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sigemptyset(3p) — Linux manual page

SIGEMPTYSET(3P)         POSIX Programmer's ManualSIGEMPTYSET(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

       Thesigemptyset() function initializes the signal set pointed to       byset, 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 seterrno to indicate the error.

ERRORS        top

       No errors are defined.The following sections are informative.

EXAMPLES        top

       None.

APPLICATION USAGE        top

       None.

RATIONALE        top

       The implementation of thesigemptyset() (orsigfillset()) 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, eithersigemptyset() orsigfillset() must be       called prior to any other use of the signal set, even if such use       is read-only (for example, as an argument tosigpending()).  This       function is not intended for dynamic allocation.       Thesigfillset() andsigemptyset() 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 bysigfillset().       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.

FUTURE DIRECTIONS        top

       None.

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   athttp://www.opengroup.org/unix/online.html .       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, seehttps://www.kernel.org/doc/man-pages/reporting_bugs.html .IEEE/The Open Group                2017SIGEMPTYSET(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)

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