pthread_sigmask(3T)pthread_sigmask(3T)NAME
pthread_sigmask() - examine/change signal mask of calling thread
SYNOPSIS PARAMETERS
how This parameter defines how the signal mask of the calling thread will be changed.
set Pointer to the set of signals that will be used to change the currently blocked signal set.
oset Pointer to where the previous signal mask will be returned.
DESCRIPTION
allows the calling thread to examine and/or change its signal mask.
Unless it is a null pointer, the argument set points to a set of signals which are to be used to change the currently blocked signal set.
The argument how indicates how the set is changed. The legal values are:
The resulting set is the union of the current set and the signal
set pointed to by set.
The resulting set is the intersection of the current set
and the complement of the signal set pointed to by set.
The resulting set is the signal set pointed to by
set.
If the argument oset is not a null pointer, the previous signal mask is returned in oset. If set is a null pointer, the value of the argu-
ment how is insignificant and the thread's signal mask is unchanged; thus, the call can be used to inquire about currently blocked signals.
If there any pending unblocked signals after the call to at least one of those signals is delivered before the call to returns.
It is impossible to block the or signal. This is enforced by the system without causing an error to be indicated.
The thread's signal mask is not changed if fails for any reason.
RETURN VALUE
Upon successful completion, returns zero. Otherwise, an error number is returned to indicate the error (the variable is not set).
ERRORS
If any of the following occur, the function returns the corresponding error number:
how contains an invalid value.
set or oset points to an invalid address. The reliable detection of this error is implementation dependent.
AUTHOR
was derived from the IEEE POSIX P1003.1c standard.
SEE ALSO sigprocmask(2).
STANDARDS CONFORMANCE
Pthread Library pthread_sigmask(3T)
Check Out this Related Man Page
PTHREAD_SIGMASK(3P) POSIX Programmer's Manual PTHREAD_SIGMASK(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond-
ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAME
pthread_sigmask, sigprocmask - examine and change blocked signals
SYNOPSIS
#include <signal.h>
int pthread_sigmask(int how, const sigset_t *restrict set,
sigset_t *restrict oset);
int sigprocmask(int how, const sigset_t *restrict set,
sigset_t *restrict oset);
DESCRIPTION
The pthread_sigmask() function shall examine or change (or both) the calling thread's signal mask, regardless of the number of threads in
the process. The function shall be equivalent to sigprocmask(), without the restriction that the call be made in a single-threaded process.
In a single-threaded process, the sigprocmask() function shall examine or change (or both) the signal mask of the calling thread.
If the argument set is not a null pointer, it points to a set of signals to be used to change the currently blocked set.
The argument how indicates the way in which the set is changed, and the application shall ensure it consists of one of the following val-
ues:
SIG_BLOCK
The resulting set shall be the union of the current set and the signal set pointed to by set.
SIG_SETMASK
The resulting set shall be the signal set pointed to by set.
SIG_UNBLOCK
The resulting set shall be the intersection of the current set and the complement of the signal set pointed to by set.
If the argument oset is not a null pointer, the previous mask shall be stored in the location pointed to by oset. If set is a null
pointer, the value of the argument how is not significant and the process' signal mask shall be unchanged; thus the call can be used to
enquire about currently blocked signals.
If there are any pending unblocked signals after the call to sigprocmask(), at least one of those signals shall be delivered before the
call to sigprocmask() returns.
It is not possible to block those signals which cannot be ignored. This shall be enforced by the system without causing an error to be
indicated.
If any of the SIGFPE, SIGILL, SIGSEGV, or SIGBUS signals are generated while they are blocked, the result is undefined, unless the signal
was generated by the kill() function, the sigqueue() function, or the raise() function.
If sigprocmask() fails, the thread's signal mask shall not be changed.
The use of the sigprocmask() function is unspecified in a multi-threaded process.
RETURN VALUE
Upon successful completion pthread_sigmask() shall return 0; otherwise, it shall return the corresponding error number.
Upon successful completion, sigprocmask() shall return 0; otherwise, -1 shall be returned, errno shall be set to indicate the error, and
the process' signal mask shall be unchanged.
ERRORS
The pthread_sigmask() and sigprocmask() functions shall fail if:
EINVAL The value of the how argument is not equal to one of the defined values.
The pthread_sigmask() function shall not return an error code of [EINTR].
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
When a process' signal mask is changed in a signal-catching function that is installed by sigaction(), the restoration of the signal mask
on return from the signal-catching function overrides that change (see sigaction()). If the signal-catching function was installed with
signal(), it is unspecified whether this occurs.
See kill() for a discussion of the requirement on delivery of signals.
FUTURE DIRECTIONS
None.
SEE ALSO
sigaction(), sigaddset(), sigdelset(), sigemptyset(), sigfillset(), sigismember(), sigpending(), sigqueue(), sigsuspend(), the Base Defini-
tions volume of IEEE Std 1003.1-2001, <signal.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
ogy -- 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 .
IEEE /The Open Group 2003 PTHREAD_SIGMASK(3P)