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Handle CSI intermediate bytes instead of printing the final byte #3

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Handle CSI intermediate bytes instead of printing the final byte #3

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8 changes: 7 additions & 1 deletion src/lib/vterm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -267,7 +267,12 @@ class VTerm {
ESdcs = 8,
EStermcap = 9,
ESst = 10,
ESkeep = 11
EScsiInter = 11,
// ESkeep is a sentinel meaning "leave the state unchanged", not a state
// of its own. NR_STATES is defined as its value and sizes escape_map[],
// and init_state() stops walking escape_sequences[] once the section
// counter reaches it. It must therefore stay last: add new states above.
ESkeep = 12
} EscapeState;

static inline const char* EscapeStateToString(EscapeState state) {
Expand All @@ -283,6 +288,7 @@ class VTerm {
case ESdcs: return "DCS";
case EStermcap: return "DCS + q";
case ESst: return "ST";
case EScsiInter: return "CSI + intermediate";
case ESkeep: return "<previous>";
}

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29 changes: 24 additions & 5 deletions src/lib/vterm_states.cpp
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Expand Up @@ -79,6 +79,13 @@ const VTerm::Sequence VTerm::escape_sequences[] = {
{ CSPAN('0', '9'), &VTerm::param_digit, ESkeep },
{ ';', &VTerm::next_param, ESkeep },
{ ':', &VTerm::next_param, ESkeep }, // some codes use ':' instead of ';' as the argument separator
// ECMA-48 5.4 defines a control sequence as "CSI P...P I...I F", where the
// Intermediate Bytes I (02/00 to 02/15) "together with the Final Byte F
// identify the control function". They therefore cannot be skipped: e.g.
// "CSI 2 SP q" (DECSCUSR) is a different function from "CSI 2 q" (DECLL).
// Track them in a separate state so the final byte is consumed as part of
// the sequence instead of falling through and being printed as text.
{ CSPAN(' ', '/'), nullptr, EScsiInter },
{ '@', &VTerm::insert_char, ESnormal },
{ 'A', &VTerm::cursor_up, ESnormal },
{ 'B', &VTerm::cursor_down, ESnormal },
Expand Down Expand Up @@ -112,7 +119,6 @@ const VTerm::Sequence VTerm::escape_sequences[] = {
{ '`', &VTerm::cursor_position_col, ESnormal },
{ ']', &VTerm::linux_specific, ESnormal },
{ '}', &VTerm::fbterm_specific, ESnormal },
{ '%', 0, ESkeep }, // this is a workaround for the wierd, undocumented code "\e[0%m" - otherwise the trailing 'm' gets printed
ENDSEQ,

// ESosc #3 "ESC ]"
Expand Down Expand Up @@ -151,27 +157,40 @@ const VTerm::Sequence VTerm::escape_sequences[] = {
{ '9', &VTerm::screen_clear, ESnormal },
ENDSEQ,

// ESgreater #8 "ESC [ >"
// ESgreater #7 "ESC [ >"
{ CSPAN('0', '9'), &VTerm::param_digit, ESkeep },
{ ';', &VTerm::next_param, ESkeep },
{ 'c', &VTerm::get_device_attribute, ESnormal }, // Send Device Attributes (Secondary DA)
{ 'm', &VTerm::set_key_modifier, ESnormal }, // Set/reset key modifier options
ENDSEQ,

// ESdcs #9 "ESC P"
// ESdcs #8 "ESC P"
{ '+', nullptr, ESkeep },
{ 'q', nullptr, EStermcap },
ENDSEQ,

// EStermcap #10 "ESC P + q"
// EStermcap #9 "ESC P + q"
{ CSPAN('0', '9'), &VTerm::param_hex_digit, ESkeep },
{ CSPAN('a', 'f'), &VTerm::param_hex_digit, ESkeep },
{ CSPAN('A', 'F'), &VTerm::param_hex_digit, ESkeep },
{ 0x1B, &VTerm::request_termcap, ESst },
ENDSEQ,

// ESst #11
// ESst #10
{ '\\', nullptr, ESnormal },
ENDSEQ,

// EScsiInter #11 "CSI ... I" where I is an intermediate byte (0x20-0x2F)
// Sequences reaching this state are not implemented by fbterm. Consume the
// remaining intermediate bytes and the final byte so that nothing is printed.
{ CSPAN(' ', '/'), nullptr, ESkeep },
{ CSPAN('@', '~'), nullptr, ESnormal },
// Exception: the undocumented "\e[0%m" is emitted by some applications and
// was previously handled by keeping '%' in EScsi so that the trailing 'm'
// reached the SGR entry. ECMA-48 assigns no function to an intermediate
// byte followed by 06/13, so treating it as SGR here does not shadow a
// standard sequence.
{ 'm', &VTerm::set_display_attr, ESnormal },
ENDSEQ

};