meaning of "the process is blocking [a specific signal]"

["Philip Guenther" <guenther@xxxxxxxxx>]

In the descriptions for tcdrain(), tcflow(), tcflush(), tcsendbreak(),
tcsetattr(), and tcsetpgrp(), sentences similar to the following
appear:
      If the calling process is blocking or ignoring SIGTTOU signals, the
      process shall be allowed to perform the operation, and no signal is sent.

I can't seem to find any text specifying what the phrase "process is
blocking [some signal]" means in a multi-threaded process.  The signal
concepts page describes what it means for a signal to be pending for a
process, but that involves whether any threads would accept the signal
via sigwait().  I.e., it's possible that the signal would not be
pending if it were sent, even though it's blocked in all threads.
Should those tc* functions result in a signal in that case?

Also, are there any requirements on whether the tc* call fail or
succeed if the signal is sent?


Philip Guenther