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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 Ta Sy Member Ta Sy 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
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 Ta Sy Code Ta Sy 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 Ta Dv BUS_OOMERR Ta
154 cannot alloc a page to map at fault
155 .It Dv SIGTRAP Ta Dv TRAP_BRKPT Ta
157 .It Ta Dv TRAP_TRACE Ta
159 .It Ta Dv TRAP_DTRACE Ta
161 .It Ta Dv TRAP_CAP Ta
162 capabilities protective trap
163 .It Dv SIGCHLD Ta Dv CLD_EXITED Ta
165 .It Ta Dv CLD_KILLED Ta
166 child has terminated abnormally and did not create a core file
167 .It Ta Dv CLD_DUMPED Ta
168 child has terminated abnormally and created a core file
169 .It Ta Dv CLD_TRAPPED Ta
170 traced child has trapped
171 .It Ta Dv CLD_STOPPED Ta
173 .It Ta Dv CLD_CONTINUED Ta
174 stopped child has continued
175 .It Dv SIGPOLL Ta Dv POLL_IN Ta
177 .It Ta Dv POLL_OUT Ta
178 output buffers available
179 .It Ta Dv POLL_MSG Ta
180 input message available
181 .It Ta Dv POLL_ERR Ta
183 .It Ta Dv POLL_PRI Ta
184 high priority input available
185 .It Ta Dv POLL_HUP Ta
187 .It Any Ta Dv SI_NOINFO Ta
190 member is meaningful; the value of all other members is unspecified.
194 .It Ta Dv SI_QUEUE Ta
197 .It Ta Dv SI_TIMER Ta
198 signal generated by expiration of a timer set by
200 .It Ta Dv SI_ASYNCIO Ta
201 signal generated by completion of an asynchronous I/O request
202 .It Ta Dv SI_MESGQ Ta
203 signal generated by arrival of a message on an empty message queue
204 .It Ta Dv SI_KERNEL Ta
205 signal generated by miscellaneous parts of the kernel
211 For synchronous signals,
213 is generally set to the address of the faulting instruction.
214 However, synchronous signals raised by a faulting memory access such as
218 may report the address of the faulting memory access (if available) in
222 Sychronous signals set
224 to a machine-dependent trap number.
226 In addition, the following signal-specific information is available:
227 .Bl -column ".Dv SIGPOLL" ".Dv CLD_CONTINUED"
228 .It Sy Signal Ta Sy Member Ta Sy Value
229 .It Dv SIGCHLD Ta Va si_pid Ta
231 .It Ta Va si_status Ta
232 exit value or signal; if
236 then it is equal to the exit value of the child process, otherwise,
237 it is equal to a signal that caused the child process to change state.
238 .It Ta Va si_uid Ta "real user ID of the process that sent the signal"
239 .It Dv SIGPOLL Ta Va si_band Ta "band event for"
240 .Dv POLL_IN , POLL_OUT ,
245 Finally, the following code-specific information is available:
246 .Bl -column ".Dv SI_ASYNCIO" ".Va si_overrun"
247 .It Sy Code Ta Sy Member Ta Sy Value
248 .It Dv SI_USER Ta Va si_pid Ta
249 the process ID that sent the signal
251 real user ID of the process that sent the signal
252 .It Dv SI_QUEUE Ta Va si_value Ta
257 the process ID that sent the signal
259 real user ID of the process that sent the signal
260 .It Dv SI_TIMER Ta Va si_value Ta
264 .It Ta Va si_timerid Ta
265 the timer ID returned by
268 .It Ta Va si_overrun Ta
269 timer overrun count corresponding to the signal
270 .It Ta Va si_errno Ta
271 If timer overrun will be
272 .Brq Dv DELAYTIMER_MAX ,
273 an error code defined in
276 .It Dv SI_ASYNCIO Ta Va si_value Ta
277 the value passed to aio system calls
278 .It Dv SI_MESGQ Ta Va si_value Ta
283 the ID of the message queue which generated the signal
284 .It Dv SI_LWP Ta Va si_pid Ta
285 the process ID that sent the signal
287 real user ID of the process that sent the signal
290 Currently, the kernel never generates the
294 signal is queued when a process changed its status or exited.
296 Realtime Extensions like aio, timer, and message queue also queue
303 are only queued if there are sufficient resources;
307 For some hardware architectures, the exact value of
309 might not be available.
318 .Xr timer_settime 2 ,
329 signal information first appeared in
335 can be generated as of
339 can be generated as of
342 This manual page was written by
343 .An David Xu Aq Mt davidxu@FreeBSD.org .