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Last update: 23 March,1998

                                                                1003.1b-93 #2

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	Interpretation Number:  (to be assigned by the IEEE)
        Topic:                  action on synchronous signal acceptance
        Relevant Sections:      3.3.1.3
        Classification:         Ambiguous



Interpretation Request: (Defect Report)
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Date: Tue, 9 Aug 1994 10:47:06 -0700
From: John.Zolnowsky@Eng.Sun.COM (John Zolnowsky-Reeltime 415-336-2078)
Subject: action on synchronous signal acceptance

Section 3.3.1.3 defines actions for signals.  The circumstance under
which these actions are to be taken is termed delivery in 3.3.1.2.
Also, in 3.3.1.2, the statement is made that signals can be blocked
from delivery, and remain pending until either unblocked or the action
is set to ignore.  No mention is made of synchronous acceptance,
as specified by sigwaitinfo() and sigtimedwait() (3.3.8).

My questions apply when a signal is synchronously accepted.

    1)  Is an implementation required to take the associated action
	when a signal is accepted synchronously?
    2)  Is an implementation permitted to take the associated action
	when a signal is accepted synchronously?
    3)  Is an implementation forbidden to take the associated action
	when a signal is accepted synchronously?


IEEE Interpretation for 1003.1b-1993
------------------------------------


The standard is not clear in this area.  It is ambiguous as to whether the 
synchronous selection of a signal by sigwaitinfo constitutes delivery or not.
The interpretation is that an implementation is permitted to take the associated
action when a signal is accepted synchronously: neither required nor forbidden.
The lack of clarity is being refered to the sponsor for consideration. The 
interpretations committee suggests that an application would prefer to only 
receive each signal once and that implementations might wish to implement the 
factility in this manner (which is allowed but not required).

The answers to the requestor's 3 questions are thus: no, yes, no.

Rationale
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None.


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