Throw an exception when there are multiple roots instead of misparsing

Ref #134

Author: xPaw

ValveKeyValue/ValveKeyValue.Test/MultipleRootObjectsTestCase.cs

@@ -0,0 +1,68 @@
+using System.Text;
+
+namespace ValveKeyValue.Test
+{
+    class MultipleRootObjectsTestCase
+    {
+        const string Kv3Header = "<!-- kv3 encoding:text:version{e21c7f3c-8a33-41c5-9977-a76d3a32aa0d} format:generic:version{7412167c-06e9-4698-aff2-e63eb59037e7} -->\n";
+
+        [Test]
+        public void SecondRootObjectInTextThrows()
+        {
+            using var stream = TestDataHelper.OpenResource("Text.multiple_root_objects.vdf");
+            var ex = Assert.Throws<KeyValueException>(
+                () => KVSerializer.Create(KVSerializationFormat.KeyValues1Text).Deserialize(stream));
+            Assert.That(ex.Message, Does.Contain("line 6, column 1"));
+        }
+
+        [Test]
+        public void SecondTopLevelPairInTextThrows()
+        {
+            const string text = "\"a\"\t\"1\"\n\"b\"\t\"2\"\n";
+
+            using var stream = new MemoryStream(Encoding.UTF8.GetBytes(text));
+            Assert.Throws<KeyValueException>(
+                () => KVSerializer.Create(KVSerializationFormat.KeyValues1Text).Deserialize(stream));
+        }
+
+        [TestCase("\"x\" = \"y\"", TestName = "Kv3TrailingKeyValuePairThrows")]
+        [TestCase("\"x\"", TestName = "Kv3TrailingStringThrows")]
+        [TestCase("{ b = 2 }", TestName = "Kv3SecondRootObjectThrows")]
+        [TestCase("[1, 2]", TestName = "Kv3SecondRootArrayThrows")]
+        [TestCase("#[00112233]", TestName = "Kv3TrailingBinaryBlobThrows")]
+        [TestCase("resource:\"path/to/file.vmdl\"", TestName = "Kv3TrailingFlaggedValueThrows")]
+        public void DataAfterRootValueInKV3Throws(string trailer)
+        {
+            var text = Kv3Header + "{\n\ta = 1\n}\n" + trailer + "\n";
+
+            using var stream = new MemoryStream(Encoding.UTF8.GetBytes(text));
+            Assert.Throws<KeyValueException>(
+                () => KVSerializer.Create(KVSerializationFormat.KeyValues3Text).Deserialize(stream));
+        }
+
+        [Test]
+        public void SecondRootObjectInBinaryThrows()
+        {
+            var data = new byte[]
+            {
+                0x00, // object: first
+                    0x66, 0x69, 0x72, 0x73, 0x74, 0x00,
+                    0x01, // string: a = 1
+                        0x61, 0x00,
+                        0x31, 0x00,
+                0x08, // end of first
+                0x00, // object: second
+                    0x73, 0x65, 0x63, 0x6F, 0x6E, 0x64, 0x00,
+                    0x01, // string: c = 3
+                        0x63, 0x00,
+                        0x33, 0x00,
+                0x08, // end of second
+                0x08, // end of document
+            };
+
+            using var stream = new MemoryStream(data);
+            Assert.Throws<KeyValueException>(
+                () => KVSerializer.Create(KVSerializationFormat.KeyValues1Binary).Deserialize(stream));
+        }
+    }
+}

ValveKeyValue/ValveKeyValue.Test/Test Data/Text/multiple_root_objects.vdf

@@ -0,0 +1,13 @@
+"first"
+{
+	"a"	"1"
+	"b"	"2"
+}
+"second"
+{
+	"c"	"3"
+}
+"third"
+{
+	"d"	"4"
+}

ValveKeyValue/ValveKeyValue.Test/Text/InvalidSyntaxTestCase.cs

@@ -14,6 +14,7 @@ class InvalidSyntaxTestCase
         [TestCase("partial_partialvalue")]
         [TestCase("partial_noclose")]
         [TestCase("invalid_zerobracerepeated")]
+        [TestCase("multiple_root_objects")]
         public void InvalidTextSyntaxThrowsKeyValueException(string resourceName)
         {
             using var stream = TestDataHelper.OpenResource("Text." + resourceName + ".vdf");

ValveKeyValue/ValveKeyValue/Deserialization/KeyValues1/KV1BinaryReader.cs

@@ -42,7 +42,7 @@ public KVHeader ReadHeader()
 
             try
             {
-                ReadObjectCore();
+                ReadRootObject();
             }
             catch (IOException ex)
             {
@@ -69,6 +69,23 @@ public void Dispose()
             }
         }
 
