Updated wasm spec and enforced UTF-8 validation on binary strings

compiler/src/main/kotlin/asmble/io/BinaryToAst.kt

@@ -2,6 +2,7 @@ package asmble.io
 
 import asmble.ast.Node
 import asmble.util.*
+import java.nio.ByteBuffer
 
 open class BinaryToAst(
     val version: Long = 1L,
@@ -215,7 +216,10 @@ open class BinaryToAst(
         else -> error("Unknown value type: $type")
     }
 
-    fun ByteReader.readString() = this.readVarUInt32AsInt().let { String(this.readBytes(it)) }
+    fun ByteReader.readString() = this.readVarUInt32AsInt().let {
+        // We have to use the decoder directly to get malformed-input errors
+        Charsets.UTF_8.newDecoder().decode(ByteBuffer.wrap(this.readBytes(it))).toString()
+    }
     fun <T> ByteReader.readList(fn: (ByteReader) -> T) = this.readVarUInt32().let { listSize ->
         (0 until listSize).map { fn(this) }
     }

compiler/src/main/kotlin/asmble/io/IoErr.kt

@@ -5,6 +5,7 @@ import asmble.AsmErr
 sealed class IoErr(message: String, cause: Throwable? = null) : RuntimeException(message, cause), AsmErr {
     class UnexpectedEnd : IoErr("Unexpected EOF") {
         override val asmErrString get() = "unexpected end"
+        override val asmErrStrings get() = listOf(asmErrString, "length out of bounds")
     }
 
     class InvalidMagicNumber : IoErr("Invalid magic number") {

compiler/src/main/kotlin/asmble/run/jvm/ExceptionTranslator.kt

@@ -3,6 +3,7 @@ package asmble.run.jvm
 import asmble.AsmErr
 import java.lang.invoke.WrongMethodTypeException
 import java.nio.BufferOverflowException
+import java.nio.charset.MalformedInputException
 
 open class ExceptionTranslator {
     fun translate(ex: Throwable): List<String> = when (ex) {
@@ -13,6 +14,7 @@ open class ExceptionTranslator {
         is ArrayIndexOutOfBoundsException -> listOf("undefined element", "elements segment does not fit")
         is AsmErr -> ex.asmErrStrings
         is IndexOutOfBoundsException -> listOf("out of bounds memory access")
+        is MalformedInputException -> listOf("invalid UTF-8 encoding")
         is NoSuchMethodException -> listOf("unknown import", "type mismatch")
         is NullPointerException -> listOf("undefined element", "uninitialized element")
         is StackOverflowError -> listOf("call stack exhausted")