1/*
2 * Copyright 2017-present Facebook, Inc.
3 *
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
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17#include <folly/compression/Zlib.h>
18
19#if FOLLY_HAVE_LIBZ
20
21#include <folly/Conv.h>
22#include <folly/Optional.h>
23#include <folly/Range.h>
24#include <folly/ScopeGuard.h>
25#include <folly/compression/Compression.h>
26#include <folly/compression/Utils.h>
27#include <folly/io/Cursor.h>
28
29using folly::io::compression::detail::dataStartsWithLE;
30using folly::io::compression::detail::prefixToStringLE;
31
32namespace folly {
33namespace io {
34namespace zlib {
35
36namespace {
37
38bool isValidStrategy(int strategy) {
39 std::array<int, 5> strategies{{
40 Z_DEFAULT_STRATEGY,
41 Z_FILTERED,
42 Z_HUFFMAN_ONLY,
43 Z_RLE,
44 Z_FIXED,
45 }};
46 return std::any_of(strategies.begin(), strategies.end(), [&](int i) {
47 return i == strategy;
48 });
49}
50
51int getWindowBits(Options::Format format, int windowSize) {
52 switch (format) {
53 case Options::Format::ZLIB:
54 return windowSize;
55 case Options::Format::GZIP:
56 return windowSize + 16;
57 case Options::Format::RAW:
58 return -windowSize;
59 case Options::Format::AUTO:
60 return windowSize + 32;
61 default:
62 return windowSize;
63 }
64}
65
66CodecType getCodecType(Options options) {
67 if (options.windowSize == 15 && options.format == Options::Format::ZLIB) {
68 return CodecType::ZLIB;
69 } else if (
70 options.windowSize == 15 && options.format == Options::Format::GZIP) {
71 return CodecType::GZIP;
72 } else {
73 return CodecType::USER_DEFINED;
74 }
75}
76
77class ZlibStreamCodec final : public StreamCodec {
78 public:
79 static std::unique_ptr<Codec> createCodec(Options options, int level);
80 static std::unique_ptr<StreamCodec> createStream(Options options, int level);
81
82 explicit ZlibStreamCodec(Options options, int level);
83 ~ZlibStreamCodec() override;
84
85 std::vector<std::string> validPrefixes() const override;
86 bool canUncompress(const IOBuf* data, Optional<uint64_t> uncompressedLength)
87 const override;
88
89 private:
90 uint64_t doMaxCompressedLength(uint64_t uncompressedLength) const override;
91
92 void doResetStream() override;
93 bool doCompressStream(
94 ByteRange& input,
95 MutableByteRange& output,
96 StreamCodec::FlushOp flush) override;
97 bool doUncompressStream(
98 ByteRange& input,
99 MutableByteRange& output,
100 StreamCodec::FlushOp flush) override;
101
102 void resetDeflateStream();
103 void resetInflateStream();
104
105 Options options_;
106
107 Optional<z_stream> deflateStream_{};
108 Optional<z_stream> inflateStream_{};
109 int level_;
110 bool needReset_{true};
111};
112static constexpr uint16_t kGZIPMagicLE = 0x8B1F;
113
114std::vector<std::string> ZlibStreamCodec::validPrefixes() const {
115 if (type() == CodecType::ZLIB) {
116 // Zlib streams start with a 2 byte header.
117 //
118 // 0 1
119 // +---+---+
120 // |CMF|FLG|
121 // +---+---+
122 //
123 // We won't restrict the values of any sub-fields except as described below.
124 //
125 // The lowest 4 bits of CMF is the compression method (CM).
126 // CM == 0x8 is the deflate compression method, which is currently the only
127 // supported compression method, so any valid prefix must have CM == 0x8.
128 //
129 // The lowest 5 bits of FLG is FCHECK.
130 // FCHECK must be such that the two header bytes are a multiple of 31 when
131 // interpreted as a big endian 16-bit number.
132 std::vector<std::string> result;
133 // 16 values for the first byte, 8 values for the second byte.
134 // There are also 4 combinations where both 0x00 and 0x1F work as FCHECK.
135 result.reserve(132);
136 // Select all values for the CMF byte that use the deflate algorithm 0x8.
137 for (uint32_t first = 0x0800; first <= 0xF800; first += 0x1000) {
138 // Select all values for the FLG, but leave FCHECK as 0 since it's fixed.
139 for (uint32_t second = 0x00; second <= 0xE0; second += 0x20) {
140 uint16_t prefix = first | second;
141 // Compute FCHECK.
142 prefix += 31 - (prefix % 31);
143 result.push_back(prefixToStringLE(Endian::big(prefix)));
144 // zlib won't produce this, but it is a valid prefix.
145 if ((prefix & 0x1F) == 31) {
146 prefix -= 31;
147 result.push_back(prefixToStringLE(Endian::big(prefix)));
148 }
149 }
150 }
151 return result;
152 } else if (type() == CodecType::GZIP) {
153 // The gzip frame starts with 2 magic bytes.
