Copyright (c) 2008, Sun Microsystems, Inc. All Rights Reserved.
Copyright 1989 AT&T
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When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
#include <siginfo.h>
If a process is catching a signal, it might request information that tells why the system generated that signal. See sigaction(2). If a process is monitoring its children, it might receive information that tells why a child changed state. See waitid(2). In either case, the system returns the information in a structure of type siginfo_t, which includes the following information:
int si_signo /* signal number */ int si_errno /* error number */ int si_code /* signal code */ union sigval si_value /* signal value */
si_signo contains the system-generated signal number. For the waitid(2) function, si_signo is always SIGCHLD.
If si_errno is non-zero, it contains an error number associated with this signal, as defined in <errno.h>.
si_code contains a code identifying the cause of the signal.
If the value of the si_code member is SI_NOINFO, only the si_signo member of siginfo_t is meaningful, and the value of all other members is unspecified.
If the value of si_code is less than or equal to 0, then the signal was generated by a user process (see kill(2), _lwp_kill(2), sigqueue(3C), sigsend(2), abort(3C), and raise(3C)) and the siginfo structure contains the following additional information:
pid_t si_pid /* sending process ID */ uid_t si_uid /* sending user ID */ ctid_t si_ctid /* sending contract ID */ zoneid_t si_zoneid /* sending zone ID */S
If the signal was generated by a user process, the following values are defined for si_code: SI_USER
The implementation sets si_code to SI_USER if the signal was sent by kill(2), sigsend(2), raise(3C) or abort(3C).
The signal was sent by _lwp_kill(2).
The signal was sent by sigqueue(3C).
The signal was generated by the expiration of a timer created by timer_settime(3C).
The signal was generated by the completion of an asynchronous I/O request.
The signal was generated by the arrival of a message on an empty message queue. See mq_notify(3C).
si_value contains the application specified value, which is passed to the application's signal-catching function at the time of the signal delivery if si_code is any of SI_QUEUE, SI_TIMER, SI_ASYNCHIO, or SI_MESGQ.
Non-user generated signals can arise for a number of reasons. For all of these cases, si_code contains a positive value reflecting the reason why the system generated the signal:
| Signal Code Reason |
| SIGILL ILL_ILLOPC illegal opcode |
| ILL_ILLOPN illegal operand |
| ILL_ILLADR illegal addressing mode |
| ILL_ILLTRP illegal trap |
| ILL_PRVOPC privileged opcode |
| ILL_PRVREG privileged register |
| ILL_COPROC co-processor error |
| ILL_BADSTK internal stack error |
| SIGFPE FPE_INTDIV integer divide by zero |
| FPE_INTOVF integer overflow |
| FPE_FLTDIV floating point divide by zero |
| FPE_FLTOVF floating point overflow |
| FPE_FLTUND floating point underflow |
| FPE_FLTRES floating point inexact result |
| FPE_FLTINV invalid floating point operation |
| FPE_FLTSUB subscript out of range |
| SIGSEGV SEGV_MAPERR address not mapped to object |
| SEGV_ACCERR invalid permissions for mapped object |
| SIGBUS BUS_ADRALN invalid address alignment |
| BUS_ADRERR non-existent physical address |
| BUS_OBJERR object specific hardware error |
| SIGTRAP TRAP_BRKPT process breakpoint |
| TRAP_TRACE process trace trap |
| SIGCHLD CLD_EXITED child has exited |
| CLD_KILLED child was killed |
| CLD_DUMPED child terminated abnormally |
| CLD_TRAPPED traced child has trapped |
| CLD_STOPPED child has stopped |
| CLD_CONTINUED stopped child had continued |
| SIGPOLL POLL_IN data input available |
| POLL_OUT output buffers available |
| POLL_MSG input message available |
| POLL_ERR I/O error |
| POLL_PRI high priority input available |
| POLL_HUP device disconnected |
Signals can also be generated from the resource control subsystem. Where these signals do not already possess kernel-level siginfo codes, the siginfo si_code will be filled with SI_RCTL to indicate a kernel-generated signal from an established resource control value.
| Signal Code Reason |
| SIGXRES SI_RCTL resource-control generated signal |
| SIGHUP |
| SIGTERM |
The uncatchable signals SIGSTOP and SIGKILL have undefined siginfo codes.
Signals sent with a siginfo code of SI_RCTL contain code-dependent information for kernel-generated signals:
| Code Field Value |
| SI_RCTL hr_time si_entity process-model entity of control |
In addition, the following signal-dependent information is available for kernel-generated signals:
| Signal Field Value |
| SIGILL caddr_t si_addr address of faulting instruction |
| SIGFPE |
| SIGSEGV caddr_t si_addr address of faulting memory reference |
| SIGBUS |
| SIGCHLD pid_t si_pid child process ID |
| int si_status exit value or signal |
| SIGPOLL long si_band |
| band event for POLL_IN, POLL_OUT, or POLL_MSG |
_lwp_kill (2), kill (2), setrctl (2), sigaction (2), sigsend (2), waitid (2), abort (3C), aio_read (3C), mq_notify (3C), raise (3C), sigqueue (3C), timer_create (3C), timer_settime (3C), signal.h (3HEAD)
For SIGCHLD signals, if si_code is equal to CLD_EXITED, then si_status is equal to the exit value of the process; otherwise, it is equal to the signal that caused the process to change state. For some implementations, the exact value of si_addr might not be available; in that case, si_addr is guaranteed to be on the same page as the faulting instruction or memory reference.