KFuzzerImpl fix

kotlinx.fuzz.api/src/main/kotlin/kotlinx/fuzz/KFuzzer.kt

@@ -246,20 +246,20 @@ interface KFuzzer {
      * insufficiently long. In this case it will be shorter.
      *
      * @param maxLength the maximum length of the array
-     * @param range denotes desired range for each value. Should be a subset of [Float.MIN_VALUE, Float.MAX_VALUE].
-     * [Float.MIN_VALUE, Float.MAX_VALUE] by default.
+     * @param range denotes desired range for each value. Should be a subset of [-Float.MAX_VALUE, Float.MAX_VALUE].
+     * [-Float.MAX_VALUE, Float.MAX_VALUE] by default.
      * @return nullable float array that has each value in given range
      */
-    fun floatsOrNull(maxLength: Int, range: FloatRange = Float.MIN_VALUE..Float.MAX_VALUE): FloatArray?
+    fun floatsOrNull(maxLength: Int, range: FloatRange = -Float.MAX_VALUE..Float.MAX_VALUE): FloatArray?
 
     /**
      * Consumes a not null double from the fuzzer input.
      *
-     * @param range denotes desired range for resulting value. Should be a subset of [Double.MIN_VALUE, Double.MAX_VALUE].
-     * [Double.MIN_VALUE, Double.MAX_VALUE] by default.
+     * @param range denotes desired range for resulting value. Should be a subset of [-Double.MAX_VALUE, Double.MAX_VALUE].
+     * [-Double.MAX_VALUE, Double.MAX_VALUE] by default.
      * @return double that has value in the given range
      */
-    fun double(range: DoubleRange = Double.MIN_VALUE..Double.MAX_VALUE): Double
+    fun double(range: DoubleRange = -Double.MAX_VALUE..Double.MAX_VALUE): Double
 
     /**
      * Consumes a nullable double from the fuzzer input.

kotlinx.fuzz.engine/src/main/kotlin/kotlinx/fuzz/KFuzzerImpl.kt

@@ -62,20 +62,49 @@ class KFuzzerImpl(data: ByteArray) : KFuzzer, Random() {
         }
     }
 
-    private fun fitIntoRange(
-        value: BigDecimal,
-        oldMin: BigDecimal,
-        oldMax: BigDecimal,
-        newMin: BigDecimal,
-        newMax: BigDecimal,
-    ): BigDecimal {
-        val normalized = value.subtract(oldMin, MathContext.DECIMAL128)
-            .divide(oldMax.subtract(oldMin, MathContext.DECIMAL128), MathContext.DECIMAL128)
-
-        return newMin.add(
-            normalized.multiply(newMax.subtract(newMin, MathContext.DECIMAL128), MathContext.DECIMAL128),
-            MathContext.DECIMAL128,
-        )
+    private inline fun<reified T : Comparable<T>> fitIntoRange(
+        value: T,
+        newRange: ClosedFloatingPointRange<T>,
+        context: MathContext = MathContext.DECIMAL128,
+    ): T {
+        when (value) {
+            is Float -> if (value.isInfinite() || value.isNaN()) {
+                return value
+            }
+            is Double -> if (value.isInfinite() || value.isNaN()) {
+                return value
+            }
+        }
+
+        val bigDecimalValue = when (value) {
+            is Float -> value.toBigDecimal()
+            is Double -> value.toBigDecimal()
+            else -> error("Not float type")
+        }
+
+        val oldUpperBound = when (T::class) {
+            Float::class -> Float.MAX_VALUE.toBigDecimal()
+            else -> Double.MAX_VALUE.toBigDecimal()
+        }
+
+        val normalized = bigDecimalValue.add(oldUpperBound, context).divide(oldUpperBound.multiply(BigDecimal(2), context), context)
+
+        val newLowerBound = when (T::class) {
+            Float::class -> (newRange.start as Float).toBigDecimal()
+            else -> (newRange.start as Double).toBigDecimal()
+        }
+
+        val newUpperBound = when (T::class) {
+            Float::class -> (newRange.endInclusive as Float).toBigDecimal()
+            else -> (newRange.endInclusive as Double).toBigDecimal()
+        }
+
+        val result = newLowerBound.add(normalized.multiply(newUpperBound.subtract(newLowerBound, context), context), context)
+
+        return when (T::class) {
+            Float::class -> result.toFloat() as T
+            else -> result.toDouble() as T
+        }
     }
 
     /**
@@ -258,14 +287,7 @@ class KFuzzerImpl(data: ByteArray) : KFuzzer, Random() {
 
     override fun float(range: FloatRange): Float {
         require(range.isNotEmpty()) { "range is empty" }
-
-        return fitIntoRange(
-            iterator.readFloat().toBigDecimal(),
-            Float.MIN_VALUE.toBigDecimal(),
-            Float.MAX_VALUE.toBigDecimal(),
-            range.start.toBigDecimal(),
-            range.endInclusive.toBigDecimal(),
-        ).toFloat()
+        return fitIntoRange(iterator.readFloat(), range)
     }
 
     override fun floatOrNull(range: FloatRange): Float? {
@@ -298,14 +320,7 @@ class KFuzzerImpl(data: ByteArray) : KFuzzer, Random() {
 
     override fun double(range: DoubleRange): Double {
         require(range.isNotEmpty()) { "range is empty" }
-
-        return fitIntoRange(
-            iterator.readDouble().toBigDecimal(),
-            Double.MIN_VALUE.toBigDecimal(),
-            Double.MAX_VALUE.toBigDecimal(),
-            range.start.toBigDecimal(),
-            range.endInclusive.toBigDecimal(),
-        ).toDouble()
+        return fitIntoRange(iterator.readDouble(), range)
     }
 
     override fun doubleOrNull(range: DoubleRange): Double? {