#include <signal.h>
int Qp0sEnableSignals( void );
Service Program Name: QPOSSRV1
Default Public Authority: *USE
Threadsafe: Yes
The Qp0sEnableSignals() function enables the process to
receive signals.
The Qp0sEnableSignals() function causes the process signal
vector to be initialized for the set of supported signals. The signal handling
action for each supported signal is set to the default action, as defined by
sigaction() (see sigaction()--Examine
and Change Signal Action). The signal blocking mask of the calling thread
is set to the empty signal set (see
sigemptyset()--Initialize and Empty Signal Set).
If the process is currently enabled for signals, a call to the
Qp0sEnableSignals() has no effect. That is, the process signal vector
and the signal blocking mask of the calling thread are unchanged and an
[EALREADY] error is returned.
Authorities and Locks
None.
Parameters
None.
Return Value
0
Qp0sEnableSignals() was
successful.
-1
Qp0sEnableSignals() was not
successful. The errno variable is set to indicate the error.
Error Conditions
If Qp0sEnableSignals() is not successful, errno
usually indicates one of the following errors. Under some conditions,
errno could indicate an error other than those listed here.
[EALREADY]
Operation already in progress.
The calling process is currently enabled for signals.
[ENOTSIGINIT]
Process not enabled for signals.
An attempt was made to call a signal function under one of the following
conditions:
The signal function is being called for a process that is not enabled for
asynchronous signals.
The signal function is being called when the system signal controls have
not been initialized.
Usage Notes
Processes, by default, are not eligible to receive signals from other
processes or the system. The Qp0sEnableSignals() function
allows the calling process to receive signals from other processes or the
system without having to call other signal functions that enable the process
for signals.
Use of the following functions enable a process for signals:
alarm()
getpgrp()
getpid()
kill()
pause()
Qp0wGetPgrp()
Qp0wGetPid()
setitimer()
sigaction()
sigprocmask()
sigsuspend()
sigtimedwait()
sigwait()
sigwaitinfo()
sleep()
Any of the Pthread APIs. See Pthread APIs for
more information.
Once a process has been enabled for signals, it remains eligible to receive
signals until either it ends or some user action is taken to prevent the
delivery of signals. The user of signals can prevent the signals from being
delivered by calling the sigprocmask() function. The user can
also ignore the signal by calling the sigaction() function.
However, not all signals can be blocked or ignored. For details, see sigaction()--Examine and Change Signal Action and sigprocmask()--Examine and Change Blocked Signals.
If a process has not been enabled for signals, the signal blocking mask for
any thread created in the process will be set to the empty set.
If a process with multiple threads is disabled for signals by calling
Qp0sDisableSignals() and then later re-enabled for signals,
only the thread that causes signals to be enabled will have its signal blocking
mask changed. The signal blocking mask for all other threads will be the value
last used to set the signal blocking mask for those threads.