mirror of
https://github.com/google/sandboxed-api.git
synced 2024-03-22 13:11:30 +08:00
347 lines
11 KiB
C++
347 lines
11 KiB
C++
// Copyright 2020 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "sandboxed_api/tools/clang_generator/emitter.h"
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#include "absl/random/random.h"
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#include "absl/strings/ascii.h"
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#include "absl/strings/escaping.h"
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#include "absl/strings/match.h"
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#include "absl/strings/str_cat.h"
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#include "absl/strings/str_format.h"
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#include "absl/strings/str_join.h"
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#include "absl/strings/str_replace.h"
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#include "absl/strings/strip.h"
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#include "clang/AST/DeclCXX.h"
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#include "sandboxed_api/tools/clang_generator/diagnostics.h"
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#include "sandboxed_api/util/status_macros.h"
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namespace sapi {
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// Common file prolog with auto-generation notice.
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// Note: The includes will be adjusted by Copybara when converting to/from
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// internal code. This is intentional.
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// Text template arguments:
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// 1. Header guard
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constexpr absl::string_view kHeaderProlog =
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R"(// AUTO-GENERATED by the Sandboxed API generator.
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// Edits will be discarded when regenerating this file.
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#ifndef %1$s
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#define %1$s
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#include <cstdint>
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#include <type_traits>
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#include "absl/base/macros.h"
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#include "absl/status/status.h"
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#include "sandboxed_api/util/statusor.h"
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#include "sandboxed_api/sandbox.h"
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#include "sandboxed_api/vars.h"
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#include "sandboxed_api/util/status_macros.h"
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)";
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constexpr absl::string_view kHeaderEpilog =
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R"(
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#endif // %1$s)";
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// Text template arguments:
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// 1. Include for embedded sandboxee objects
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constexpr absl::string_view kEmbedInclude = R"(#include "%1$s_embed.h"
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)";
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// Text template arguments:
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// 1. Namespace name
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constexpr absl::string_view kNamespaceBeginTemplate =
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R"(
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namespace %1$s {
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)";
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constexpr absl::string_view kNamespaceEndTemplate =
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R"(
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} // namespace %1$s
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)";
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// Text template arguments:
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// 1. Class name
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// 2. Embedded object identifier
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constexpr absl::string_view kEmbedClassTemplate = R"(
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// Sandbox with embedded sandboxee and default policy
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class %1$s : public ::sapi::Sandbox {
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public:
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%1$s() : ::sapi::Sandbox(%2$s_embed_create()) {}
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};
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)";
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// Text template arguments:
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// 1. Class name
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constexpr absl::string_view kClassHeaderTemplate = R"(
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// Sandboxed API
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class %1$s {
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public:
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explicit %1$s(::sapi::Sandbox* sandbox) : sandbox_(sandbox) {}
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ABSL_DEPRECATED("Call sandbox() instead")
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::sapi::Sandbox* GetSandbox() const { return sandbox(); }
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::sapi::Sandbox* sandbox() const { return sandbox_; }
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)";
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constexpr absl::string_view kClassFooterTemplate = R"(
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private:
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::sapi::Sandbox* sandbox_;
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};
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)";
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std::string GetIncludeGuard(absl::string_view filename) {
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if (filename.empty()) {
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static auto* bit_gen = new absl::BitGen();
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return absl::StrCat(
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// Copybara will transform the string. This is intentional.
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"SANDBOXED_API_GENERATED_HEADER_",
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absl::AsciiStrToUpper(absl::StrCat(
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absl::Hex(absl::Uniform<uint64_t>(*bit_gen), absl::kZeroPad16))),
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"_");
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}
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constexpr absl::string_view kUnderscorePrefix = "SAPI_";
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std::string guard;
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guard.reserve(filename.size() + kUnderscorePrefix.size() + 1);
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for (auto c : filename) {
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if (absl::ascii_isalpha(c)) {
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guard += absl::ascii_toupper(c);
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continue;
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}
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if (guard.empty()) {
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guard = kUnderscorePrefix;
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}
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if (absl::ascii_isdigit(c)) {
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guard += c;
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} else if (guard.back() != '_') {
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guard += '_';
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}
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}
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if (!absl::EndsWith(guard, "_")) {
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guard += '_';
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}
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return guard;
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}
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// Returns the namespace components of a declaration's qualified name.
