SIGINFO(3) |
FreeBSD Library Functions Manual |
SIGINFO(3) |
NAME
siginfo —
signal generation information
DESCRIPTION
A process may request signal information when it is catching a signal. The information specifies why the system generated that signal. To request signal information in a signal handler, the user can set
SA_SIGINFO in
sa_flags before
sigaction(2) is called, otherwise the user can use
sigwaitinfo(2) and
sigtimedwait(2) to get signal information. In either case, the system returns the information in a structure of type
siginfo_t, which includes the following information:
Type |
Member |
Description |
int |
si_signo |
signal number |
int |
si_errno |
error number |
int |
si_code |
signal code |
union sigval |
si_value |
signal value |
pid_t |
si_pid |
sending process ID |
uid_t |
si_uid |
sending process's real user ID |
void |
*si_addr |
address of faulting instruction |
int |
si_status |
exit value or signal |
long |
si_band |
band event for SIGPOLL |
int |
si_trapno |
machine trap code |
int |
si_timerid |
POSIX timer ID |
int |
si_overrun |
POSIX timer overrun count |
int |
si_mqd |
POSIX message queue ID |
The si_signo member contains the signal number.
The si_errno member contains an error number defined in the file < errno.h>.
The si_code member contains a code which describes the cause of the signal. The macros specified in the Code column of the following table are defined for use as values of si_code that are signal-specific or non-signal-specific reasons why the signal was generated:
Signal |
Code |
Reason |
SIGILL |
ILL_ILLOPC |
illegal opcode |
|
ILL_ILLOPN |
illegal operand |
|
ILL_ILLADR |
illegal addressing mode |
|
ILL_ILLTRP |
illegal trap |
|
ILL_PRVOPC |
illegal privileged opcode |
|
ILL_PRVREG |
illegal privileged register |
|
ILL_COPROC |
coprocessor 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 |
nonexistent physical address |
|
BUS_OBJERR |
object-specific hardware error |
SIGTRAP |
TRAP_BRKPT |
process breakpoint |
|
TRAP_TRACE |
process trace trap |
|
TRAP_DTRACE |
DTrace induced trap |
SIGCHLD |
CLD_EXITED |
child has exited |
|
CLD_KILLED |
child has terminated abnormally and did not create a core file |
|
CLD_DUMPED |
child has terminated abnormally and created a core file |
|
CLD_TRAPPED |
traced child has trapped |
|
CLD_STOPPED |
child has stopped |
|
CLD_CONTINUED |
stopped child has 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 |
Any |
SI_NOINFO |
Only the si_signo member is meaningful; the value of all other members is unspecified. |
|
SI_USER |
signal sent by kill(2) |
|
SI_QUEUE |
signal sent by sigqueue(2) |
|
SI_TIMER |
signal generated by expiration of a timer set by timer_settime(2) |
|
SI_ASYNCIO |
signal generated by completion of an asynchronous I/O request |
|
SI_MESGQ |
signal generated by arrival of a message on an empty message queue |
|
SI_KERNEL |
signal generated by miscellaneous parts of the kernel |
|
SI_LWP |
signal sent by pthread_kill(3) |
In addition, the following signal-specific information is available:
Signal |
Member |
Value |
SIGILL |
si_addr |
address of faulting instruction |
|
si_trapno |
machine dependent of trap code |
SIGFPE |
si_addr |
address of faulting instruction |
|
si_trapno |
machine dependent of trap code |
SIGSEGV |
si_addr |
address of faulting memory reference |
|
si_trapno |
machine dependent of trap code |
SIGBUS |
si_addr |
address of faulting instruction |
|
si_trapno |
machine dependent of trap code |
SIGCHLD |
si_pid |
child process ID |
|
si_status |
exit value or signal; if si_code is equal to CLD_EXITED, then it is equal to the exit value of the child process, otherwise, it is equal to a signal that caused the child process to change state. |
|
si_uid |
real user ID of the process that sent the signal |
SIGPOLL |
si_band |
band event for POLL_IN, POLL_OUT, or POLL_MSG |
Finally, the following code-specific information is available:
Code |
Member |
Value |
SI_USER |
si_pid |
the process ID that sent the signal |
|
si_uid |
real user ID of the process that sent the signal |
SI_QUEUE |
si_value |
the value passed to sigqueue(2) system call |
|
si_pid |
the process ID that sent the signal |
|
si_uid |
real user ID of the process that sent the signal |
SI_TIMER |
si_value |
the value passed to timer_create(2) system call |
|
si_timerid |
the timer ID returned by timer_create(2) system call |
|
si_overrun |
timer overrun count corresponding to the signal |
|
si_errno |
If timer overrun will be { DELAYTIMER_MAX}, an error code defined in < errno.h> is set |
SI_ASYNCIO |
si_value |
the value passed to aio system calls |
SI_MESGQ |
si_value |
the value passed to mq_notify(2) system call |
|
si_mqd |
the ID of the message queue which generated the signal |
SI_LWP |
si_pid |
the process ID that sent the signal |
|
si_uid |
real user ID of the process that sent the signal |
NOTES
Currently, the kernel never generates the
SIGPOLL signal.
SIGCHLD signal is queued when a process changed its status or exited. POSIX Realtime Extensions like aio, timer, and message queue also queue signals. Signals with code
SI_USER,
SI_KERNEL or
SI_LWP are only queued if there are sufficient resources; otherwise,
SI_NOINFO results. For some hardware architectures, the exact value of
si_addr might not be available.
STANDARDS
The
siginfo_t type conforms to IEEE Std 1003.1-2004 (“POSIX.1”).
HISTORY
Full support for POSIX signal information first appeared in
FreeBSD 7.0. The codes
SI_USER and
SI_KERNEL can be generated as of
FreeBSD 8.1. The code
SI_LWP can be generated as of
FreeBSD 9.0.
AUTHORS
This manual page was written by
David Xu <davidxu@FreeBSD.org>.