Don't emit wrappers for functions that have thunks

PiperOrigin-RevId: 897564703
Change-Id: I75e73a3f9fccd81b9eca1ec37682ec8eaf14fec1

Author: Sandboxed API Team

sandboxed_api/tools/clang_generator/BUILD

@@ -83,6 +83,7 @@ cc_test(
         "emitter_test.cc",
         "frontend_action_test_util.cc",
         "frontend_action_test_util.h",
+        "sandboxed_library_emitter_test.cc",
     ],
     copts = sapi_platform_copts(),
     data = [

sandboxed_api/tools/clang_generator/CMakeLists.txt

@@ -150,6 +150,7 @@ if(BUILD_TESTING AND SAPI_BUILD_TESTING)
     frontend_action_test_util.cc
     frontend_action_test_util.h
     emitter_test.cc
+    sandboxed_library_emitter_test.cc
   )
   target_link_libraries(sapi_generator_test PRIVATE
     absl::check

sandboxed_api/tools/clang_generator/sandboxed_library_emitter.cc

@@ -468,6 +468,9 @@ absl::StatusOr<std::string> SandboxedLibraryEmitter::EmitSandboxeeHdr(
   EmitLibraryHeaders(options, out);
 
   for (const auto* func : SortedFuncs()) {
+    if (func->sandboxee_thunk) {
+      continue;
+    }
     EmitWrapperDecl(out, *func);
     out += ";\n\n";
   }

sandboxed_api/tools/clang_generator/sandboxed_library_emitter_test.cc

@@ -0,0 +1,69 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "sandboxed_api/tools/clang_generator/sandboxed_library_emitter.h"
+
+#include <memory>
+#include <string>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/status/status.h"
+#include "absl/status/status_matchers.h"
+#include "absl/status/statusor.h"
+#include "sandboxed_api/tools/clang_generator/frontend_action_test_util.h"
+#include "sandboxed_api/tools/clang_generator/generator.h"
+
+namespace sapi {
+namespace {
+
+using ::absl_testing::IsOk;
+using ::testing::HasSubstr;
+using ::testing::Not;
+
+class SandboxedLibraryEmitterTest : public FrontendActionTest {};
+
+TEST_F(SandboxedLibraryEmitterTest, SandboxeeThunkNotUsed) {
+  GeneratorOptions options;
+  options.name = "MyLib";
+  SandboxedLibraryEmitter emitter;
+  ASSERT_THAT(
+      RunFrontendAction(R"(
+        extern "C" int func_with_thunk(int a);
+
+        [[clang::annotate("sandbox", "sandboxee_thunk", "func_with_thunk")]]
+        int func_with_thunk_thunk(int a) {
+          return func_with_thunk(a) + 1;
+        }
+      )",
+                        std::make_unique<GeneratorAction>(&emitter, &options)),
+      IsOk());
+
+  ASSERT_EQ(emitter.PostParseAllFiles(), absl::OkStatus());
+  absl::StatusOr<std::string> host_src = emitter.EmitHostSrc(options);
+  ASSERT_THAT(host_src, IsOk());
+  EXPECT_THAT(*host_src, HasSubstr("api.sapi_wrapper_func_with_thunk("));
+
+  absl::StatusOr<std::string> sandboxee_src = emitter.EmitSandboxeeSrc(options);
+  ASSERT_THAT(sandboxee_src, IsOk());
+  // Problem: wrapper for func_with_thunk is generated, and thunk is not used.
+  EXPECT_THAT(*sandboxee_src, HasSubstr("sapi_wrapper_func_with_thunk"));
+  // The wrapper should call func_with_thunk, not func_with_thunk_thunk
+  EXPECT_THAT(*sandboxee_src,
+              HasSubstr("int sapi_ret_val = func_with_thunk(a);"));
+  EXPECT_THAT(*sandboxee_src, Not(HasSubstr("func_with_thunk_thunk")));
+}
+
+}  // namespace
+}  // namespace sapi