[BRLTTY] can't read screen content

[Samuel Thibault]

Samuel Thibault, le dim. 24 mai 2026 16:40:09 +0200, a ecrit:
> Dave Mielke, le dim. 24 mai 2026 10:26:02 -0400, a ecrit:
> > [quoted lines by Samuel Thibault on 2026/05/24 at 16:22 +0200]
> > 
> > >On printing \033%@ on debian 13 with a 6.12.63 kernel, I indeed get this
> > >on cat-ing /dev/vcsu1:
> > >
> > >openat(AT_FDCWD, "vcsu1", O_RDONLY)
> > >read(0, 0x12341234, 4096) = -1 ENODATA (No data available)
> > >
> > >so the read fails, thus why brltty fails to read the screen. It should
> > >catch such error and fall back to using /dev/vcsa.
> > 
> > Yes, it already does that.
> 
> In my tests it doesn't.

More precisely, we get:

brltty: truncated unicode data: expected 852 bytes but only read 0
brltty: short unicode read: expected 56232 bytes but read 0
brltty: cache refresh failed

and thus refreshState == REFRESH_FAILED and thus 
problemText = gettext("can't read screen content");

Samuel