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Examines or changes blocked signals.
Syntax | |
#include <signal.h>
int sigprocmask (int how, const sigset_t *set,
sigset_t *oset);
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Parameters | |
- how
Indicates how the process's signal mask should be changed by
the parameter set. One only of the following values must be passed:
- SIG_BLOCK
Add the specified signals in set to the process's signal mask.
- SIG_UNBLOCK
Delete the specified signals in set from the process's signal mask.
- SIG_SETMASK
Replace the process's signal mask with the signal mask pointed to by set.
- set
If not NULL, a pointer to a structure of type sigset_t containing a set of signals to use when changing the calling process's signal mask in the manner defined by how. If NULL, how is ignored and the process's signal mask remains unchanged.
- oset
If not NULL, a pointer to a structure of sigset_t that returns the process's previous signal mask (prior to any changes). If NULL, the current signal mask is not returned.
Return Values | |
- 0
Success.
- -1
An error occurred. The process's signal mask is not changed, and errno is set to indicate the error condition.
Description | |
The sigprocmask() function allows the caller to examine or change (or both) the calling process's signal mask. If any pending unblocked signals remain after a call to sigprocmask(), at least one of those signals is delivered to the calling process before the function returns.
It is not possible to block the signals SIGKILL and SIGSTOP. If specified in the structure pointed to by set, they are removed by the system without error.
Implementation Considerations | |
Refer to the EFAULT error description below.
Refer to Table 3-6 “POSIX/iX Signals” for implementation considerations associated with signals.
Errors | |
If an error occurs, errno is set to one of the following values:
| EFAULT | CAUSE
| The system detected a bad address in attempting to use
the set or oset parameters. | | | ACTION
| Make sure that the pointer is correctly initialized.
| | EINVAL | CAUSE
| The value of how is not valid. | | | ACTION
| Specify valid values for how.
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See Also | |
sigaction(), sigpending(), sigsuspend(), <signal.h>, POSIX.1 (Section 3.3.5)
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