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Date: Thu, 14 May 2009 09:20:17 +0200 (CEST)
From: Cedric Roux <sed@...e.fr>
To: linux-kernel@...r.kernel.org
Cc: Alan Cox <alan@...rguk.ukuu.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
mtk manpages <mtk.manpages@...il.com>,
linux-api@...r.kernel.org
Subject: Re: [PATCH] [try 3] vt: add ioctl commands to /dev/vcsaN to get/put
the current palette of the given tty
Hi,
I sent this patch a month ago and didn't get any reply.
Should I consider you dropped it and should I forget
about it or what?
I know you are busy, sorry to bother with this mini-stuff,
I just would like to know.
Best regards,
Cedric.
----- "Cedric Roux" <sed@...e.fr> wrote:
> From: Cedric Roux <sed@...e.fr>
>
> A ioctl interface and two ioctl commands added to /dev/vcsaN
> to get/put the current palette of the given tty.
>
> Signed-off-by: Cedric Roux <sed@...e.fr>
> ---
> This patch exists because there is no way to get the current
> installed palette of a given tty. The PIO_CMAP and GIO_CMAP
> in vt_ioctl.c:vt_ioctl play with the global default colormap.
> And /dev/vcsaN don't dump the palette through their read
> interface. And since a user may change colors of a given
> tty by escape sequences, one should be able to retrieve
> the palette through /dev/vcsaN, leading to this patch.
>
> Some points I am not fully confident with:
> - vt.c:set_colormap is now used in vc_screen.c so cannot be static
> anymore.
> The goal of this patch is to allow read access to the palette,
> I can remove the PIO_CMAP case and make set_colormap static again.
> This case is there because /dev/vcsaN is read/write so the access
> to the palette should also be read/write. (Or I can do it
> differently, no problem, just tell me how.)
> - the palette is returned as it is stored in the kernel, without
> taking into account color_table. So if a userland program
> gets an attribute for a given character, it won't match
> with the palette information. Say the user reads 0xXY through
> /dev/vcsa and takes Y as an index in the palette, it will return
> a bad color. One should do palette[color_table[Y]] to get the real
> color.
> Two "solutions" to this "problem" (it might be an non-issue):
> + export the palette by indexing with color_table:
> I don't like it.
> + let the userland program deal with that:
> the program may open a tty, send escape sequences to
> set the current color, write a character at a given position
> (through the tty, not /dev/vcs) and read back the attribute
> through /dev/vcsa this time. She will see what attribute
> corresponds to what color she sets by using escape sequences.
> If the color_table is non-mutable, all this is a non-issue.
> Userland programs just store the color_table and live with that.
> I've seen no code that modifies the color_table, so I bet it's
> non-mutable. (May it change in the future?)
> - lock_kernel() is called. Maybe it's not necessary? I'm not
> confident enough. You decide.
>
> diff -uprN -X linux-2.6.29.1/Documentation/dontdiff
> linux-2.6.29.1-vanilla/drivers/char/vc_screen.c
> linux-2.6.29.1/drivers/char/vc_screen.c
> --- linux-2.6.29.1-vanilla/drivers/char/vc_screen.c 2009-04-02
> 22:55:27.000000000 +0200
> +++ linux-2.6.29.1/drivers/char/vc_screen.c 2009-04-14
> 10:16:33.000000000 +0200
> @@ -19,6 +19,8 @@
> * machek@...2.feld.cvut.cz - modified not to send characters to
> wrong console
> * - fixed some fatal off-by-one bugs (0-- no longer == -1 ->
> looping and looping and looping...)
> * - making it shorter - scr_readw are macros which expand in PRETTY
> long code
> + *
> + * Colormap put/get for /dev/vcsaN, Cedric Roux <sed@...e.fr>, March
> 2009.
> */
>
> #include <linux/kernel.h>
> @@ -470,11 +472,67 @@ vcs_open(struct inode *inode, struct fil
> return ret;
> }
>
> +static long
> +vcs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> +{
> + unsigned int currcons = iminor(file->f_path.dentry->d_inode);
> + struct vc_data *vc;
> + unsigned char pal[16*3];
> + long ret = 0;
> +
> + /* access only defined for /dev/vcsaN, not /dev/vcsN */
> + if (currcons < 128)
> + return -ENOTTY;
> +
> + lock_kernel();
> +
> + acquire_console_sem();
> +
> + currcons &= 127;
> + if (currcons == 0)
> + currcons = fg_console;
> + else
> + currcons--;
> + if (!vc_cons_allocated(currcons)) {
> + ret = -ENXIO;
> + goto unlock_out;
> + }
> + vc = vc_cons[currcons].d;
> +
> + switch (cmd) {
> + case PIO_CMAP:
> + if (copy_from_user(pal, (void __user *)arg, 16*3)) {
> + ret = -EFAULT;
> + goto unlock_out;
> + }
> + memcpy(vc->vc_palette, pal, 16*3);
> + set_palette(vc);
> + break;
> + case GIO_CMAP:
> + if (copy_to_user((void __user *)arg, vc->vc_palette, 16*3)) {
> + ret = -EFAULT;
> + goto unlock_out;
> + }
> + break;
> + default:
> + ret = -ENOIOCTLCMD;
> + break;
> + }
> +
> +unlock_out:
> + release_console_sem();
> +
> + unlock_kernel();
> +
> + return ret;
> +}
> +
> static const struct file_operations vcs_fops = {
> .llseek = vcs_lseek,
> .read = vcs_read,
> .write = vcs_write,
> .open = vcs_open,
> + .unlocked_ioctl = vcs_ioctl,
> };
>
> static struct class *vc_class;
> diff -uprN -X linux-2.6.29.1/Documentation/dontdiff
> linux-2.6.29.1-vanilla/drivers/char/vt.c
> linux-2.6.29.1/drivers/char/vt.c
> --- linux-2.6.29.1-vanilla/drivers/char/vt.c 2009-04-02
> 22:55:27.000000000 +0200
> +++ linux-2.6.29.1/drivers/char/vt.c 2009-04-14 10:17:20.000000000
> +0200
> @@ -156,7 +156,6 @@ static void set_cursor(struct vc_data *v
> static void hide_cursor(struct vc_data *vc);
> static void console_callback(struct work_struct *ignored);
> static void blank_screen_t(unsigned long dummy);
> -static void set_palette(struct vc_data *vc);
>
> static int printable; /* Is console ready for printing? */
> int default_utf8 = true;
> @@ -3753,7 +3752,7 @@ void poke_blanked_console(void)
> * Palettes
> */
>
> -static void set_palette(struct vc_data *vc)
> +void set_palette(struct vc_data *vc)
> {
> WARN_CONSOLE_UNLOCKED();
>
> diff -uprN -X linux-2.6.29.1/Documentation/dontdiff
> linux-2.6.29.1-vanilla/include/linux/vt_kern.h
> linux-2.6.29.1/include/linux/vt_kern.h
> --- linux-2.6.29.1-vanilla/include/linux/vt_kern.h 2009-04-02
> 22:55:27.000000000 +0200
> +++ linux-2.6.29.1/include/linux/vt_kern.h 2009-04-14
> 10:17:59.000000000 +0200
> @@ -97,6 +97,7 @@ void reset_vc(struct vc_data *vc);
> extern int unbind_con_driver(const struct consw *csw, int first, int
> last,
> int deflt);
> int vty_init(const struct file_operations *console_fops);
> +void set_palette(struct vc_data *vc);
>
> /*
> * vc_screen.c shares this temporary buffer with the console write
> code so that
--
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