SIGEMPTYSET(3P)           POSIX Programmer's Manual          SIGEMPTYSET(3P)

PROLOG         top

       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.

NAME         top

       sigemptyset — initialize and empty a signal set

SYNOPSIS         top

       #include <signal.h>

       int sigemptyset(sigset_t *set);

DESCRIPTION         top

       The sigemptyset() function initializes the signal set pointed to by
       set, such that all signals defined in POSIX.1‐2008 are excluded.

RETURN VALUE         top

       Upon successful completion, sigemptyset() shall return 0; otherwise,
       it shall return −1 and set errno to indicate the error.

ERRORS         top

       No errors are defined.

       The following sections are informative.

EXAMPLES         top




RATIONALE         top

       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 POSIX.1‐2008. Although it is outside the scope of this
       volume of POSIX.1‐2008 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.



SEE ALSO         top

       Section 2.4, Signal Concepts, pthread_sigmask(3p), sigaction(3p),
       sigaddset(3p), sigdelset(3p), sigfillset(3p), sigismember(3p),
       sigpending(3p), sigsuspend(3p)

       The Base Definitions volume of POSIX.1‐2008, signal.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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 .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see .

IEEE/The Open Group                 2013                     SIGEMPTYSET(3P)

Pages that refer to this page: signal.h(0p)pthread_sigmask(3p)sigaction(3p)sigaddset(3p)sigdelset(3p)sigfillset(3p)sigismember(3p)sigpending(3p)sigsuspend(3p)