+        void ReadRootObject()
+        {
+            var type = ReadNextNodeType();
+
+            if (type == endMarker)
+            {
+                return;
+            }
+
+            ReadValue(type);
+
+            if (ReadNextNodeType() != endMarker)
+            {
+                throw new KeyValueException("Found data after the root object, documents with multiple root objects are not supported.");
+            }
+        }
+
         void ReadObjectCore()
         {
             KV1BinaryNodeType type = ReadNextNodeType();

ValveKeyValue/ValveKeyValue/Deserialization/KeyValues1/KV1TextReader.cs

@@ -140,6 +140,11 @@ void ReadText(string text)
             {
                 // If we're after a value when we find more text, then we must be starting a new key/value pair.
                 case KV1TextReaderState.InObjectAfterValue:
+                    if (stateMachine.IsAtDocumentLevel)
+                    {
+                        throw new KeyValueException($"Found data after the root object at {tokenReader.PreviousTokenPosition}, documents with multiple root objects are not supported.");
+                    }
+
                     FinalizeCurrentObject(@explicit: false);
                     stateMachine.PushObject();
                     SetObjectKey(text);

ValveKeyValue/ValveKeyValue/Deserialization/KeyValues1/KV1TextReaderStateMachine.cs

@@ -16,6 +16,8 @@ public KV1TextReaderStateMachine()
 
         public bool IsInObject => states.Count > 0;
 
+        public bool IsAtDocumentLevel => states.Count == 1;
+
         public bool IsAtStart => states.Count == 1 && CurrentObject.States.Count == 1 && Current == KV1TextReaderState.InObjectBeforeKey;
 
         public void PushObject() => states.Push(new KVPartialState<KV1TextReaderState>());

ValveKeyValue/ValveKeyValue/Deserialization/KeyValues3/KV3TextReader.cs

@@ -156,6 +156,8 @@ void ReadComma()
 
         void ReadFlag(string text)
         {
+            ThrowIfAfterRootValue();
+
             if (stateMachine.Current != KV3TextReaderState.InArray && stateMachine.Current != KV3TextReaderState.InObjectAfterKey)
             {
                 throw new InvalidOperationException($"Attempted to read flag while in state {stateMachine.Current}.");
@@ -166,8 +168,20 @@ void ReadFlag(string text)
             stateMachine.SetFlag(flag);
         }
 
+        // The document pseudo-object is only ever in InObjectBeforeKey once the root value
+        // has been fully read, so any further data-bearing token at that point is trailing garbage.
+        void ThrowIfAfterRootValue()
+        {
+            if (stateMachine.IsAtDocumentLevel && stateMachine.Current == KV3TextReaderState.InObjectBeforeKey)
+            {
+                throw new KeyValueException($"Found data after the root value at {tokenReader.PreviousTokenPosition}, documents with multiple root values are not supported.");
+            }
+        }
+
         void ReadText(string text)
         {
+            ThrowIfAfterRootValue();
+
             switch (stateMachine.Current)
             {
                 case KV3TextReaderState.InArray:
@@ -200,6 +214,8 @@ void ReadText(string text)
 
         void ReadBinaryBlob(string text)
         {
+            ThrowIfAfterRootValue();
+
             var bytes = HexStringHelper.ParseHexStringAsByteArray(text);
             var value = KVObject.Blob(bytes);
             value.Flag = stateMachine.GetAndResetFlag();
@@ -228,6 +244,8 @@ void ReadBinaryBlob(string text)
 
         void BeginNewArray()
         {
+            ThrowIfAfterRootValue();
+
             if (stateMachine.Current != KV3TextReaderState.InArray && stateMachine.Current != KV3TextReaderState.InObjectAfterKey)
             {
                 throw new InvalidOperationException($"Attempted to begin new array while in state {stateMachine.Current}.");
@@ -266,6 +284,8 @@ void SetObjectKey(string name)
 
         void BeginNewObject()
         {
+            ThrowIfAfterRootValue();
+
             if (stateMachine.Current != KV3TextReaderState.InArray && stateMachine.Current != KV3TextReaderState.InObjectAfterKey)
             {
                 throw new InvalidOperationException($"Attempted to begin new object while in state {stateMachine.Current}.");

ValveKeyValue/ValveKeyValue/Deserialization/KeyValues3/KV3TextReaderStateMachine.cs

@@ -16,6 +16,8 @@ public KV3TextReaderStateMachine()
 
         public bool IsInObject => states.Count > 0;
 
+        public bool IsAtDocumentLevel => states.Count == 1;
+
         public bool IsInArray => states.Count > 0 && CurrentObject.IsArray;
 
         public void PushObject() => states.Push(new KVPartialState<KV3TextReaderState>());