The VMIN and VTIME c_cc values were incorrectly defined as MIN and TIME.
Obtained from: NetBSD PR# 3243
This commit is contained in:
Mike Pritchard
parent
d06ae27bd3
commit
ed7922d368
@ -30,7 +30,7 @@
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)termios.4 8.4 (Berkeley) 4/19/94
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.\" $Id$
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.\" $Id: termios.4,v 1.4 1997/03/07 02:49:36 jmg Exp $
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.\"
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.Dd April 19, 1994
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.Dt TERMIOS 4
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@ -346,62 +346,62 @@ queue.
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.Ss Noncanonical Mode Input Processing
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In noncanonical mode input processing, input bytes are not assembled into
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lines, and erase and kill processing does not occur. The values of the
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.Dv MIN
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.Dv VMIN
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and
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.Dv TIME
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.Dv VTIME
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members of the
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.Fa c_cc
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array are used to determine how to
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process the bytes received.
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.Pp
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.Dv MIN
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.Dv VMIN
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represents the minimum number of bytes that should be received when
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the
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.Xr read 2
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function successfully returns.
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.Dv TIME
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.Dv VTIME
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is a timer of 0.1 second
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granularity that is used to time out bursty and short term data
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transmissions. If
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.Dv MIN
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.Dv VMIN
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is greater than
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.Dv \&{ Dv MAX_INPUT Ns \&} ,
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the response to the
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request is undefined. The four possible values for
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.Dv MIN
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.Dv VMIN
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and
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.Dv TIME
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.Dv VTIME
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and
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their interactions are described below.
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.Ss "Case A: MIN > 0, TIME > 0"
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.Ss "Case A: VMIN > 0, VTIME > 0"
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In this case
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.Dv TIME
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.Dv VTIME
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serves as an inter-byte timer and is activated after
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the first byte is received. Since it is an inter-byte timer, it is reset
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after a byte is received. The interaction between
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.Dv MIN
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.Dv VMIN
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and
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.Dv TIME
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.Dv VTIME
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is as
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follows: as soon as one byte is received, the inter-byte timer is
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started. If
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.Dv MIN
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.Dv VMIN
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bytes are received before the inter-byte timer expires
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(remember that the timer is reset upon receipt of each byte), the read is
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satisfied. If the timer expires before
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.Dv MIN
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.Dv VMIN
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bytes are received, the
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characters received to that point are returned to the user. Note that if
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.Dv TIME
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.Dv VTIME
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expires at least one byte is returned because the timer would
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not have been enabled unless a byte was received. In this case
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.Pf \&( Dv MIN
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.Pf \&( Dv VMIN
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> 0,
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.Dv TIME
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.Dv VTIME
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> 0) the read blocks until the
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.Dv MIN
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.Dv VMIN
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and
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.Dv TIME
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.Dv VTIME
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mechanisms are
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activated by the receipt of the first byte, or a signal is received. If
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data is in the buffer at the time of the
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@ -409,27 +409,27 @@ data is in the buffer at the time of the
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the result is as
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if data had been received immediately after the
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.Fn read .
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.Ss "Case B: MIN > 0, TIME = 0"
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.Ss "Case B: VMIN > 0, VTIME = 0"
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In this case, since the value of
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.Dv TIME
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.Dv VTIME
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is zero, the timer plays no role
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and only
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.Dv MIN
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.Dv VMIN
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is significant. A pending read is not satisfied until
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.Dv MIN
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.Dv VMIN
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bytes are received (i.e., the pending read blocks until
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.Dv MIN
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.Dv VMIN
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bytes
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are received), or a signal is received. A program that uses this case to
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read record-based terminal
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.Dv I/O
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may block indefinitely in the read
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operation.
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.Ss "Case C: MIN = 0, TIME > 0"
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.Ss "Case C: VMIN = 0, VTIME > 0"
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In this case, since
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.Dv MIN
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.Dv VMIN
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= 0,
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.Dv TIME
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.Dv VTIME
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no longer represents an inter-byte
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timer. It now serves as a read timer that is activated as soon as the
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read function is processed. A read is satisfied as soon as a single
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@ -438,12 +438,12 @@ the timer expires, no bytes are returned. If the timer does not
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expire, the only way the read can be satisfied is if a byte is received.
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In this case the read will not block indefinitely waiting for a byte; if
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no byte is received within
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.Dv TIME Ns *0.1
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.Dv VTIME Ns *0.1
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seconds after the read is initiated,
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the read returns a value of zero, having read no data. If data is
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in the buffer at the time of the read, the timer is started as if
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data had been received immediately after the read.
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.Ss Case D: MIN = 0, TIME = 0
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.Ss Case D: VMIN = 0, VTIME = 0
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The minimum of either the number of bytes requested or the number of
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bytes currently available is returned without waiting for more
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bytes to be input. If no characters are available, read returns a
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@ -1290,10 +1290,10 @@ If
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.Dv ICANON
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is not set, read requests are satisfied directly from the input
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queue. A read is not satisfied until at least
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.Dv MIN
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.Dv VMIN
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bytes have been
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received or the timeout value
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.Dv TIME
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.Dv VTIME
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expired between bytes. The time value
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represents tenths of seconds. See
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.Sx "Noncanonical Mode Input Processing"
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