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1 | /* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */ |
2 | /* |
3 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
4 | * All rights reserved. |
5 | * |
6 | * This source code is licensed under both the BSD-style license (found in the |
7 | * LICENSE file in the root directory of https://github.com/facebook/zstd) and |
8 | * the GPLv2 (found in the COPYING file in the root directory of |
9 | * https://github.com/facebook/zstd). You may select, at your option, one of the |
10 | * above-listed licenses. |
11 | */ |
12 | |
13 | #ifndef LINUX_ZSTD_H |
14 | #define LINUX_ZSTD_H |
15 | |
16 | /** |
17 | * This is a kernel-style API that wraps the upstream zstd API, which cannot be |
18 | * used directly because the symbols aren't exported. It exposes the minimal |
19 | * functionality which is currently required by users of zstd in the kernel. |
20 | * Expose extra functions from lib/zstd/zstd.h as needed. |
21 | */ |
22 | |
23 | /* ====== Dependency ====== */ |
24 | #include <linux/types.h> |
25 | #include <linux/zstd_errors.h> |
26 | #include <linux/zstd_lib.h> |
27 | |
28 | /* ====== Helper Functions ====== */ |
29 | /** |
30 | * zstd_compress_bound() - maximum compressed size in worst case scenario |
31 | * @src_size: The size of the data to compress. |
32 | * |
33 | * Return: The maximum compressed size in the worst case scenario. |
34 | */ |
35 | size_t zstd_compress_bound(size_t src_size); |
36 | |
37 | /** |
38 | * zstd_is_error() - tells if a size_t function result is an error code |
39 | * @code: The function result to check for error. |
40 | * |
41 | * Return: Non-zero iff the code is an error. |
42 | */ |
43 | unsigned int zstd_is_error(size_t code); |
44 | |
45 | /** |
46 | * enum zstd_error_code - zstd error codes |
47 | */ |
48 | typedef ZSTD_ErrorCode zstd_error_code; |
49 | |
50 | /** |
51 | * zstd_get_error_code() - translates an error function result to an error code |
52 | * @code: The function result for which zstd_is_error(code) is true. |
53 | * |
54 | * Return: A unique error code for this error. |
55 | */ |
56 | zstd_error_code zstd_get_error_code(size_t code); |
57 | |
58 | /** |
59 | * zstd_get_error_name() - translates an error function result to a string |
60 | * @code: The function result for which zstd_is_error(code) is true. |
61 | * |
62 | * Return: An error string corresponding to the error code. |
63 | */ |
64 | const char *zstd_get_error_name(size_t code); |
65 | |
66 | /** |
67 | * zstd_min_clevel() - minimum allowed compression level |
68 | * |
69 | * Return: The minimum allowed compression level. |
70 | */ |
71 | int zstd_min_clevel(void); |
72 | |
73 | /** |
74 | * zstd_max_clevel() - maximum allowed compression level |
75 | * |
76 | * Return: The maximum allowed compression level. |
77 | */ |
78 | int zstd_max_clevel(void); |
79 | |
80 | /* ====== Parameter Selection ====== */ |
81 | |
82 | /** |
83 | * enum zstd_strategy - zstd compression search strategy |
84 | * |
85 | * From faster to stronger. See zstd_lib.h. |
86 | */ |
87 | typedef ZSTD_strategy zstd_strategy; |
88 | |
89 | /** |
90 | * struct zstd_compression_parameters - zstd compression parameters |
91 | * @windowLog: Log of the largest match distance. Larger means more |
92 | * compression, and more memory needed during decompression. |
93 | * @chainLog: Fully searched segment. Larger means more compression, |
94 | * slower, and more memory (useless for fast). |
95 | * @hashLog: Dispatch table. Larger means more compression, |
96 | * slower, and more memory. |
97 | * @searchLog: Number of searches. Larger means more compression and slower. |
98 | * @searchLength: Match length searched. Larger means faster decompression, |
99 | * sometimes less compression. |
100 | * @targetLength: Acceptable match size for optimal parser (only). Larger means |
101 | * more compression, and slower. |
