Ensure that serialization exception is thrown from JSON parser on inv…

…alid inputs

Fixes #704

runtime/commonMain/src/kotlinx/serialization/json/JsonConfiguration.kt

@@ -17,13 +17,13 @@ import kotlin.jvm.*
  * * [ignoreUnknownKeys] ignores encounters of unknown properties in the input JSON.
  *
  * * [isLenient] removes JSON specification restriction (RFC-4627) and makes parser
- *   more liberal to the malformed input. In lenient modes quoted string literals,
+ *   more liberal to the malformed input. In lenient mode quoted boolean literals,
  *   and unquoted string literals are allowed.
  *
  * * [serializeSpecialFloatingPointValues] removes JSON specification restriction on
  *   special floating-point values such as `NaN` and `Infinity` and enables their
- *   serialization. When enabling it, please assure that the receiving party will be
- *   able to parse these special value.
+ *   serialization. When enabling it, please ensure that the receiving party will be
+ *   able to parse these special values.
  *
  * * [unquotedPrint] specifies whether keys and values should be quoted when building the
  *   JSON string. This option is intended to be used for debugging and pretty-printing,
@@ -114,6 +114,6 @@ public data class JsonConfiguration @UnstableDefault constructor(
         "'ignoreUnknownKeys', 'isLenient' and 'serializeSpecialFloatingPointValues'")
 @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
 @kotlin.internal.LowPriorityInOverloadResolution
-fun JsonConfiguration(strictMode: Boolean = true, unquoted: Boolean = false) {
+public fun JsonConfiguration(strictMode: Boolean = true, unquoted: Boolean = false) {
     error("Should not be called")
 }

runtime/commonMain/src/kotlinx/serialization/json/JsonElementSerializer.kt

@@ -41,8 +41,7 @@ public object JsonElementSerializer : KSerializer<JsonElement> {
     }
 
     override fun deserialize(decoder: Decoder): JsonElement {
-        verify(decoder)
-        val input = decoder as JsonInput
+        val input = decoder.asJsonInput()
         return input.decodeJson()
     }
 }
@@ -66,11 +65,8 @@ public object JsonPrimitiveSerializer : KSerializer<JsonPrimitive> {
     }
 
     override fun deserialize(decoder: Decoder): JsonPrimitive {
-        verify(decoder)
-        val result = (decoder as JsonInput).decodeJson()
-        require(result is JsonPrimitive) {
-            "Unexpected JsonElement type: " + result::class
-        }
+        val result = decoder.asJsonInput().decodeJson()
+        if (result !is JsonPrimitive) throw JsonDecodingException(-1, "Unexpected JSON element, expected JsonPrimitive, had ${result::class}", result.toString())
         return result
     }
 }
@@ -131,11 +127,8 @@ public object JsonLiteralSerializer : KSerializer<JsonLiteral> {
     }
 
     override fun deserialize(decoder: Decoder): JsonLiteral {
-        verify(decoder)
-        val result = (decoder as JsonInput).decodeJson()
-        require(result is JsonLiteral) {
-            "Unexpected JsonElement type: " + result::class
-        }
+        val result = decoder.asJsonInput().decodeJson()
+        if (result !is JsonLiteral) throw JsonDecodingException(-1, "Unexpected JSON element, expected JsonLiteral, had ${result::class}", result.toString())
         return result
     }
 }
@@ -188,13 +181,21 @@ public object JsonArraySerializer : KSerializer<JsonArray> {
 }
 
 private fun verify(encoder: Encoder) {
-    require(encoder is JsonOutput) {
-        "Json element serializer can be used only by Json format, had $encoder"
-    }
+    encoder.asJsonOutput()
 }
 
 private fun verify(decoder: Decoder) {
-    require(decoder is JsonInput) {
-        "Json element serializer can be used only by Json format, had $decoder"
-    }
+    decoder.asJsonInput()
 }
+
+internal fun Decoder.asJsonInput(): JsonInput = this as? JsonInput
+    ?: throw IllegalStateException(
+        "This serializer can be used only with Json format." +
+                "Expected Decoder to be JsonInput, got ${this::class}"
+    )
+
+internal fun Encoder.asJsonOutput() = this as? JsonOutput
+    ?: throw IllegalStateException(
+        "This serializer can be used only with Json format." +
+                "Expected Encoder to be JsonOutput, got ${this::class}"
+    )

runtime/commonMain/src/kotlinx/serialization/json/JsonExceptions.kt

@@ -7,7 +7,7 @@ package kotlinx.serialization.json
 import kotlinx.serialization.*
 
