[v3,2/2] VT: Allow to get max font width and height

From: Alexey Gladkov <legion@kernel.org>

The Console drivers has more restrictive font size limits than vt_ioctl.
This leads to errors that are difficult to handle. If a font whose size
is not supported is used, an EINVAL error will be returned, which is
also returned in case of errors in the font itself. At the moment there
is no way to understand what font sizes the current console driver
supports.

To solve this problem, we need to transfer information about the
supported font to userspace from the console driver.

Signed-off-by: Alexey Gladkov <legion@kernel.org>
---
 drivers/video/console/newport_con.c | 21 +++++++++++++++++----
 drivers/video/console/sticon.c      | 25 +++++++++++++++++++++++--
 drivers/video/console/vgacon.c      | 21 ++++++++++++++++++++-
 drivers/video/fbdev/core/fbcon.c    | 22 +++++++++++++++++++++-
 4 files changed, 81 insertions(+), 8 deletions(-)

On Tue, Mar 12, 2024 at 03:23:58PM +0100, legion@kernel.org wrote:
>  drivers/video/console/newport_con.c | 21 +++++++++++++++++----
>  drivers/video/console/sticon.c      | 25 +++++++++++++++++++++++--
>  drivers/video/console/vgacon.c      | 21 ++++++++++++++++++++-
>  drivers/video/fbdev/core/fbcon.c    | 22 +++++++++++++++++++++-
>  4 files changed, 81 insertions(+), 8 deletions(-)

newport_con.c is an interesting one, apparently it's for SGI Indy and
Indigo2, both are discontinued in 1997. Do we still have a way to test
this driver?

Oleg

On 3/12/24 15:23, legion@kernel.org wrote:
> From: Alexey Gladkov <legion@kernel.org>
>
> The Console drivers has more restrictive font size limits than vt_ioctl.
> This leads to errors that are difficult to handle. If a font whose size
> is not supported is used, an EINVAL error will be returned, which is
> also returned in case of errors in the font itself. At the moment there
> is no way to understand what font sizes the current console driver
> supports.
>
> To solve this problem, we need to transfer information about the
> supported font to userspace from the console driver.
>
> Signed-off-by: Alexey Gladkov <legion@kernel.org>

