Fix Iterable, Sequence and String index overflow in windowed

libraries/stdlib/common/src/generated/_Collections.kt

@@ -2160,7 +2160,7 @@ public fun <T> Iterable<T>.windowed(size: Int, step: Int = 1, partialWindows: Bo
         val resultCapacity = thisSize / step + if (thisSize % step == 0) 0 else 1
         val result = ArrayList<List<T>>(resultCapacity)
         var index = 0
-        while (index < thisSize) {
+        while (index in 0 until thisSize) {
             val windowSize = size.coerceAtMost(thisSize - index)
             if (windowSize < size && !partialWindows) break
             result.add(List(windowSize) { this[it + index] })
@@ -2197,12 +2197,14 @@ public fun <T, R> Iterable<T>.windowed(size: Int, step: Int = 1, partialWindows:
     checkWindowSizeStep(size, step)
     if (this is RandomAccess && this is List) {
         val thisSize = this.size
-        val result = ArrayList<R>((thisSize + step - 1) / step)
+        val resultCapacity = thisSize / step + if (thisSize % step == 0) 0 else 1
+        val result = ArrayList<R>(resultCapacity)
         val window = MovingSubList(this)
         var index = 0
-        while (index < thisSize) {
+        while (index in 0 until thisSize) {
-            window.move(index, (index + size).coerceAtMost(thisSize))
+            val windowSize = size.coerceAtMost(thisSize - index)
-            if (!partialWindows && window.size < size) break
+            if (!partialWindows && windowSize < size) break
+            window.move(index, index + windowSize)
             result.add(transform(window))
             index += step
         }

libraries/stdlib/common/src/generated/_Strings.kt

@@ -1377,9 +1377,9 @@ public fun <R> CharSequence.windowed(size: Int, step: Int = 1, partialWindows: B
     val resultCapacity = thisSize / step + if (thisSize % step == 0) 0 else 1
     val result = ArrayList<R>(resultCapacity)
     var index = 0
-    while (index < thisSize) {
+    while (index in 0 until thisSize) {
         val end = index + size
-        val coercedEnd = if (end > thisSize) { if (partialWindows) thisSize else break } else end
+        val coercedEnd = if (end < 0 || end > thisSize) { if (partialWindows) thisSize else break } else end
         result.add(transform(subSequence(index, coercedEnd)))
         index += step
     }
@@ -1427,7 +1427,11 @@ public fun CharSequence.windowedSequence(size: Int, step: Int = 1, partialWindow
 public fun <R> CharSequence.windowedSequence(size: Int, step: Int = 1, partialWindows: Boolean = false, transform: (CharSequence) -> R): Sequence<R> {
     checkWindowSizeStep(size, step)
     val windows = (if (partialWindows) indices else 0 until length - size + 1) step step
-    return windows.asSequence().map { index -> transform(subSequence(index, (index + size).coerceAtMost(length))) }
+    return windows.asSequence().map { index ->
+        val end = index + size
+        val coercedEnd = if (end < 0 || end > length) length else end
+        transform(subSequence(index, coercedEnd))
+    }
 }
 
 /**

libraries/stdlib/test/collections/IterableTests.kt

@@ -199,6 +199,24 @@ abstract class OrderedIterableTests<T : Iterable<String>>(createFrom: (Array<out
             assertFailsWith<IllegalArgumentException>("size $illegalValue") { data.windowed(illegalValue, 1) }
             assertFailsWith<IllegalArgumentException>("step $illegalValue") { data.windowed(1, illegalValue) }
         }
+
+        // index overflow tests
+        for (partialWindows in listOf(true, false)) {
+
+            val windowed1 = data.windowed(5, Int.MAX_VALUE, partialWindows)
+            assertEquals(data.take(5), windowed1.single())
+            val windowed2 = data.windowed(Int.MAX_VALUE, 5, partialWindows)
+            assertEquals(if (partialWindows) listOf(data.toList(), listOf("5", "6")) else listOf(), windowed2)
+            val windowed3 = data.windowed(Int.MAX_VALUE, Int.MAX_VALUE, partialWindows)
+            assertEquals(if (partialWindows) listOf(data.toList()) else listOf(), windowed3)
+
+            val windowedTransform1 = data.windowed(5, Int.MAX_VALUE, partialWindows) { it.joinToString("") }
+            assertEquals("01234", windowedTransform1.single())
+            val windowedTransform2 = data.windowed(Int.MAX_VALUE, 5, partialWindows) { it.joinToString("") }
+            assertEquals(if (partialWindows) listOf("0123456", "56") else listOf(), windowedTransform2)
+            val windowedTransform3 = data.windowed(Int.MAX_VALUE, Int.MAX_VALUE, partialWindows) { it.joinToString("") }
+            assertEquals(if (partialWindows) listOf("0123456") else listOf(), windowedTransform3)
+        }
     }
 
