Require exact integer values for sliders

Amolith created 3 days ago

Check integer range bounds, current values, and options as XML integer
text before parsing them as floats. Also require each parsed value to
round-trip to the same integer and reject no-option unit-step ranges
outside float's consecutive exact integer window.

Change summary

src/main/java/eu/siacs/conversations/entities/Conversation.java     | 22 
src/test/java/eu/siacs/conversations/entities/ConversationTest.java | 21 
2 files changed, 40 insertions(+), 3 deletions(-)

Detailed changes

src/main/java/eu/siacs/conversations/entities/Conversation.java

@@ -1878,14 +1878,14 @@ public class Conversation extends AbstractEntity
         final String minValue = range == null ? null : range.getAttribute("min");
         final String maxValue = range == null ? null : range.getAttribute("max");
         final boolean integerDatatype = isIntegerDatatype(datatype);
-        if (integerDatatype && (!isIntegerLexicalValue(minValue) || !isIntegerLexicalValue(maxValue))) return null;
+        if (integerDatatype && (!isExactIntegerSliderValue(minValue) || !isExactIntegerSliderValue(maxValue))) return null;
         final Float min = parseFloat(minValue);
         final Float max = parseFloat(maxValue);
         if (min == null || max == null || min >= max) return null;
 
         final String value = firstValue(field);
         if (value == null || value.equals("")) return null;
-        if (integerDatatype && !isIntegerLexicalValue(value)) return null;
+        if (integerDatatype && !isExactIntegerSliderValue(value)) return null;
         final Float parsedValue = parseFloat(value);
         if (parsedValue == null || parsedValue < min || parsedValue > max) return null;
 
@@ -1894,6 +1894,7 @@ public class Conversation extends AbstractEntity
 
         final Float step;
         if (options.size() < 2) {
+            if (integerDatatype && !isExactIntegerUnitRange(minValue, maxValue)) return null;
             step = integerDatatype ? 1f : 0f;
         } else {
             step = uniformStep(options);
@@ -1932,7 +1933,7 @@ public class Conversation extends AbstractEntity
         final List<Float> values = new ArrayList<>();
         for (final Option option : Option.forField(field)) {
             final String optionValue = option.getValue();
-            if (integerDatatype && !isIntegerLexicalValue(optionValue)) return null;
+            if (integerDatatype && !isExactIntegerSliderValue(optionValue)) return null;
             final Float value = parseFloat(optionValue);
             if (value == null) return null;
             values.add(value);
@@ -1968,6 +1969,21 @@ public class Conversation extends AbstractEntity
         return Math.abs(Math.rint(multiple) - multiple) < 0.0001f;
     }
 
+    private static boolean isExactIntegerSliderValue(final String value) {
+        if (!isIntegerLexicalValue(value)) return false;
+        final Float parsed = parseFloat(value);
+        return parsed != null
+                && new BigDecimal(Float.toString(parsed)).compareTo(new BigDecimal(value)) == 0;
+    }
+
+    private static boolean isExactIntegerUnitRange(final String minValue, final String maxValue) {
+        final BigDecimal min = new BigDecimal(minValue);
+        final BigDecimal max = new BigDecimal(maxValue);
+        final BigDecimal maxConsecutiveInteger = new BigDecimal("16777216");
+        return min.compareTo(maxConsecutiveInteger.negate()) >= 0
+                && max.compareTo(maxConsecutiveInteger) <= 0;
+    }
+
     private static boolean isIntegerLexicalValue(final String value) {
         if (value == null || value.equals("")) return false;
         final int start = value.charAt(0) == '+' || value.charAt(0) == '-' ? 1 : 0;

src/test/java/eu/siacs/conversations/entities/ConversationTest.java

@@ -241,6 +241,27 @@ public class ConversationTest {
         Assert.assertNull(Conversation.steppedSliderStep(field));
     }
 
+    @Test
+    public void steppedSliderStepRejectsFractionalIntegerValueAtFloatPrecisionBoundary() {
+        final var field = sliderField("xs:integer", "16777216", "16777218", "16777216.5");
+
+        Assert.assertNull(Conversation.steppedSliderStep(field));
+    }
+
+    @Test
+    public void steppedSliderStepRejectsIntegerValueRoundedByFloatParsing() {
+        final var field = sliderField("xs:integer", "16777216", "16777218", "16777217");
+
+        Assert.assertNull(Conversation.steppedSliderStep(field));
+    }
+
+    @Test
+    public void steppedSliderStepRejectsIntegerRangeWithUnrepresentableIntermediateValue() {
+        final var field = sliderField("xs:integer", "16777216", "16777218", "16777216");
+
+        Assert.assertNull(Conversation.steppedSliderStep(field));
+    }
+
     @Test
     public void formatSliderValueDoesNotClampLargeIntegerDatatypesToInt() {
         Assert.assertEquals("3000000000", Conversation.formatSliderValue(3_000_000_000f, "xs:long"));