Content-type: text/html Man page of siginfo.h


Section: Headers (3HEAD)
Updated: 19 Jul 2004
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siginfo.h, siginfo - signal generation information  


#include <siginfo.h> 


If a process is catching a signal, it might request information that tells why the system generated that signal. See sigaction(2). If a process is monitoring its children, it might 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 */
union sigval   si_value        /* signal value */

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 the si_code member is SI_NOINFO, only the si_signo member of siginfo_t is meaningful, and the value of all other members is unspecified.  

User Signals

If the value of si_code is less than or equal to 0, then the signal was generated by a user process (see kill(2), _lwp_kill(2), sigqueue(3RT), sigsend(2), abort(3C), and raise(3C)) and the siginfo structure contains the following additional information:

pid_t        si_pid      /* sending process ID */
uid_t        si_uid      /* sending user ID */
ctid_t       si_ctid     /* sending contract ID */
zoneid_t     si_zoneid   /* sending zone ID */S

If the signal was generated by a user process, the following values are defined for si_code:

SI_USER The implementation sets si_code to SI_USER if the signal was sent by kill(2), sigsend(2), raise(3C) or abort(3C).

SI_LWP The signal was sent by _lwp_kill(2).

SI_QUEUE The signal was sent by sigqueue(3RT).

SI_TIMER The signal was generated by the expiration of a timer created by timer_settime(3RT).

SI_ASYNCIO The signal was generated by the completion of an asynchronous I/O request.

SI_MESGQ The signal was generated by the arrival of a message on an empty message queue. See mq_notify(3RT).

si_value contains the application specified value, which is passed to the application's signal-catching function at the time of the signal delivery if si_code is any of SI_QUEUE, SI_TIMER, SI_ASYNCHIO, or SI_MESGQ.  

System Signals

Non-user generated signals can arise for a number of reasons. For all of these cases, si_code contains a positive value reflecting the reason why the system generated the signal:

SIGILLILL_ILLOPCillegal opcode
ILL_ILLOPNillegal operand
ILL_ILLADRillegal addressing mode
ILL_ILLTRPillegal trap
ILL_PRVOPCprivileged opcode
ILL_PRVREGprivileged register
ILL_COPROCco-processor error
ILL_BADSTKinternal stack error
SIGFPEFPE_INTDIVinteger divide by zero
FPE_INTOVFinteger overflow
FPE_FLTDIVfloating point divide by zero
FPE_FLTOVFfloating point overflow
FPE_FLTUNDfloating point underflow
FPE_FLTRESfloating point inexact result
FPE_FLTINVinvalid floating point operation
FPE_FLTSUBsubscript out of range
SIGSEGVSEGV_MAPERRaddress not mapped to object
SEGV_ACCERR invalid permissions for mapped object
SIGBUSBUS_ADRALNinvalid address alignment
BUS_ADRERRnon-existent physical address
BUS_OBJERRobject specific hardware error
SIGTRAPTRAP_BRKPTprocess breakpoint
TRAP_TRACEprocess trace trap
SIGCHLDCLD_EXITEDchild has exited
CLD_KILLEDchild was killed
CLD_DUMPEDchild terminated abnormally
CLD_TRAPPEDtraced child has trapped
CLD_STOPPEDchild has stopped
CLD_CONTINUEDstopped child had continued
SIGPOLLPOLL_INdata input available
POLL_OUToutput buffers available
POLL_MSGinput message available
POLL_PRIhigh priority input available
POLL_HUPdevice disconnected

Signals can also be generated from the resource control subsystem. Where these signals do not already possess kernel-level siginfo codes, the siginfo si_code will be filled with SI_RCTL to indicate a kernel-generated signal from an established resource control value.

SIGXRESSI_RCTL resource-control generated signal

The uncatchable signals SIGSTOP and SIGKILL have undefined siginfo codes.

Signals sent with a siginfo code of SI_RCTL contain code-dependent information for kernel-generated signals:

Code FieldValue
SI_RCTLhr_time si_entityprocess-model entity of control

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

SIGILLcaddr_t si_addraddress of faulting instruction
SIGSEGVcaddr_t si_addr address of faulting memory reference
SIGCHLDpid_t si_pidchild process ID
int si_statusexit value or signal
SIGPOLLlong si_band band event for POLL_IN, POLL_OUT, or POLL_MSG



_lwp_kill(2), kill(2), setrctl(2), sigaction(2), sigsend(2), waitid(2), abort(3C), aio_read(3RT), mq_notify(3RT), raise(3C), signal.h(3HEAD), sigqueue(3RT), timer_create(3RT), timer_settime(3RT)  


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



User Signals
System Signals

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Time: 02:37:12 GMT, October 02, 2010