Merge pull request #40 from cblichmann:clang-tool

PiperOrigin-RevId: 313577454
Change-Id: I4de93e1ffca003899ae3c7110ab3fd10f700907c

.gitignore

@@ -2,11 +2,16 @@
 .DS_Store
 # Build files
 bazel-*
+# Local CMake build dir
 build/
 # Editor backup files
 *.swp
 *~
+# Compiled Python files and cache
+*.py[co]
+__py_cache__/
 # IDE files
+.clangd/
 .vscode/
 .idea
 compile_commands.json

CMakeLists.txt

@@ -31,6 +31,24 @@ include(SapiDeps)
 include(SapiUtil)
 include(SapiBuildDefs)
 
+# Fix Ninja generator output to not rebuild entire sub-trees needlessly.
+if(CMAKE_GENERATOR MATCHES "Ninja")
+  file(WRITE "${SAPI_BINARY_DIR}/UserMakeRulesOverride.cmake"
+    "STRING(REPLACE \"-MD\" \"-MMD\" CMAKE_DEPFILE_FLAGS_C \"\${CMAKE_DEPFILE_FLAGS_C}\")\n"
+    "STRING(REPLACE \"-MD\" \"-MMD\" CMAKE_DEPFILE_FLAGS_CXX \"\${CMAKE_DEPFILE_FLAGS_CXX}\")\n"
+  )
+  set(CMAKE_USER_MAKE_RULES_OVERRIDE
+      "${SAPI_BINARY_DIR}/UserMakeRulesOverride.cmake" CACHE INTERNAL "")
+endif()
+
+if (SAPI_FORCE_COLOR_OUTPUT)
+  if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")  # GCC
+    add_compile_options(-fdiagnostics-color=always)
+  elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")  # Clang or Apple Clang
+    add_compile_options(-fcolor-diagnostics)
+  endif()
+endif()
+
 # Make Bazel-style includes work
 configure_file(cmake/libcap_capability.h.in
                libcap/include/sys/capability.h

cmake/SapiBuildDefs.cmake

@@ -128,25 +128,42 @@ function(add_sapi_library)
     get_filename_component(src "${src}" ABSOLUTE)
     list(APPEND _sapi_full_inputs "${src}")
   endforeach()
-  list_join(_sapi_full_inputs "," _sapi_full_inputs)
   if(NOT _sapi_NOEMBED)
     set(_sapi_embed_dir "${CMAKE_CURRENT_BINARY_DIR}")
     set(_sapi_embed_name "${_sapi_NAME}")
   endif()
-  add_custom_command(
-    OUTPUT "${_sapi_gen_header}"
-    COMMAND "${SAPI_PYTHON3_EXECUTABLE}" -B
-            "${SAPI_SOURCE_DIR}/sandboxed_api/tools/generator2/sapi_generator.py"
-            "--sapi_name=${_sapi_LIBRARY_NAME}"
-            "--sapi_out=${_sapi_gen_header}"
-            "--sapi_embed_dir=${_sapi_embed_dir}"
-            "--sapi_embed_name=${_sapi_embed_name}"
-            "--sapi_functions=${_sapi_funcs}"
-            "--sapi_ns=${_sapi_NAMESPACE}"
-            # TODO(cblichmann): Implement sapi_isystem
-            "--sapi_in=${_sapi_full_inputs}"
-    COMMENT "Generating interface"
-  )
+  # TODO(cblichmann): Implement sapi_isystem
+  if(SAPI_ENABLE_GENERATOR)
+    add_custom_command(
+      OUTPUT "${_sapi_gen_header}"
+      COMMAND sapi_generator_tool
+              "--sapi_name=${_sapi_LIBRARY_NAME}"
+              "--sapi_out=${_sapi_gen_header}"
+              "--sapi_embed_dir=${_sapi_embed_dir}"
+              "--sapi_embed_name=${_sapi_embed_name}"
+              "--sapi_functions=${_sapi_funcs}"
+              "--sapi_ns=${_sapi_NAMESPACE}"
+              ${_sapi_full_inputs}
+      COMMENT "Generating interface"
+      DEPENDS ${_sapi_INPUTS}
+      VERBATIM
+    )
+  else()
+    list_join(_sapi_full_inputs "," _sapi_full_inputs)
+    add_custom_command(
+      OUTPUT "${_sapi_gen_header}"
+      COMMAND "${SAPI_PYTHON3_EXECUTABLE}" -B
+              "${SAPI_SOURCE_DIR}/sandboxed_api/tools/generator2/sapi_generator.py"
+              "--sapi_name=${_sapi_LIBRARY_NAME}"
+              "--sapi_out=${_sapi_gen_header}"
+              "--sapi_embed_dir=${_sapi_embed_dir}"
+              "--sapi_embed_name=${_sapi_embed_name}"
+              "--sapi_functions=${_sapi_funcs}"
+              "--sapi_ns=${_sapi_NAMESPACE}"
+              "--sapi_in=${_sapi_full_inputs}"
+      COMMENT "Generating interface"
+    )
+  endif()
 
   # Library with the interface
   if(NOT _sapi_SOURCES)

cmake/SapiDeps.cmake

@@ -89,10 +89,12 @@ if(SAPI_ENABLE_EXAMPLES)
   endif()
 endif()
 
-# Find Python 3 and add its location to the cache so that its available in
-# the add_sapi_library() macro in embedding projects.
-find_package(Python3 COMPONENTS Interpreter REQUIRED)
-set(SAPI_PYTHON3_EXECUTABLE "${Python3_EXECUTABLE}" CACHE INTERNAL "" FORCE)
+if(NOT SAPI_ENABLE_GENERATOR)
+  # Find Python 3 and add its location to the cache so that its available in
+  # the add_sapi_library() macro in embedding projects.
+  find_package(Python3 COMPONENTS Interpreter REQUIRED)
+  set(SAPI_PYTHON3_EXECUTABLE "${Python3_EXECUTABLE}" CACHE INTERNAL "" FORCE)
+endif()
 
