siginfo(5)siginfo(5)NAMEsiginfo - Details of signal generation
SYNOPSIS
#include <siginfo.h>
DESCRIPTION
The siginfo structure provides processes with information on why a sig‐
nal was generated, or a process that is monitoring child processes may
receive information that specifies why a child process changed state.
See the sigaction(2) and waitid(2) reference pages for more informa‐
tion.
The type siginfo_t contains the following members: Contains the system
generated signal number. Note that for the waitid function, this field
is always SIGCHLD. Contains, if non-zero, the errno that is associated
with the signal. Specifies a code that determines whether the signal
was generated by a user process, a specific signal, or by the kernel.
When the value of si_code is less than or equal to zero (0), the signal
was generated by a user process and the siginfo structure contains the
following additional members:
pid_t si_pid /*sending process ID*/ uid_t si_uid /*sending
user ID*/
See the kill(2) and sigsend(2) reference pages for more informa‐
tion on these fields.
The following table describes the meaning of the code generated
by a signal. The table lists signals in alphabetical order.
─────────────────────────────────────────────────────────
Signal Code Definition
─────────────────────────────────────────────────────────
SIGBUS BUS_ADRALN invalid address alignment
BUS_ADRERR non-existent physical address
BUS_OBJERR object specific hardware
error
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 has continued
CLD_SIGEXITING child is about to exit
because it received a fatal
signal
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 opera‐
tion
FPE_FLTSUB subscript out of range
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
SIGSEGV SEGV_MAPERR address not mapped to object
SEGV_ACCERR invalid permissions for
mapped object
SIGTRAP TRAP_BRKPT process breakpoint
TRAP_TRACE process trace trap
─────────────────────────────────────────────────────────
When a signal is generated by the system, the meaning of the
code is as follows:
────────────────────────────────────────────────────────────
Signal Field Description
────────────────────────────────────────────────────────────
SIGILL caddr_t si_addr address of faulting instruction
SIGFPE
SIGSEGV caddr_t si_addr address of faulting memory
SIGBUS reference
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
────────────────────────────────────────────────────────────
Note, if the signal is SIGCHLD, and the si_code is equivalent to
CLD_EXITED, si_status is equivalent to the exit value of the
process. If si_code is not equivalent to CLD_EXITED, the
si_status field is equivalent to the signal that caused the
process to change state. In some instances, si_addr may not be
defined, but si_addr will appear on the same page as the fault‐
ing instruction or memory reference.
SEE ALSO
Functions: kill(2), sigaction(2), sigsend(2), waitid(2)
Files: signal(4)siginfo(5)
