1.\" Copyright (c) 2005 David Xu <davidxu@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as 9.\" the first lines of this file unmodified other than the possible 10.\" addition of one or more copyright notices. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice(s), this list of conditions and the following disclaimer in 13.\" the documentation and/or other materials provided with the 14.\" distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE 20.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 23.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 24.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 25.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 26.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd December 8, 2005 31.Dt SIGINFO 3 32.Os 33.Sh NAME 34.Nm siginfo 35.Nd "signal generation information" 36.Sh SYNOPSIS 37.In signal.h 38.Sh DESCRIPTION 39A process may request signal information when it is catching a signal. 40The information specifies why the system generated that signal. 41To request signal information in a signal handler, the user can set 42.Dv SA_SIGINFO 43in 44.Va sa_flags 45before 46.Xr sigaction 2 47is called, 48otherwise the user can use 49.Xr sigwaitinfo 2 50and 51.Xr sigtimedwait 2 52to get signal information. 53In either case, the system returns the information in a structure of type 54.Vt siginfo_t , 55which 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 59signal number 60.It Vt int Ta Va si_errno Ta 61error number 62.It Vt int Ta Va si_code Ta 63signal code 64.It Vt union sigval Ta Va si_value Ta 65signal value 66.It Vt pid_t Ta Va si_pid Ta 67sending process ID 68.It Vt uid_t Ta Va si_uid Ta 69sending process's real user ID 70.It Vt void Ta Va *si_addr Ta 71address of faulting instruction 72.It Vt int Ta Va si_status Ta 73exit value or signal 74.It Vt long Ta Va si_band Ta 75band event for 76.Dv SIGPOLL 77.It Vt int Ta Va si_trapno Ta 78machine trap code 79.It Vt int Ta Va si_timerid Ta 80.Tn POSIX 81timer ID 82.It Vt int Ta Va si_overrun Ta 83.Tn POSIX 84timer overrun count 85.It Vt int Ta Va si_mqd Ta 86.Tn POSIX 87message queue ID 88.El 89.Pp 90The 91.Va si_signo 92member contains the signal number. 93.Pp 94The 95.Va si_errno 96member contains an error number defined in the file 97.In errno.h . 98.Pp 99The 100.Va si_code 101member contains a code which describes the cause of the signal. 102The macros specified in the 103.Dq Code 104column of the following table are defined 105for use as values of 106.Va si_code 107that are signal-specific or non-signal-specific reasons why the signal was 108generated: 109.Bl -column ".Dv SIGPOLL" ".Dv CLD_CONTINUED" 110.It Sy "Signal Code Reason" 111.It Dv SIGILL Ta Dv ILL_ILLOPC Ta 112illegal opcode 113.It Ta Dv ILL_ILLOPN Ta 114illegal operand 115.It Ta Dv ILL_ILLADR Ta 116illegal addressing mode 117.It Ta Dv ILL_ILLTRP Ta 118illegal trap 119.It Ta Dv ILL_PRVOPC Ta 120illegal privileged opcode 121.It Ta Dv ILL_PRVREG Ta 122illegal privileged register 123.It Ta Dv ILL_COPROC Ta 124coprocessor error 125.It Ta Dv ILL_BADSTK Ta 126internal stack error 127.It Dv SIGFPE Ta Dv FPE_INTDIV Ta 128integer divide by zero 129.It Ta Dv FPE_INTOVF Ta 130integer overflow 131.It Ta Dv FPE_FLTDIV Ta 132floating-point divide by zero 133.It Ta Dv FPE_FLTOVF Ta 134floating-point overflow 135.It Ta Dv FPE_FLTUND Ta 136floating-point underflow 137.It Ta Dv FPE_FLTRES Ta 138floating-point inexact result 139.It Ta Dv FPE_FLTINV Ta 140invalid floating-point operation 141.It Ta Dv FPE_FLTSUB Ta 142subscript out of range 143.It Dv SIGSEGV Ta Dv SEGV_MAPERR Ta 144address not mapped to object 145.It Ta Dv SEGV_ACCERR Ta 146invalid permissions for mapped object 147.It Dv SIGBUS Ta Dv BUS_ADRALN Ta 148invalid address alignment 149.It Ta Dv BUS_ADRERR Ta 150nonexistent physical address 151.It Ta Dv BUS_OBJERR Ta 152object-specific hardware error 153.It Dv SIGTRAP Ta Dv TRAP_BRKPT Ta 154process breakpoint 155.It Ta Dv TRAP_TRACE Ta 156process trace trap 157.It Dv SIGCHLD Ta Dv CLD_EXITED Ta 158child has exited 159.It Ta Dv CLD_KILLED Ta 160child has terminated abnormally and did not create a core file 161.It Ta Dv CLD_DUMPED Ta 162child has terminated