Re: [Minios-devel] [PATCH v2 3/4] mini-os: Enable console to be configured as raw tty using termios

[Simon Waterman <watermansrdev@xxxxxxxxx>]

On 20/06/17 13:08, Wei Liu wrote:
> On Sun, Jun 18, 2017 at 11:21:21PM +0100, Simon Waterman wrote:
> > Add minimal implementation of termios functions so that a console
> > can be configured in raw mode if an application requires it.
> >
> > Signed-off-by: Simon Waterman <watermansrdev@xxxxxxxxx>
> > ---
> >   lib/sys.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
> >   1 file changed, 42 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/sys.c b/lib/sys.c
> > index 1420722..6173471 100644
> > --- a/lib/sys.c
> > +++ b/lib/sys.c
> > @@ -32,6 +32,7 @@
> >   #include <xenbus.h>
> >   #include <xenstore.h>
> >   #include <poll.h>
> > +#include <termios.h>
> >   
> >   #include <sys/types.h>
> >   #include <sys/unistd.h>
> > @@ -1436,6 +1437,47 @@ int nice(int inc)
> >       return 0;
> >   }
> >   
> > +/* Limited termios terminal settings support */
> > +const struct termios default_termios = {0,           /* iflag */
> > +                                        ONLCR,       /* oflag */
> > +                                        0,           /* lflag */
> > +                                        CREAD | CS8, /* cflag */
> > +                                        {}};         /* cc */
> > +
> > +int tcsetattr(int fildes, int action, const struct termios *tios)
> > +{
> > +    if (files[fildes].type != FTYPE_CONSOLE) {
> > +        errno = ENOTTY;
> > +        return -1;
> > +    }
> > +
> > +    if (tios->c_oflag & ONLCR)
> > +        files[fildes].cons.dev->is_raw = false;
> > +    else
> > +        files[fildes].cons.dev->is_raw = true;
> > +
> > +    return 0;
> > +}
> > +
> > +int tcgetattr(int fildes, struct termios *tios)
> > +{
> > +    if (files[fildes].type != FTYPE_CONSOLE) {
> > +        errno = ENOTTY;
> > +        return -1;
> > +    }
> > +
> > +    memcpy(tios, &default_termios, sizeof(struct termios));
> > +
> > +    if (files[fildes].cons.dev->is_raw)
> > +        tios->c_oflag &= ~ONLCR;
> > +
> > +    return 0;
> > +}
> > +
> > +void cfmakeraw(struct termios *termios_p)
> > +{
> > +    termios_p->c_oflag &= ~ONLCR;
> > +}
> I'm not sure if this function does the right thing. Linux's TERMIOS(3)
> says cfmakeraw does only the following to c_oflag:
>
>             termios_p->c_oflag &= ~OPOST;
>
> What source (spec) did you reference?
I don't think cfmakeraw is defined in POSIX but you're right. All the
implementations change OPOST.  I should have paid more attention to the
man page.

I will redo the patch. I propose to make OPOST configurable but ONLCR
fixed (enabled).

Sound okay or do you prefer I let both OPOST and ONLCR be configured?
If I do that I'll need to persist TERMIOS settings for each console whereas
at the moment I manufacture them from is_raw if needed.


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