summaryrefslogtreecommitdiff
path: root/include/linux/zstd.h
blob: 113408eef6ecef6ad973fc3393f34fb5fc499c34 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */
/*
 * Copyright (c) Yann Collet, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of https://github.com/facebook/zstd) and
 * the GPLv2 (found in the COPYING file in the root directory of
 * https://github.com/facebook/zstd). You may select, at your option, one of the
 * above-listed licenses.
 */

#ifndef LINUX_ZSTD_H
#define LINUX_ZSTD_H

/**
 * This is a kernel-style API that wraps the upstream zstd API, which cannot be
 * used directly because the symbols aren't exported. It exposes the minimal
 * functionality which is currently required by users of zstd in the kernel.
 * Expose extra functions from lib/zstd/zstd.h as needed.
 */

/* ======   Dependency   ====== */
#include <linux/types.h>
#include <linux/zstd_errors.h>
#include <linux/zstd_lib.h>

/* ======   Helper Functions   ====== */
/**
 * zstd_compress_bound() - maximum compressed size in worst case scenario
 * @src_size: The size of the data to compress.
 *
 * Return:    The maximum compressed size in the worst case scenario.
 */
size_t zstd_compress_bound(size_t src_size);

/**
 * zstd_is_error() - tells if a size_t function result is an error code
 * @code:  The function result to check for error.
 *
 * Return: Non-zero iff the code is an error.
 */
unsigned int zstd_is_error(size_t code);

/**
 * enum zstd_error_code - zstd error codes
 */
typedef ZSTD_ErrorCode zstd_error_code;

/**
 * zstd_get_error_code() - translates an error function result to an error code
 * @code:  The function result for which zstd_is_error(code) is true.
 *
 * Return: A unique error code for this error.
 */
zstd_error_code zstd_get_error_code(size_t code);

/**
 * zstd_get_error_name() - translates an error function result to a string
 * @code:  The function result for which zstd_is_error(code) is true.
 *
 * Return: An error string corresponding to the error code.
 */
const char *zstd_get_error_name(size_t code);

/**
 * zstd_min_clevel() - minimum allowed compression level
 *
 * Return: The minimum allowed compression level.
 */
int zstd_min_clevel(void);

/**
 * zstd_max_clevel() - maximum allowed compression level
 *
 * Return: The maximum allowed compression level.
 */
int zstd_max_clevel(void);

/* ======   Parameter Selection   ====== */

/**
 * enum zstd_strategy - zstd compression search strategy
 *
 * From faster to stronger. See zstd_lib.h.
 */
typedef ZSTD_strategy zstd_strategy;

/**
 * struct zstd_compression_parameters - zstd compression parameters
 * @windowLog:    Log of the largest match distance. Larger means more
 *                compression, and more memory needed during decompression.
 * @chainLog:     Fully searched segment. Larger means more compression,
 *                slower, and more memory (useless for fast).
 * @hashLog:      Dispatch table. Larger means more compression,
 *                slower, and more memory.
 * @searchLog:    Number of searches. Larger means more compression and slower.
 * @searchLength: Match length searched. Larger means faster decompression,
 *                sometimes less compression.
 * @targetLength: Acceptable match size for optimal parser (only). Larger means
 *                more compression, and slower.
 * @strategy:     The zstd compression strategy.
 *
 * See zstd_lib.h.
 */
typedef ZSTD_compressionParameters zstd_compression_parameters;

/**
 * struct zstd_frame_parameters - zstd frame parameters
 * @contentSizeFlag: Controls whether content size will be present in the
 *                   frame header (when known).
 * @checksumFlag:    Controls whether a 32-bit checksum is generated at the
 *                   end of the frame for error detection.
 * @noDictIDFlag:    Controls whether dictID will be saved into the frame
 *                   header when using dictionary compression.
 *
 * The default value is all fields set to 0. See zstd_lib.h.
 */
typedef ZSTD_frameParameters zstd_frame_parameters;

/**
 * struct zstd_parameters - zstd parameters
 * @cParams: The compression parameters.
 * @fParams: The frame parameters.
 */
typedef ZSTD_parameters zstd_parameters;