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std::vector<std::string> GetNamespacePath(const clang::TypeDecl* decl) {
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std::vector<std::string> comps;
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for (const auto* ctx = decl->getDeclContext(); ctx; ctx = ctx->getParent()) {
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if (const auto* nd = llvm::dyn_cast<clang::NamespaceDecl>(ctx)) {
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comps.push_back(nd->getNameAsString());
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}
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}
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std::reverse(comps.begin(), comps.end());
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return comps;
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}
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// Serializes the given Clang AST declaration back into compilable source code.
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std::string PrintAstDecl(const clang::Decl* decl) {
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// TODO(cblichmann): Make types nicer
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// - Rewrite typedef to using
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// - Rewrite function pointers using std::add_pointer_t<>;
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if (const auto* record = llvm::dyn_cast<clang::CXXRecordDecl>(decl)) {
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// For C++ classes/structs, only emit a forward declaration.
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return absl::StrCat(record->isClass() ? "class " : "struct ",
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std::string(record->getName()));
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}
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std::string pretty;
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llvm::raw_string_ostream os(pretty);
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decl->print(os);
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return os.str();
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}
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std::string GetParamName(const clang::ParmVarDecl* decl, int index) {
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if (std::string name = decl->getName().str(); !name.empty()) {
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return absl::StrCat(name, "_"); // Suffix to avoid collisions
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}
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return absl::StrCat("unnamed", index, "_");
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}
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std::string PrintFunctionPrototype(const clang::FunctionDecl* decl) {
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// TODO(cblichmann): Fix function pointers and anonymous namespace formatting
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std::string out =
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absl::StrCat(decl->getDeclaredReturnType().getAsString(), " ",
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std::string(decl->getQualifiedNameAsString()), "(");
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std::string print_separator;
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for (int i = 0; i < decl->getNumParams(); ++i) {
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const clang::ParmVarDecl* param = decl->getParamDecl(i);
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absl::StrAppend(&out, print_separator);
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print_separator = ", ";
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absl::StrAppend(&out, param->getType().getAsString());
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if (std::string name = param->getName().str(); !name.empty()) {
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absl::StrAppend(&out, " ", name);
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}
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}
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absl::StrAppend(&out, ")");
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return out;
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}
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sapi::StatusOr<std::string> EmitFunction(const clang::FunctionDecl* decl) {
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std::string out;
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absl::StrAppend(&out, "\n// ", PrintFunctionPrototype(decl), "\n");
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const std::string function_name = decl->getNameAsString();
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const clang::QualType return_type = decl->getDeclaredReturnType();
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const bool returns_void = return_type->isVoidType();
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const clang::ASTContext& context = decl->getASTContext();
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// "Status<OptionalReturn> FunctionName("
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absl::StrAppend(&out, MapQualTypeReturn(context, return_type), " ",
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function_name, "(");
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struct ParameterInfo {
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clang::QualType qual;
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std::string name;
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};
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std::vector<ParameterInfo> params;
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std::string print_separator;
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for (int i = 0; i < decl->getNumParams(); ++i) {
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const clang::ParmVarDecl* param = decl->getParamDecl(i);
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ParameterInfo& param_info = params.emplace_back();
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param_info.qual = param->getType();
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param_info.name = GetParamName(param, i);
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absl::StrAppend(&out, print_separator);
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print_separator = ", ";
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absl::StrAppend(&out, MapQualTypeParameter(context, param_info.qual), " ",
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param_info.name);
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}
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absl::StrAppend(&out, ") {\n");
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absl::StrAppend(&out, MapQualType(context, return_type), " v_ret_;\n");
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for (const auto& [qual, name] : params) {
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if (!IsPointerOrReference(qual)) {
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absl::StrAppend(&out, MapQualType(context, qual), " v_", name, "(", name,
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");\n");
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}
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}
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absl::StrAppend(&out, "\nSAPI_RETURN_IF_ERROR(sandbox_->Call(\"", function_name,
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"\", &v_ret_");
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for (const auto& [qual, name] : params) {
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absl::StrAppend(&out, ", ", IsPointerOrReference(qual) ? "" : "&v_", name);
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}
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absl::StrAppend(&out, "));\nreturn ",
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(returns_void ? "absl::OkStatus()" : "v_ret_.GetValue()"),
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";\n}\n");
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return out;
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}
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sapi::StatusOr<std::string> EmitHeader(
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std::vector<clang::FunctionDecl*> functions, const QualTypeSet& types,
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const GeneratorOptions& options) {
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std::string out;
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const std::string include_guard = GetIncludeGuard(options.out_file);
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absl::StrAppendFormat(&out, kHeaderProlog, include_guard);
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// When embedding the sandboxee, add embed header include
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if (!options.embed_name.empty()) {
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// Not using JoinPath() because even on Windows include paths use plain
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// slashes.
