| Message ID | 20191008132043.7966-6-daniel.thompson@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | kdb: Cleanup code to read user input and handle escape sequences | expand |
Hi, On Tue, Oct 8, 2019 at 6:21 AM Daniel Thompson <daniel.thompson@linaro.org> wrote: > > Currently if sequences such as "\ehelp\r" are delivered to the console then > the h gets eaten by the escape handling code. Since pressing escape > becomes something of a nervous twitch for vi users (and that escape doesn't > have much effect at a shell prompt) it is more helpful to emit the 'h' than > the '\e'. I have no objection to this change. > We don't simply choose to emit the final character for all escape sequences > since that will do odd things for unsupported escape sequences (in > other words we retain the existing behaviour once we see '\e['). It's not like it handles unsupported escape sequences terribly well anyway, of course. As soon as if finds something it doesn't recognize then it stops processing the escape sequence and will just interpret the rest of it verbatim. Like if I press Ctrl-Home on my keyboard I see "5H" spit out, for instance. > Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> > --- > kernel/debug/kdb/kdb_io.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c > index 288dd1babf90..b3fb88b1ee34 100644 > --- a/kernel/debug/kdb/kdb_io.c > +++ b/kernel/debug/kdb/kdb_io.c > @@ -158,8 +158,8 @@ static int kdb_getchar(void) > > *pbuf++ = key; > key = kdb_read_handle_escape(buf, pbuf - buf); > - if (key < 0) /* no escape sequence; return first character */ > - return buf[0]; > + if (key < 0) /* no escape sequence; return best character */ > + return buf[pbuf - buf != 2 ? 0 : 1]; optional nit: for me the inverse is easier to conceptualize, AKA: buf[pbuf - buf == 2 ? 1 : 0]; -Doug
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c index 288dd1babf90..b3fb88b1ee34 100644 --- a/kernel/debug/kdb/kdb_io.c +++ b/kernel/debug/kdb/kdb_io.c @@ -158,8 +158,8 @@ static int kdb_getchar(void) *pbuf++ = key; key = kdb_read_handle_escape(buf, pbuf - buf); - if (key < 0) /* no escape sequence; return first character */ - return buf[0]; + if (key < 0) /* no escape sequence; return best character */ + return buf[pbuf - buf != 2 ? 0 : 1]; if (key > 0) return key; }
Currently if sequences such as "\ehelp\r" are delivered to the console then the h gets eaten by the escape handling code. Since pressing escape becomes something of a nervous twitch for vi users (and that escape doesn't have much effect at a shell prompt) it is more helpful to emit the 'h' than the '\e'. We don't simply choose to emit the final character for all escape sequences since that will do odd things for unsupported escape sequences (in other words we retain the existing behaviour once we see '\e['). Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> --- kernel/debug/kdb/kdb_io.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 2.21.0