 # Undo global change
 set(CMAKE_FIND_LIBRARY_SUFFIXES ${_sapi_saved_CMAKE_FIND_LIBRARY_SUFFIXES})

cmake/SapiOptions.cmake

@@ -34,3 +34,6 @@ option(SAPI_ENABLE_EXAMPLES "Build example code" ON)
 option(SAPI_DOWNLOAD_ZLIB "Download zlib at config time (only if SAPI_ENABLE_EXAMPLES is set)" ON)
 
 option(SAPI_ENABLE_TESTS "Build unit tests" ON)
+option(SAPI_ENABLE_GENERATOR "Build Clang based code generator from source" OFF)
+
+option(SAPI_FORCE_COLOR_OUTPUT "Force colored compiler diagnostics when using Ninja" ON)

cmake/glog/Download.cmake

@@ -36,6 +36,7 @@ endif()
 set(WITH_GFLAGS OFF CACHE BOOL "" FORCE)
 set(HAVE_LIB_GFLAGS 1)
 
+set(WITH_UNWIND OFF CACHE BOOL "" FORCE)
 set(UNWIND_LIBRARY FALSE)
 set(HAVE_PWD_H FALSE)
 

sandboxed_api/CMakeLists.txt

@@ -13,9 +13,12 @@
 # limitations under the License.
 
 add_subdirectory(bazel)  # For filewrapper
-add_subdirectory(examples)
 add_subdirectory(sandbox2)
 add_subdirectory(util)
+if(SAPI_ENABLE_GENERATOR)
+  add_subdirectory(tools/clang_generator)
+endif()
+add_subdirectory(examples)
 
 # sandboxed_api:proto_arg
 sapi_protobuf_generate_cpp(_sapi_proto_arg_pb_cc _sapi_proto_arg_pb_h

sandboxed_api/sandbox2/examples/zlib/CMakeLists.txt

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+find_package(ZLIB REQUIRED)
+
 # sandboxed_api/sandbox2/examples/zlib:zpipe_sandbox
 add_executable(sandbox2_zpipe_sandbox
   zpipe_sandbox.cc

sandboxed_api/sandbox2/util/fileops.cc

@@ -48,8 +48,8 @@ int FDCloser::Release() {
 
 bool GetCWD(std::string* result) {
   // Calling getcwd() with a nullptr buffer is a commonly implemented extension.
-  std::unique_ptr<char, void (*)(char*)> cwd{getcwd(nullptr, 0),
-                                             [](char* p) { free(p); }};
+  std::unique_ptr<char, void (*)(char*)> cwd(getcwd(nullptr, 0),
+                                             [](char* p) { free(p); });
   if (!cwd) {
     return false;
   }
@@ -57,6 +57,12 @@ bool GetCWD(std::string* result) {
   return true;
 }
 
+std::string GetCWD() {
+  std::string cwd;
+  GetCWD(&cwd);
+  return cwd;
+}
+
 // Makes a path absolute with respect to base. Returns true on success. Result
 // may be an alias of base or filename.
 bool MakeAbsolute(const std::string& filename, const std::string& base,

sandboxed_api/sandbox2/util/fileops.h

@@ -42,6 +42,10 @@ class FDCloser {
   int fd_;
 };
 
+// Returns the current working directory. On error, returns an empty string. Use
+// errno/GetLastError() to check the root cause in that case.
+std::string GetCWD();
+
 // Returns the target of a symlink. Returns an empty string on failure.
 std::string ReadLink(const std::string& filename);
 

sandboxed_api/tools/clang_generator/CMakeLists.txt

@@ -0,0 +1,62 @@
+# Copyright 2020 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
+#
+#     http://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.
+
+# Minimum supported: LLVM 9
+find_package(LLVM REQUIRED)
+find_package(Clang REQUIRED)
+
+add_library(sapi_generator
+  diagnostics.cc
+  diagnostics.h
+  emitter.h
+  emitter.cc
+  generator.h
+  generator.cc
+  types.h
+  types.cc
+)
+add_library(sapi::generator ALIAS sapi_generator)
+target_compile_definitions(sapi_generator PUBLIC
+  ${LLVM_DEFINITIONS}
+)
+target_include_directories(sapi_generator PUBLIC
+  ${LLVM_INCLUDE_DIRS}
+)
+llvm_map_components_to_libnames(_sapi_generator_llvm_libs
+  core
+)
+target_link_libraries(sapi_generator PUBLIC
+  sapi::base
+  absl::flat_hash_set
+  absl::memory
+  absl::random_random
+  absl::status
+  absl::strings
+  clangFormat
+  clangFrontendTool
+  clangTooling
+  sandbox2::fileops
+  sapi::status
+  ${_sapi_generator_llvm_libs}
+)
+
+add_executable(sapi_generator_tool
+  generator_tool.cc
+)
+target_link_libraries(sapi_generator_tool PRIVATE
+  sapi::base
+  sandbox2::fileops
+  sapi::generator
+)
+

sandboxed_api/tools/clang_generator/diagnostics.cc

@@ -0,0 +1,56 @@
+// Copyright 2020 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
+//
+//     http://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/diagnostics.h"
+
+#include "absl/strings/cord.h"
+
+namespace sapi {
+
+constexpr absl::string_view kSapiStatusPayload =
+    "https://github.com/google/sandboxed-api";
+
+absl::Status MakeStatusWithDiagnostic(clang::SourceLocation loc,
+                                      absl::string_view message) {
+  absl::Status status = absl::UnknownError(message);
+  absl::Cord payload;
+  uint64_t raw_loc = loc.getRawEncoding();
+  payload.Append(
+      absl::string_view(reinterpret_cast<char*>(&raw_loc), sizeof(raw_loc)));
+  status.SetPayload(kSapiStatusPayload, std::move(payload));
+  return status;
+}
+
+absl::optional<clang::SourceLocation> GetDiagnosticLocationFromStatus(
+    const absl::Status& status) {
+  if (auto payload =
+          status.GetPayload(kSapiStatusPayload).value_or(absl::Cord());
+      payload.size() == sizeof(uint64_t)) {
+    return clang::SourceLocation::getFromRawEncoding(
+        *reinterpret_cast<const uint64_t*>(payload.Flatten().data()));
+  }
+  return absl::nullopt;
+}
+
+clang::DiagnosticBuilder ReportFatalError(clang::DiagnosticsEngine& de,
+                                          clang::SourceLocation loc,
+                                          absl::string_view message) {
+  clang::DiagnosticBuilder builder =
+      de.Report(loc, de.getCustomDiagID(clang::DiagnosticsEngine::Fatal,
+                                        "header generation failed: %0"));
+  builder.AddString(llvm::StringRef(message.data(), message.size()));
+  return builder;
+}
+
+}  // namespace sapi