102 | * @strategy: The zstd compression strategy. |
103 | * |
104 | * See zstd_lib.h. |
105 | */ |
106 | typedef ZSTD_compressionParameters zstd_compression_parameters; |
107 | |
108 | /** |
109 | * struct zstd_frame_parameters - zstd frame parameters |
110 | * @contentSizeFlag: Controls whether content size will be present in the |
111 | * frame header (when known). |
112 | * @checksumFlag: Controls whether a 32-bit checksum is generated at the |
113 | * end of the frame for error detection. |
114 | * @noDictIDFlag: Controls whether dictID will be saved into the frame |
115 | * header when using dictionary compression. |
116 | * |
117 | * The default value is all fields set to 0. See zstd_lib.h. |
118 | */ |
119 | typedef ZSTD_frameParameters zstd_frame_parameters; |
120 | |
121 | /** |
122 | * struct zstd_parameters - zstd parameters |
123 | * @cParams: The compression parameters. |
124 | * @fParams: The frame parameters. |
125 | */ |
126 | typedef ZSTD_parameters zstd_parameters; |
127 | |
128 | /** |
129 | * zstd_get_params() - returns zstd_parameters for selected level |
130 | * @level: The compression level |
131 | * @estimated_src_size: The estimated source size to compress or 0 |
132 | * if unknown. |
133 | * |
134 | * Return: The selected zstd_parameters. |
135 | */ |
136 | zstd_parameters zstd_get_params(int level, |
137 | unsigned long long estimated_src_size); |
138 | |
139 | /* ====== Single-pass Compression ====== */ |
140 | |
141 | typedef ZSTD_CCtx zstd_cctx; |
142 | |
143 | /** |
144 | * zstd_cctx_workspace_bound() - max memory needed to initialize a zstd_cctx |
145 | * @parameters: The compression parameters to be used. |
146 | * |
147 | * If multiple compression parameters might be used, the caller must call |
148 | * zstd_cctx_workspace_bound() for each set of parameters and use the maximum |
149 | * size. |
150 | * |
151 | * Return: A lower bound on the size of the workspace that is passed to |
152 | * zstd_init_cctx(). |
153 | */ |
154 | size_t zstd_cctx_workspace_bound(const zstd_compression_parameters *parameters); |
155 | |
156 | /** |
157 | * zstd_init_cctx() - initialize a zstd compression context |
158 | * @workspace: The workspace to emplace the context into. It must outlive |
159 | * the returned context. |
160 | * @workspace_size: The size of workspace. Use zstd_cctx_workspace_bound() to |
161 | * determine how large the workspace must be. |
162 | * |
163 | * Return: A zstd compression context or NULL on error. |
164 | */ |
165 | zstd_cctx *zstd_init_cctx(void *workspace, size_t workspace_size); |
166 | |
167 | /** |
168 | * zstd_compress_cctx() - compress src into dst with the initialized parameters |
169 | * @cctx: The context. Must have been initialized with zstd_init_cctx(). |
170 | * @dst: The buffer to compress src into. |
171 | * @dst_capacity: The size of the destination buffer. May be any size, but |
172 | * ZSTD_compressBound(srcSize) is guaranteed to be large enough. |
173 | * @src: The data to compress. |
174 | * @src_size: The size of the data to compress. |
175 | * @parameters: The compression parameters to be used. |
176 | * |
177 | * Return: The compressed size or an error, which can be checked using |
178 | * zstd_is_error(). |
179 | */ |
180 | size_t zstd_compress_cctx(zstd_cctx *cctx, void *dst, size_t dst_capacity, |
181 | const void *src, size_t src_size, const zstd_parameters *parameters); |
182 | |
183 | /* ====== Single-pass Decompression ====== */ |
184 | |
185 | typedef ZSTD_DCtx zstd_dctx; |
186 | |
187 | /** |
188 | * zstd_dctx_workspace_bound() - max memory needed to initialize a zstd_dctx |
189 | * |
190 | * Return: A lower bound on the size of the workspace that is passed to |
191 | * zstd_init_dctx(). |
192 | */ |
193 | size_t zstd_dctx_workspace_bound(void); |
194 | |
195 | /** |
196 | * zstd_init_dctx() - initialize a zstd decompression context |
