Add a wasmtime-specific wasmtime_wat2wasm C API (#1206)

* Add a wasmtime-specific `wasmtime_wat2wasm` C API

This commit implements a wasmtime-specific C API for converting the text
format to the binary format. An upstream spec issue exists for adding
this to the C API, but in the meantime we can experiment with our own
version of this API and use it in the C# extension, for example!

Closes #1000

* Reorder arguments

* Use wasm_byte_vec_t for input `*.wat`

* Mark wat input as const

* Return an error message and use `fixed`

* Actually include the error message

* Use `fixed` in `Module.cs` as well

crates/misc/dotnet/src/Engine.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Text;
+using System.Runtime.InteropServices;
 
 namespace Wasmtime
 {
@@ -40,6 +42,34 @@ namespace Wasmtime
             return new Store(this);
         }
 
+        /// <summary>
+        /// Converts the WebAssembly text format to the binary format
+        /// </summary>
+        /// <returns>Returns the binary-encoded wasm module.</returns>
+        public byte[] WatToWasm(string wat)
+        {
+            var watBytes = Encoding.UTF8.GetBytes(wat);
+            unsafe
+            {
+                fixed (byte *ptr = watBytes)
+                {
+                    Interop.wasm_byte_vec_t watByteVec;
+                    watByteVec.size = (UIntPtr)watBytes.Length;
+                    watByteVec.data = ptr;
+                    if (!Interop.wasmtime_wat2wasm(Handle, ref watByteVec, out var bytes, out var error)) {
+                        var errorSpan = new ReadOnlySpan<byte>(error.data, checked((int)error.size));
+                        var message = Encoding.UTF8.GetString(errorSpan);
+                        Interop.wasm_byte_vec_delete(ref error);
+                        throw new WasmtimeException("failed to parse input wat: " + message);
+                    }
+                    var byteSpan = new ReadOnlySpan<byte>(bytes.data, checked((int)bytes.size));
+                    var ret = byteSpan.ToArray();
+                    Interop.wasm_byte_vec_delete(ref bytes);
+                    return ret;
+                }
+            }
+        }
+
         /// <inheritdoc/>
         public void Dispose()
         {

crates/misc/dotnet/src/Interop.cs

@@ -899,7 +899,7 @@ namespace Wasmtime
         public static extern bool wasi_config_set_stdin_file(
             WasiConfigHandle config,
             [MarshalAs(UnmanagedType.LPUTF8Str)] string path
-        ); 
+        );
 
         [DllImport(LibraryName)]
         public static extern void wasi_config_inherit_stdin(WasiConfigHandle config);
@@ -909,7 +909,7 @@ namespace Wasmtime
         public static extern bool wasi_config_set_stdout_file(
             WasiConfigHandle config,
             [MarshalAs(UnmanagedType.LPUTF8Str)] string path
-        ); 
+        );
 
         [DllImport(LibraryName)]
         public static extern void wasi_config_inherit_stdout(WasiConfigHandle config);
@@ -919,7 +919,7 @@ namespace Wasmtime
         public static extern bool wasi_config_set_stderr_file(
             WasiConfigHandle config,
             [MarshalAs(UnmanagedType.LPUTF8Str)] string path
-        ); 
+        );
 
         [DllImport(LibraryName)]
         public static extern void wasi_config_inherit_stderr(WasiConfigHandle config);
@@ -974,5 +974,14 @@ namespace Wasmtime
 
         [DllImport(LibraryName)]
         public static extern void wasmtime_config_cranelift_opt_level_set(WasmConfigHandle config, wasmtime_opt_level_t level);
+
+        [DllImport(LibraryName, CharSet=CharSet.Ansi)]
+        [return: MarshalAs(UnmanagedType.I1)]
+        public static extern bool wasmtime_wat2wasm(
+            EngineHandle engine,
+            ref wasm_byte_vec_t wat,
+            out wasm_byte_vec_t vec,
+            out wasm_byte_vec_t error_message
+        );
    }
 }

crates/misc/dotnet/src/Module.cs

@@ -15,15 +15,13 @@ namespace Wasmtime
                 throw new ArgumentNullException(nameof(store));
             }
 
-            var bytesHandle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
-
-            try
+            unsafe
             {
-                unsafe
+                fixed (byte *ptr = bytes)
                 {
                     Interop.wasm_byte_vec_t vec;
                     vec.size = (UIntPtr)bytes.Length;
-                    vec.data = (byte*)bytesHandle.AddrOfPinnedObject();
+                    vec.data = ptr;
 
                     Handle = Interop.wasm_module_new(store.Handle, ref vec);
                 }
@@ -33,10 +31,6 @@ namespace Wasmtime
                     throw new WasmtimeException($"WebAssembly module '{name}' is not valid.");
                 }
             }
-            finally
-            {
-                bytesHandle.Free();
-            }
 
             Store = store;
             Name = name;

crates/misc/dotnet/tests/Fixtures/ModuleFixture.cs

@@ -13,7 +13,9 @@ namespace Wasmtime.Tests
                 .WithReferenceTypes(true)
                 .Build();
             Store = Engine.CreateStore();
-            Module = Store.CreateModule(Path.Combine("Modules", ModuleFileName));
+            var wat = Path.Combine("Modules", ModuleFileName);
+            var wasm = Engine.WatToWasm(File.ReadAllText(wat));
+            Module = Store.CreateModule(wat, wasm);
         }
 
         public void Dispose()

crates/misc/dotnet/tests/FunctionExportsTests.cs

@@ -8,7 +8,7 @@ namespace Wasmtime.Tests
 {
     public class FunctionExportsFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "FunctionExports.wasm";
+        protected override string ModuleFileName => "FunctionExports.wat";
     }
 