/**
 * zstd_get_params() - returns zstd_parameters for selected level
 * @level:              The compression level
 * @estimated_src_size: The estimated source size to compress or 0
 *                      if unknown.
 *
 * Return:              The selected zstd_parameters.
 */
zstd_parameters zstd_get_params(int level,
	unsigned long long estimated_src_size);

/* ======   Single-pass Compression   ====== */

typedef ZSTD_CCtx zstd_cctx;

/**
 * zstd_cctx_workspace_bound() - max memory needed to initialize a zstd_cctx
 * @parameters: The compression parameters to be used.
 *
 * If multiple compression parameters might be used, the caller must call
 * zstd_cctx_workspace_bound() for each set of parameters and use the maximum
 * size.
 *
 * Return:      A lower bound on the size of the workspace that is passed to
 *              zstd_init_cctx().
 */
size_t zstd_cctx_workspace_bound(const zstd_compression_parameters *parameters);

/**
 * zstd_init_cctx() - initialize a zstd compression context
 * @workspace:      The workspace to emplace the context into. It must outlive
 *                  the returned context.
 * @workspace_size: The size of workspace. Use zstd_cctx_workspace_bound() to
 *                  determine how large the workspace must be.
 *
 * Return:          A zstd compression context or NULL on error.
 */
zstd_cctx *zstd_init_cctx(void *workspace, size_t workspace_size);

/**
 * zstd_compress_cctx() - compress src into dst with the initialized parameters
 * @cctx:         The context. Must have been initialized with zstd_init_cctx().
 * @dst:          The buffer to compress src into.
 * @dst_capacity: The size of the destination buffer. May be any size, but
 *                ZSTD_compressBound(srcSize) is guaranteed to be large enough.
 * @src:          The data to compress.
 * @src_size:     The size of the data to compress.
 * @parameters:   The compression parameters to be used.
 *
 * Return:        The compressed size or an error, which can be checked using
 *                zstd_is_error().
 */
size_t zstd_compress_cctx(zstd_cctx *cctx, void *dst, size_t dst_capacity,
	const void *src, size_t src_size, const zstd_parameters *parameters);

/* ======   Single-pass Decompression   ====== */

typedef ZSTD_DCtx zstd_dctx;

/**
 * zstd_dctx_workspace_bound() - max memory needed to initialize a zstd_dctx
 *
 * Return: A lower bound on the size of the workspace that is passed to
 *         zstd_init_dctx().
 */
size_t zstd_dctx_workspace_bound(void);

/**
 * zstd_init_dctx() - initialize a zstd decompression context
 * @workspace:      The workspace to emplace the context into. It must outlive
 *                  the returned context.
 * @workspace_size: The size of workspace. Use zstd_dctx_workspace_bound() to
 *                  determine how large the workspace must be.
 *
 * Return:          A zstd decompression context or NULL on error.
 */
zstd_dctx *zstd_init_dctx(void *workspace, size_t workspace_size);

/**
 * zstd_decompress_dctx() - decompress zstd compressed src into dst
 * @dctx:         The decompression context.
 * @dst:          The buffer to decompress src into.
 * @dst_capacity: The size of the destination buffer. Must be at least as large
 *                as the decompressed size. If the caller cannot upper bound the
 *                decompressed size, then it's better to use the streaming API.
 * @src:          The zstd compressed data to decompress. Multiple concatenated
 *                frames and skippable frames are allowed.
 * @src_size:     The exact size of the data to decompress.
 *
 * Return:        The decompressed size or an error, which can be checked using
 *                zstd_is_error().
 */
size_t zstd_decompress_dctx(zstd_dctx *dctx, void *dst, size_t dst_capacity,
	const void *src, size_t src_size);

/* ======   Streaming Buffers   ====== */

/**
 * struct zstd_in_buffer - input buffer for streaming
 * @src:  Start of the input buffer.
 * @size: Size of the input buffer.
 * @pos:  Position where reading stopped. Will be updated.
 *        Necessarily 0 <= pos <= size.
 *
 * See zstd_lib.h.
 */
typedef ZSTD_inBuffer zstd_in_buffer;

/**
 * struct zstd_out_buffer - output buffer for streaming
 * @dst:  Start of the output buffer.
 * @size: Size of the output buffer.
 * @pos:  Position where writing stopped. Will be updated.
 *        Necessarily 0 <= pos <= size.
 *
 * See zstd_lib.h.
 */
typedef ZSTD_outBuffer zstd_out_buffer;

