From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael Kerrisk (man-pages)" Subject: Re: [patch] termios.3: Add missing details on behaviour of PARMRK Date: Wed, 02 Dec 2015 20:18:22 +0100 Message-ID: <565F43FE.8060700@gmail.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Olivier TARTROU Cc: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, libc-alpha-9JcytcrH/bA+uJoB2kUjGw@public.gmane.org List-Id: linux-man@vger.kernel.org Hello Olivier, On 11/05/2015 10:38 PM, Olivier TARTROU wrote: > For a serial terminal, with a specific configuration, input bytes with > value 0377 are passed to the program as two bytes, 0377 0377. > > This (correct) behaviour is described in the documentation of the GNU > C Library (https://www.gnu.org/software/libc/manual/html_node/Input-Modes.html#Input-Modes) > but not in the termios.3 man page. > > Problematic configuration: INPCK set, IGNPAR not set, PARMRK set, > ISTRIP not set. > > This man page problem affects several users. Examples: > * http://sourceforge.net/p/ftdi-usb-sio/mailman/message/4079724/ > * http://mailman.uclinux.org/pipermail/uclinux-dev/2006-November/040984.html > * ... > > The patch below corrects this problem. This patch applies to release 4.02. Thanks. I confirm your point. Patch applied. Just a note though: your mailer broke the patch (line-wrapping), and also "git am" didn't work cleanly because of the way you generated the patch. But, otherwise a nice patch have, so thanks again. Cheers, Michael > --- old/termios.3 2015-11-04 20:32:56.117200840 +0100 > +++ new/termios.3 2015-11-04 23:31:23.165191198 +0100 > @@ -36,6 +36,8 @@ > .\" Added a section on canonical and noncanonical mode. > .\" Enhanced the discussion of "raw" mode for cfmakeraw(). > .\" Document CMSPAR. > +.\" 2015-11-04, Olivier TARTROU : > +.\" Reworked description of PARMRK from > https://www.gnu.org/software/libc/manual/html_node/Input-Modes.html#Input-Modes > .\" > .TH TERMIOS 3 2015-03-02 "Linux" "Linux Programmer's Manual" > .SH NAME > @@ -133,8 +135,17 @@ > Ignore framing errors and parity errors. > .TP > .B PARMRK > -If \fBIGNPAR\fP is not set, prefix a character with a parity error or > -framing error with \\377 \\0. > +If this bit is set, input bytes with parity or framing errors are > +marked when passed to the program. This bit is meaningful only when > +\fBINPCK\fP is set and \fBIGNPAR\fP is not set. > +The way erroneous bytes are marked is with two preceding bytes, > +\\377 and \\0. Thus, the program actually reads three bytes for one > +erroneous byte received from the terminal. > +If a valid byte has the value \\377, and \fBISTRIP\fP (see below) is > +not set, the program might confuse it with the prefix that marks a > +parity error. So a valid byte \\377 is passed to the program as two > +bytes, \\377 \\377, in this case. > + > If neither \fBIGNPAR\fP nor \fBPARMRK\fP > is set, read a character with a parity error or framing error > as \\0. > > > Best regards, > > Olivier TARTROU > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html