man3p/sigprocmask.3p

   1 .\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
   2 .TH "PTHREAD_SIGMASK" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
   3 .\" pthread_sigmask
   4 .SH NAME
   5 pthread_sigmask, sigprocmask \- examine and change blocked signals
   6 .SH SYNOPSIS
   7 .LP
   8 \fB#include <signal.h>
   9 .br
  10 .sp
  11 \fP
  12 .LP
  13 \fBint pthread_sigmask(int\fP \fIhow\fP\fB, const sigset_t *restrict\fP
  14 \fIset\fP\fB,
  15 .br
  16 \ \ \ \ \ \  sigset_t *restrict\fP \fIoset\fP\fB);
  17 .br
  18 \fP
  19 .LP
  20 \fBint sigprocmask(int\fP \fIhow\fP\fB, const sigset_t *restrict\fP
  21 \fIset\fP\fB,
  22 .br
  23 \ \ \ \ \ \  sigset_t *restrict\fP \fIoset\fP\fB); \fP
  24 \fB
  25 .br
  26 \fP
  27 .SH DESCRIPTION
  28 .LP
  29 The \fIpthread_sigmask\fP() function shall examine or change (or both)
  30 the calling thread's signal mask, regardless of the number
  31 of threads in the process. The function shall be equivalent to \fIsigprocmask\fP(),
  32 without the restriction that the call be made
  33 in a single-threaded process.
  34 .LP
  35 In a single-threaded process, the \fIsigprocmask\fP() function shall
  36 examine or change (or both) the signal mask of the calling
  37 thread.
  38 .LP
  39 If the argument \fIset\fP is not a null pointer, it points to a set
  40 of signals to be used to change the currently blocked
  41 set.
  42 .LP
  43 The argument \fIhow\fP indicates the way in which the set is changed,
  44 and the application shall ensure it consists of one of
  45 the following values:
  46 .TP 7
  47 SIG_BLOCK
  48 The resulting set shall be the union of the current set and the signal
  49 set pointed to by \fIset\fP.
  50 .TP 7
  51 SIG_SETMASK
  52 The resulting set shall be the signal set pointed to by \fIset\fP.
  53 .TP 7
  54 SIG_UNBLOCK
  55 The resulting set shall be the intersection of the current set and
  56 the complement of the signal set pointed to by
  57 \fIset\fP.
  58 .sp
  59 .LP
  60 If the argument \fIoset\fP is not a null pointer, the previous mask
  61 shall be stored in the location pointed to by \fIoset\fP.
  62 If \fIset\fP is a null pointer, the value of the argument \fIhow\fP
  63 is not significant and the process' signal mask shall be
  64 unchanged; thus the call can be used to enquire about currently blocked
  65 signals.
  66 .LP
  67 If there are any pending unblocked signals after the call to \fIsigprocmask\fP(),
  68 at least one of those signals shall be
  69 delivered before the call to \fIsigprocmask\fP() returns.
  70 .LP
  71 It is not possible to block those signals which cannot be ignored.
  72 This shall be enforced by the system without causing an error
  73 to be indicated.
  74 .LP
  75 If any of the SIGFPE, SIGILL, SIGSEGV, or SIGBUS signals are generated
  76 while they are blocked, the result is undefined, unless
  77 the signal was generated by the \fIkill\fP() function, the \fIsigqueue\fP()
  78 function, or the \fIraise\fP()
  79 function.
  80 .LP
  81 If \fIsigprocmask\fP() fails, the thread's signal mask shall not be
  82 changed.
  83 .LP
  84 The use of the \fIsigprocmask\fP() function is unspecified in a multi-threaded
  85 process.
  86 .SH RETURN VALUE
  87 .LP
  88 Upon successful completion \fIpthread_sigmask\fP() shall return 0;
  89 otherwise, it shall return the corresponding error number.
  90 .LP
  91 Upon successful completion, \fIsigprocmask\fP() shall return 0; otherwise,
  92 -1 shall be returned, \fIerrno\fP shall be set to
  93 indicate the error, and the process' signal mask shall be unchanged.
  94 .SH ERRORS
  95 .LP
  96 The \fIpthread_sigmask\fP()  and \fIsigprocmask\fP() functions
  97 shall fail if:
  98 .TP 7
  99 .B EINVAL
 100 The value of the \fIhow\fP argument is not equal to one of the defined
 101 values.
 102 .sp
 103 .LP
 104 The \fIpthread_sigmask\fP() function shall not return an error code
 105 of [EINTR].
 106 .LP
 107 \fIThe following sections are informative.\fP
 108 .SH EXAMPLES
 109 .LP
 110 None.
 111 .SH APPLICATION USAGE
 112 .LP
 113 None.
 114 .SH RATIONALE
 115 .LP
 116 When a process' signal mask is changed in a signal-catching function
 117 that is installed by \fIsigaction\fP(), the restoration of the signal
 118 mask on return from the signal-catching
 119 function overrides that change (see \fIsigaction\fP()). If the signal-catching
 120 function
 121 was installed with \fIsignal\fP(), it is unspecified whether this
 122 occurs.
 123 .LP
 124 See \fIkill\fP() for a discussion of the requirement on delivery of
 125 signals.
 126 .SH FUTURE DIRECTIONS
 127 .LP
 128 None.
 129 .SH SEE ALSO
 130 .LP
 131 \fIsigaction\fP() , \fIsigaddset\fP() , \fIsigdelset\fP() , \fIsigemptyset\fP()
 132 , \fIsigfillset\fP() , \fIsigismember\fP() , \fIsigpending\fP() ,
 133 \fIsigqueue\fP() , \fIsigsuspend\fP() , the Base Definitions volume
 134 of IEEE\ Std\ 1003.1-2001, \fI<signal.h>\fP
 135 .SH COPYRIGHT
 136 Portions of this text are reprinted and reproduced in electronic form
 137 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
 138 -- Portable Operating System Interface (POSIX), The Open Group Base
 139 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
 140 Electrical and Electronics Engineers, Inc and The Open Group. In the
 141 event of any discrepancy between this version and the original IEEE and
 142 The Open Group Standard, the original IEEE and The Open Group Standard
 143 is the referee document. The original Standard can be obtained online at
 144 http://www.opengroup.org/unix/online.html .