/* ======   Streaming Compression   ====== */

typedef ZSTD_CStream zstd_cstream;

/**
 * zstd_cstream_workspace_bound() - memory needed to initialize a zstd_cstream
 * @cparams: The compression parameters to be used for compression.
 *
 * Return:   A lower bound on the size of the workspace that is passed to
 *           zstd_init_cstream().
 */
size_t zstd_cstream_workspace_bound(const zstd_compression_parameters *cparams);

/**
 * zstd_init_cstream() - initialize a zstd streaming compression context
 * @parameters        The zstd parameters to use for compression.
 * @pledged_src_size: If params.fParams.contentSizeFlag == 1 then the caller
 *                    must pass the source size (zero means empty source).
 *                    Otherwise, the caller may optionally pass the source
 *                    size, or zero if unknown.
 * @workspace:        The workspace to emplace the context into. It must outlive
 *                    the returned context.
 * @workspace_size:   The size of workspace.
 *                    Use zstd_cstream_workspace_bound(params->cparams) to
 *                    determine how large the workspace must be.
 *
 * Return:            The zstd streaming compression context or NULL on error.
 */
zstd_cstream *zstd_init_cstream(const zstd_parameters *parameters,
	unsigned long long pledged_src_size, void *workspace, size_t workspace_size);

/**
 * zstd_reset_cstream() - reset the context using parameters from creation
 * @cstream:          The zstd streaming compression context to reset.
 * @pledged_src_size: Optionally the source size, or zero if unknown.
 *
 * Resets the context using the parameters from creation. Skips dictionary
 * loading, since it can be reused. If `pledged_src_size` is non-zero the frame
 * content size is always written into the frame header.
 *
 * Return:            Zero or an error, which can be checked using
 *                    zstd_is_error().
 */
size_t zstd_reset_cstream(zstd_cstream *cstream,
	unsigned long long pledged_src_size);

/**
 * zstd_compress_stream() - streaming compress some of input into output
 * @cstream: The zstd streaming compression context.
 * @output:  Destination buffer. `output->pos` is updated to indicate how much
 *           compressed data was written.
 * @input:   Source buffer. `input->pos` is updated to indicate how much data
 *           was read. Note that it may not consume the entire input, in which
 *           case `input->pos < input->size`, and it's up to the caller to
 *           present remaining data again.
 *
 * The `input` and `output` buffers may be any size. Guaranteed to make some
 * forward progress if `input` and `output` are not empty.
 *
 * Return:   A hint for the number of bytes to use as the input for the next
 *           function call or an error, which can be checked using
 *           zstd_is_error().
 */
size_t zstd_compress_stream(zstd_cstream *cstream, zstd_out_buffer *output,
	zstd_in_buffer *input);

/**
 * zstd_flush_stream() - flush internal buffers into output
 * @cstream: The zstd streaming compression context.
 * @output:  Destination buffer. `output->pos` is updated to indicate how much
 *           compressed data was written.
 *
 * zstd_flush_stream() must be called until it returns 0, meaning all the data
 * has been flushed. Since zstd_flush_stream() causes a block to be ended,
 * calling it too often will degrade the compression ratio.
 *
 * Return:   The number of bytes still present within internal buffers or an
 *           error, which can be checked using zstd_is_error().
 */
size_t zstd_flush_stream(zstd_cstream *cstream, zstd_out_buffer *output);

/**
 * zstd_end_stream() - flush internal buffers into output and end the frame
 * @cstream: The zstd streaming compression context.
 * @output:  Destination buffer. `output->pos` is updated to indicate how much
 *           compressed data was written.
 *
 * zstd_end_stream() must be called until it returns 0, meaning all the data has
 * been flushed and the frame epilogue has been written.
 *
 * Return:   The number of bytes still present within internal buffers or an
 *           error, which can be checked using zstd_is_error().
 */
size_t zstd_end_stream(zstd_cstream *cstream, zstd_out_buffer *output);

/* ======   Streaming Decompression   ====== */

typedef ZSTD_DStream zstd_dstream;

