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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/json/json_reader.h"
#include <utility>
#include "base/features.h"
#include "base/logging.h"
#include "base/metrics/histogram_macros.h"
#include "base/rust_buildflags.h"
#include "third_party/abseil-cpp/absl/types/optional.h"
#if BUILDFLAG(BUILD_RUST_JSON_READER)
#include "base/strings/string_piece_rust.h"
#include "third_party/rust/serde_json_lenient/v0_1/wrapper/functions.h"
#include "third_party/rust/serde_json_lenient/v0_1/wrapper/lib.rs.h"
#endif // BUILDFLAG(BUILD_RUST_JSON_READER)
#include "base/json/json_parser.h"
namespace base {
#if BUILDFLAG(BUILD_RUST_JSON_READER)
namespace {
using serde_json_lenient::ContextPointer;
const char kSecurityJsonParsingTime[] = "Security.JSONParser.ParsingTime";
ContextPointer& ListAppendList(ContextPointer& ctx, size_t reserve) {
auto& value = reinterpret_cast<base::Value&>(ctx);
value.GetList().reserve(reserve);
value.GetList().Append(base::Value::List());
return reinterpret_cast<ContextPointer&>(value.GetList().back());
}
ContextPointer& ListAppendDict(ContextPointer& ctx) {
auto& value = reinterpret_cast<base::Value&>(ctx);
value.GetList().Append(base::Value::Dict());
return reinterpret_cast<ContextPointer&>(value.GetList().back());
}
void ListAppendNone(ContextPointer& ctx) {
auto& value = reinterpret_cast<base::Value&>(ctx);
value.GetList().Append(base::Value());
}
template <class T, class As = T>
void ListAppendValue(ContextPointer& ctx, T v) {
auto& value = reinterpret_cast<base::Value&>(ctx);
value.GetList().Append(As{v});
}
ContextPointer& DictSetList(ContextPointer& ctx,
rust::Str key,
size_t reserve) {
auto& dict = reinterpret_cast<base::Value&>(ctx).GetDict();
base::Value::List list;
list.reserve(reserve);
dict.Set(base::RustStrToStringPiece(key), std::move(list));
return reinterpret_cast<ContextPointer&>(
*dict.Find(base::RustStrToStringPiece(key)));
}
ContextPointer& DictSetDict(ContextPointer& ctx, rust::Str key) {
auto& dict = reinterpret_cast<base::Value&>(ctx).GetDict();
dict.Set(base::RustStrToStringPiece(key), base::Value(base::Value::Dict()));
return reinterpret_cast<ContextPointer&>(
*dict.Find(base::RustStrToStringPiece(key)));
}
void DictSetNone(ContextPointer& ctx, rust::Str key) {
auto& dict = reinterpret_cast<base::Value&>(ctx).GetDict();
dict.Set(base::RustStrToStringPiece(key), base::Value());
}
template <class T, class As = T>
void DictSetValue(ContextPointer& ctx, rust::Str key, T v) {
auto& dict = reinterpret_cast<base::Value&>(ctx).GetDict();
dict.Set(base::RustStrToStringPiece(key), base::Value(As{v}));
}
JSONReader::Result DecodeJSONInRust(const base::StringPiece& json,
int options,
size_t max_depth) {
const serde_json_lenient::JsonOptions rust_options = {
.allow_trailing_commas =
(options & base::JSON_ALLOW_TRAILING_COMMAS) != 0,
.replace_invalid_characters =
(options & base::JSON_REPLACE_INVALID_CHARACTERS) != 0,
.allow_comments = (options & base::JSON_ALLOW_COMMENTS) != 0,
.allow_control_chars = (options & base::JSON_ALLOW_CONTROL_CHARS) != 0,
.allow_vert_tab = (options & base::JSON_ALLOW_VERT_TAB) != 0,
.allow_x_escapes = (options & base::JSON_ALLOW_X_ESCAPES) != 0,
.max_depth = max_depth,
};
const serde_json_lenient::Functions functions = {
.list_append_none_fn = ListAppendNone,
.list_append_bool_fn = ListAppendValue<bool>,
.list_append_i32_fn = ListAppendValue<int32_t>,
