pthread_sigmask(3p)

1PTHREAD_SIGMASK(3P)        POSIX Programmer's Manual       PTHREAD_SIGMASK(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       pthread_sigmask, sigprocmask - examine and change blocked signals
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SYNOPSIS

15       #include <signal.h>
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19       int pthread_sigmask(int how, const sigset_t *restrict set,
20              sigset_t *restrict oset);
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23       int sigprocmask(int how, const sigset_t *restrict set,
24              sigset_t *restrict oset);
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DESCRIPTION

28       The pthread_sigmask() function shall examine or change  (or  both)  the
29       calling  thread's  signal  mask, regardless of the number of threads in
30       the process. The function shall be equivalent to sigprocmask(), without
31       the restriction that the call be made in a single-threaded process.
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33       In  a single-threaded process, the sigprocmask() function shall examine
34       or change (or both) the signal mask of the calling thread.
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36       If the argument set is not a null pointer, it points to a set  of  sig‐
37       nals to be used to change the currently blocked set.
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39       The argument how indicates the way in which the set is changed, and the
40       application shall ensure it consists of one of the following values:
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42       SIG_BLOCK
43              The resulting set shall be the union of the current set and  the
44              signal set pointed to by set.
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46       SIG_SETMASK
47              The resulting set shall be the signal set pointed to by set.
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49       SIG_UNBLOCK
50              The  resulting  set shall be the intersection of the current set
51              and the complement of the signal set pointed to by set.
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54       If the argument oset is not a null pointer, the previous mask shall  be
55       stored  in  the location pointed to by oset.  If set is a null pointer,
56       the value of the argument how is not significant and the process'  sig‐
57       nal mask shall be unchanged; thus the call can be used to enquire about
58       currently blocked signals.
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60       If there are any pending unblocked signals after the call  to  sigproc‐
61       mask(),  at  least  one  of those signals shall be delivered before the
62       call to sigprocmask() returns.
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64       It is not possible to block those  signals  which  cannot  be  ignored.
65       This  shall  be  enforced  by the system without causing an error to be
66       indicated.
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68       If any of the SIGFPE, SIGILL, SIGSEGV, or SIGBUS signals are  generated
69       while  they are blocked, the result is undefined, unless the signal was
70       generated by the kill()  function,  the  sigqueue()  function,  or  the
71       raise() function.
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73       If sigprocmask() fails, the thread's signal mask shall not be changed.
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75       The  use  of  the  sigprocmask()  function  is  unspecified in a multi-
76       threaded process.
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RETURN VALUE

79       Upon successful completion pthread_sigmask() shall return 0; otherwise,
80       it shall return the corresponding error number.
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82       Upon successful completion, sigprocmask() shall return 0; otherwise, -1
83       shall be returned, errno shall be set to indicate the  error,  and  the
84       process' signal mask shall be unchanged.
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ERRORS

87       The pthread_sigmask()  and sigprocmask() functions shall fail if:
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89       EINVAL The value of the how argument is not equal to one of the defined
90              values.
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93       The pthread_sigmask() function  shall  not  return  an  error  code  of
94       [EINTR].
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96       The following sections are informative.
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EXAMPLES

99       None.
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APPLICATION USAGE

102       None.
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RATIONALE

105       When  a  process'  signal mask is changed in a signal-catching function
106       that is installed by sigaction(), the restoration of the signal mask on
107       return  from  the  signal-catching  function overrides that change (see
108       sigaction()). If the signal-catching function was installed  with  sig‐
109       nal(), it is unspecified whether this occurs.
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111       See kill() for a discussion of the requirement on delivery of signals.
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FUTURE DIRECTIONS

114       None.
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COPYRIGHT

122       Portions  of  this text are reprinted and reproduced in electronic form
123       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
124       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
125       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
126       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
127       event of any discrepancy between this version and the original IEEE and
128       The  Open Group Standard, the original IEEE and The Open Group Standard
129       is the referee document. The original Standard can be  obtained  online
130       at http://www.opengroup.org/unix/online.html .
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134IEEE/The Open Group                  2003                  PTHREAD_SIGMASK(3P)