Re: [PATCH RFC v5 07/12] qmp: add chardev-window-size-changed command

[Filip Hejsek <filip.hejsek@gmail.com>]

On Mon, 2025-09-22 at 08:45 +0200, Markus Armbruster wrote:
> Filip Hejsek <filip.hejsek@gmail.com> writes:
> 
> > From: Szymon Lukasz <noh4hss@gmail.com>
> > 
> > The managment software can use this command to notify QEMU about the
> > size of the terminal connected to a chardev, QEMU can then forward this
> > information to the guest if the chardev is connected to a virtio console
> > device.
> > 
> > Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
> > Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
> > [Filip: rename command, change documentation]
> > Signed-off-by: Filip Hejsek <filip.hejsek@gmail.com>
> > ---
> >  chardev/char.c | 14 ++++++++++++++
> >  qapi/char.json | 30 ++++++++++++++++++++++++++++++
> >  2 files changed, 44 insertions(+)
> > 
> > diff --git a/chardev/char.c b/chardev/char.c
> > index b45d79cb9b57643827eb7479257fdda2cf6b0434..f3aad545afe3d325aac388015b3d5517c2e48f0d 100644
> > --- a/chardev/char.c
> > +++ b/chardev/char.c
> > @@ -1269,6 +1269,20 @@ bool qmp_add_client_char(int fd, bool has_skipauth, bool skipauth,
> >      return true;
> >  }
> >  
> > +void qmp_chardev_window_size_changed(const char *id, uint16_t cols,
> > +                                     uint16_t rows, Error **errp)
> > +{
> > +    Chardev *chr;
> > +
> > +    chr = qemu_chr_find(id);
> > +    if (chr == NULL) {
> > +        error_setg(errp, "Chardev '%s' not found", id);
> > +        return;
> > +    }
> > +
> > +    qemu_chr_resize(chr, cols, rows);
> > +}
> > +
> >  /*
> >   * Add a timeout callback for the chardev (in milliseconds), return
> >   * the GSource object created. Please use this to add timeout hook for
> > diff --git a/qapi/char.json b/qapi/char.json
> > index f0a53f742c8bee24c377551803a864fd36ac78cf..93b0d239276077d808af2e5479d539728377a99f 100644
> > --- a/qapi/char.json
> > +++ b/qapi/char.json
> > @@ -874,6 +874,36 @@
> >  { 'command': 'chardev-send-break',
> >    'data': { 'id': 'str' } }
> >  
> > +##
> > +# @chardev-window-size-changed:
> > +#
> > +# Notifies a chardev about the current size of the terminal connected
> > +# to this chardev. The information will be forwarded to the guest if
> > +# the chardev is connected to a virtio console device.
> > +#
> > +# The initial size is 0x0, which should be interpreted as an unknown size.
> > +#
> > +# Some backends detect the terminal size automatically, in which case
> > +# the size may unpredictably revert to the detected one at any time.
> 
> Nicely done now!
> 
> docs/devel/qapi-code-gen.rst:
> 
>     For legibility, wrap text paragraphs so every line is at most 70
>     characters long.
> 
>     Separate sentences with two spaces.
> 
> > +#
> > +# @id: the chardev's ID, must exist
> 
> Let's drop ", must exist" for consistency with ID descriptions
> elsewhere.

All chardev @id parameters in qapi/char.json have ", must exist"
(although you're right that nothing else has it).

> > +#
> > +# @cols: the number of columns
> > +#
> > +# @rows: the number of rows
> > +#
> > +# Since: 10.2
> > +#
> > +# .. qmp-example::
> > +#
> > +#     -> { "execute": "chardev-window-size-changed", "arguments": { "id": "foo", "cols": 80, "rows": 24 } }
> > +#     <- { "return": {} }
> > +##
> > +{ 'command': 'chardev-window-size-changed',
> > +  'data': { 'id': 'str',
> > +            'cols': 'uint16',
> > +            'rows': 'uint16' } }
> > +
> >  ##
> >  # @VSERPORT_CHANGE:
> >  #
> 
> Acked-by: Markus Armbruster <armbru@redhat.com>