.list_append_f64_fn = ListAppendValue<double>,
.list_append_str_fn = ListAppendValue<rust::Str, std::string>,
.list_append_list_fn = ListAppendList,
.list_append_dict_fn = ListAppendDict,
.dict_set_none_fn = DictSetNone,
.dict_set_bool_fn = DictSetValue<bool>,
.dict_set_i32_fn = DictSetValue<int32_t>,
.dict_set_f64_fn = DictSetValue<double>,
.dict_set_str_fn = DictSetValue<rust::Str, std::string>,
.dict_set_list_fn = DictSetList,
.dict_set_dict_fn = DictSetDict,
};
base::Value value(base::Value::Type::LIST);
auto& ctx = reinterpret_cast<ContextPointer&>(value);
serde_json_lenient::DecodeError error;
bool ok = serde_json_lenient::decode_json(
base::StringPieceToRustSlice(json), rust_options, functions, ctx, error);
if (!ok) {
return base::unexpected(base::JSONReader::Error{
.message = std::string(error.message),
.line = error.line,
.column = error.column,
});
}
return std::move(std::move(value.GetList()).back());
}
} // anonymous namespace
#endif // BUILDFLAG(BUILD_RUST_JSON_READER)
// static
absl::optional<Value> JSONReader::Read(StringPiece json,
int options,
size_t max_depth) {
#if BUILDFLAG(BUILD_RUST_JSON_READER)
SCOPED_UMA_HISTOGRAM_TIMER_MICROS(kSecurityJsonParsingTime);
if (UsingRust()) {
JSONReader::Result result = DecodeJSONInRust(json, options, max_depth);
if (!result.has_value()) {
return absl::nullopt;
}
return std::move(*result);
} else {
internal::JSONParser parser(options, max_depth);
return parser.Parse(json);
}
#else // BUILDFLAG(BUILD_RUST_JSON_READER)
internal::JSONParser parser(options, max_depth);
return parser.Parse(json);
#endif // BUILDFLAG(BUILD_RUST_JSON_READER)
}
// static
absl::optional<Value::Dict> JSONReader::ReadDict(StringPiece json,
int options,
size_t max_depth) {
absl::optional<Value> value = Read(json, options, max_depth);
if (!value || !value->is_dict()) {
return absl::nullopt;
}
return std::move(*value).TakeDict();
}
// static
JSONReader::Result JSONReader::ReadAndReturnValueWithError(StringPiece json,
int options) {
#if BUILDFLAG(BUILD_RUST_JSON_READER)
SCOPED_UMA_HISTOGRAM_TIMER_MICROS(kSecurityJsonParsingTime);
if (UsingRust()) {
return DecodeJSONInRust(json, options, internal::kAbsoluteMaxDepth);
} else {
internal::JSONParser parser(options);
auto value = parser.Parse(json);
if (!value) {
Error error;
error.message = parser.GetErrorMessage();
error.line = parser.error_line();
error.column = parser.error_column();
return base::unexpected(std::move(error));
}
return std::move(*value);
}
#else // BUILDFLAG(BUILD_RUST_JSON_READER)
internal::JSONParser parser(options);
auto value = parser.Parse(json);
if (!value) {
Error error;
error.message = parser.GetErrorMessage();
error.line = parser.error_line();
error.column = parser.error_column();
return base::unexpected(std::move(error));
}
return std::move(*value);
#endif // BUILDFLAG(BUILD_RUST_JSON_READER)
}
// static
bool JSONReader::UsingRust() {
// If features have not yet been enabled, we cannot check the feature, so fall
// back to the C++ parser. In practice, this seems to apply to
// `ReadPrefsFromDisk()`, which is parsing trusted JSON.
if (!base::FeatureList::GetInstance()) {
return false;
}
#if BUILDFLAG(BUILD_RUST_JSON_READER)
return base::FeatureList::IsEnabled(base::features::kUseRustJsonParser);
#else // BUILDFLAG(BUILD_RUST_JSON_READER)
return false;
#endif // BUILDFLAG(BUILD_RUST_JSON_READER)
}
} // namespace base
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