ждать сигнала (wait for a signal)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
sigsuspend — wait for a signal
Синопсис (Synopsis)
#include <signal.h>
int sigsuspend(const sigset_t *sigmask);
Описание (Description)
The sigsuspend() function shall replace the current signal mask
of the calling thread with the set of signals pointed to by
sigmask and then suspend the thread until delivery of a signal
whose action is either to execute a signal-catching function or
to terminate the process. This shall not cause any other signals
that may have been pending on the process to become pending on
the thread.
If the action is to terminate the process then sigsuspend() shall
never return. If the action is to execute a signal-catching
function, then sigsuspend() shall return after the signal-
catching function returns, with the signal mask restored to the
set that existed prior to the sigsuspend() call.
It is not possible to block signals that cannot be ignored. This
is enforced by the system without causing an error to be
indicated.
Возвращаемое значение (Return value)
Since sigsuspend() suspends thread execution indefinitely, there
is no successful completion return value. If a return occurs, -1
shall be returned and errno set to indicate the error.
Ошибки (Error)
The sigsuspend() function shall fail if:
EINTR A signal is caught by the calling process and control is
returned from the signal-catching function.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
Normally, at the beginning of a critical code section, a
specified set of signals is blocked using the sigprocmask()
function. When the thread has completed the critical section and
needs to wait for the previously blocked signal(s), it pauses by
calling sigsuspend() with the mask that was returned by the
sigprocmask() call.
Обоснование (Rationale)
Code which wants to avoid the ambiguity of the signal mask for
thread cancellation handlers can install an additional
cancellation handler which resets the signal mask to the expected
value.
void cleanup(void *arg)
{
sigset_t *ss = (sigset_t *) arg;
pthread_sigmask(SIG_SETMASK, ss, NULL);
}
int call_sigsuspend(const sigset_t *mask)
{
sigset_t oldmask;
int result;
pthread_sigmask(SIG_SETMASK, NULL, &oldmask);
pthread_cleanup_push(cleanup, &oldmask);
result = sigsuspend(sigmask);
pthread_cleanup_pop(0);
return result;
}
Будущие направления (Future directions)
None.
Смотри также (See also)
Section 2.4, Signal Concepts, pause(3p), sigaction(3p),
sigaddset(3p), sigdelset(3p), sigemptyset(3p), sigfillset(3p)
The Base Definitions volume of POSIX.1‐2017, signal.h(0p)
