fix(pe): ignore unused export ordinal slots

Fixes #6577

docs/binary-diagnostics.md

@@ -323,7 +323,8 @@ count and SHA-256.
 - PE rows reproduce the export directory: each used export-address-table slot
   with its `ordinal`, one row per name (aliases share an ordinal), `address`
   as the preferred-base virtual address, or `forwarder` text when the slot
-  forwards to another DLL. Ordinal-only exports have a null `name`. The
+  forwards to another DLL. Unused zero-address slots are omitted;
+  ordinal-only exports have a null `name`. The
   directory's DLL name, ordinal base and timestamp are reported, and an image
   without an export directory is a complete empty inventory.
 - ELF rows list defined `.dynsym` symbols with global, weak or GNU-unique

src/native/exports/NativeExportParser.test.ts

@@ -127,6 +127,22 @@ describe("PE export directories", () => {
     ).toThrow("16-bit ordinals");
   });
 
+  it("ignores a trailing unused slot after the last 16-bit ordinal", () => {
+    const result = parse(
+      peExportImage({
+        ordinalBase: 0xffff,
+        functions: [{ rva: 0x2000 }, null],
+        names: [{ name: "Kept", index: 0 }],
+      }),
+    );
+
+    expect(result).toMatchObject({
+      coverage: { status: "complete", examined_entries: 2, exports: 1 },
+      issues: [],
+      exports: [{ name: "Kept", ordinal: 0xffff }],
+    });
+  });
+
   it("refuses an export table above the inventory allowance", () => {
     expect(() =>
       parseNativeExports(

src/native/exports/NativeExportParser.ts

@@ -134,11 +134,6 @@ const parsePeExports = (bytes: Buffer, artifact: Artifact): NativeExports => {
   const functionCount = reader.u32(header + 20);
   const nameCount = reader.u32(header + 24);
   rowBudget(functionCount, "PE export address table");
-  if (ordinalBase + functionCount > 0x10000)
-    throw new BinaryFormatFailure(
-      "malformed",
-      "PE export ordinal base and address-table size exceed 16-bit ordinals",
-    );
   rowBudget(nameCount, "PE export name table");
   const functions =
     functionCount === 0 ? 0 : map(reader.u32(header + 28), functionCount * 4);
@@ -193,6 +188,11 @@ const parsePeExports = (bytes: Buffer, artifact: Artifact): NativeExports => {
     // A zero slot is an unused ordinal, not an export.
     if (rva === 0) continue;
     const ordinal = ordinalBase + index;
+    if (ordinal > 0xffff)
+      throw new BinaryFormatFailure(
+        "malformed",
+        "PE exported ordinal exceeds 16-bit ordinals",
+      );
     let target: Pick<PeExport, "address" | "forwarder">;
     if (rva >= directory.virtual_address && rva < forwarderEnd) {
       try {

tests/acceptance/applications/nativeExportsOrdinalSlots.test.ts

@@ -0,0 +1,49 @@
+import { writeFile } from "node:fs/promises";
+import { join } from "node:path";
+import { expect } from "vitest";
+import { toolContract } from "../../../src/contracts/toolContracts.js";
+import { nativeExportsSchema } from "../../../src/domain/native/nativeExports.js";
+import { peExportImage } from "../../fixtures/binaryDiagnostics/nativeExports.js";
+import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
+import { cliTest } from "../../support/cli/cliFixture.js";
+
+cliTest(
+  "reports the last PE ordinal when an unused EAT slot follows it",
+  async ({ cli }) => {
+    const root = await createTestTempDirectory("rea-pe-export-last-ordinal-");
+    const path = join(root, "exports.dll");
+    await writeFile(
+      path,
+      peExportImage({
+        ordinalBase: 0xffff,
+        functions: [{ rva: 0x1300 }, null],
+        names: [{ name: "Kept", index: 0 }],
+      }),
+    );
+
+    const result = await cli.run({
+      arguments: ["inspect-native-exports", path, "--json"],
+    });
+
+    expect(result.exitCode, result.stderr).toBe(0);
+    const evidence = toolContract("inspect_native_exports").outputSchema.parse(
+      result.json,
+    );
+    expect(nativeExportsSchema.parse(evidence.normalized_result)).toMatchObject(
+      {
+        format: "pe",
+        coverage: { status: "complete", examined_entries: 2, exports: 1 },
+        issues: [],
+        exports: [
+          {
+            name: "Kept",
+            ordinal: 0xffff,
+            address: "0x180001300",
+            forwarder: null,
+          },
+        ],
+      },
+    );
+  },
+  30_000,
+);