sandboxed_api/tools/clang_generator/diagnostics.h

@@ -0,0 +1,41 @@
+// Copyright 2020 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
+//
+//     http://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.
+
+#ifndef SANDBOXED_API_TOOLS_CLANG_GENERATOR_DIAGNOSTICS_H_
+#define SANDBOXED_API_TOOLS_CLANG_GENERATOR_DIAGNOSTICS_H_
+
+#include "absl/status/status.h"
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/SourceLocation.h"
+
+namespace sapi {
+
+// Returns a new UNKNOWN status with a payload that encodes the specified Clang
+// source location.
+absl::Status MakeStatusWithDiagnostic(clang::SourceLocation loc,
+                                      absl::string_view message);
+
+// Extracts the Clang source location encoded in a status payload.
+absl::optional<clang::SourceLocation> GetDiagnosticLocationFromStatus(
+    const absl::Status& status);
+
+clang::DiagnosticBuilder ReportFatalError(clang::DiagnosticsEngine& de,
+                                          clang::SourceLocation loc,
+                                          absl::string_view message);
+
+}  // namespace sapi
+
+#endif  // SANDBOXED_API_TOOLS_CLANG_GENERATOR_DIAGNOSTICS_H_

sandboxed_api/tools/clang_generator/emitter.cc

@@ -0,0 +1,343 @@
+// Copyright 2020 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
+//
+//     http://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/emitter.h"
+
+#include "absl/random/random.h"
+#include "absl/strings/ascii.h"
+#include "absl/strings/escaping.h"
+#include "absl/strings/match.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_join.h"
+#include "absl/strings/str_replace.h"
+#include "absl/strings/strip.h"
+#include "clang/AST/DeclCXX.h"
+#include "sandboxed_api/tools/clang_generator/diagnostics.h"
+#include "sandboxed_api/util/status_macros.h"
+
+namespace sapi {
+
+// Common file prolog with auto-generation notice.
+// Note: The includes will be adjusted by Copybara when converting to/from
+//       internal code. This is intentional.
+// Text template arguments:
+//   1. Header guard
+constexpr absl::string_view kHeaderProlog =
+    R"(// AUTO-GENERATED by the Sandboxed API generator.
+// Edits will be discarded when regenerating this file.
+
+#ifndef %1$s
+#define %1$s
+
+#include <cstdint>
+#include <type_traits>
+
+#include "absl/base/macros.h"
+#include "absl/status/status.h"
+#include "sandboxed_api/sandbox.h"
+#include "sandboxed_api/vars.h"
+#include "sandboxed_api/util/status_macros.h"
+#include "sandboxed_api/util/statusor.h"
+
+)";
+constexpr absl::string_view kHeaderEpilog =
+    R"(
+#endif  // %1$s)";
+
+// Text template arguments:
+//   1. Include for embedded sandboxee objects
+constexpr absl::string_view kEmbedInclude = R"(#include "%1$s_embed.h"
+
+)";
+
+// Text template arguments:
+//   1. Namespace name
+constexpr absl::string_view kNamespaceBeginTemplate =
+    R"(
+namespace %1$s {
+
+)";
+constexpr absl::string_view kNamespaceEndTemplate =
+    R"(
+}  // namespace %1$s
+)";
+
+// Text template arguments:
+//   1. Class name
+//   2. Embedded object identifier
+constexpr absl::string_view kEmbedClassTemplate = R"(
+// Sandbox with embedded sandboxee and default policy
+class %1$s : public ::sapi::Sandbox {
+ public:
+  %1$s() : ::sapi::Sandbox(%2$s_embed_create()) {}
+};
+
+)";
+
+// Text template arguments:
+//   1. Class name
+constexpr absl::string_view kClassHeaderTemplate = R"(
+// Sandboxed API
+class %1$s {
+ public:
+  explicit %1$s(::sapi::Sandbox* sandbox) : sandbox_(sandbox) {}
+
+  ABSL_DEPRECATED("Call sandbox() instead")
+  ::sapi::Sandbox* GetSandbox() const { return sandbox(); }
+  ::sapi::Sandbox* sandbox() const { return sandbox_; }
+)";
+
+constexpr absl::string_view kClassFooterTemplate = R"(
+ private:
+  ::sapi::Sandbox* sandbox_;
+};
+)";
+
+std::string GetIncludeGuard(absl::string_view filename) {
+  if (filename.empty()) {
+    static auto* bit_gen = new absl::BitGen();
+    return absl::StrCat(
+        // Copybara will transform the string. This is intentional.
+        "SANDBOXED_API_GENERATED_HEADER_",
+        absl::Hex(absl::Uniform<uint64_t>(*bit_gen), absl::kZeroPad16), "_");
+  }
+
+  constexpr absl::string_view kUnderscorePrefix = "SAPI";
+  std::string guard;
+  guard.reserve(filename.size() + kUnderscorePrefix.size() + 1);
+  for (auto c : filename) {
+    if (absl::ascii_isalpha(c)) {
+      guard += c;
+      continue;
+    }
+    if (guard.empty()) {
+      guard = kUnderscorePrefix;
+    }
+    if (absl::ascii_isdigit(c)) {
+      guard += c;
+    } else if (guard.back() != '_') {
+      guard += '_';
+    }
+  }
+  if (!absl::EndsWith(guard, "_")) {
+    guard += '_';
+  }
+  return guard;
+}
+
+// Returns the namespace components of a declaration's qualified name.
+std::vector<std::string> GetNamespacePath(const clang::TypeDecl* decl) {
+  std::vector<std::string> comps;
+  for (const auto* ctx = decl->getDeclContext(); ctx; ctx = ctx->getParent()) {
+    if (const auto* nd = llvm::dyn_cast<clang::NamespaceDecl>(ctx)) {
+      comps.push_back(nd->getNameAsString());
+    }
+  }
+  std::reverse(comps.begin(), comps.end());
+  return comps;
+}
+
+// Serializes the given Clang AST declaration back into compilable source code.
+std::string PrintAstDecl(const clang::Decl* decl) {
+  // TODO(cblichmann): Make types nicer
+  //   - Rewrite typedef to using
+  //   - Rewrite function pointers using std::add_pointer_t<>;
+
+  if (const auto* record = llvm::dyn_cast<clang::CXXRecordDecl>(decl)) {
+    // For C++ classes/structs, only emit a forward declaration.
+    return absl::StrCat(record->isClass() ? "class " : "struct ",
+                        std::string(record->getName()));
+  }
+  std::string pretty;
+  llvm::raw_string_ostream os(pretty);
+  decl->print(os);
+  return os.str();
+}
+
+std::string GetParamName(const clang::ParmVarDecl* decl, int index) {
+  if (std::string name = decl->getName(); !name.empty()) {
+    return absl::StrCat(name, "_");  // Suffix to avoid collisions
+  }
+  return absl::StrCat("unnamed", index, "_");
+}
+
+std::string PrintFunctionPrototype(const clang::FunctionDecl* decl) {
+  // TODO(cblichmann): Fix function pointers and anonymous namespace formatting
+  std::string out =
+      absl::StrCat(decl->getDeclaredReturnType().getAsString(), " ",
