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Commit 64751001 authored by Hans Boehm's avatar Hans Boehm
Browse files

Deal with small displays and a cancellation race 

Bug: 34824406
Bug: 34949414

Check for unreasonably small display sizes and avoid crashing.

Incomplete fix for a cancellation race in which we write the expression
value back after the evaluation has been cancelled, and possibly
replaced.

Test: Some experiments with manually setting maxChars in redisplay().
Normal unit tests.

Change-Id: I7e11043eb5999bf373d66cc827de83024ef217f0
parent 615b4119

src/com/android/calculator2/CalculatorResult.java

+9 −1
Original line number Diff line number Diff line
@@ -745,6 +745,10 @@ public class CalculatorResult extends AlignedTextView implements MenuItem.OnMenu 
                        ++exponent;

                    }

                }

                if (dropDigits >= result.length() - 1) {

                    // Display too small to show meaningful result.

                    return KeyMaps.ELLIPSIS + "E" + KeyMaps.ELLIPSIS;

                }

                result = result.substring(0, result.length() - dropDigits);

                if (lastDisplayedOffset != null) {

                    lastDisplayedOffset[0] -= dropDigits;
@@ -919,11 +923,15 @@ public class CalculatorResult extends AlignedTextView implements MenuItem.OnMenu 
    }



    public void redisplay() {

        int maxChars = getMaxChars();

        if (maxChars < 4) {

            // Display currently too small to display a reasonable result. Punt to avoid crash.

            return;

        }

        if (mScroller.isFinished() && length() > 0) {

            setAccessibilityLiveRegion(ACCESSIBILITY_LIVE_REGION_POLITE);

        }

        int currentCharOffset = getCharOffset(mCurrentPos);

        int maxChars = getMaxChars();

        int lastDisplayedOffset[] = new int[1];

        String result = getFormattedResult(currentCharOffset, maxChars, lastDisplayedOffset,

                mAppendExponent /* forcePrecision; preserve entire result */,

src/com/android/calculator2/Evaluator.java

+4 −0
Original line number Diff line number Diff line
@@ -574,6 +574,10 @@ public class Evaluator implements CalculatorExpr.ExprResolver { 
                if (res == null) {

                    try {

                        res = mExprInfo.mExpr.eval(mDm, Evaluator.this);

                        if (isCancelled()) {

                            // TODO: This remains very slightly racey. Fix this.

                            throw new CR.AbortedException();

                        }

                        res = putResultIfAbsent(mIndex, res);

                    } catch (StackOverflowError e) {

                        // Absurdly large integer exponents can cause this. There might be other