sigprocmask.3

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3 代码 · 共 73 行

.\" SCCSID: @(#)sigprocmask.3	2.3	8/10/87
.TH sigprocmask 3
.SH Name
sigprocmask \- examine and change blocked signals (POSIX)
.SH Syntax
.nf
.B #include <signal.h>
.PP
.B int sigprocmask(\fIhow, set, oset\fP)
.B int \fIhow\fP;
.B sigset_t \fI*set, *oset\fP;
.SH Description
.NXR "sigprocmask system call"
.NXR "signal" "blocking"
The
.PN sigprocmask
system call
is used to examine and/or change the calling process's signal mask. If the
value of the argument
.I set
is not NULL, it points to a set of signals that will be used to 
change the currently blocked set.
.PP
The value of the argument
.I how
indicates the manner in which the set is changed as defined by the following
values, defined in <signal.h>:
.IP "SIG_BLOCK" 
The resulting signal set is the union of the current set and the signal set
pointed to by the argument
.I set.
.IP "SIG_UNBLOCK"
The resulting signal set is the intersection of the current set and the 
complement of the signal set pointed to by the argument
.I set.
.IP "SIG_SETMASK"
The resulting signal set is the signal set pointed to by the argument
.I set.
.PP
If the argument
.I oset
is not NULL, the previous mask is stored in the space pointed to by
.I oset.
If the value of the argument
.I set
is NULL, the process's signal mask is unchanged; thus, the
.MS sigprocmask 3
function can be used to enquire about currently blocked signals.
.PP
The signal masks used as arguments to this function are manipulated using the
.MS sigsetops 3
functions.
.PP
As a system restriction, SIGKILL and SIGSTOP cannot
be blocked. 
.SH Return Values
A 0 return value indicates a successful call.
A \-1 return value
indicates an error and
.I errno
is set to indicated the reason.
.SH Diagnostics
The
.PN sigprocmask
function fails and the signal mask remains unchanged if the
follow occurs:
.TP 15
[EINVAL]
The value of the \fIhow\fP argument is not equal to one of the defined
values.
.SH See Also
kill(2), sigsetmask(2), sigvec(2), sigblock(2), sigsetops(3)