SIGINFO.H(3HEAD) | Headers | SIGINFO.H(3HEAD) |
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.
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(3C), 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
SI_LWP
SI_QUEUE
SI_TIMER
SI_ASYNCIO
SI_MESGQ
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.
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:
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 | co-processor 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 |
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.
Signal | Code | Reason |
SIGXRES | SI_RCTL | resource-control generated signal |
SIGHUP | ||
SIGTERM |
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 | Field | Value |
SI_RCTL | hr_time si_entity | process-model entity of control |
In addition, the following signal-dependent information is available for kernel-generated signals:
Signal | Field | Value |
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 |
_lwp_kill(2), kill(2), setrctl(2), sigaction(2), sigsend(2), waitid(2), abort(3C), aio_read(3C), mq_notify(3C), raise(3C), sigqueue(3C), timer_create(3C), timer_settime(3C), signal.h(3HEAD)
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.
February 5, 2008 | OmniOS |