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Fixed: fully consume unknown CSI sequences containing non-numeric parameter byte #4417

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Merged
agnostic-apollo merged 1 commit into from
Mar 15, 2025
Merged

Fixed: fully consume unknown CSI sequences containing non-numeric parameter byte #4417

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47 changes: 45 additions & 2 deletions terminal-emulator/src/main/java/com/termux/terminal/TerminalEmulator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,10 @@ public final class TerminalEmulator {
private static final int ESC_APC = 20;
/** Escape processing: "ESC _" or Application Program Command (APC), followed by Escape. */
private static final int ESC_APC_ESCAPE = 21;
/** Escape processing: ESC [ <parameter bytes> */
private static final int ESC_CSI_UNSUPPORTED_PARAMETER_BYTE = 22;
/** Escape processing: ESC [ <parameter bytes> <intermediate bytes> */
private static final int ESC_CSI_UNSUPPORTED_INTERMEDIATE_BYTE = 23;

/** The number of parameter arguments including colon separated sub-parameters. */
private static final int MAX_ESCAPE_PARAMETERS = 32;
Expand Down Expand Up @@ -658,6 +662,10 @@ public void processCodePoint(int b) {
case ESC_CSI:
doCsi(b);
break;
case ESC_CSI_UNSUPPORTED_PARAMETER_BYTE:
case ESC_CSI_UNSUPPORTED_INTERMEDIATE_BYTE:
doCsiUnsupportedParameterOrIntermediateByte(b);
break;
case ESC_CSI_EXCLAMATION:
if (b == 'p') { // Soft terminal reset (DECSTR, http://vt100.net/docs/vt510-rm/DECSTR).
reset();
Expand Down Expand Up @@ -1059,6 +1067,37 @@ private int nextTabStop(int numTabs) {
return mRightMargin - 1;
}

/**
* Process byte while in the {@link #ESC_CSI_UNSUPPORTED_PARAMETER_BYTE} or
* {@link #ESC_CSI_UNSUPPORTED_INTERMEDIATE_BYTE} escape state.
*
* Parse unsupported parameter, intermediate and final bytes but ignore them.
*
* > For Control Sequence Introducer, ... the ESC [ is followed by
* > - any number (including none) of "parameter bytes" in the range 0x30–0x3F (ASCII 0–9:;<=>?),
* > - then by any number of "intermediate bytes" in the range 0x20–0x2F (ASCII space and !"#$%&'()*+,-./),
* > - then finally by a single "final byte" in the range 0x40–0x7E (ASCII @A–Z[\]^_`a–z{|}~).
*
* - https://en.wikipedia.org/wiki/ANSI_escape_code#Control_Sequence_Introducer_commands
* - https://invisible-island.net/xterm/ecma-48-parameter-format.html#section5.4
*/
private void doCsiUnsupportedParameterOrIntermediateByte(int b) {
if (mEscapeState == ESC_CSI_UNSUPPORTED_PARAMETER_BYTE && b >= 0x30 && b <= 0x3F) {
// Supported `0–9:;>?` or unsupported `<=` parameter byte after an
// initial unsupported parameter byte in `doCsi()`, or a sequential parameter byte.
continueSequence(ESC_CSI_UNSUPPORTED_PARAMETER_BYTE);
} else if (b >= 0x20 && b <= 0x2F) {
// Optional intermediate byte `!"#$%&'()*+,-./` after parameter or intermediate byte.
continueSequence(ESC_CSI_UNSUPPORTED_INTERMEDIATE_BYTE);
} else if (b >= 0x40 && b <= 0x7E) {
// Final byte `@A–Z[\]^_`a–z{|}~` after parameter or intermediate byte.
// Calling `unknownSequence()` would log an error with only a final byte, so ignore it for now.
finishSequence();
} else {
unknownSequence(b);
}
}

/** Process byte while in the {@link #ESC_CSI_QUESTIONMARK} escape state. */
private void doCsiQuestionMark(int b) {
switch (b) {
Expand Down Expand Up @@ -1656,12 +1695,16 @@ private void doCsi(int b) {
}
mCursorCol = newCol;
break;
case '?': // Esc [ ? -- start of a private mode set
case '?': // Esc [ ? -- start of a private parameter byte
continueSequence(ESC_CSI_QUESTIONMARK);
break;
case '>': // "Esc [ >" --
case '>': // "Esc [ >" -- start of a private parameter byte
continueSequence(ESC_CSI_BIGGERTHAN);
break;
case '<': // "Esc [ <" -- start of a private parameter byte
case '=': // "Esc [ =" -- start of a private parameter byte
continueSequence(ESC_CSI_UNSUPPORTED_PARAMETER_BYTE);
break;
case '`': // Horizontal position absolute (HPA - http://www.vt100.net/docs/vt510-rm/HPA).
setCursorColRespectingOriginMode(getArg0(1) - 1);
break;
Expand Down
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