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std::string include_file(absl::StripSuffix(
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absl::StrReplaceAll(options.embed_dir, {{"\\", "/"}}), "/"));
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if (!include_file.empty()) {
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absl::StrAppend(&include_file, "/");
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}
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absl::StrAppend(&include_file, options.embed_name);
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absl::StrAppendFormat(&out, kEmbedInclude, include_file);
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}
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// If specified, wrap the generated API in a namespace
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if (options.has_namespace()) {
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absl::StrAppendFormat(&out, kNamespaceBeginTemplate,
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options.namespace_name);
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}
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// Emit type dependencies
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// TODO(cblichmann): Coalesce namespaces
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std::string out_types = "// Types this API depends on\n";
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bool added_types = false;
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for (const clang::QualType& qual : types) {
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clang::TypeDecl* decl = nullptr;
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if (const auto* typedef_type = qual->getAs<clang::TypedefType>()) {
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decl = typedef_type->getDecl();
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} else if (const auto* enum_type = qual->getAs<clang::EnumType>()) {
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decl = enum_type->getDecl();
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} else {
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decl = qual->getAsRecordDecl();
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}
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if (!decl) {
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continue;
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}
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const std::vector<std::string> ns_path = GetNamespacePath(decl);
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std::string nested_ns_name;
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if (!ns_path.empty()) {
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if (const auto& ns_root = ns_path.front();
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ns_root == "std" || ns_root == "sapi" || ns_root == "__gnu_cxx") {
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// Filter out any and all declarations from the C++ standard library,
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// from SAPI itself and from other well-known namespaces. This avoids
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// re-declaring things like standard integer types, for example.
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continue;
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}
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nested_ns_name = absl::StrCat(ns_path[0].empty() ? "" : " ",
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absl::StrJoin(ns_path, "::"));
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absl::StrAppend(&out_types, "namespace", nested_ns_name, " {\n");
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}
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absl::StrAppend(&out_types, PrintAstDecl(decl), ";");
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if (!ns_path.empty()) {
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absl::StrAppend(&out_types, "\n} // namespace", nested_ns_name);
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}
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absl::StrAppend(&out_types, "\n");
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added_types = true;
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}
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if (added_types) {
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absl::StrAppend(&out, out_types);
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}
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// Optionally emit a default sandbox that instantiates an embedded sandboxee
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if (!options.embed_name.empty()) {
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// TODO(cblichmann): Make the "Sandbox" suffix configurable.
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absl::StrAppendFormat(
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&out, kEmbedClassTemplate, absl::StrCat(options.name, "Sandbox"),
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absl::StrReplaceAll(options.embed_name, {{"-", "_"}}));
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}
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// Emit the actual Sandboxed API
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// TODO(cblichmann): Make the "Api" suffix configurable or at least optional.
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absl::StrAppendFormat(&out, kClassHeaderTemplate,
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absl::StrCat(options.name, "Api"));
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std::string out_func;
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for (const clang::FunctionDecl* decl : functions) {
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SAPI_ASSIGN_OR_RETURN(out_func, EmitFunction(decl));
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absl::StrAppend(&out, out_func);
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}
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absl::StrAppend(&out, kClassFooterTemplate);
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// Close out the header: close namespace (if needed) and end include guard
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if (options.has_namespace()) {
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absl::StrAppendFormat(&out, kNamespaceEndTemplate, options.namespace_name);
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}
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absl::StrAppendFormat(&out, kHeaderEpilog, include_guard);
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return out;
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}
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} // namespace sapi
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