154 return {prefixToStringLE(kGZIPMagicLE)};
155 } else {
156 return {};
157 }
158}
159
160bool ZlibStreamCodec::canUncompress(const IOBuf* data, Optional<uint64_t>)
161 const {
162 if (type() == CodecType::ZLIB) {
163 uint16_t value;
164 Cursor cursor{data};
165 if (!cursor.tryReadBE(value)) {
166 return false;
167 }
168 // zlib compressed if using deflate and is a multiple of 31.
169 return (value & 0x0F00) == 0x0800 && value % 31 == 0;
170 } else if (type() == CodecType::GZIP) {
171 return dataStartsWithLE(data, kGZIPMagicLE);
172 } else {
173 return false;
174 }
175}
176
177uint64_t ZlibStreamCodec::doMaxCompressedLength(
178 uint64_t uncompressedLength) const {
179 // When passed a nullptr, deflateBound() adds 6 bytes for a zlib wrapper. A
180 // gzip wrapper is 18 bytes, so we add the 12 byte difference.
181 return deflateBound(nullptr, uncompressedLength) +
182 (options_.format == Options::Format::GZIP ? 12 : 0);
183}
184
185std::unique_ptr<Codec> ZlibStreamCodec::createCodec(
186 Options options,
187 int level) {
188 return std::make_unique<ZlibStreamCodec>(options, level);
189}
190
191std::unique_ptr<StreamCodec> ZlibStreamCodec::createStream(
192 Options options,
193 int level) {
194 return std::make_unique<ZlibStreamCodec>(options, level);
195}
196
197static bool inBounds(int value, int low, int high) {
198 return (value >= low) && (value <= high);
199}
200
201static int zlibConvertLevel(int level) {
202 switch (level) {
203 case COMPRESSION_LEVEL_FASTEST:
204 return 1;
205 case COMPRESSION_LEVEL_DEFAULT:
206 return 6;
207 case COMPRESSION_LEVEL_BEST:
208 return 9;
209 }
210 if (!inBounds(level, 0, 9)) {
211 throw std::invalid_argument(
212 to<std::string>("ZlibStreamCodec: invalid level: ", level));
213 }
214 return level;
215}
216
217ZlibStreamCodec::ZlibStreamCodec(Options options, int level)
218 : StreamCodec(
219 getCodecType(options),
220 zlibConvertLevel(level),
221 getCodecType(options) == CodecType::GZIP ? "gzip" : "zlib"),
222 level_(zlibConvertLevel(level)) {
223 options_ = options;
224
225 // Although zlib allows a windowSize of 8..15, a value of 8 is not
226 // properly supported and is treated as a value of 9. This means data deflated
227 // with windowSize==8 can not be re-inflated with windowSize==8. windowSize==8
228 // is also not supported for gzip and raw deflation.
229 // Hence, the codec supports only 9..15.
230 if (!inBounds(options_.windowSize, 9, 15)) {
231 throw std::invalid_argument(to<std::string>(
232 "ZlibStreamCodec: invalid windowSize option: ", options.windowSize));
233 }
234 if (!inBounds(options_.memLevel, 1, 9)) {
235 throw std::invalid_argument(to<std::string>(
236 "ZlibStreamCodec: invalid memLevel option: ", options.memLevel));
237 }
238 if (!isValidStrategy(options_.strategy)) {
239 throw std::invalid_argument(to<std::string>(
240 "ZlibStreamCodec: invalid strategy: ", options.strategy));
241 }
242}
243
244ZlibStreamCodec::~ZlibStreamCodec() {
245 if (deflateStream_) {
246 deflateEnd(deflateStream_.get_pointer());
247 deflateStream_.clear();
248 }
249 if (inflateStream_) {
250 inflateEnd(inflateStream_.get_pointer());
251 inflateStream_.clear();
252 }
253}
254
255void ZlibStreamCodec::doResetStream() {
256 needReset_ = true;
257}
258
259void ZlibStreamCodec::resetDeflateStream() {
260 if (deflateStream_) {
261 int const rc = deflateReset(deflateStream_.get_pointer());
262 if (rc != Z_OK) {
263 deflateStream_.clear();
264 throw std::runtime_error(
265 to<std::string>("ZlibStreamCodec: deflateReset error: ", rc));
266 }
267 return;
268 }
269 deflateStream_ = z_stream{};
270
271 // The automatic header detection format is only for inflation.
272 // Use zlib for deflation if the format is auto.
