Messages in this thread | | | Subject | RE: termios VMIN and VTIME behavior | From | Alan Cox <> | Date | Wed, 23 Nov 2005 11:15:27 +0000 |
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On Maw, 2005-11-22 at 20:32 -0800, Mike Voytovich wrote: > Please disregard - the user app was reading less than VMIN in the read() > call, so I suppose the current behavior in that case would be correct > (returning immediately with the number of bytes passed into read() > rather than waiting for VMIN or VTIME to be met before returning). > > It doesn't appear that the behavior in this case is explicitly defined > by POSIX, but it seems like a reasonable thing to do.
Its pretty well defined. It was designed to optimise block serial operations (uucp and the like)
VMIN - number of bytes you expect this packet VTIME - when to give up waiting
The form 0, VTIME also being used to do polling on old SYSV that lacked select/poll
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