NAME

siginfo — signal information

SYNOPSIS

#include <signal.h>

DESCRIPTION

siginfo is a structure type which contains information about a signal delivered to a process.

siginfo includes the following members:

int si_signo; 
int si_errno; 
int si_code;

si_signo contains the signal number generated by the system.

If si_errno is non-zero, then it contains a system specific error number associated with this signal. This number is defined in errno(2).

If si_code is less than or equal to zero, the signal was generated by a user process or a user requested service:

SI_USER

The signal was generated via kill(2). The siginfo structure contains the following additional members:

pid_t si_pid; 
uid_t si_uid;

The si_pid field contains the pid of the sending process and the si_uid field contains the user id of the sending process.

SI_TIMER

The signal was generated because a timer set by timer_settime(2) has expired. The siginfo structure contains the following additional members:

sigval_t si_value;

The si_value field contains the value set via timer_create(2).

SI_ASYNCIO

The signal was generated by completion of an asynchronous I/O operation. The siginfo structure contains the following additional members:

int si_fd; 
long si_band;

The si_fd argument contains the file descriptor number on which the operation was completed and the si_band field contains the side and priority of the operation. If the operation was a normal read, si_band will contain POLLIN | POLLRDNORM; on an out-of-band read it will contain POLLPRI | POLLRDBAND; on a normal write it will contain POLLOUT | POLLWRNORM; on an out-of-band write it will contain POLLPRI | POLLWRBAND.

If si_code is positive, then it contains a signal specific reason why the signal was generated:

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

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

SIGCHLD

CLD_EXITED

Child has exited

CLD_KILLED

Child has terminated abnormally but 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

For SIGILL, SIGFPE, and SIGTRAP the siginfo structure contains the following additional members:

void *si_addr; 
int si_trap;

si_addr contains the address of the faulting instruction and si_trap contains a hardware specific reason.

For SIGBUS and SIGSEGV the siginfo structure contains the following additional members:

void *si_addr; 
int si_trap;

si_addr contains the address of the faulting data and si_trap contains a hardware specific reason.

For some architectures the value of si_addr may be inaccurate.

For SIGPOLL the siginfo structure contains the following additional members:

int si_fd; 
long si_band;

The si_fd argument contains the file descriptor number on which the operation was completed and the si_band field contains the side and priority of the operation as described above.

Finally, for SIGCHLD the siginfo structure contains the following additional members:

pid_t si_pid; 
uid_t si_uid; 
int si_status; 
clock_t	si_utime; 
clock_t	si_stime;

The si_pid field contains the pid of the process who's status changed, the si_uid field contains the user id of the that process, the si_status field contains a status code described in waitpid(2), and the si_utime and si_stime fields contain the user and system process accounting time.

STANDARDS

The siginfo type conforms to X/Open System Interfaces and Headers Issue 5 (“XSH5”).

HISTORY

The siginfo functionality first appeared in AT&T System V Release 4 UNIX.