2 * Copyright 2016-present Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include <folly/experimental/bser/Bser.h>
19 #include <folly/String.h>
20 #include <folly/io/Cursor.h>
22 using namespace folly;
23 using folly::io::Cursor;
27 static dynamic parseBser(Cursor& curs);
29 template <typename... ARGS>
30 [[noreturn]] static void throwDecodeError(Cursor& curs, ARGS&&... args) {
31 throw BserDecodeError(folly::to<std::string>(
32 std::forward<ARGS>(args)...,
35 " bytes remaining in cursor"));
38 static int64_t decodeInt(Cursor& curs) {
39 auto enc = (BserType)curs.read<int8_t>();
42 return curs.read<int8_t>();
44 return curs.read<int16_t>();
46 return curs.read<int32_t>();
48 return curs.read<int64_t>();
51 curs, "invalid integer encoding detected (", (int8_t)enc, ")");
55 static std::string decodeString(Cursor& curs) {
56 auto len = decodeInt(curs);
60 throw std::range_error("string length must not be negative");
63 // We could use Cursor::readFixedString() here, but we'd like
64 // to throw our own exception with some increased diagnostics.
67 // The start of the string data, mutable.
70 auto pulled = curs.pullAtMost(dest, len);
71 if (pulled != size_t(len)) {
72 // Saw this case when decodeHeader was returning the incorrect length
73 // and we were splitting off too few bytes from the IOBufQueue
76 "no data available while decoding a string, header was "
77 "not decoded properly");
83 static dynamic decodeArray(Cursor& curs) {
84 dynamic arr = dynamic::array();
85 auto size = decodeInt(curs);
87 arr.push_back(parseBser(curs));
92 static dynamic decodeObject(Cursor& curs) {
93 dynamic obj = dynamic::object;
94 auto size = decodeInt(curs);
96 if ((BserType)curs.read<int8_t>() != BserType::String) {
97 throwDecodeError(curs, "expected String");
99 auto key = decodeString(curs);
100 obj[key] = parseBser(curs);
105 static dynamic decodeTemplate(Cursor& curs) {
106 dynamic arr = folly::dynamic::array;
108 // List of property names
109 if ((BserType)curs.read<int8_t>() != BserType::Array) {
110 throw std::runtime_error("Expected array encoding for property names");
112 auto names = decodeArray(curs);
114 auto size = decodeInt(curs);
117 dynamic obj = dynamic::object;
119 for (auto& name : names) {
120 auto bytes = curs.peekBytes();
121 if ((BserType)bytes.at(0) == BserType::Skip) {
122 obj[name.getString()] = nullptr;
127 obj[name.getString()] = parseBser(curs);
130 arr.push_back(std::move(obj));
136 static dynamic parseBser(Cursor& curs) {
137 switch ((BserType)curs.read<int8_t>()) {
139 return curs.read<int8_t>();
140 case BserType::Int16:
141 return curs.read<int16_t>();
142 case BserType::Int32:
143 return curs.read<int32_t>();
144 case BserType::Int64:
145 return curs.read<int64_t>();
146 case BserType::Real: {
148 curs.pull((void*)&dval, sizeof(dval));
155 case BserType::False:
157 case BserType::String:
158 return decodeString(curs);
159 case BserType::Array:
160 return decodeArray(curs);
161 case BserType::Object:
162 return decodeObject(curs);
163 case BserType::Template:
164 return decodeTemplate(curs);
166 throw std::runtime_error(
167 "Skip not valid at this location in the bser stream");
169 throw std::runtime_error("invalid bser encoding");
173 static size_t decodeHeader(Cursor& curs) {
174 char header[sizeof(kMagic)];
175 curs.pull(header, sizeof(header));
176 if (memcmp(header, kMagic, sizeof(kMagic))) {
177 throw std::runtime_error("invalid BSER magic header");
180 auto enc = (BserType)curs.peekBytes().at(0);
186 case BserType::Int16:
189 case BserType::Int32:
192 case BserType::Int64:
199 return int_size + 3 /* magic + int type */ + decodeInt(curs);
202 size_t decodePduLength(const folly::IOBuf* buf) {
204 return decodeHeader(curs);
207 folly::dynamic parseBser(const IOBuf* buf) {
211 return parseBser(curs);
214 folly::dynamic parseBser(ByteRange str) {
215 auto buf = IOBuf::wrapBuffer(str.data(), str.size());
216 return parseBser(&*buf);
219 folly::dynamic parseBser(StringPiece str) {
220 return parseBser(ByteRange((uint8_t*)str.data(), str.size()));