abnormally and created a core file 163.It Ta Dv CLD_TRAPPED Ta 164traced child has trapped 165.It Ta Dv CLD_STOPPED Ta 166child has stopped 167.It Ta Dv CLD_CONTINUED Ta 168stopped child has continued 169.It Dv SIGPOLL Ta Dv POLL_IN Ta 170data input available 171.It Ta Dv POLL_OUT Ta 172output buffers available 173.It Ta Dv POLL_MSG Ta 174input message available 175.It Ta Dv POLL_ERR Ta 176I/O error 177.It Ta Dv POLL_PRI Ta 178high priority input available 179.It Ta Dv POLL_HUP Ta 180device disconnected 181.It Any Ta Dv SI_NOINFO Ta 182Only the 183.Va si_signo 184member is meaningful; the value of all other members is unspecified. 185.It Ta Dv SI_USER Ta 186signal sent by 187.Xr kill 2 188.It Ta Dv SI_QUEUE Ta 189signal sent by 190.Xr sigqueue 2 191.It Ta Dv SI_TIMER Ta 192signal generated by expiration of a timer set by 193.Xr timer_settime 2 194.It Ta Dv SI_ASYNCIO Ta 195signal generated by completion of an asynchronous I/O request 196.It Ta Dv SI_MESGQ Ta 197signal generated by arrival of a message on an empty message queue 198.El 199.Pp 200In addition, the following signal-specific information is available: 201.Bl -column ".Dv SIGPOLL" ".Dv CLD_CONTINUED" 202.It Sy "Signal Member Value" 203.It Dv SIGILL Ta Va si_addr Ta 204address of faulting instruction 205.It Ta Va si_trapno Ta 206machine dependent of trap code 207.It Dv SIGFPE Ta Va si_addr Ta 208address of faulting instruction 209.It Ta Va si_trapno Ta 210machine dependent of trap code 211.It Dv SIGSEGV Ta Va si_addr Ta 212address of faulting memory reference 213.It Ta Va si_trapno Ta 214machine dependent of trap code 215.It Dv SIGBUS Ta Va si_addr Ta 216address of faulting instruction 217.It Ta Va si_trapno Ta 218machine dependent of trap code 219.It Dv SIGCHLD Ta Vt Va si_pid Ta 220child process ID 221.It Ta Va si_status Ta 222exit value or signal 223- If 224.Va si_code 225is equal to 226.Dv CLD_EXITED , 227then it is equal to the exit value of the child process, otherwise, 228it is equal to a signal that caused the child process to change state. 229.It Ta Va si_uid Ta "real user ID of the process that sent the signal" 230.It Dv SIGPOLL Ta Va si_band Ta "band event for" 231.Dv POLL_IN , POLL_OUT , 232or 233.Dv POLL_MSG 234.El 235.Pp 236Finally, the following code-specific information is available: 237.Bl -column ".Dv SI_QUEUE" ".Va si_overrun" 238.It Sy "Code Member Value" 239.It Dv SI_QUEUE Ta Va si_value Ta 240the value passed to 241.Xr sigqueue 2 242system call 243.It Ta Va si_pid Ta 244the process ID that sent the signal 245.It Ta Va si_uid Ta 246real user ID of the process that sent the signal 247.It Dv SI_TIMER Ta Va si_value Ta 248the value passed to 249.Xr timer_create 2 250system call 251.It Ta Va si_timerid Ta 252the timer ID returned by 253.Xr timer_create 2 254system call 255.It Ta Va si_overrun Ta 256timer overrun count corresponding to the signal 257.It Ta Va si_errno Ta 258If timer overrun will be 259.Brq Dv DELAYTIMER_MAX , 260an error code defined in 261.In errno.h 262is set 263.It Dv SI_ASYNCIO Ta Va si_value Ta 264the value passed to aio system calls 265.It Dv SI_MESGQ Ta Va si_value Ta 266the value passed to 267.Xr mq_notify 2 268system call 269.It Ta Va si_mqd Ta 270the ID of the message queue which generated the signal 271.El 272.Sh NOTES 273Currently, the kernel never generates 274.Dv SIGPOLL 275signal. 276Also, the 277.Xr kill 2 278system call does not queue signals, so you will not get code 279.Dv SI_USER . 280.Dv SIGCHLD 281signal is queued when a process changed its status or exited. 282.Tn POSIX 283Realtime Extensions like aio, timer, message queue also queue 284signals. 285For some hardware architectures, the exact value of 286.Va si_addr 287might not be available. 288.Sh SEE ALSO 289.Xr aio_read 2 , 290.Xr kill 2 , 291.Xr mq_notify 2 , 292.Xr sigaction 2 , 293.Xr sigqueue 2 , 294.Xr sigwaitinfo 2 , 295.Xr timer_create 2 , 296.Xr timer_settime 2 , 297.Xr waitpid 2 298.Sh STANDARDS 299The 300.Vt siginfo_t 301type conforms to 302.St -p1003.1-2004 . 303.Sh HISTORY 304Full support for 305.Tn POSIX 306signal information first appeared in 307.Fx 7.0 . 308.Sh AUTHORS 309This manual page was written by 310.An "David Xu" Aq davidxu@FreeBSD.org . 311