Acked-by: Helge Deller <deller@gmx.de>

Helge


> ---
>   drivers/video/console/newport_con.c | 21 +++++++++++++++++----
>   drivers/video/console/sticon.c      | 25 +++++++++++++++++++++++--
>   drivers/video/console/vgacon.c      | 21 ++++++++++++++++++++-
>   drivers/video/fbdev/core/fbcon.c    | 22 +++++++++++++++++++++-
>   4 files changed, 81 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/video/console/newport_con.c b/drivers/video/console/newport_con.c
> index e8e4f82cd4a1..87f174a95fa8 100644
> --- a/drivers/video/console/newport_con.c
> +++ b/drivers/video/console/newport_con.c
> @@ -33,6 +33,9 @@
>
>   #define NEWPORT_LEN	0x10000
>
> +#define NEWPORT_MAX_FONT_WIDTH 8
> +#define NEWPORT_MAX_FONT_HEIGHT 16
> +
>   #define FONT_DATA ((unsigned char *)font_vga_8x16.data)
>
>   static unsigned char *font_data[MAX_NR_CONSOLES];
> @@ -328,8 +331,8 @@ static void newport_init(struct vc_data *vc, int init)
>   {
>   	int cols, rows;
>
> -	cols = newport_xsize / 8;
> -	rows = newport_ysize / 16;
> +	cols = newport_xsize / NEWPORT_MAX_FONT_WIDTH;
> +	rows = newport_ysize / NEWPORT_MAX_FONT_HEIGHT;
>   	vc->vc_can_do_color = 1;
>   	if (init) {
>   		vc->vc_cols = cols;
> @@ -507,8 +510,8 @@ static int newport_set_font(int unit, struct console_font *op, unsigned int vpit
>
>   	/* ladis: when I grow up, there will be a day... and more sizes will
>   	 * be supported ;-) */
> -	if ((w != 8) || (h != 16) || (vpitch != 32)
> -	    || (op->charcount != 256 && op->charcount != 512))
> +	if ((w != NEWPORT_MAX_FONT_WIDTH) || (h != NEWPORT_MAX_FONT_HEIGHT) ||
> +	    (vpitch != 32) || (op->charcount != 256 && op->charcount != 512))
>   		return -EINVAL;
>
>   	if (!(new_data = kmalloc(FONT_EXTRA_WORDS * sizeof(int) + size,
> @@ -569,6 +572,15 @@ static int newport_font_default(struct vc_data *vc, struct console_font *op, cha
>   	return newport_set_def_font(vc->vc_num, op);
>   }
>
> +static int newport_font_info(struct vc_data *vc, struct console_font_info *info)
> +{
> +	info->min_width = info->max_width = NEWPORT_MAX_FONT_WIDTH;
> +	info->min_height = info->max_height = NEWPORT_MAX_FONT_HEIGHT;
> +	info->flags = KD_FONT_INFO_FLAG_LOW_SIZE | KD_FONT_INFO_FLAG_HIGH_SIZE;
> +
> +	return 0;
> +}
> +
>   static int newport_font_set(struct vc_data *vc, struct console_font *font,
>   			    unsigned int vpitch, unsigned int flags)
>   {
> @@ -688,6 +700,7 @@ const struct consw newport_con = {
>   	.con_scroll	  = newport_scroll,
>   	.con_switch	  = newport_switch,
>   	.con_blank	  = newport_blank,
> +	.con_font_info	  = newport_font_info,
>   	.con_font_set	  = newport_font_set,
>   	.con_font_default = newport_font_default,
>   	.con_save_screen  = newport_save_screen
> diff --git a/drivers/video/console/sticon.c b/drivers/video/console/sticon.c
> index 992a4fa431aa..d32ca458eb77 100644
> --- a/drivers/video/console/sticon.c
> +++ b/drivers/video/console/sticon.c
> @@ -56,6 +56,11 @@
>   #define BLANK 0
>   static int vga_is_gfx;
>
> +#define STICON_MIN_FONT_WIDTH 6
> +#define STICON_MIN_FONT_HEIGHT 6
> +#define STICON_MAX_FONT_WIDTH 32
> +#define STICON_MAX_FONT_HEIGHT 32
> +
>   #define STI_DEF_FONT	sticon_sti->font
>
>   /* borrowed from fbcon.c */
> @@ -180,8 +185,10 @@ static int sticon_set_font(struct vc_data *vc, struct console_font *op,
>   	struct sti_cooked_font *cooked_font;
>   	unsigned char *data = op->data, *p;
>
> -	if ((w < 6) || (h < 6) || (w > 32) || (h > 32) || (vpitch != 32)
> -	    || (op->charcount != 256 && op->charcount != 512))
> +	if (!in_range(w, STICON_MIN_FONT_WIDTH, STICON_MAX_FONT_WIDTH) ||
> +	    !in_range(h, STICON_MIN_FONT_HEIGHT, STICON_MAX_FONT_HEIGHT) ||
> +	    (vpitch != 32) ||
> +	    (op->charcount != 256 && op->charcount != 512))
>   		return -EINVAL;
>   	pitch = ALIGN(w, 8) / 8;
>   	bpc = pitch * h;
> @@ -273,6 +280,19 @@ static int sticon_font_set(struct vc_data *vc, struct console_font *font,
>   	return sticon_set_font(vc, font, vpitch);
>   }
>
> +static int sticon_font_info(struct vc_data *vc, struct console_font_info *info)
> +{
> +	info->min_width = STICON_MIN_FONT_WIDTH;
> +	info->min_height = STICON_MIN_FONT_HEIGHT;
> +
> +	info->max_width = STICON_MAX_FONT_WIDTH;
> +	info->max_height = STICON_MAX_FONT_HEIGHT;
> +
> +	info->flags = KD_FONT_INFO_FLAG_LOW_SIZE | KD_FONT_INFO_FLAG_HIGH_SIZE;
> +
> +	return 0;
> +}
> +
>   static void sticon_init(struct vc_data *c, int init)
>   {
>       struct sti_struct *sti = sticon_sti;
> @@ -371,6 +391,7 @@ static const struct consw sti_con = {
>   	.con_scroll		= sticon_scroll,