+                   std::string(decl->getQualifiedNameAsString()), "(");
+
+  std::string print_separator;
+  for (int i = 0; i < decl->getNumParams(); ++i) {
+    const clang::ParmVarDecl* param = decl->getParamDecl(i);
+
+    absl::StrAppend(&out, print_separator);
+    print_separator = ", ";
+    absl::StrAppend(&out, param->getType().getAsString());
+    if (std::string name = param->getName(); !name.empty()) {
+      absl::StrAppend(&out, " ", name);
+    }
+  }
+  absl::StrAppend(&out, ")");
+  return out;
+}
+
+sapi::StatusOr<std::string> EmitFunction(const clang::FunctionDecl* decl) {
+  std::string out;
+  absl::StrAppend(&out, "\n// ", PrintFunctionPrototype(decl), "\n");
+  const std::string function_name = decl->getNameAsString();
+  const clang::QualType return_type = decl->getDeclaredReturnType();
+  const bool returns_void = return_type->isVoidType();
+
+  const clang::ASTContext& context = decl->getASTContext();
+
+  // "Status<OptionalReturn> FunctionName("
+  absl::StrAppend(&out, MapQualTypeReturn(context, return_type), " ",
+                  function_name, "(");
+
+  struct ParameterInfo {
+    clang::QualType qual;
+    std::string name;
+  };
+  std::vector<ParameterInfo> params;
+
+  std::string print_separator;
+  for (int i = 0; i < decl->getNumParams(); ++i) {
+    const clang::ParmVarDecl* param = decl->getParamDecl(i);
+
+    ParameterInfo& param_info = params.emplace_back();
+    param_info.qual = param->getType();
+    param_info.name = GetParamName(param, i);
+
+    absl::StrAppend(&out, print_separator);
+    print_separator = ", ";
+    absl::StrAppend(&out, MapQualTypeParameter(context, param_info.qual), " ",
+                    param_info.name);
+  }
+
+  absl::StrAppend(&out, ") {\n");
+  absl::StrAppend(&out, MapQualType(context, return_type), " v_ret_;\n");
+  for (const auto& [qual, name] : params) {
+    if (!IsPointerOrReference(qual)) {
+      absl::StrAppend(&out, MapQualType(context, qual), " v_", name, "(", name,
+                      ");\n");
+    }
+  }
+  absl::StrAppend(&out, "\nSAPI_RETURN_IF_ERROR(sandbox_->Call(\"", function_name,
+                  "\", &v_ret_");
+  for (const auto& [qual, name] : params) {
+    absl::StrAppend(&out, ", ", IsPointerOrReference(qual) ? "" : "&v_", name);
+  }
+  absl::StrAppend(&out, "));\nreturn ",
+                  (returns_void ? "absl::OkStatus()" : "v_ret_.GetValue()"),
+                  ";\n}\n");
+  return out;
+}
+
+sapi::StatusOr<std::string> EmitHeader(
+    std::vector<clang::FunctionDecl*> functions, const QualTypeSet& types,
+    const GeneratorOptions& options) {
+  std::string out;
+  const std::string include_guard = GetIncludeGuard(options.out_file);
+  absl::StrAppendFormat(&out, kHeaderProlog, include_guard);
+
+  // When embedding the sandboxee, add embed header include
+  if (!options.embed_name.empty()) {
+    // Not using JoinPath() because even on Windows include paths use plain
+    // slashes.
+    std::string include_file(absl::StripSuffix(
+        absl::StrReplaceAll(options.embed_dir, {{"\\", "/"}}), "/"));
+    if (!include_file.empty()) {
+      absl::StrAppend(&include_file, "/");
+    }
+    absl::StrAppend(&include_file, options.embed_name);
+    absl::StrAppendFormat(&out, kEmbedInclude, include_file);
+  }
+
+  // If specified, wrap the generated API in a namespace
+  if (options.has_namespace()) {
+    absl::StrAppendFormat(&out, kNamespaceBeginTemplate,
+                          options.namespace_name);
+  }
+
+  // Emit type dependencies
+  // TODO(cblichmann): Coalesce namespaces
+  std::string out_types = "// Types this API depends on\n";
+  bool added_types = false;
+  for (const clang::QualType& qual : types) {
+    clang::TypeDecl* decl = nullptr;
+    if (const auto* typedef_type = qual->getAs<clang::TypedefType>()) {
+      decl = typedef_type->getDecl();
+    } else if (const auto* enum_type = qual->getAs<clang::EnumType>()) {
+      decl = enum_type->getDecl();
+    } else {
+      decl = qual->getAsRecordDecl();
+    }
+    if (!decl) {
+      continue;
+    }
+
+    const std::vector<std::string> ns_path = GetNamespacePath(decl);
+    std::string nested_ns_name;
+    if (!ns_path.empty()) {
+      if (const auto& ns_root = ns_path.front();
+          ns_root == "std" || ns_root == "sapi" || ns_root == "__gnu_cxx") {
+        // Filter out any and all declarations from the C++ standard library,
+        // from SAPI itself and from other well-known namespaces. This avoids
+        // re-declaring things like standard integer types, for example.
+        continue;
+      }
+      nested_ns_name = absl::StrCat(ns_path[0].empty() ? "" : " ",
+                                    absl::StrJoin(ns_path, "::"));
+      absl::StrAppend(&out_types, "namespace", nested_ns_name, " {\n");
+    }
+    absl::StrAppend(&out_types, PrintAstDecl(decl), ";");
+    if (!ns_path.empty()) {
+      absl::StrAppend(&out_types, "\n}  // namespace", nested_ns_name);
+    }
+    absl::StrAppend(&out_types, "\n");
+    added_types = true;
+  }
+  if (added_types) {
+    absl::StrAppend(&out, out_types);
+  }
+
+  // Optionally emit a default sandbox that instantiates an embedded sandboxee
+  if (!options.embed_name.empty()) {
+    // TODO(cblichmann): Make the "Sandbox" suffix configurable.
+    absl::StrAppendFormat(
+        &out, kEmbedClassTemplate, absl::StrCat(options.name, "Sandbox"),
+        absl::StrReplaceAll(options.embed_name, {{"-", "_"}}));
+  }
+
+  // Emit the actual Sandboxed API
+  // TODO(cblichmann): Make the "Api" suffix configurable or at least optional.
+  absl::StrAppendFormat(&out, kClassHeaderTemplate,
+                        absl::StrCat(options.name, "Api"));
+  std::string out_func;
+  for (const clang::FunctionDecl* decl : functions) {
+    SAPI_ASSIGN_OR_RETURN(out_func, EmitFunction(decl));
+    absl::StrAppend(&out, out_func);
+  }
+  absl::StrAppend(&out, kClassFooterTemplate);
+
+  // Close out the header: close namespace (if needed) and end include guard
+  if (options.has_namespace()) {
+    absl::StrAppendFormat(&out, kNamespaceEndTemplate, options.namespace_name);
+  }
+  absl::StrAppendFormat(&out, kHeaderEpilog, include_guard);
+  return out;
+}
+
+}  // namespace sapi