     public class FunctionExportsTests : IClassFixture<FunctionExportsFixture>

crates/misc/dotnet/tests/FunctionImportsTests.cs

@@ -8,7 +8,7 @@ namespace Wasmtime.Tests
 {
     public class FunctionImportsFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "FunctionImports.wasm";
+        protected override string ModuleFileName => "FunctionImports.wat";
     }
 
     public class FunctionImportsTests : IClassFixture<FunctionImportsFixture>

crates/misc/dotnet/tests/FunctionThunkingTests.cs

@@ -7,7 +7,7 @@ namespace Wasmtime.Tests
 {
     public class FunctionThunkingFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "FunctionThunking.wasm";
+        protected override string ModuleFileName => "FunctionThunking.wat";
     }
 
     public class FunctionThunkingTests : IClassFixture<FunctionThunkingFixture>

crates/misc/dotnet/tests/GlobalExportsTests.cs

@@ -10,7 +10,7 @@ namespace Wasmtime.Tests
 {
     public class GlobalExportsFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "GlobalExports.wasm";
+        protected override string ModuleFileName => "GlobalExports.wat";
     }
 
     public class GlobalExportsTests : IClassFixture<GlobalExportsFixture>

crates/misc/dotnet/tests/GlobalImportBindingTests.cs

@@ -6,7 +6,7 @@ namespace Wasmtime.Tests
 {
     public class GlobalImportBindingFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "GlobalImportBindings.wasm";
+        protected override string ModuleFileName => "GlobalImportBindings.wat";
     }
 
     public class GlobalImportBindingTests : IClassFixture<GlobalImportBindingFixture>

crates/misc/dotnet/tests/GlobalImportsTests.cs

@@ -8,7 +8,7 @@ namespace Wasmtime.Tests
 {
     public class GlobalImportsFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "GlobalImports.wasm";
+        protected override string ModuleFileName => "GlobalImports.wat";
     }
 
     public class GlobalImportsTests : IClassFixture<GlobalImportsFixture>

crates/misc/dotnet/tests/MemoryExportsTests.cs

@@ -8,7 +8,7 @@ namespace Wasmtime.Tests
 {
     public class MemoryExportsFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "MemoryExports.wasm";
+        protected override string ModuleFileName => "MemoryExports.wat";
     }
 
     public class MemoryExportsTests : IClassFixture<MemoryExportsFixture>

crates/misc/dotnet/tests/MemoryImportBindingTests.cs

@@ -6,7 +6,7 @@ namespace Wasmtime.Tests
 {
     public class MemoryImportBindingFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "MemoryImportBinding.wasm";
+        protected override string ModuleFileName => "MemoryImportBinding.wat";
     }
 
     public class MemoryImportBindingTests : IClassFixture<MemoryImportBindingFixture>

crates/misc/dotnet/tests/MemoryImportFromModuleTests.cs

@@ -6,7 +6,7 @@ namespace Wasmtime.Tests
 {
     public class MemoryImportFromModuleFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "MemoryImportFromModule.wasm";
+        protected override string ModuleFileName => "MemoryImportFromModule.wat";
     }
 
     public class MemoryImportFromModuleTests : IClassFixture<MemoryImportFromModuleFixture>

crates/misc/dotnet/tests/MemoryImportNoUpperBoundTests.cs

@@ -6,7 +6,7 @@ namespace Wasmtime.Tests
 {
     public class MemoryImportNoUpperBoundFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "MemoryImportNoUpperBound.wasm";
+        protected override string ModuleFileName => "MemoryImportNoUpperBound.wat";
     }
 
     public class MemoryImportNoUpperBoundTests : IClassFixture<MemoryImportNoUpperBoundFixture>

crates/misc/dotnet/tests/MemoryImportWithUpperBoundTests.cs

@@ -6,7 +6,7 @@ namespace Wasmtime.Tests
 {
     public class MemoryImportWithUpperBoundFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "MemoryImportWithUpperBound.wasm";
+        protected override string ModuleFileName => "MemoryImportWithUpperBound.wat";
     }
 
     public class MemoryImportWithUpperBoundTests : IClassFixture<MemoryImportWithUpperBoundFixture>

crates/misc/dotnet/tests/TableExportsTests.cs

@@ -8,7 +8,7 @@ namespace Wasmtime.Tests
 {
     public class TableExportsFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "TableExports.wasm";
+        protected override string ModuleFileName => "TableExports.wat";
     }
 
     public class TableExportsTests : IClassFixture<TableExportsFixture>

crates/misc/dotnet/tests/TableImportsTests.cs

@@ -8,7 +8,7 @@ namespace Wasmtime.Tests
 {
     public class TableImportsFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "TableImports.wasm";
+        protected override string ModuleFileName => "TableImports.wat";
     }
 
     public class TableImportsTests : IClassFixture<TableImportsFixture>

crates/misc/dotnet/tests/TempFile.cs

@@ -21,4 +21,4 @@ namespace Wasmtime.Tests
 
         public string Path { get; private set; }
     }
-}
+}

crates/misc/dotnet/tests/WasiTests.cs

@@ -9,7 +9,7 @@ namespace Wasmtime.Tests
 {
     public class WasiFixture : ModuleFixture
     {
-        protected override string ModuleFileName => "Wasi.wasm";
+        protected override string ModuleFileName => "Wasi.wat";
     }
 
     public class WasiTests : IClassFixture<WasiFixture>

crates/misc/dotnet/tests/Wasmtime.Tests.csproj

@@ -27,7 +27,7 @@
   </Target>
 
   <ItemGroup>
-    <None Update="Modules/*.wasm" CopyToOutputDirectory="PreserveNewest" />
+    <None Update="Modules/*.wat" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
 
 </Project>