siginfo(5)							    siginfo(5)

NAME    [Toc]    [Back]

     siginfo - signal generation information

SYNOPSIS    [Toc]    [Back]

     #include <siginfo.h>

DESCRIPTION    [Toc]    [Back]

     If	a process is catching a	signal,	it may request information that	tells
     why the system generated that signal (see sigaction(2)).  If a process is
     monitoring	its children, it may 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 */

     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 si_code is less than or equal to 0, then the signal was
     generated either by a user	process	or on behalf of	a user initiated
     service.  In this case si_code defines which service initiated the
     request and determines what (if any) additional information is included
     in	the siginfo structure.	The following are the possible user initiated
     si_code values:

     SI_USER	 The signal was	generated via kill(2) or sigsend(2).  The
		 siginfo structure contains the	following additional
		 information:


		 pid_t si_pid	/* sending process ID */
		 uid_t si_uid	/* sending user	ID */

     SI_QUEUE	 The signal was	generated via sigqueue(3).  The	siginfo
		 structure contains the	following additional information:


		 pid_t si_pid	/* sending process ID */
		 uid_t si_uid	/* sending user	ID */
		 union sigval si_value;	/* value sent via sigqueue */

     Otherwise,	si_code	contains a signal-specific reason why the signal was
     generated,	as follows:





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siginfo(5)							    siginfo(5)



     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      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      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

     In	addition, the following	signal-dependent information is	available for
     kernel-generated signals:

     Signal	    Field			Value





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siginfo(5)							    siginfo(5)



    _________________________________________________________________
     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

SEE ALSO    [Toc]    [Back]

     kill(2), sigaction(2), sigqueue(2), sigsend(2), waitid(2),	signal(5)

NOTES    [Toc]    [Back]

     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 may not be available; in that
     case, si_addr is guaranteed to be on the same page	as the faulting
     instruction or memory reference.


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