sandboxed_api/tools/clang_generator/emitter.h

@@ -0,0 +1,45 @@
+// Copyright 2020 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
+//
+//     http://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.
+
+#ifndef SANDBOXED_API_TOOLS_CLANG_GENERATOR_EMITTER_H_
+#define SANDBOXED_API_TOOLS_CLANG_GENERATOR_EMITTER_H_
+
+#include <string>
+
+#include "absl/status/status.h"
+#include "absl/strings/string_view.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/Type.h"
+#include "sandboxed_api/tools/clang_generator/generator.h"
+#include "sandboxed_api/tools/clang_generator/types.h"
+#include "sandboxed_api/util/statusor.h"
+
+namespace sapi {
+
+// Constructs an include guard name for the given filename. The name is of the
+// same for as the include guards in this project.
+// For example,
+//   sandboxed_api/examples/zlib/zlib-sapi.sapi.h
+// will be mapped to
+//   SANDBOXED_API_EXAMPLES_ZLIB_ZLIB_SAPI_SAPI_H_
+std::string GetIncludeGuard(absl::string_view filename);
+
+// Outputs a formatted header for a list of functions and their related types.
+sapi::StatusOr<std::string> EmitHeader(
+    std::vector<clang::FunctionDecl*> functions, const QualTypeSet& types,
+    const GeneratorOptions& options);
+
+}  // namespace sapi
+
+#endif  // SANDBOXED_API_TOOLS_CLANG_GENERATOR_EMITTER_H_

sandboxed_api/tools/clang_generator/generator.cc

@@ -0,0 +1,127 @@
+// Copyright 2020 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
+//
+//     http://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/generator.h"
+
+#include <fstream>
+#include <iostream>
+
+#include "absl/status/status.h"
+#include "clang/Format/Format.h"
+#include "sandboxed_api/sandbox2/util/fileops.h"
+#include "sandboxed_api/tools/clang_generator/diagnostics.h"
+#include "sandboxed_api/tools/clang_generator/emitter.h"
+#include "sandboxed_api/util/status_macros.h"
+#include "sandboxed_api/util/statusor.h"
+
+namespace sapi {
+namespace {
+
+// Replaces the file extension of a path name.
+std::string ReplaceFileExtension(absl::string_view path,
+                                 absl::string_view new_extension) {
+  auto last_slash = path.rfind('/');
+  auto pos = path.rfind('.', last_slash);
+  if (pos != absl::string_view::npos && last_slash != absl::string_view::npos) {
+    pos += last_slash;
+  }
+  return absl::StrCat(path.substr(0, pos), new_extension);
+}
+
+std::string GetOutputFilename(absl::string_view source_file) {
+  return ReplaceFileExtension(source_file, ".sapi.h");
+}
+
+inline absl::string_view ToStringView(llvm::StringRef ref) {
+  return absl::string_view(ref.data(), ref.size());
+}
+
+}  // namespace
+
+bool GeneratorASTVisitor::VisitFunctionDecl(clang::FunctionDecl* decl) {
+  if (!decl->isCXXClassMember() &&  // Skip classes
+      decl->isExternC() &&          // Skip non external functions
+      !decl->isTemplated() &&       // Skip function templates
+      // Process either all function or just the requested ones
+      (options_->function_names.empty() ||
+       options_->function_names.count(ToStringView(decl->getName())) > 0)) {
+    functions_.push_back(decl);
+    GatherRelatedTypes(decl->getDeclaredReturnType(), &types_);
+    for (const clang::ParmVarDecl* param : decl->parameters()) {
+      GatherRelatedTypes(param->getType(), &types_);
+    }
+  }
+  return true;
+}
+
+namespace internal {
+
+sapi::StatusOr<std::string> ReformatGoogleStyle(const std::string& filename,
+                                                  const std::string& code) {
+  // Configure code style based on Google style, but enforce pointer alignment
+  clang::format::FormatStyle style =
+      clang::format::getGoogleStyle(clang::format::FormatStyle::LK_Cpp);
+  style.DerivePointerAlignment = false;
+  style.PointerAlignment = clang::format::FormatStyle::PAS_Left;
+
+  clang::tooling::Replacements replacements = clang::format::reformat(
+      style, code, llvm::makeArrayRef(clang::tooling::Range(0, code.size())),
+      filename);
+
+  llvm::Expected<std::string> formatted_header =
+      clang::tooling::applyAllReplacements(code, replacements);
+  if (!formatted_header) {
+    return absl::InternalError(llvm::toString(formatted_header.takeError()));
+  }
+  return *formatted_header;
+}
+
+}  // namespace internal
+
+absl::Status GeneratorASTConsumer::GenerateAndSaveHeader() {
+  const std::string out_file =
+      options_->out_file.empty() ? GetOutputFilename(in_file_)
+                                 : sandbox2::file_util::fileops::MakeAbsolute(
+                                       options_->out_file, options_->work_dir);
+
+  SAPI_ASSIGN_OR_RETURN(const std::string header,
+                   EmitHeader(visitor_.functions_, visitor_.types_, *options_));
+  SAPI_ASSIGN_OR_RETURN(const std::string formatted_header,
+                   internal::ReformatGoogleStyle(in_file_, header));
+
+  std::ofstream os(out_file, std::ios::out | std::ios::trunc);
+  os << formatted_header;
+  if (!os) {
+    return absl::UnknownError("I/O error");
+  }
+  return absl::OkStatus();
+}
+
+void GeneratorASTConsumer::HandleTranslationUnit(clang::ASTContext& context) {
+  absl::Status status;
+  if (!visitor_.TraverseDecl(context.getTranslationUnitDecl())) {
+    status = absl::InternalError("AST traversal exited early");
+  } else {
+    status = GenerateAndSaveHeader();
+  }
+
+  if (!status.ok()) {
+    ReportFatalError(context.getDiagnostics(),
+                     GetDiagnosticLocationFromStatus(status).value_or(
+                         context.getTranslationUnitDecl()->getBeginLoc()),
+                     status.message());
+  }
+}
+
+}  // namespace sapi

