellaneous parts of the kernel
207 In addition, the following signal-specific information is available:
208 .Bl -column ".Dv SIGPOLL" ".Dv CLD_CONTINUED"
209 .It Sy "Signal Member Value"
210 .It Dv SIGILL Ta Va si_addr Ta
211 address of faulting instruction
212 .It Ta Va si_trapno Ta
213 machine dependent of trap code
214 .It Dv SIGFPE Ta Va si_addr Ta
215 address of faulting instruction
216 .It Ta Va si_trapno Ta
217 machine dependent of trap code
218 .It Dv SIGSEGV Ta Va si_addr Ta
219 address of faulting memory reference
220 .It Ta Va si_trapno Ta
221 machine dependent of trap code
222 .It Dv SIGBUS Ta Va si_addr Ta
223 address of faulting instruction
224 .It Ta Va si_trapno Ta
225 machine dependent of trap code
226 .It Dv SIGCHLD Ta Va si_pid Ta
228 .It Ta Va si_status Ta
229 exit value or signal; if
233 then it is equal to the exit value of the child process, otherwise,
234 it is equal to a signal that caused the child process to change state.
235 .It Ta Va si_uid Ta "real user ID of the process that sent the signal"
236 .It Dv SIGPOLL Ta Va si_band Ta "band event for"
237 .Dv POLL_IN , POLL_OUT ,
242 Finally, the following code-specific information is available:
243 .Bl -column ".Dv SI_QUEUE" ".Va si_overrun"
244 .It Sy "Code Member Value"
245 .It Dv SI_USER Ta Va si_pid Ta
246 the process ID that sent the signal
248 real user ID of the process that sent the signal
249 .It Dv SI_QUEUE Ta Va si_value Ta
254 the process ID that sent the signal
256 real user ID of the process that sent the signal
257 .It Dv SI_TIMER Ta Va si_value Ta
261 .It Ta Va si_timerid Ta
262 the timer ID returned by
265 .It Ta Va si_overrun Ta
266 timer overrun count corresponding to the signal
267 .It Ta Va si_errno Ta
268 If timer overrun will be
269 .Brq Dv DELAYTIMER_MAX ,
270 an error code defined in
273 .It Dv SI_ASYNCIO Ta Va si_value Ta
274 the value passed to aio system calls
275 .It Dv SI_MESGQ Ta Va si_value Ta
280 the ID of the message queue which generated the signal
281 .It Dv SI_LWP Ta Va si_pid Ta
282 the process ID that sent the signal
284 real user ID of the process that sent the signal
287 Currently, the kernel never generates the
291 signal is queued when a process changed its status or exited.
293 Realtime Extensions like aio, timer, and message queue also queue
300 are only queued if there are sufficient resources;
304 For some hardware architectures, the exact value of
306 might not be available.
315 .Xr timer_settime 2 ,
326 signal information first appeared in
332 can be generated as of
336 can be generated as of
339 This manual page was written by
340 .An "David Xu" Aq davidxu@FreeBSD.org .