/**
 * zstd_dstream_workspace_bound() - memory needed to initialize a zstd_dstream
 * @max_window_size: The maximum window size allowed for compressed frames.
 *
 * Return:           A lower bound on the size of the workspace that is passed
 *                   to zstd_init_dstream().
 */
size_t zstd_dstream_workspace_bound(size_t max_window_size);

/**
 * zstd_init_dstream() - initialize a zstd streaming decompression context
 * @max_window_size: The maximum window size allowed for compressed frames.
 * @workspace:       The workspace to emplace the context into. It must outlive
 *                   the returned context.
 * @workspaceSize:   The size of workspace.
 *                   Use zstd_dstream_workspace_bound(max_window_size) to
 *                   determine how large the workspace must be.
 *
 * Return:           The zstd streaming decompression context.
 */
zstd_dstream *zstd_init_dstream(size_t max_window_size, void *workspace,
	size_t workspace_size);

/**
 * zstd_reset_dstream() - reset the context using parameters from creation
 * @dstream: The zstd streaming decompression context to reset.
 *
 * Resets the context using the parameters from creation. Skips dictionary
 * loading, since it can be reused.
 *
 * Return:   Zero or an error, which can be checked using zstd_is_error().
 */
size_t zstd_reset_dstream(zstd_dstream *dstream);

/**
 * zstd_decompress_stream() - streaming decompress some of input into output
 * @dstream: The zstd streaming decompression context.
 * @output:  Destination buffer. `output.pos` is updated to indicate how much
 *           decompressed data was written.
 * @input:   Source buffer. `input.pos` is updated to indicate how much data was
 *           read. Note that it may not consume the entire input, in which case
 *           `input.pos < input.size`, and it's up to the caller to present
 *           remaining data again.
 *
 * The `input` and `output` buffers may be any size. Guaranteed to make some
 * forward progress if `input` and `output` are not empty.
 * zstd_decompress_stream() will not consume the last byte of the frame until
 * the entire frame is flushed.
 *
 * Return:   Returns 0 iff a frame is completely decoded and fully flushed.
 *           Otherwise returns a hint for the number of bytes to use as the
 *           input for the next function call or an error, which can be checked
 *           using zstd_is_error(). The size hint will never load more than the
 *           frame.
 */
size_t zstd_decompress_stream(zstd_dstream *dstream, zstd_out_buffer *output,
	zstd_in_buffer *input);

/* ======   Frame Inspection Functions ====== */

/**
 * zstd_find_frame_compressed_size() - returns the size of a compressed frame
 * @src:      Source buffer. It should point to the start of a zstd encoded
 *            frame or a skippable frame.
 * @src_size: The size of the source buffer. It must be at least as large as the
 *            size of the frame.
 *
 * Return:    The compressed size of the frame pointed to by `src` or an error,
 *            which can be check with zstd_is_error().
 *            Suitable to pass to ZSTD_decompress() or similar functions.
 */
size_t zstd_find_frame_compressed_size(const void *src, size_t src_size);

/**
 * struct zstd_frame_params - zstd frame parameters stored in the frame header
 * @frameContentSize: The frame content size, or ZSTD_CONTENTSIZE_UNKNOWN if not
 *                    present.
 * @windowSize:       The window size, or 0 if the frame is a skippable frame.
 * @blockSizeMax:     The maximum block size.
 * @frameType:        The frame type (zstd or skippable)
 * @headerSize:       The size of the frame header.
 * @dictID:           The dictionary id, or 0 if not present.
 * @checksumFlag:     Whether a checksum was used.
 *
 * See zstd_lib.h.
 */
typedef ZSTD_frameHeader zstd_frame_header;

/**
 * zstd_get_frame_header() - extracts parameters from a zstd or skippable frame
 * @params:   On success the frame parameters are written here.
 * @src:      The source buffer. It must point to a zstd or skippable frame.
 * @src_size: The size of the source buffer.
 *
 * Return:    0 on success. If more data is required it returns how many bytes
 *            must be provided to make forward progress. Otherwise it returns
 *            an error, which can be checked using zstd_is_error().
 */
size_t zstd_get_frame_header(zstd_frame_header *params, const void *src,
	size_t src_size);

#endif  /* LINUX_ZSTD_H */