[PATCH 21/25] edit: Improve behaviour on efi-stdio console

[Jules Maselbas]

Hi,

On Mon, Dec 13, 2021 at 10:09:01PM +0100, Sascha Hauer wrote:
> Our console driver for the EFI simple text protocol does not support
> the "\e[1S" escape sequence to scroll the window which means sedit
> doesn't work properly. Disable smartscroll when the efi-stdio console
> is active. While at it put the screen height reduction into the same
> dynamic test.

FYI

>From the terminfo manpage:
In order to scroll text up, a program will go to the bottom left corner
of the screen and send the ind (index) string. [...] Parameterized
versions of the scrolling sequences are indn and rin which have the same
semantics as ind and ri except that they take one parameter, and scroll
that many lines. [...]

>From infocmp on my system: ind=\n and indn=\e[%p1$pS

So the smart scroll could be replaced by a move to the last line plus \n


> 
> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> ---
>  commands/edit.c | 46 ++++++++++++++++++++++++++++++++++++----------
>  1 file changed, 36 insertions(+), 10 deletions(-)
> 
> diff --git a/commands/edit.c b/commands/edit.c
> index 30448cbc04..592cf4aa3d 100644
> --- a/commands/edit.c
> +++ b/commands/edit.c
> @@ -522,6 +522,25 @@ static int read_modal_key(bool is_modal)
>  	return -EAGAIN;
>  }
>  
> +static bool is_efi_console_active(void)
> +{
> +	struct console_device *cdev;
> +
> +	if (!IS_ENABLED(CONFIG_DRIVER_SERIAL_EFI_STDIO))
> +		return false;
> +
> +	for_each_console(cdev) {
> +		if (!(cdev->f_active & CONSOLE_STDIN))
> +			continue;
> +		if (!(cdev->f_active & CONSOLE_STDOUT))
> +			continue;
> +		if (!strcmp(dev_name(cdev->dev), "efi-stdio"))
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
>  static int do_edit(int argc, char *argv[])
>  {
>  	bool is_vi = false;
> @@ -539,16 +558,7 @@ static int do_edit(int argc, char *argv[])
>  		return 1;
>  
>  	screenwidth = 80;
> -
> -	/*
> -	 * The EFI simple text output protocol wraps to the next line and scrolls
> -	 * down when we write to the right bottom screen position. Reduce the number
> -	 * of rows by one to work around this.
> -	 */
> -	if (IS_ENABLED(CONFIG_EFI_BOOTUP))
> -		screenheight = 24;
> -	else
> -		screenheight = 25;
> +	screenheight = 25;
>  
>  	/* check if we are not called as "edit" */
>  	if (*argv[0] != 'e') {
> @@ -560,6 +570,22 @@ static int do_edit(int argc, char *argv[])
>  			is_vi = true;
>  	}
>  
> +	if (is_efi_console_active()) {
> +		/*
> +		 * The EFI simple text output protocol wraps to the next line and
> +		 * scrolls down when we write to the right bottom screen position.
> +		 * Reduce the number of rows by one to work around this.
> +		 */
> +		screenheight--;
> +
> +		/*
> +		 * Our console driver for the EFI simple text output protocol does
> +		 * not implement the "\e[1S" sequence we use for scrolling the
> +		 * screen.
> +		 */
> +		smartscroll = 0;
> +	}
> +
>  	cursx  = 0;
>  	cursy  = 0;
>  	textx  = 0;
> -- 
> 2.30.2
> 
> 
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