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Date:	Sun, 28 Feb 2010 11:13:32 +0800 (HKT)
From:	Dave Lee <mailtolky AT yahoo DOT com DOT hk>
Subject:	Non-canonical mode input via tcsetattr(), under mintty console
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Hi all,

I was testing a program that uses non-canonical mode input via
tcsetattr().

The intent of the program is:
(1) have read() to wait if nothing has been entered;
(2) read() should not return until 1 character is read
    and put into the buffer.

The essence is this:

>       struct termios newtty;
>           .
>           .
>           .
>       tcgetattr (0, &newtty);
>       newtty.c_lflags &=3D (~ICANON);
>
>       newtty.c_cc[VMIN] =3D 1;
>       newtty.c_cc[VTIME] =3D 0;
>
>       tcsetattr (0, TCSANOW, &newtty);
>
>       unsigned char buf[100];
>       size_t n =3D read (0, buf, sizeof(buf));
>           .
>           .
>           .

I had no problem while entering an ASCII character. I also had success
if I entered a non-ASCII character under standard console, but not under
mintty.

Specifically, I entered the chinese character "=E4=BE=8B" (which means "rul=
e"
or "example"). It occupies 3 bytes in UTF-8 representation: E4, BE, 8B.

On standard console, the read() call returned THREE bytes (n =3D=3D 3), and
(not surprisingly) E4, BE and 8B were returned to buf[].

On mintty console, the read() call returned ONE byte (n =3D=3D 1), and only
E4 were returned to buf[]. I could grab the other two bytes if I did
additional calls to read().

I have attached a sample program for testing purpose. Basically it waits
for input, and when something is entered, prints it. Instruction is
included in the source.

I suspected this is a bug shown under mintty (but not standard
console). Is it the case?

Thanks,

Dave Lee.


=20=20=20=20=20=20
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