>   	.con_switch		= sticon_switch,
>   	.con_blank		= sticon_blank,
> +	.con_font_info		= sticon_font_info,
>   	.con_font_set		= sticon_font_set,
>   	.con_font_default	= sticon_font_default,
>   	.con_build_attr		= sticon_build_attr,
> diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
> index 8ef1579fa57f..b75d31ef3353 100644
> --- a/drivers/video/console/vgacon.c
> +++ b/drivers/video/console/vgacon.c
> @@ -61,6 +61,10 @@ static struct vgastate vgastate;
>   #define BLANK 0x0020
>
>   #define VGA_FONTWIDTH       8   /* VGA does not support fontwidths != 8 */
> +
> +#define VGACON_MAX_FONT_WIDTH VGA_FONTWIDTH
> +#define VGACON_MAX_FONT_HEIGHT 32
> +
>   /*
>    *  Interface used by the world
>    */
> @@ -1013,6 +1017,19 @@ static int vgacon_adjust_height(struct vc_data *vc, unsigned fontheight)
>   	return 0;
>   }
>
> +static int vgacon_font_info(struct vc_data *vc, struct console_font_info *info)
> +{
> +	info->min_width = VGACON_MAX_FONT_WIDTH;
> +	info->min_height = 0;
> +
> +	info->max_width = VGACON_MAX_FONT_WIDTH;
> +	info->max_height = VGACON_MAX_FONT_HEIGHT;
> +
> +	info->flags = KD_FONT_INFO_FLAG_LOW_SIZE | KD_FONT_INFO_FLAG_HIGH_SIZE;
> +
> +	return 0;
> +}
> +
>   static int vgacon_font_set(struct vc_data *c, struct console_font *font,
>   			   unsigned int vpitch, unsigned int flags)
>   {
> @@ -1022,7 +1039,8 @@ static int vgacon_font_set(struct vc_data *c, struct console_font *font,
>   	if (vga_video_type < VIDEO_TYPE_EGAM)
>   		return -EINVAL;
>
> -	if (font->width != VGA_FONTWIDTH || font->height > 32 || vpitch != 32 ||
> +	if (font->width != VGACON_MAX_FONT_WIDTH ||
> +	    font->height > VGACON_MAX_FONT_HEIGHT || vpitch != 32 ||
>   	    (charcount != 256 && charcount != 512))
>   		return -EINVAL;
>
> @@ -1177,6 +1195,7 @@ const struct consw vga_con = {
>   	.con_scroll = vgacon_scroll,
>   	.con_switch = vgacon_switch,
>   	.con_blank = vgacon_blank,
> +	.con_font_info = vgacon_font_info,
>   	.con_font_set = vgacon_font_set,
>   	.con_font_get = vgacon_font_get,
>   	.con_resize = vgacon_resize,
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 46823c2e2ba1..e10abe416159 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -101,6 +101,9 @@ enum {
>   	FBCON_LOGO_DONTSHOW	= -3	/* do not show the logo */
>   };
>
> +#define FBCON_MAX_FONT_WIDTH 32
> +#define FBCON_MAX_FONT_HEIGHT 32
> +
>   static struct fbcon_display fb_display[MAX_NR_CONSOLES];
>
>   static struct fb_info *fbcon_registered_fb[FB_MAX];
> @@ -2456,6 +2459,21 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount,
>   	return ret;
>   }
>
> +
> +static int fbcon_font_info(struct vc_data *vc, struct console_font_info *info)
> +{
> +	info->min_width = 0;
> +	info->min_height = 0;
> +
> +	info->max_width = FBCON_MAX_FONT_WIDTH;
> +	info->max_height = FBCON_MAX_FONT_HEIGHT;
> +
> +	info->flags = KD_FONT_INFO_FLAG_LOW_SIZE | KD_FONT_INFO_FLAG_HIGH_SIZE;
> +
> +	return 0;
> +}
> +
> +
>   /*
>    *  User asked to set font; we are guaranteed that charcount does not exceed 512
>    *  but lets not assume that, since charcount of 512 is small for unicode support.
> @@ -2483,7 +2501,8 @@ static int fbcon_set_font(struct vc_data *vc, struct console_font *font,
>   	    h > FBCON_SWAP(info->var.rotate, info->var.yres, info->var.xres))
>   		return -EINVAL;
>
> -	if (font->width > 32 || font->height > 32)
> +	if (font->width > FBCON_MAX_FONT_WIDTH ||
> +	    font->height > FBCON_MAX_FONT_HEIGHT)
>   		return -EINVAL;
>
>   	/* Make sure drawing engine can handle the font */
> @@ -3158,6 +3177,7 @@ static const struct consw fb_con = {
>   	.con_scroll 		= fbcon_scroll,
>   	.con_switch 		= fbcon_switch,
>   	.con_blank 		= fbcon_blank,
> +	.con_font_info 		= fbcon_font_info,
>   	.con_font_set 		= fbcon_set_font,
>   	.con_font_get 		= fbcon_get_font,
>   	.con_font_default	= fbcon_set_def_font,

On 13. 03. 24, 18:40, Oleg Bulatov wrote:
> On Tue, Mar 12, 2024 at 03:23:58PM +0100, legion@kernel.org wrote:
>>   drivers/video/console/newport_con.c | 21 +++++++++++++++++----
>>   drivers/video/console/sticon.c      | 25 +++++++++++++++++++++++--
>>   drivers/video/console/vgacon.c      | 21 ++++++++++++++++++++-
>>   drivers/video/fbdev/core/fbcon.c    | 22 +++++++++++++++++++++-
>>   4 files changed, 81 insertions(+), 8 deletions(-)
> 
> newport_con.c is an interesting one, apparently it's for SGI Indy and
> Indigo2, both are discontinued in 1997. Do we still have a way to test
> this driver?

I doubt that.

Care to submit a removal patch? I am afraid, there is no other way to 
find out anyway...

thanks,