273 int const windowBits = getWindowBits(
274 options_.format == Options::Format::AUTO ? Options::Format::ZLIB
275 : options_.format,
276 options_.windowSize);
277
278 int const rc = deflateInit2(
279 deflateStream_.get_pointer(),
280 level_,
281 Z_DEFLATED,
282 windowBits,
283 options_.memLevel,
284 options_.strategy);
285 if (rc != Z_OK) {
286 deflateStream_.clear();
287 throw std::runtime_error(
288 to<std::string>("ZlibStreamCodec: deflateInit error: ", rc));
289 }
290}
291
292void ZlibStreamCodec::resetInflateStream() {
293 if (inflateStream_) {
294 int const rc = inflateReset(inflateStream_.get_pointer());
295 if (rc != Z_OK) {
296 inflateStream_.clear();
297 throw std::runtime_error(
298 to<std::string>("ZlibStreamCodec: inflateReset error: ", rc));
299 }
300 return;
301 }
302 inflateStream_ = z_stream{};
303 int const rc = inflateInit2(
304 inflateStream_.get_pointer(),
305 getWindowBits(options_.format, options_.windowSize));
306 if (rc != Z_OK) {
307 inflateStream_.clear();
308 throw std::runtime_error(
309 to<std::string>("ZlibStreamCodec: inflateInit error: ", rc));
310 }
311}
312
313static int zlibTranslateFlush(StreamCodec::FlushOp flush) {
314 switch (flush) {
315 case StreamCodec::FlushOp::NONE:
316 return Z_NO_FLUSH;
317 case StreamCodec::FlushOp::FLUSH:
318 return Z_SYNC_FLUSH;
319 case StreamCodec::FlushOp::END:
320 return Z_FINISH;
321 default:
322 throw std::invalid_argument("ZlibStreamCodec: Invalid flush");
323 }
324}
325
326static int zlibThrowOnError(int rc) {
327 switch (rc) {
328 case Z_OK:
329 case Z_BUF_ERROR:
330 case Z_STREAM_END:
331 return rc;
332 default:
333 throw std::runtime_error(to<std::string>("ZlibStreamCodec: error: ", rc));
334 }
335}
336
337bool ZlibStreamCodec::doCompressStream(
338 ByteRange& input,
339 MutableByteRange& output,
340 StreamCodec::FlushOp flush) {
341 if (needReset_) {
342 resetDeflateStream();
343 needReset_ = false;
344 }
345 DCHECK(deflateStream_.hasValue());
346 // zlib will return Z_STREAM_ERROR if output.data() is null.
347 if (output.data() == nullptr) {
348 return false;
349 }
350 deflateStream_->next_in = const_cast<uint8_t*>(input.data());
351 deflateStream_->avail_in = input.size();
352 deflateStream_->next_out = output.data();
353 deflateStream_->avail_out = output.size();
354 SCOPE_EXIT {
355 input.uncheckedAdvance(input.size() - deflateStream_->avail_in);
356 output.uncheckedAdvance(output.size() - deflateStream_->avail_out);
357 };
358 int const rc = zlibThrowOnError(
359 deflate(deflateStream_.get_pointer(), zlibTranslateFlush(flush)));
360 switch (flush) {
361 case StreamCodec::FlushOp::NONE:
362 return false;
363 case StreamCodec::FlushOp::FLUSH:
364 return deflateStream_->avail_in == 0 && deflateStream_->avail_out != 0;
365 case StreamCodec::FlushOp::END:
366 return rc == Z_STREAM_END;
367 default:
368 throw std::invalid_argument("ZlibStreamCodec: Invalid flush");
369 }
370}
371
372bool ZlibStreamCodec::doUncompressStream(
373 ByteRange& input,
374 MutableByteRange& output,
375 StreamCodec::FlushOp flush) {
376 if (needReset_) {
377 resetInflateStream();
378 needReset_ = false;
379 }
380 DCHECK(inflateStream_.hasValue());
381 // zlib will return Z_STREAM_ERROR if output.data() is null.
382 if (output.data() == nullptr) {
383 return false;
384 }
385 inflateStream_->next_in = const_cast<uint8_t*>(input.data());
386 inflateStream_->avail_in = input.size();
387 inflateStream_->next_out = output.data();
388 inflateStream_->avail_out = output.size();
389 SCOPE_EXIT {
390 input.advance(input.size() - inflateStream_->avail_in);
391 output.advance(output.size() - inflateStream_->avail_out);
392 };
393 int const rc = zlibThrowOnError(
394 inflate(inflateStream_.get_pointer(), zlibTranslateFlush(flush)));
395 return rc == Z_STREAM_END;
396}
397
398} // namespace
399
400Options defaultGzipOptions() {
401 return Options(Options::Format::GZIP);
402}
403
404Options defaultZlibOptions() {
405 return Options(Options::Format::ZLIB);
406}
407
408std::unique_ptr<Codec> getCodec(Options options, int level) {
409 return ZlibStreamCodec::createCodec(options, level);
410}
411
412std::unique_ptr<StreamCodec> getStreamCodec(Options options, int level) {
413 return ZlibStreamCodec::createStream(options, level);
414}
415
416} // namespace zlib
417} // namespace io
418} // namespace folly
419
420#endif // FOLLY_HAVE_LIBZ
421