console: consume APC, DM, DCS
The Linux console's VT102 implementation already consumes OSC ("Operating System Command") sequences, probably because that's how palette changes are transmitted. In addition to OSC, there are three other major clases of ANSI control strings: APC ("Application Program Command"), PM ("Privacy Message"), and DCS ("Device Control String"). They are handled similarly to OSC in terms of termination. Source: vt100.net Add three new enumerated states, one for each of these types. All three are handled the same way right now--they simply consume input until terminated. I hope to expand upon this firmament in the future. Add new predicate ansi_control_string(), returning true for any of these states. Replace explicit checks against ESosc with calls to this function. Transition to these states appropriately from the escape initiation (ESesc) state. This was motivated by the following Notcurses bugs: https://github.com/dankamongmen/notcurses/issues/2050 https://github.com/dankamongmen/notcurses/issues/1828 https://github.com/dankamongmen/notcurses/issues/2069 where standard VT sequences are not consumed by the Linux console. It's not necessary that the Linux console *support* these sequences, but it ought *consume* these well-specified classes of sequences. Tested by sending a variety of escape sequences to the console, and verifying that they still worked, or were now properly consumed. Verified that the escapes were properly terminated at a generic level. Verified that the Notcurses tools continued to show expected output on the Linux console, except now without escape bleedthrough. Link: https://lore.kernel.org/lkml/YSydL0q8iaUfkphg@schwarzgerat.orthanc/ Signed-off-by:nick black <dankamongmen@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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