sandboxed_api/tools/clang_generator/generator.h

@@ -0,0 +1,123 @@
+// Copyright 2020 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
+//
+//     http://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.
+
+#ifndef SANDBOXED_API_TOOLS_CLANG_GENERATOR_GENERATOR_H_
+#define SANDBOXED_API_TOOLS_CLANG_GENERATOR_GENERATOR_H_
+
+#include <string>
+
+#include "absl/container/flat_hash_set.h"
+#include "absl/status/status.h"
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/RecursiveASTVisitor.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/FrontendAction.h"
+#include "clang/Tooling/Tooling.h"
+#include "sandboxed_api/tools/clang_generator/types.h"
+#include "sandboxed_api/util/statusor.h"
+
+namespace sapi {
+
+struct GeneratorOptions {
+  template <typename ContainerT>
+  GeneratorOptions& set_function_names(const ContainerT& value) {
+    function_names.clear();
+    function_names.insert(std::begin(value), std::end(value));
+    return *this;
+  }
+
+  bool has_namespace() const { return !namespace_name.empty(); }
+
+  absl::flat_hash_set<std::string> function_names;
+
+  // Output options
+  std::string work_dir;
+  std::string name;            // Name of the Sandboxed API
+  std::string namespace_name;  // Namespace to wrap the SAPI in
+  std::string out_file;        // Output path of the generated header
+  std::string embed_dir;       // Directory with embedded includes
+  std::string embed_name;      // Identifier of the embed object
+};
+
+class GeneratorASTVisitor
+    : public clang::RecursiveASTVisitor<GeneratorASTVisitor> {
+ public:
+  bool VisitFunctionDecl(clang::FunctionDecl* decl);
+
+ private:
+  friend class GeneratorASTConsumer;
+  const GeneratorOptions* options_ = nullptr;
+
+  std::vector<clang::FunctionDecl*> functions_;
+  QualTypeSet types_;
+};
+
+namespace internal {
+
+sapi::StatusOr<std::string> ReformatGoogleStyle(const std::string& filename,
+                                                  const std::string& code);
+
+}  // namespace internal
+
+class GeneratorASTConsumer : public clang::ASTConsumer {
+ public:
+  GeneratorASTConsumer(std::string in_file, const GeneratorOptions* options)
+      : in_file_(std::move(in_file)), options_(options) {
+    visitor_.options_ = options_;
+  }
+
+ private:
+  void HandleTranslationUnit(clang::ASTContext& context) override;
+
+  absl::Status GenerateAndSaveHeader();
+
+  std::string in_file_;
+  const GeneratorOptions* options_;
+
+  GeneratorASTVisitor visitor_;
+};
+
+class GeneratorAction : public clang::ASTFrontendAction {
+ public:
+  explicit GeneratorAction(const GeneratorOptions* options)
+      : options_(options) {}
+
+ private:
+  std::unique_ptr<clang::ASTConsumer> CreateASTConsumer(
+      clang::CompilerInstance&, llvm::StringRef in_file) override {
+    return absl::make_unique<GeneratorASTConsumer>(std::string(in_file),
+                                                   options_);
+  }
+
+  bool hasCodeCompletionSupport() const override { return false; }
+
+  const GeneratorOptions* options_;
+};
+
+class GeneratorFactory : public clang::tooling::FrontendActionFactory {
+ public:
+  explicit GeneratorFactory(GeneratorOptions options = {})
+      : options_(std::move(options)) {}
+
+ private:
+  clang::FrontendAction* create() override {
+    return new GeneratorAction(&options_);
+  }
+
+  GeneratorOptions options_;
+};
+
+}  // namespace sapi
+
+#endif  // SANDBOXED_API_TOOLS_CLANG_GENERATOR_GENERATOR_H_

