sigprocmask(2)

1sigprocmask(2)                   System Calls                   sigprocmask(2)
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NAME

6       sigprocmask - change or examine caller's signal mask
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SYNOPSIS

9       #include <signal.h>
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11       int sigprocmask(int how, const sigset_t *restrict set,
12            sigset_t *restrict oset);
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DESCRIPTION

16       The  sigprocmask()  function is used to examine and/or change the call‐
17       er's signal mask. If the value is  SIG_BLOCK, the set pointed to by the
18       set  argument  is  added  to  the  current signal mask. If the value is
19       SIG_UNBLOCK, the set pointed by the  set argument is removed  from  the
20       current  signal  mask. If the value is  SIG_SETMASK, the current signal
21       mask is replaced by the set pointed to by the   set  argument.  If  the
22       oset  argument  is  not  NULL, the previous mask is stored in the space
23       pointed to by oset. If the value of the  set  argument  is   NULL,  the
24       value   how  is  not  significant  and  the  caller's  signal  mask  is
25       unchanged; thus, the call  can  be  used  to  inquire  about  currently
26       blocked  signals.  If  the  set  or  oset argument points to an invalid
27       address, the behavior is undefined and errno may be set to EFAULT.
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30       If there are any pending unblocked signals after the call  to  sigproc‐
31       mask(), at least one of those signals will be delivered before the call
32       to sigprocmask() returns.
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35       It is not possible to block signals that cannot be  caught  or  ignored
36       (see sigaction(2)). It is also not possible to block or unblock SIGCAN‐
37       CEL, as SIGCANCEL is reserved for the implementation  of  POSIX  thread
38       cancellation   (see   pthread_cancel(3C)   and  cancellation(5)).  This
39       restriction is silently enforced by the standard C library.
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42       If sigprocmask() fails, the caller's signal mask is not changed.
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RETURN VALUES

45       Upon successful completion, 0 is returned. Otherwise,  −1  is  returned
46       and errno is set to indicate the error.
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ERRORS

49       The sigprocmask() function will fail if:
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51       EINVAL    The  value  of  the  how  argument is not equal to one of the
52                 defined values.
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56       The sigprocmask() function may fail if:
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58       EFAULT    The set or oset argument points to an illegal address.
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ATTRIBUTES

62       See attributes(5) for descriptions of the following attributes:
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67       ┌─────────────────────────────┬─────────────────────────────┐
68       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
69       ├─────────────────────────────┼─────────────────────────────┤
70       │Interface Stability          │Standard                     │
71       ├─────────────────────────────┼─────────────────────────────┤
72       │MT-Level                     │Async-Signal-Safe            │
73       └─────────────────────────────┴─────────────────────────────┘
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NOTES

80       The  call  to  sigprocmask()  affects  only the calling thread's signal
81       mask. It is identical to a call to pthread_sigmask(3C).
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84       Signals that are generated synchronously should not be masked. If  such
85       a signal is blocked and delivered, the receiving process is killed.
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89SunOS 5.11                        23 Mar 2005                   sigprocmask(2)