Fixed: Fix CSI parameters parsing like for SGR sequences that start w…

…ith a `;` or have sequential `;` characters

https://vt100.net/docs/vt510-rm/chapter4.html#S4.3.3

https://en.wikipedia.org/wiki/ANSI_escape_code#CSI_(Control_Sequence_Introducer)_sequences

Credits for finding the issue belongs to @Screwtapello

mawww/kakoune#4339 (comment)

Closes #2272, Closes mawww/kakoune#4339

terminal-emulator/src/main/java/com/termux/terminal/TerminalEmulator.java

@@ -126,6 +126,10 @@ public final class TerminalEmulator {
  private String mTitle;
  private final Stack<String> mTitleStack = new Stack<>();
 
+ /** If processing first character of first parameter of {@link #ESC_CSI}. */
+ private boolean mIsCSIStart;
+ /** The last character processed of a parameter of {@link #ESC_CSI}. */
+ private Integer mLastCSIArg;
 
  /** The cursor position. Between (0,0) and (mRows-1, mColumns-1). */
  private int mCursorRow, mCursorCol;
@@ -1386,6 +1390,8 @@ private void doEsc(int b) {
  break;
  case '[':
  continueSequence(ESC_CSI);
+ mIsCSIStart = true;
+ mLastCSIArg = null;
  break;
  case '=': // DECKPAM
  setDecsetinternalBit(DECSET_BIT_APPLICATION_KEYPAD, true);
@@ -2093,28 +2099,55 @@ private void scrollDownOneLine() {
  }
  }
 
- /** Process the next ASCII character of a parameter. */
- private void parseArg(int b) {
- if (b >= '0' && b <= '9') {
- if (mArgIndex < mArgs.length) {
- int oldValue = mArgs[mArgIndex];
- int thisDigit = b - '0';
- int value;
- if (oldValue >= 0) {
- value = oldValue * 10 + thisDigit;
- } else {
- value = thisDigit;
- }
- mArgs[mArgIndex] = value;
+ /**
+ * Process the next ASCII character of a parameter.
+ *
+ * Parameter characters modify the action or interpretation of the sequence. You can use up to
+ * 16 parameters per sequence. You must use the ; character to separate parameters.
+ * All parameters are unsigned, positive decimal integers, with the most significant
+ * digit sent first. Any parameter greater than 9999 (decimal) is set to 9999
+ * (decimal). If you do not specify a value, a 0 value is assumed. A 0 value
+ * or omitted parameter indicates a default value for the sequence. For most
+ * sequences, the default value is 1.
+ *
+ * https://vt100.net/docs/vt510-rm/chapter4.html#S4.3.3
+ * */
+ private void parseArg(int inputByte) {
+ int[] bytes = new int[]{inputByte};
+ // Only doing this for ESC_CSI and not for other ESC_CSI_* since they seem to be using their
+ // own defaults with getArg*() calls, but there may be missed cases
+ if (mEscapeState == ESC_CSI) {
+ if ((mIsCSIStart && inputByte == ';') || // If sequence starts with a ; character, like \033[;m
+ (!mIsCSIStart && mLastCSIArg != null && mLastCSIArg == ';' && inputByte == ';')) { // If sequence contains sequential ; characters, like \033[;;m
+ bytes = new int[]{'0', ';'}; // Assume 0 was passed
  }
- continueSequence(mEscapeState);
- } else if (b == ';') {
- if (mArgIndex < mArgs.length) {
- mArgIndex++;
+ }
+
+ mIsCSIStart = false;
+
+ for (int b : bytes) {
+ if (b >= '0' && b <= '9') {
+ if (mArgIndex < mArgs.length) {
+ int oldValue = mArgs[mArgIndex];
+ int thisDigit = b - '0';
+ int value;
+ if (oldValue >= 0) {
+ value = oldValue * 10 + thisDigit;
+ } else {
+ value = thisDigit;
+ }
+ mArgs[mArgIndex] = value;
+ }
+ continueSequence(mEscapeState);
+ } else if (b == ';') {
+ if (mArgIndex < mArgs.length) {
+ mArgIndex++;
+ }
+ continueSequence(mEscapeState);
+ } else {
+ unknownSequence(b);
  }
- continueSequence(mEscapeState);
- } else {
- unknownSequence(b);
+ mLastCSIArg = b;
  }
  }
 

terminal-emulator/src/test/java/com/termux/terminal/TerminalTest.java

@@ -151,6 +151,19 @@ public void testSelectGraphics() {
  assertEquals(TextStyle.COLOR_INDEX_FOREGROUND, mTerminal.mForeColor);
  assertEquals(TextStyle.COLOR_INDEX_BACKGROUND, mTerminal.mBackColor);
 
+ // Test CSI resetting to default if sequence starts with ; or has sequential ;;
+ // Check TerminalEmulator.parseArg()
+ enterString("\033[31m\033[m");
+ assertEquals(TextStyle.COLOR_INDEX_FOREGROUND, mTerminal.mForeColor);
+ enterString("\033[31m\033[;m");
+ assertEquals(TextStyle.COLOR_INDEX_FOREGROUND, mTerminal.mForeColor);
+ enterString("\033[31m\033[0m");
+ assertEquals(TextStyle.COLOR_INDEX_FOREGROUND, mTerminal.mForeColor);
+ enterString("\033[31m\033[0;m");
+ assertEquals(TextStyle.COLOR_INDEX_FOREGROUND, mTerminal.mForeColor);
+ enterString("\033[31;;m");
+ assertEquals(TextStyle.COLOR_INDEX_FOREGROUND, mTerminal.mForeColor);
+
  // 256 colors:
  enterString("\033[38;5;119m");
  assertEquals(119, mTerminal.mForeColor);