 

libraries/stdlib/test/collections/SequenceTest.kt

@@ -311,6 +311,24 @@ public class SequenceTest {
         }
 
         ensureIsIntermediate(source = sequenceOf(1, 2, 3)) { it.windowed(2, 1) }
+
+        // index overflow tests
+        for (partialWindows in listOf(true, false)) {
+
+            val windowed1 = seq.windowed(5, Int.MAX_VALUE, partialWindows)
+            assertEquals(seq.take(5).toList(), windowed1.single())
+            val windowed2 = seq.windowed(Int.MAX_VALUE, 5, partialWindows)
+            assertEquals(if (partialWindows) listOf(seq.toList(), listOf(5, 6)) else listOf(), windowed2.toList())
+            val windowed3 = seq.windowed(Int.MAX_VALUE, Int.MAX_VALUE, partialWindows)
+            assertEquals(if (partialWindows) listOf(seq.toList()) else listOf(), windowed3.toList())
+
+            val windowedTransform1 = seq.windowed(5, Int.MAX_VALUE, partialWindows) { it.joinToString("") }
+            assertEquals("01234", windowedTransform1.single())
+            val windowedTransform2 = seq.windowed(Int.MAX_VALUE, 5, partialWindows) { it.joinToString("") }
+            assertEquals(if (partialWindows) listOf("0123456", "56") else listOf(), windowedTransform2.toList())
+            val windowedTransform3 = seq.windowed(Int.MAX_VALUE, Int.MAX_VALUE, partialWindows) { it.joinToString("") }
+            assertEquals(if (partialWindows) listOf("0123456") else listOf(), windowedTransform3.toList())
+        }
     }
 
     @Test fun zip() {

libraries/stdlib/test/text/StringTest.kt

@@ -1130,6 +1130,38 @@ class StringTest {
                         data.windowedSequence(window, step, partialWindows = true).iterator()) { iteratorBehavior() }
             }
         }
+
+        // index overflow tests
+        for (partialWindows in listOf(true, false)) {
+
+            val windowed1 = data.windowed(5, Int.MAX_VALUE, partialWindows)
+            assertEquals("abcde", windowed1.single())
+            val windowed2 = data.windowed(Int.MAX_VALUE, 5, partialWindows)
+            assertEquals(if (partialWindows) listOf(data.toString(), data.substring(5, 7)) else listOf(), windowed2)
+            val windowed3 = data.windowed(Int.MAX_VALUE, Int.MAX_VALUE, partialWindows)
+            assertEquals(if (partialWindows) listOf(data.toString()) else listOf(), windowed3)
+
+            val windowedTransform1 = data.windowed(5, Int.MAX_VALUE, partialWindows) { it }
+            assertEquals("abcde", windowedTransform1.single())
+            val windowedTransform2 = data.windowed(Int.MAX_VALUE, 5, partialWindows) { it }
+            assertEquals(if (partialWindows) listOf(data.toString(), data.substring(5, 7)) else listOf(), windowedTransform2)
+            val windowedTransform3 = data.windowed(Int.MAX_VALUE, Int.MAX_VALUE, partialWindows) { it }
+            assertEquals(if (partialWindows) listOf(data.toString()) else listOf(), windowedTransform3)
+
+            val windowedSequence1 = data.windowedSequence(5, Int.MAX_VALUE, partialWindows)
+            assertEquals("abcde", windowedSequence1.single())
+            val windowedSequence2 = data.windowedSequence(Int.MAX_VALUE, 5, partialWindows)
+            assertEquals(if (partialWindows) listOf(data.toString(), data.substring(5, 7)) else listOf(), windowedSequence2.toList())
+            val windowedSequence3 = data.windowedSequence(Int.MAX_VALUE, Int.MAX_VALUE, partialWindows)
+            assertEquals(if (partialWindows) listOf(data.toString()) else listOf(), windowedSequence3.toList())
+
+            val windowedSequenceTransform1 = data.windowedSequence(5, Int.MAX_VALUE, partialWindows) { it }
+            assertEquals("abcde", windowedSequenceTransform1.single())
+            val windowedSequenceTransform2 = data.windowedSequence(Int.MAX_VALUE, 5, partialWindows) { it }
+            assertEquals(if (partialWindows) listOf(data.toString(), data.substring(5, 7)) else listOf(), windowedSequenceTransform2.toList())
+            val windowedSequenceTransform3 = data.windowedSequence(Int.MAX_VALUE, Int.MAX_VALUE, partialWindows) { it }
+            assertEquals(if (partialWindows) listOf(data.toString()) else listOf(), windowedSequenceTransform3.toList())
+        }
     }
 
