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SubjectRe: [RESEND PATCH v3 1/2] VT: Add KDFONTINFO ioctl
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Hi,

On 02. 04. 24, 12:32, Alexey Gladkov wrote:
> Each driver has its own restrictions on font size. There is currently no
> way to understand what the requirements are. The new ioctl allows
> userspace to get the minmum and maximum font size values.

minimum

> Acked-by: Helge Deller <deller@gmx.de>
> Signed-off-by: Alexey Gladkov <legion@kernel.org>
> ---
> drivers/tty/vt/vt.c | 24 ++++++++++++++++++++++++
> drivers/tty/vt/vt_ioctl.c | 13 +++++++++++++
> include/linux/console.h | 2 ++
> include/linux/vt_kern.h | 1 +
> include/uapi/linux/kd.h | 13 ++++++++++++-
> 5 files changed, 52 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> index 156efda7c80d..8c2a3d98b5ec 100644
> --- a/drivers/tty/vt/vt.c
> +++ b/drivers/tty/vt/vt.c
> @@ -4680,6 +4680,30 @@ int con_font_op(struct vc_data *vc, struct console_font_op *op)
> return -ENOSYS;
> }
>
> +int con_font_info(struct vc_data *vc, struct console_font_info *info)
> +{
> + int rc = -EINVAL;

This initialization appears to be unneeded.

> +
> + info->min_height = 0;
> + info->max_height = max_font_height;
> +
> + info->min_width = 0;
> + info->max_width = max_font_width;
> +
> + info->flags = KD_FONT_INFO_FLAG_LOW_SIZE | KD_FONT_INFO_FLAG_HIGH_SIZE;
> +
> + console_lock();
> + if (vc->vc_mode != KD_TEXT)
> + rc = -EINVAL;
> + else if (vc->vc_sw->con_font_info)
> + rc = vc->vc_sw->con_font_info(vc, info);
> + else
> + rc = -ENOSYS;
> + console_unlock();
> +
> + return rc;
> +}
> +
> /*
> * Interface exported to selection and vcs.
> */
> diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
> index 8c685b501404..b3b4e4b69366 100644
> --- a/drivers/tty/vt/vt_ioctl.c
> +++ b/drivers/tty/vt/vt_ioctl.c
> @@ -479,6 +479,19 @@ static int vt_k_ioctl(struct tty_struct *tty, unsigned int cmd,
> break;
> }
>
> + case KDFONTINFO: {
> + struct console_font_info fnt_info;
> +
> + if (copy_from_user(&fnt_info, up, sizeof(fnt_info)))
> + return -EFAULT;

Who uses the copied values?

> + ret = con_font_info(vc, &fnt_info);
> + if (ret)
> + return ret;
> + if (copy_to_user(up, &fnt_info, sizeof(fnt_info)))

We should do the preferred sizeof(*up) here...

> + return -EFAULT;
> + break;
> + }
> +
> default:
> return -ENOIOCTLCMD;
> }
..
> --- a/include/uapi/linux/kd.h
> +++ b/include/uapi/linux/kd.h
> @@ -183,8 +183,19 @@ struct console_font {
>
> #define KD_FONT_FLAG_DONT_RECALC 1 /* Don't recalculate hw charcell size [compat] */
>
> +#define KDFONTINFO 0x4B73 /* font information */

Why not properly define the number using IOC() et al.? K (that 0x4b) is
even reserved for kd.h.

> +#define KD_FONT_INFO_FLAG_LOW_SIZE (1U << 0) /* 256 */
> +#define KD_FONT_INFO_FLAG_HIGH_SIZE (1U << 1) /* 512 */

_BITUL()

> +struct console_font_info {
> + unsigned int min_width, min_height; /* minimal font size */
> + unsigned int max_width, max_height; /* maximum font size */
> + unsigned int flags; /* KD_FONT_INFO_FLAG_* */

This does not look like a well-defined™ and extendable uapi structure.
While it won't change anything here, still use fixed-length __u32.

And you should perhaps add some reserved fields. Do not repeat the same
mistakes as your predecessors with the current kd uapi.

> +};

thanks,
--
js
suse labs


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