fix(dotnet): preserve leading Unicode content in metadata strings (#667)

Signed-off-by: RudyCelekli <47457359+rudycelekli@users.noreply.github.com>

src/dotnet/ManagedArtifactInspector.test.ts

@@ -139,3 +139,19 @@ describe("managed artifact inventory", () => {
     });
   });
 });
+
+it("preserves U+FEFF in references and fixed attribute strings", () => {
+  const bytes = buildManagedPeFixture({
+    references: ["\uFEFFSystem.Runtime", "System.\uFEFFRuntime"],
+    targetFramework: "\uFEFF.NETCoreApp,Version=v8.0",
+  });
+  const result = inspectManagedArtifactBytes(
+    bytes,
+    managedPeFixtureTarget(bytes),
+  );
+  expect(result.references.map((reference) => reference.name)).toEqual([
+    "\uFEFFSystem.Runtime",
+    "System.\uFEFFRuntime",
+  ]);
+  expect(result.target_frameworks).toEqual(["\uFEFF.NETCoreApp,Version=v8.0"]);
+});

src/dotnet/ManagedMemberInspector.test.ts

@@ -146,3 +146,22 @@ it("keeps an admitted but unimplemented element type unsupported", () => {
     issue: "unsupported element type 0x14",
   });
 });
+
+it("preserves leading U+FEFF as metadata name content", () => {
+  const bytes = buildManagedPeFixture({
+    typeNamespace: "\uFEFFFixture",
+    typeName: "\uFEFFProgram",
+    methodName: "\uFEFFMain",
+    fieldName: "\uFEFFcounter",
+  });
+  const result = inspectManagedMembersBytes(
+    bytes,
+    managedPeFixtureTarget(bytes),
+  );
+  expect(result.types[0]?.full_name).toBe("\uFEFFFixture.\uFEFFProgram");
+  expect(result.methods[0]?.name).toBe("\uFEFFMain");
+  expect(result.fields[0]?.name).toBe("\uFEFFcounter");
+  expect(result.call_edges[0]?.caller).toBe(
+    "\uFEFFFixture.\uFEFFProgram.\uFEFFMain",
+  );
+});

src/dotnet/ManagedMetadataHeaps.ts

@@ -131,7 +131,7 @@ export const readMetadataString = (
       start,
     );
   try {
-    return new TextDecoder("utf-8", { fatal: true }).decode(
+    return new TextDecoder("utf-8", { fatal: true, ignoreBOM: true }).decode(
       bytes.subarray(start, end),
     );
   } catch (cause: unknown) {

src/dotnet/ManagedMetadataInventoryRows.ts

@@ -345,7 +345,7 @@ const decodeFixedString = (blob: Buffer): string | null => {
   const start = 2 + length.prefix;
   if (start > blob.length - length.length) return null;
   try {
-    return new TextDecoder("utf-8", { fatal: true }).decode(
+    return new TextDecoder("utf-8", { fatal: true, ignoreBOM: true }).decode(
       blob.subarray(start, start + length.length),
     );
   } catch (cause: unknown) {

tests/boundary/providers/managed/managedStaticProvider.test.ts

@@ -147,3 +147,37 @@ const asManagedMemberResult = (execution: AnalysisExecution) =>
 
 const asManagedNativeBoundaryResult = (execution: AnalysisExecution) =>
   managedNativeBoundaryInspectionSchema.parse(execution.result);
+
+it("retains U+FEFF metadata through the filesystem target and provider", async () => {
+  const directory = await createTestTempDirectory("rea-managed-bom-");
+  const path = join(directory, "fixture.exe");
+  await writeFile(
+    path,
+    buildManagedPeFixture({
+      typeName: "\uFEFFProgram",
+      methodName: "\uFEFFMain",
+      fieldName: "\uFEFFcounter",
+      references: ["\uFEFFSystem.Runtime"],
+      targetFramework: "\uFEFF.NETCoreApp,Version=v8.0",
+    }),
+  );
+  const parsed = await parseBinaryTarget(path);
+  expect(parsed.ok).toBe(true);
+  if (!parsed.ok) return;
+  const client = new ManagedStaticProvider().createClient(parsed.value);
+  const artifact = await client.execute("inspect_managed_artifact", {});
+  expect(artifact.ok).toBe(true);
+  if (!artifact.ok) return;
+  expect(asManagedResult(artifact.value)).toMatchObject({
+    references: [expect.objectContaining({ name: "\uFEFFSystem.Runtime" })],
+    target_frameworks: ["\uFEFF.NETCoreApp,Version=v8.0"],
+  });
+  const members = await client.execute("inspect_managed_members", {});
+  expect(members.ok).toBe(true);
+  if (!members.ok) return;
+  expect(asManagedMemberResult(members.value)).toMatchObject({
+    types: [expect.objectContaining({ name: "\uFEFFProgram" })],
+    methods: [expect.objectContaining({ name: "\uFEFFMain" })],
+    fields: [expect.objectContaining({ name: "\uFEFFcounter" })],
+  });
+});