unix - SIGALRM blocked by a mask -

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i have doubt happens when sigalrm signal gets blocked, go pending state , delivered after unblocked or lost?

the sigalrm held pending, , delivered unblocked.

a blocked signal (sig_block) remains pending until is:

  1. delivered, being unblocked , having either default (sig_dfl or "uncaught") disposition or user-supplied ("caught") disposition, struct sigaction's sa_handler.
  2. accepted, sigwait, sigwaitinfo, or sigtimedwait, meaning removed set of pending signals without further action
  3. discarded, changing disposition sig_ign ("ignored"). ignored signals will not held pending in case

conventional unix signals typically not queue, 1 signal of given type may pending @ time, , subsequently generated signals of same type lost.

(as aside, implementation chooses order of signal delivery , acceptance, example, delivering or accepting lower-numbered signals before higher-numbered signals. means newly unblocked sigalrm might not delivered first if other signals ready delivery. in practice, however, delivered immediately.)


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