197 | * @workspace: The workspace to emplace the context into. It must outlive |
198 | * the returned context. |
199 | * @workspace_size: The size of workspace. Use zstd_dctx_workspace_bound() to |
200 | * determine how large the workspace must be. |
201 | * |
202 | * Return: A zstd decompression context or NULL on error. |
203 | */ |
204 | zstd_dctx *zstd_init_dctx(void *workspace, size_t workspace_size); |
205 | |
206 | /** |
207 | * zstd_decompress_dctx() - decompress zstd compressed src into dst |
208 | * @dctx: The decompression context. |
209 | * @dst: The buffer to decompress src into. |
210 | * @dst_capacity: The size of the destination buffer. Must be at least as large |
211 | * as the decompressed size. If the caller cannot upper bound the |
212 | * decompressed size, then it's better to use the streaming API. |
213 | * @src: The zstd compressed data to decompress. Multiple concatenated |
214 | * frames and skippable frames are allowed. |
215 | * @src_size: The exact size of the data to decompress. |
216 | * |
217 | * Return: The decompressed size or an error, which can be checked using |
218 | * zstd_is_error(). |
219 | */ |
220 | size_t zstd_decompress_dctx(zstd_dctx *dctx, void *dst, size_t dst_capacity, |
221 | const void *src, size_t src_size); |
222 | |
223 | /* ====== Streaming Buffers ====== */ |
224 | |
225 | /** |
226 | * struct zstd_in_buffer - input buffer for streaming |
227 | * @src: Start of the input buffer. |
228 | * @size: Size of the input buffer. |
229 | * @pos: Position where reading stopped. Will be updated. |
230 | * Necessarily 0 <= pos <= size. |
231 | * |
232 | * See zstd_lib.h. |
233 | */ |
234 | typedef ZSTD_inBuffer zstd_in_buffer; |
235 | |
236 | /** |
237 | * struct zstd_out_buffer - output buffer for streaming |
238 | * @dst: Start of the output buffer. |
239 | * @size: Size of the output buffer. |
240 | * @pos: Position where writing stopped. Will be updated. |
241 | * Necessarily 0 <= pos <= size. |
242 | * |
243 | * See zstd_lib.h. |
244 | */ |
245 | typedef ZSTD_outBuffer zstd_out_buffer; |
246 | |
247 | /* ====== Streaming Compression ====== */ |
248 | |
249 | typedef ZSTD_CStream zstd_cstream; |
250 | |
251 | /** |
252 | * zstd_cstream_workspace_bound() - memory needed to initialize a zstd_cstream |
253 | * @cparams: The compression parameters to be used for compression. |
254 | * |
255 | * Return: A lower bound on the size of the workspace that is passed to |
256 | * zstd_init_cstream(). |
257 | */ |
258 | size_t zstd_cstream_workspace_bound(const zstd_compression_parameters *cparams); |
259 | |
260 | /** |
261 | * zstd_init_cstream() - initialize a zstd streaming compression context |
262 | * @parameters The zstd parameters to use for compression. |
263 | * @pledged_src_size: If params.fParams.contentSizeFlag == 1 then the caller |
264 | * must pass the source size (zero means empty source). |
265 | * Otherwise, the caller may optionally pass the source |
266 | * size, or zero if unknown. |
267 | * @workspace: The workspace to emplace the context into. It must outlive |
268 | * the returned context. |
269 | * @workspace_size: The size of workspace. |
270 | * Use zstd_cstream_workspace_bound(params->cparams) to |
271 | * determine how large the workspace must be. |
272 | * |
273 | * Return: The zstd streaming compression context or NULL on error. |
274 | */ |
275 | zstd_cstream *zstd_init_cstream(const zstd_parameters *parameters, |
276 | unsigned long long pledged_src_size, void *workspace, size_t workspace_size); |
277 | |
278 | /** |
279 | * zstd_reset_cstream() - reset the context using parameters from creation |
280 | * @cstream: The zstd streaming compression context to reset. |
281 | * @pledged_src_size: Optionally the source size, or zero if unknown. |
282 | * |
283 | * Resets the context using the parameters from creation. Skips dictionary |