 /**
- * Generic exception indicating a problem with JSON serialization.
+ * Generic exception indicating a problem with JSON serialization and deserialization.
  */
 public open class JsonException(message: String) : SerializationException(message)
 
@@ -39,7 +39,9 @@ internal fun InvalidFloatingPoint(value: Number, key: String, type: String, outp
 
 internal fun UnknownKeyException(key: String, input: String) = JsonDecodingException(
     -1,
-    "JSON encountered unknown key: '$key'. You can enable 'ignoreUnknownKeys' property to ignore unknown keys. JSON input: $input")
+    "JSON encountered unknown key: '$key'. You can enable 'JsonConfiguration.ignoreUnknownKeys' property to ignore unknown keys.\n" +
+            " JSON input: ${input.minify()}"
+)
 
 internal fun InvalidKeyKindException(keyDescriptor: SerialDescriptor) = JsonEncodingException(
     "Value of type '${keyDescriptor.serialName}' can't be used in JSON as a key in the map. " +
@@ -48,7 +50,7 @@ internal fun InvalidKeyKindException(keyDescriptor: SerialDescriptor) = JsonEnco
 )
 
 private fun String.minify(offset: Int = -1): String {
-    if (offset < 200) return this
+    if (length < 200) return this
     if (offset == -1) {
         val start = this.length - 60
         if (start <= 0) return this

runtime/commonMain/src/kotlinx/serialization/json/JsonInput.kt

@@ -51,9 +51,3 @@ public interface JsonInput : Decoder, CompositeDecoder {
      */
     public fun decodeJson(): JsonElement
 }
-
-internal fun Decoder.asJsonInput() = this as? JsonInput
-        ?: throw SerializationException(
-            "This serializer can be used only with Json format." +
-                    "Expected Decoder to be JsonInput, got ${this::class}"
-        )

runtime/commonMain/src/kotlinx/serialization/json/JsonOutput.kt

@@ -51,9 +51,3 @@ public interface JsonOutput: Encoder, CompositeEncoder {
      */
     public fun encodeJson(element: JsonElement)
 }
-
-internal fun Encoder.asJsonOutput() = this as? JsonOutput
-        ?: throw SerializationException(
-            "This serializer can be used only with Json format." +
-                    "Expected Encoder to be JsonOutput, got ${this::class}"
-        )

runtime/commonMain/src/kotlinx/serialization/json/internal/JsonReader.kt

@@ -225,16 +225,14 @@ internal class JsonReader(private val source: String) {
         length = 0 // in buffer
         var currentPosition = startPosition + 1
         var lastPosition = currentPosition
-        val length = source.length
         while (source[currentPosition] != STRING) {
-            if (currentPosition >= length) fail("Unexpected EOF", currentPosition)
             if (source[currentPosition] == STRING_ESC) {
                 appendRange(source, lastPosition, currentPosition)
                 val newPosition = appendEsc(source, currentPosition + 1)
                 currentPosition = newPosition
                 lastPosition = newPosition
-            } else {
-                currentPosition++
+            } else if (++currentPosition >= source.length) {
+                fail("EOF", currentPosition)
             }
         }
         if (lastPosition == startPosition + 1) {

runtime/commonMain/src/kotlinx/serialization/json/internal/StreamingJsonInput.kt

@@ -121,7 +121,7 @@ internal class StreamingJsonInput internal constructor(
 
             if (!configuration.ignoreUnknownKeys) {
                 reader.fail(
-                    "Encountered an unknown key '$key'. You can enable 'ignoreUnknownKeys' property" +
+                    "Encountered an unknown key '$key'. You can enable 'JsonConfiguration.ignoreUnknownKeys' property" +
                             " to ignore unknown keys"
                 )
             } else {
@@ -165,13 +165,14 @@ internal class StreamingJsonInput internal constructor(
      * The rest of the primitives are allowed to be quoted and unqouted
      * to simplify integrations with third-party API.
      */
-    override fun decodeByte(): Byte = reader.takeString().toByte()
-    override fun decodeShort(): Short = reader.takeString().toShort()
-    override fun decodeInt(): Int = reader.takeString().toInt()
-    override fun decodeLong(): Long = reader.takeString().toLong()
-    override fun decodeFloat(): Float = reader.takeString().toFloat()
-    override fun decodeDouble(): Double = reader.takeString().toDouble()
-    override fun decodeChar(): Char = reader.takeString().single()
+    override fun decodeByte(): Byte = reader.takeString().parse("byte") { toByte() }
+    override fun decodeShort(): Short = reader.takeString().parse("short") { toShort() }
+    override fun decodeInt(): Int = reader.takeString().parse("int") { toInt() }
+    override fun decodeLong(): Long = reader.takeString().parse("long") { toLong() }
+    override fun decodeFloat(): Float = reader.takeString().parse("float") { toFloat() }
+    override fun decodeDouble(): Double = reader.takeString().parse("double") { toDouble() }
+    override fun decodeChar(): Char = reader.takeString().parse("char") { single() }
+
     override fun decodeString(): String {
         return if (configuration.isLenient) {
             reader.takeString()
@@ -180,6 +181,14 @@ internal class StreamingJsonInput internal constructor(
         }
     }
 
