pthread_sigmask - Examine or change the current thread's signal mask.
DECthreads POSIX 1003.1c Library (libpthread.so)
const sigset_t *set,
Interfaces documented on this reference page conform to industry standards as follows:
IEEE Std 1003.1c-1995, POSIX System Application Program Interface
Indicates the manner in which the set of masked signals is changed. The optional values are as follows: The resulting set is the union of the current set and the signal set pointed to by the set argument.) The resulting set is the intersection of the current set and the complement of the signal set pointed to by the set argument. The resulting set is the signal set pointed to by the set argument. Specifies the signal set by pointing to a set of signals used to change the blocked set. If this set value is NULL, the how argument is ignored and the process signal mask is unchanged. Receives the value of the current signal mask (unless this value is NULL).
This routine is for Tru64 UNIX systems only.
This routine examines or changes the calling thread's signal mask. Typically, you use the SIG_BLOCK option for the how value to block signals during a critical section of code, and then use this routine's SIG_SETMASK option to restore the mask to the previous value returned by the previous call to the pthread_sigmask(3) routine.
If there are any unblocked signals pending after a call to this routine, at least one of those signals is delivered before this routine returns.
This routine does not allow the SIGKILL or SIGSTOP signals to be blocked. If a program attempts to block one of these signals, pthread_sigmask(3) gives no indication of the error.
If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: Successful completion. The value specified for how is invalid.
Manuals: Guide to DECthreads and Programmer's Guide