284 | * loading, since it can be reused. If `pledged_src_size` is non-zero the frame |
285 | * content size is always written into the frame header. |
286 | * |
287 | * Return: Zero or an error, which can be checked using |
288 | * zstd_is_error(). |
289 | */ |
290 | size_t zstd_reset_cstream(zstd_cstream *cstream, |
291 | unsigned long long pledged_src_size); |
292 | |
293 | /** |
294 | * zstd_compress_stream() - streaming compress some of input into output |
295 | * @cstream: The zstd streaming compression context. |
296 | * @output: Destination buffer. `output->pos` is updated to indicate how much |
297 | * compressed data was written. |
298 | * @input: Source buffer. `input->pos` is updated to indicate how much data |
299 | * was read. Note that it may not consume the entire input, in which |
300 | * case `input->pos < input->size`, and it's up to the caller to |
301 | * present remaining data again. |
302 | * |
303 | * The `input` and `output` buffers may be any size. Guaranteed to make some |
304 | * forward progress if `input` and `output` are not empty. |
305 | * |
306 | * Return: A hint for the number of bytes to use as the input for the next |
307 | * function call or an error, which can be checked using |
308 | * zstd_is_error(). |
309 | */ |
310 | size_t zstd_compress_stream(zstd_cstream *cstream, zstd_out_buffer *output, |
311 | zstd_in_buffer *input); |
312 | |
313 | /** |
314 | * zstd_flush_stream() - flush internal buffers into output |
315 | * @cstream: The zstd streaming compression context. |
316 | * @output: Destination buffer. `output->pos` is updated to indicate how much |
317 | * compressed data was written. |
318 | * |
319 | * zstd_flush_stream() must be called until it returns 0, meaning all the data |
320 | * has been flushed. Since zstd_flush_stream() causes a block to be ended, |
321 | * calling it too often will degrade the compression ratio. |
322 | * |
323 | * Return: The number of bytes still present within internal buffers or an |
324 | * error, which can be checked using zstd_is_error(). |
325 | */ |
326 | size_t zstd_flush_stream(zstd_cstream *cstream, zstd_out_buffer *output); |
327 | |
328 | /** |
329 | * zstd_end_stream() - flush internal buffers into output and end the frame |
330 | * @cstream: The zstd streaming compression context. |
331 | * @output: Destination buffer. `output->pos` is updated to indicate how much |
332 | * compressed data was written. |
333 | * |
334 | * zstd_end_stream() must be called until it returns 0, meaning all the data has |
335 | * been flushed and the frame epilogue has been written. |
336 | * |
337 | * Return: The number of bytes still present within internal buffers or an |
338 | * error, which can be checked using zstd_is_error(). |
339 | */ |
340 | size_t zstd_end_stream(zstd_cstream *cstream, zstd_out_buffer *output); |
341 | |
342 | /* ====== Streaming Decompression ====== */ |
343 | |
344 | typedef ZSTD_DStream zstd_dstream; |
345 | |
346 | /** |
347 | * zstd_dstream_workspace_bound() - memory needed to initialize a zstd_dstream |
348 | * @max_window_size: The maximum window size allowed for compressed frames. |
349 | * |
350 | * Return: A lower bound on the size of the workspace that is passed |
351 | * to zstd_init_dstream(). |
352 | */ |
353 | size_t zstd_dstream_workspace_bound(size_t max_window_size); |
354 | |
355 | /** |
356 | * zstd_init_dstream() - initialize a zstd streaming decompression context |
357 | * @max_window_size: The maximum window size allowed for compressed frames. |
358 | * @workspace: The workspace to emplace the context into. It must outlive |
359 | * the returned context. |
360 | * @workspaceSize: The size of workspace. |
361 | * Use zstd_dstream_workspace_bound(max_window_size) to |
362 | * determine how large the workspace must be. |
363 | * |
364 | * Return: The zstd streaming decompression context. |
365 | */ |
366 | zstd_dstream *zstd_init_dstream(size_t max_window_size, void *workspace, |