+    private inline fun <T> String.parse(type: String, block: String.() -> T): T {
+        try {
+            return block()
+        } catch (e: Throwable) {
+            reader.fail("Failed to parse '$type'")
+        }
+    }
+
     override fun decodeEnum(enumDescriptor: SerialDescriptor): Int {
         return enumDescriptor.getElementIndexOrThrow(decodeString())
     }

runtime/commonMain/src/kotlinx/serialization/json/internal/TreeJsonInput.kt

@@ -73,11 +73,6 @@ private sealed class AbstractJsonTreeInput(
 
     protected abstract fun currentElement(tag: String): JsonElement
 
-    override fun decodeTaggedChar(tag: String): Char {
-        val o = getValue(tag)
-        return if (o.content.length == 1) o.content[0] else throw SerializationException("$o can't be represented as Char")
-    }
-
     override fun decodeTaggedEnum(tag: String, enumDescription: SerialDescriptor): Int =
         enumDescription.getElementIndexOrThrow(getValue(tag).content)
 
@@ -100,12 +95,22 @@ private sealed class AbstractJsonTreeInput(
         return value.boolean
     }
 
-    override fun decodeTaggedByte(tag: String): Byte = getValue(tag).int.toByte()
-    override fun decodeTaggedShort(tag: String) = getValue(tag).int.toShort()
-    override fun decodeTaggedInt(tag: String) = getValue(tag).int
-    override fun decodeTaggedLong(tag: String) = getValue(tag).long
-    override fun decodeTaggedFloat(tag: String) = getValue(tag).float
-    override fun decodeTaggedDouble(tag: String) = getValue(tag).double
+    override fun decodeTaggedByte(tag: String) = getValue(tag).primitive("byte") { int.toByte() }
+    override fun decodeTaggedShort(tag: String) = getValue(tag).primitive("short") { int.toShort() }
+    override fun decodeTaggedInt(tag: String) = getValue(tag).primitive("int") { int }
+    override fun decodeTaggedLong(tag: String) = getValue(tag).primitive("long") { long }
+    override fun decodeTaggedFloat(tag: String) = getValue(tag).primitive("float") { float }
+    override fun decodeTaggedDouble(tag: String) = getValue(tag).primitive("double") { double }
+    override fun decodeTaggedChar(tag: String): Char = getValue(tag).primitive("char") { content.single() }
+
+    private inline fun <T: Any> JsonPrimitive.primitive(primitive: String, block: JsonPrimitive.() -> T): T {
+        try {
+            return block()
+        } catch (e: Throwable) {
+            throw JsonDecodingException(-1, "Failed to parse '$primitive'", currentObject().toString())
+        }
+    }
+
     override fun decodeTaggedString(tag: String): String {
         val value = getValue(tag)
         if (!json.configuration.isLenient) {

runtime/commonTest/src/kotlinx/serialization/json/JsonParserFailureModesTest.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2017-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.serialization.json
+
+import kotlinx.serialization.*
+import kotlin.test.*
+
+class JsonParserFailureModesTest : JsonTestBase() {
+
+    @Serializable
+    data class Holder(
+        val id: Long
+    )
+
+    @Test
+    fun testFailureModes() = parametrizedTest {
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{"id": "}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{"id": ""}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{"id":a}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{"id":2.0}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{"id2":2}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{"id"}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{"id}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{"i}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{"}""", it) }
+        assertFailsWith<MissingFieldException> { Json.plain.parse(Holder.serializer(), """{}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """}""", it) }
+        assertFailsWith<JsonDecodingException> { Json.plain.parse(Holder.serializer(), """{""", it) }
+    }
+}