Originální popis anglicky:
sigemptyset - initialize and empty a signal set
Návod, kniha: POSIX Programmer's Manual
#include <signal.h>
int sigemptyset(sigset_t *
set);
The
sigemptyset() function initializes the signal set pointed to by
set, such that all signals defined in
IEEE Std 1003.1-2001 are excluded.
Upon successful completion,
sigemptyset() shall return 0; otherwise, it
shall return -1 and set
errno to indicate the error.
No errors are defined.
The following sections are informative.
None.
None.
The implementation of the
sigemptyset() (or
sigfillset()) function
could quite trivially clear (or set) all the bits in the signal set.
Alternatively, it would be reasonable to initialize part of the structure,
such as a version field, to permit binary-compatibility between releases where
the size of the set varies. For such reasons, either
sigemptyset() or
sigfillset() must be called prior to any other use of the signal set,
even if such use is read-only (for example, as an argument to
sigpending()). This function is not intended for dynamic allocation.
The
sigfillset() and
sigemptyset() functions require that the
resulting signal set include (or exclude) all the signals defined in this
volume of IEEE Std 1003.1-2001. Although it is outside the scope
of this volume of IEEE Std 1003.1-2001 to place this requirement
on signals that are implemented as extensions, it is recommended that
implementation-defined signals also be affected by these functions. However,
there may be a good reason for a particular signal not to be affected. For
example, blocking or ignoring an implementation-defined signal may have
undesirable side effects, whereas the default action for that signal is
harmless. In such a case, it would be preferable for such a signal to be
excluded from the signal set returned by
sigfillset().
In early proposals there was no distinction between invalid and unsupported
signals (the names of optional signals that were not supported by an
implementation were not defined by that implementation). The [EINVAL] error
was thus specified as a required error for invalid signals. With that
distinction, it is not necessary to require implementations of these functions
to determine whether an optional signal is actually supported, as that could
have a significant performance impact for little value. The error could have
been required for invalid signals and optional for unsupported signals, but
this seemed unnecessarily complex. Thus, the error is optional in both cases.
None.
Signal Concepts ,
sigaction() ,
sigaddset() ,
sigdelset() ,
sigfillset() ,
sigismember() ,
sigpending() ,
sigprocmask() ,
sigsuspend() , the Base
Definitions volume of IEEE Std 1003.1-2001,
<signal.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
