Fix crash in state restoration with multiple of 32 fields (#707)

* If the field cound was exactly multiples of 32 the bitmap count would be be too high (e.g. 2 with field count 32 and 3 with field count 64) leading to a crash when calling the copyt function via reflection.

Added test that tests that case.

* Use ceil to calculate bitmap size.

---------

Co-authored-by: Andreas Rossbacher <andreas.rossbacher@airbnb.com>

mvrx/src/main/kotlin/com/airbnb/mvrx/PersistState.kt

@@ -7,6 +7,7 @@ import android.os.Parcelable
 import java.io.Serializable
 import java.lang.reflect.Constructor
 import java.lang.reflect.Method
+import kotlin.math.ceil
 
 /**
  * Annotate a field in your [MavericksViewModel] state with [PersistState] to have it automatically persisted when Android kills your process
@@ -128,7 +129,7 @@ fun <T : MavericksState> restorePersistedMavericksState(
     val fieldCount = constructor.parameterTypes.size
 
     // There is 1 bitmask for each block of 32 parameters.
-    val parameterBitMasks = IntArray(fieldCount / 32 + 1) { 0 }
+    val parameterBitMasks = IntArray(ceil(fieldCount / 32.0).toInt())
     val parameters = arrayOfNulls<Any?>(fieldCount)
     parameters[0] = initialState
     for (i in 0 until fieldCount) {

mvrx/src/test/kotlin/com/airbnb/mvrx/PersistedStateTest.kt

@@ -238,6 +238,58 @@ class PersistedStateTest : BaseTest() {
         persistMavericksState(State())
     }
 
+    @Test
+    fun testClassWithExactly32Parameters() {
+        data class StateWith32Params(
+            val p0: Int = 0,
+            @PersistState val p1: Int = 0,
+            val p2: Int = 0,
+            @PersistState val p3: Int = 0,
+            val p4: Int = 0,
+            @PersistState val p5: Int = 0,
+            val p6: Int = 0,
+            @PersistState val p7: Int = 0,
+            val p8: Int = 0,
+            @PersistState val p9: Int = 0,
+            val p10: Int = 0,
+            @PersistState val p11: Int = 0,
+            val p12: Int = 0,
+            @PersistState val p13: Int = 0,
+            val p14: Int = 0,
+            @PersistState val p15: Int = 0,
+            val p16: Int = 0,
+            @PersistState val p17: Int = 0,
+            val p18: Int = 0,
+            @PersistState val p19: Int = 0,
+            val p20: Int = 0,
+            @PersistState val p21: Int = 0,
+            val p22: Int = 0,
+            @PersistState val p23: Int = 0,
+            val p24: Int = 0,
+            @PersistState val p25: Int = 0,
+            val p26: Int = 0,
+            @PersistState val p27: Int = 0,
+            val p28: Int = 0,
+            @PersistState val p29: Int = 0,
+            val p30: Int = 0,
+            @PersistState val p31: Int = 0,
+        ) : MavericksState
+
+        val bundle = persistMavericksState(
+            StateWith32Params(
+                p0 = 1,
+                p1 = 2,
+                p30 = 0,
+                p31 = 17,
+            )
+        )
+        val newState = restorePersistedMavericksState(bundle, StateWith32Params())
+        assertEquals(2, newState.p1)
+        assertEquals(17, newState.p31)
+        assertEquals(0, newState.p30)
+        assertEquals(17, newState.p31)
+    }
+
     @Test
     fun testClassWithMoreThan32Parameters() {
         data class StateWithLotsOfParameters(