sandboxed_api/tools/clang_generator/generator_tool.cc

@@ -0,0 +1,106 @@
+// Copyright 2020 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
+//
+//     http://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 <string>
+#include <vector>
+
+#include "absl/memory/memory.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/Frontend/FrontendActions.h"
+#include "clang/Tooling/CommonOptionsParser.h"
+#include "llvm/Support/CommandLine.h"
+#include "sandboxed_api/sandbox2/util/fileops.h"
+#include "sandboxed_api/tools/clang_generator/generator.h"
+
+namespace sapi {
+namespace {
+
+static auto* g_tool_category =
+    new llvm::cl::OptionCategory("Sandboxed API Options");
+
+static auto* g_common_help =
+    new llvm::cl::extrahelp(clang::tooling::CommonOptionsParser::HelpMessage);
+static auto* g_extra_help = new llvm::cl::extrahelp(
+    "Full documentation at: <https://developers.google.com/sandboxed-api/>\n"
+    "Report bugs to <https://github.com/google/sandboxed-api/issues>\n");
+
+// Command line options
+static auto* g_sapi_embed_dir = new llvm::cl::opt<std::string>(
+    "sapi_embed_dir", llvm::cl::desc("Directory with embedded includes"),
+    llvm::cl::cat(*g_tool_category));
+static auto* g_sapi_embed_name = new llvm::cl::opt<std::string>(
+    "sapi_embed_name", llvm::cl::desc("Identifier of the embed object"),
+    llvm::cl::cat(*g_tool_category));
+static auto* g_sapi_functions = new llvm::cl::list<std::string>(
+    "sapi_functions", llvm::cl::CommaSeparated,
+    llvm::cl::desc("List of functions to generate a Sandboxed API for. If "
+                   "empty, generates a SAPI for all functions found."),
+    llvm::cl::cat(*g_tool_category));
+static auto* g_sapi_in = new llvm::cl::list<std::string>(
+    "sapi_in", llvm::cl::CommaSeparated,
+    llvm::cl::desc("List of input files to analyze. Deprecated, use positional "
+                   "arguments instead."),
+    llvm::cl::cat(*g_tool_category));
+static auto* g_sapi_isystem = new llvm::cl::opt<std::string>(
+    "sapi_isystem", llvm::cl::desc("Extra system include paths"),
+    llvm::cl::cat(*g_tool_category));
+static auto* g_sapi_limit_scan_depth = new llvm::cl::opt<bool>(
+    "sapi_limit_scan_depth",
+    llvm::cl::desc(
+        "Whether to only scan for functions in the top-most translation unit"),
+    llvm::cl::cat(*g_tool_category));
+static auto* g_sapi_name = new llvm::cl::opt<std::string>(
+    "sapi_name", llvm::cl::desc("Name of the Sandboxed API library"),
+    llvm::cl::cat(*g_tool_category));
+static auto* g_sapi_ns = new llvm::cl::opt<std::string>(
+    "sapi_ns", llvm::cl::desc("C++ namespace to wrap Sandboxed API class in"),
+    llvm::cl::cat(*g_tool_category));
+static auto* g_sapi_out = new llvm::cl::opt<std::string>(
+    "sapi_out",
+    llvm::cl::desc(
+        "Ouput path of the generated header. If empty, simply appends .sapi.h "
+        "to the basename of the first source file specified."),
+    llvm::cl::cat(*g_tool_category));
+
+}  // namespace
+
+GeneratorOptions GeneratorOptionsFromFlags() {
+  GeneratorOptions options;
+  options.function_names.insert(g_sapi_functions->begin(),
+                                g_sapi_functions->end());
+  options.work_dir = sandbox2::file_util::fileops::GetCWD();
+  options.name = *g_sapi_name;
+  options.namespace_name = *g_sapi_ns;
+  options.out_file = *g_sapi_out;
+  options.embed_dir = *g_sapi_embed_dir;
+  options.embed_name = *g_sapi_embed_name;
+  return options;
+}
+
+}  // namespace sapi
+
+int main(int argc, const char** argv) {
+  clang::tooling::CommonOptionsParser opt_parser(
+      argc, argv, *sapi::g_tool_category, llvm::cl::ZeroOrMore,
+      "Generates a Sandboxed API header for C/C++ translation units.");
+  std::vector<std::string> sources = opt_parser.getSourcePathList();
+  for (const auto& sapi_in : *sapi::g_sapi_in) {
+    sources.push_back(sapi_in);
+  }
+
+  clang::tooling::ClangTool tool(opt_parser.getCompilations(), sources);
+  return tool.run(absl::make_unique<sapi::GeneratorFactory>(
+                      sapi::GeneratorOptionsFromFlags())
+                      .get());
+}

