siginfo(5) File Formats Manual siginfo(5)
NAME
siginfo - Details of signal generation
SYNOPSIS
#include <siginfo.h>
DESCRIPTION
The siginfo structure provides processes with information on why a signal 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
information.
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 information 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
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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 faulting instruction
or memory reference.
SEE ALSO
Functions: kill(2), sigaction(2), sigsend(2), waitid(2)
Files: signal(4)
siginfo(5)