367 | size_t workspace_size); |
368 | |
369 | /** |
370 | * zstd_reset_dstream() - reset the context using parameters from creation |
371 | * @dstream: The zstd streaming decompression context to reset. |
372 | * |
373 | * Resets the context using the parameters from creation. Skips dictionary |
374 | * loading, since it can be reused. |
375 | * |
376 | * Return: Zero or an error, which can be checked using zstd_is_error(). |
377 | */ |
378 | size_t zstd_reset_dstream(zstd_dstream *dstream); |
379 | |
380 | /** |
381 | * zstd_decompress_stream() - streaming decompress some of input into output |
382 | * @dstream: The zstd streaming decompression context. |
383 | * @output: Destination buffer. `output.pos` is updated to indicate how much |
384 | * decompressed data was written. |
385 | * @input: Source buffer. `input.pos` is updated to indicate how much data was |
386 | * read. Note that it may not consume the entire input, in which case |
387 | * `input.pos < input.size`, and it's up to the caller to present |
388 | * remaining data again. |
389 | * |
390 | * The `input` and `output` buffers may be any size. Guaranteed to make some |
391 | * forward progress if `input` and `output` are not empty. |
392 | * zstd_decompress_stream() will not consume the last byte of the frame until |
393 | * the entire frame is flushed. |
394 | * |
395 | * Return: Returns 0 iff a frame is completely decoded and fully flushed. |
396 | * Otherwise returns a hint for the number of bytes to use as the |
397 | * input for the next function call or an error, which can be checked |
398 | * using zstd_is_error(). The size hint will never load more than the |
399 | * frame. |
400 | */ |
401 | size_t zstd_decompress_stream(zstd_dstream *dstream, zstd_out_buffer *output, |
402 | zstd_in_buffer *input); |
403 | |
404 | /* ====== Frame Inspection Functions ====== */ |
405 | |
406 | /** |
407 | * zstd_find_frame_compressed_size() - returns the size of a compressed frame |
408 | * @src: Source buffer. It should point to the start of a zstd encoded |
409 | * frame or a skippable frame. |
410 | * @src_size: The size of the source buffer. It must be at least as large as the |
411 | * size of the frame. |
412 | * |
413 | * Return: The compressed size of the frame pointed to by `src` or an error, |
414 | * which can be check with zstd_is_error(). |
415 | * Suitable to pass to ZSTD_decompress() or similar functions. |
416 | */ |
417 | size_t zstd_find_frame_compressed_size(const void *src, size_t src_size); |
418 | |
419 | /** |
420 | * struct zstd_frame_params - zstd frame parameters stored in the frame header |
421 | * @frameContentSize: The frame content size, or ZSTD_CONTENTSIZE_UNKNOWN if not |
422 | * present. |
423 | * @windowSize: The window size, or 0 if the frame is a skippable frame. |
424 | * @blockSizeMax: The maximum block size. |
425 | * @frameType: The frame type (zstd or skippable) |
426 | * @headerSize: The size of the frame header. |
427 | * @dictID: The dictionary id, or 0 if not present. |
428 | * @checksumFlag: Whether a checksum was used. |
429 | * |
430 | * See zstd_lib.h. |
431 | */ |
432 | typedef ZSTD_frameHeader zstd_frame_header; |
433 | |
434 | /** |
435 | * zstd_get_frame_header() - extracts parameters from a zstd or skippable frame |
436 | * @params: On success the frame parameters are written here. |
437 | * @src: The source buffer. It must point to a zstd or skippable frame. |
438 | * @src_size: The size of the source buffer. |
439 | * |
440 | * Return: 0 on success. If more data is required it returns how many bytes |
441 | * must be provided to make forward progress. Otherwise it returns |
442 | * an error, which can be checked using zstd_is_error(). |
443 | */ |
444 | size_t zstd_get_frame_header(zstd_frame_header *params, const void *src, |
445 | size_t src_size); |
446 | |
447 | #endif /* LINUX_ZSTD_H */ |