sigemptyset(3p) — Linux manual page


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

RETURN VALUE         top

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

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.1‐2017. Although it is outside the scope
       of this volume of POSIX.1‐2017 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.1‐2017, signal.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       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               2017                   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)