sandboxed_api/tools/clang_generator/types.cc

@@ -0,0 +1,203 @@
+// Copyright 2020 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
+//
+//     http://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/types.h"
+
+#include "absl/strings/str_cat.h"
+
+namespace sapi {
+
+void GatherRelatedTypes(clang::QualType qual, QualTypeSet* types) {
+  if (const auto* typedef_type = qual->getAs<clang::TypedefType>()) {
+    GatherRelatedTypes(typedef_type->getDecl()->getUnderlyingType(), types);
+    types->insert(qual);
+    return;
+  }
+
+  if (qual->isFunctionPointerType() || qual->isFunctionReferenceType() ||
+      qual->isMemberFunctionPointerType()) {
+    if (const auto* function_type = qual->getPointeeOrArrayElementType()
+                                        ->getAs<clang::FunctionProtoType>()) {
+      // Note: Do not add the function type itself, as this will always be a
+      //       pointer argument. We only need to collect all its related types.
+      GatherRelatedTypes(function_type->getReturnType(), types);
+      for (const clang::QualType& param : function_type->getParamTypes()) {
+        GatherRelatedTypes(param, types);
+      }
+      return;
+    }
+  }
+
+  if (IsPointerOrReference(qual)) {
+    clang::QualType pointee = qual->getPointeeType();
+    while (IsPointerOrReference(pointee)) {
+      pointee = pointee->getPointeeType();
+    }
+    GatherRelatedTypes(pointee, types);
+    return;
+  }
+
+  // C array with specified constant size (i.e. int a[42])?
+  if (const clang::ArrayType* array_type = qual->getAsArrayTypeUnsafe()) {
+    GatherRelatedTypes(array_type->getElementType(), types);
+    return;
+  }
+
+  if (IsSimple(qual) || qual->isEnumeralType()) {
+    if (const clang::EnumType* enum_type = qual->getAs<clang::EnumType>()) {
+      // Collect the underlying integer type of enum classes as well, as it may
+      // be a typedef.
+      if (const clang::EnumDecl* decl = enum_type->getDecl(); decl->isFixed()) {
+        GatherRelatedTypes(decl->getIntegerType(), types);
+      }
+    }
+    types->insert(qual);
+    return;
+  }
+
+  if (const auto* record_type = qual->getAs<clang::RecordType>()) {
+    const clang::RecordDecl* decl = record_type->getDecl();
+    for (const clang::FieldDecl* field : decl->fields()) {
+      GatherRelatedTypes(field->getType(), types);
+    }
+    types->insert(qual);
+    return;
+  }
+}
+
+namespace {
+
+// Removes "const" from a qualified type if it denotes a pointer or reference
+// type.
+clang::QualType MaybeRemoveConst(const clang::ASTContext& context,
+                                 clang::QualType qual) {
+  if (IsPointerOrReference(qual)) {
+    clang::QualType pointee_qual = qual->getPointeeType();
+    pointee_qual.removeLocalConst();
+    qual = context.getPointerType(pointee_qual);
+  }
+  return qual;
+}
+
+}  // namespace
+
+std::string MapQualType(const clang::ASTContext& context,
+                        clang::QualType qual) {
+  if (const auto* builtin = qual->getAs<clang::BuiltinType>()) {
+    switch (builtin->getKind()) {
+      case clang::BuiltinType::Void:
+      case clang::BuiltinType::NullPtr:
+        return "::sapi::v::Void";
+
+      /*
+       * Unsigned types
+       */
+      case clang::BuiltinType::Bool:
+        return "::sapi::v::Bool";
+      // Unsigned character types
+      case clang::BuiltinType::Char_U:
+      case clang::BuiltinType::UChar:
+        return "::sapi::v::UChar";
+      case clang::BuiltinType::WChar_U:
+        return "::sapi::v::ULong";  // 32-bit, correct for Linux and UTF-32
+      // Added in C++20
+      case clang::BuiltinType::Char8:  // Underlying type: unsigned char
+        return "::sapi::v::UChar";
+      case clang::BuiltinType::Char16:  // Underlying type: uint_least16_t
+        return "::sapi::v::UShort";
+      case clang::BuiltinType::Char32:  // Underlying type: uint_least32_t
+        return "::sapi::v::ULong";
+      // Standard unsigned types
+      case clang::BuiltinType::UShort:
+        return "::sapi::v::UShort";
+      case clang::BuiltinType::UInt:
+        return "::sapi::v::UInt";
+      case clang::BuiltinType::ULong:
+        return "::sapi::v::ULong";
+      case clang::BuiltinType::ULongLong:
+        return "::sapi::v::ULLong";
+      // TODO(cblichmann): Add 128-bit integer support
+      // case clang::BuiltinType::UInt128:
+      //   return "::sapi::v::UInt128";
+
+      /*
+       * Signed types
+       */
+      // Signed character types
+      case clang::BuiltinType::Char_S:
+      case clang::BuiltinType::SChar:
+        return "::sapi::v::Char";
+      case clang::BuiltinType::WChar_S:
+        return "::sapi::v::Long";  // 32-bit, correct for Linux and UTF-32
+
+      // Standard signed types
+      case clang::BuiltinType::Short:
+        return "::sapi::v::Short";
+      case clang::BuiltinType::Int:
+        return "::sapi::v::Int";
+      case clang::BuiltinType::Long:
+        return "::sapi::v::Long";
+      case clang::BuiltinType::LongLong:
+        return "::sapi::v::LLong";
+      // TODO(cblichmann): Add 128-bit integer support
+      // case clang::BuiltinType::Int128:
+      //   return "::sapi::v::Int128";
+
+      /*
+       * Floating-point types
+       */
+      // TODO(cblichmann): Map half/__fp16, _Float16 and __float128 types
+      case clang::BuiltinType::Float:
+        return "::sapi::v::Reg<float>";
+      case clang::BuiltinType::Double:
+        return "::sapi::v::Reg<double>";
+      case clang::BuiltinType::LongDouble:
+        return "::sapi::v::Reg<long double>";
+
+      default:
+        break;
+    }
+  } else if (const auto* enum_type = qual->getAs<clang::EnumType>()) {
+    return absl::StrCat("::sapi::v::IntBase<",
+                        enum_type->getDecl()->getQualifiedNameAsString(), ">");
+  } else if (IsPointerOrReference(qual)) {
+    // Remove "const" qualifier from a pointer or reference type's pointee, as
+    // e.g. const pointers do not work well with SAPI.
+    return absl::StrCat("::sapi::v::Reg<",
+                        MaybeRemoveConst(context, qual).getAsString(), ">");
+  }
+  // Best-effort mapping to "int", leave a comment.
+  return absl::StrCat("::sapi::v::Int /* aka '", qual.getAsString(), "' */");
+}
+
+std::string MapQualTypeParameter(const clang::ASTContext& /*context*/,
+                                 clang::QualType qual) {
+  // TODO(cblichmann): Define additional mappings, as appropriate
+  //   _Bool              -> bool
+  //   unsigned long long -> uint64_t (where applicable)
+  //   ...
+  return IsPointerOrReference(qual) ? "::sapi::v::Ptr*" : qual.getAsString();
+}
+
+std::string MapQualTypeReturn(const clang::ASTContext& context,
+                              clang::QualType qual) {
+  if (qual->isVoidType()) {
+    return "absl::Status";
+  }
+  // Remove const qualifier like in MapQualType().
+  return absl::StrCat("::sapi::StatusOr<",
+                      MaybeRemoveConst(context, qual).getAsString(), ">");
+}
+
+}  // namespace sapi

sandboxed_api/tools/clang_generator/types.h

@@ -0,0 +1,78 @@
+// Copyright 2020 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
+//
+//     http://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.
+
+#ifndef SANDBOXED_API_TOOLS_CLANG_GENERATOR_TYPES_H_
+#define SANDBOXED_API_TOOLS_CLANG_GENERATOR_TYPES_H_
+
+#include <string>
+#include <vector>
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Type.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
+
+namespace sapi {
+
+using QualTypeSet =
+    llvm::SetVector<clang::QualType, std::vector<clang::QualType>,
+                    llvm::SmallPtrSet<clang::QualType, 8>>;
+
+// Returns whether a type is "simple". Simple types are arithemtic types,
+// i.e. signed and unsigned integer, character and bool types, as well as
+// "void".
+inline bool IsSimple(clang::QualType qual) {
+  return qual->isArithmeticType() || qual->isVoidType();
+}
+
+inline bool IsPointerOrReference(clang::QualType qual) {
+  return qual->isPointerType() || qual->isMemberPointerType() ||
+         qual->isLValueReferenceType() || qual->isRValueReferenceType();
+}
+
+// Computes the transitive closure of all types that a type depends on. Those
+// are types that need to be declared before a declaration of the type denoted
+// by the qual parameter is valid. For example, given
+//   struct SubStruct { bool truth_value; };
+//   struct AggregateStruct {
+//     int int_member;
+//     SubStruct struct_member;
+//   };
+//
+// calling this function on the type "AggregateStruct" yields these types:
+//   int
+//   SubStruct
+//   bool
+void GatherRelatedTypes(clang::QualType qual, QualTypeSet* types);
+
+// Maps a qualified type to a fully qualified SAPI-compatible type name. This
+// is used for the generated code that invokes the actual function call RPC.
+// If no mapping can be found, "int" is assumed.
+std::string MapQualType(const clang::ASTContext& context, clang::QualType qual);
+
+// Maps a qualified type used as a function parameter to a type name compatible
+// with the generated Sandboxed API.
+std::string MapQualTypeParameter(const clang::ASTContext& context,
+                                 clang::QualType qual);
+
+// Maps a qualified type used as a function return type to a type name
+// compatible with the generated Sandboxed API. Uses MapQualTypeParameter() and
+// wraps the type in a sapi::StatusOr<> if qual is non-void. Otherwise returns
+// absl::Status.
+std::string MapQualTypeReturn(const clang::ASTContext& context,
+                              clang::QualType qual);
+
+}  // namespace sapi
+
+#endif  // SANDBOXED_API_TOOLS_CLANG_GENERATOR_TYPES_H_