     @Test fun map() = withOneCharSequenceArg { arg1 ->

libraries/tools/kotlin-stdlib-gen/src/templates/Generators.kt

@@ -655,12 +655,14 @@ object Generators : TemplateGroupBase() {
             checkWindowSizeStep(size, step)
             if (this is RandomAccess && this is List) {
                 val thisSize = this.size
-                val result = ArrayList<R>((thisSize + step - 1) / step)
+                val resultCapacity = thisSize / step + if (thisSize % step == 0) 0 else 1
+                val result = ArrayList<R>(resultCapacity)
                 val window = MovingSubList(this)
                 var index = 0
-                while (index < thisSize) {
+                while (index in 0 until thisSize) {
-                    window.move(index, (index + size).coerceAtMost(thisSize))
+                    val windowSize = size.coerceAtMost(thisSize - index)
-                    if (!partialWindows && window.size < size) break
+                    if (!partialWindows && windowSize < size) break
+                    window.move(index, index + windowSize)
                     result.add(transform(window))
                     index += step
                 }
@@ -681,11 +683,12 @@ object Generators : TemplateGroupBase() {
             """
             checkWindowSizeStep(size, step)
             val thisSize = this.length
-            val result = ArrayList<R>((thisSize + step - 1) / step)
+            val resultCapacity = thisSize / step + if (thisSize % step == 0) 0 else 1
+            val result = ArrayList<R>(resultCapacity)
             var index = 0
-            while (index < thisSize) {
+            while (index in 0 until thisSize) {
                 val end = index + size
-                val coercedEnd = if (end > thisSize) { if (partialWindows) thisSize else break } else end
+                val coercedEnd = if (end < 0 || end > thisSize) { if (partialWindows) thisSize else break } else end
                 result.add(transform(subSequence(index, coercedEnd)))
                 index += step
             }
@@ -731,9 +734,10 @@ object Generators : TemplateGroupBase() {
             checkWindowSizeStep(size, step)
             if (this is RandomAccess && this is List) {
                 val thisSize = this.size
-                val result = ArrayList<List<T>>((thisSize + step - 1) / step)
+                val resultCapacity = thisSize / step + if (thisSize % step == 0) 0 else 1
+                val result = ArrayList<List<T>>(resultCapacity)
                 var index = 0
-                while (index < thisSize) {
+                while (index in 0 until thisSize) {
                     val windowSize = size.coerceAtMost(thisSize - index)
                     if (windowSize < size && !partialWindows) break
                     result.add(List(windowSize) { this[it + index] })
@@ -785,7 +789,11 @@ object Generators : TemplateGroupBase() {
             """
             checkWindowSizeStep(size, step)
             val windows = (if (partialWindows) indices else 0 until length - size + 1) step step
-            return windows.asSequence().map { index -> transform(subSequence(index, (index + size).coerceAtMost(length))) }
+            return windows.asSequence().map { index ->
+                val end = index + size
+                val coercedEnd = if (end < 0 || end > length) length else end
+                transform(subSequence(index, coercedEnd))
+            }
             """
         }
     }