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| /* SPDX-License-Identifier: 0BSD */ | |
| /* | |
| * XZ decompressor | |
| * | |
| * Authors: Lasse Collin <lasse.collin@tukaani.org> | |
| * Igor Pavlov <https://7-zip.org/> | |
| */ | |
| extern "C" { | |
| /* In Linux, this is used to make extern functions static when needed. */ | |
| /** | |
| * enum xz_mode - Operation mode | |
| * | |
| * @XZ_SINGLE: Single-call mode. This uses less RAM than | |
| * multi-call modes, because the LZMA2 | |
| * dictionary doesn't need to be allocated as | |
| * part of the decoder state. All required data | |
| * structures are allocated at initialization, | |
| * so xz_dec_run() cannot return XZ_MEM_ERROR. | |
| * @XZ_PREALLOC: Multi-call mode with preallocated LZMA2 | |
| * dictionary buffer. All data structures are | |
| * allocated at initialization, so xz_dec_run() | |
| * cannot return XZ_MEM_ERROR. | |
| * @XZ_DYNALLOC: Multi-call mode. The LZMA2 dictionary is | |
| * allocated once the required size has been | |
| * parsed from the stream headers. If the | |
| * allocation fails, xz_dec_run() will return | |
| * XZ_MEM_ERROR. | |
| * | |
| * It is possible to enable support only for a subset of the above | |
| * modes at compile time by defining XZ_DEC_SINGLE, XZ_DEC_PREALLOC, | |
| * or XZ_DEC_DYNALLOC. The xz_dec kernel module is always compiled | |
| * with support for all operation modes, but the preboot code may | |
| * be built with fewer features to minimize code size. | |
| */ | |
| enum xz_mode { | |
| XZ_SINGLE, | |
| XZ_PREALLOC, | |
| XZ_DYNALLOC | |
| }; | |
| /** | |
| * enum xz_ret - Return codes | |
| * @XZ_OK: Everything is OK so far. More input or more | |
| * output space is required to continue. This | |
| * return code is possible only in multi-call mode | |
| * (XZ_PREALLOC or XZ_DYNALLOC). | |
| * @XZ_STREAM_END: Operation finished successfully. | |
| * @XZ_UNSUPPORTED_CHECK: Integrity check type is not supported. Decoding | |
| * is still possible in multi-call mode by simply | |
| * calling xz_dec_run() again. | |
| * Note that this return value is used only if | |
| * XZ_DEC_ANY_CHECK was defined at build time, | |
| * which is not used in the kernel. Unsupported | |
| * check types return XZ_OPTIONS_ERROR if | |
| * XZ_DEC_ANY_CHECK was not defined at build time. | |
| * @XZ_MEM_ERROR: Allocating memory failed. This return code is | |
| * possible only if the decoder was initialized | |
| * with XZ_DYNALLOC. The amount of memory that was | |
| * tried to be allocated was no more than the | |
| * dict_max argument given to xz_dec_init(). | |
| * @XZ_MEMLIMIT_ERROR: A bigger LZMA2 dictionary would be needed than | |
| * allowed by the dict_max argument given to | |
| * xz_dec_init(). This return value is possible | |
| * only in multi-call mode (XZ_PREALLOC or | |
| * XZ_DYNALLOC); the single-call mode (XZ_SINGLE) | |
| * ignores the dict_max argument. | |
| * @XZ_FORMAT_ERROR: File format was not recognized (wrong magic | |
| * bytes). | |
| * @XZ_OPTIONS_ERROR: This implementation doesn't support the requested | |
| * compression options. In the decoder this means | |
| * that the header CRC32 matches, but the header | |
| * itself specifies something that we don't support. | |
| * @XZ_DATA_ERROR: Compressed data is corrupt. | |
| * @XZ_BUF_ERROR: Cannot make any progress. Details are slightly | |
| * different between multi-call and single-call | |
| * mode; more information below. | |
| * | |
| * In multi-call mode, XZ_BUF_ERROR is returned when two consecutive calls | |
| * to XZ code cannot consume any input and cannot produce any new output. | |
| * This happens when there is no new input available, or the output buffer | |
| * is full while at least one output byte is still pending. Assuming your | |
| * code is not buggy, you can get this error only when decoding a compressed | |
| * stream that is truncated or otherwise corrupt. | |
| * | |
| * In single-call mode, XZ_BUF_ERROR is returned only when the output buffer | |
| * is too small or the compressed input is corrupt in a way that makes the | |
| * decoder produce more output than the caller expected. When it is | |
| * (relatively) clear that the compressed input is truncated, XZ_DATA_ERROR | |
| * is used instead of XZ_BUF_ERROR. | |
| */ | |
| enum xz_ret { | |
| XZ_OK, | |
| XZ_STREAM_END, | |
| XZ_UNSUPPORTED_CHECK, | |
| XZ_MEM_ERROR, | |
| XZ_MEMLIMIT_ERROR, | |
| XZ_FORMAT_ERROR, | |
| XZ_OPTIONS_ERROR, | |
| XZ_DATA_ERROR, | |
| XZ_BUF_ERROR | |
| }; | |
| /** | |
| * struct xz_buf - Passing input and output buffers to XZ code | |
| * @in: Beginning of the input buffer. This may be NULL if and only | |
| * if in_pos is equal to in_size. | |
| * @in_pos: Current position in the input buffer. This must not exceed | |
| * in_size. | |
| * @in_size: Size of the input buffer | |
| * @out: Beginning of the output buffer. This may be NULL if and only | |
| * if out_pos is equal to out_size. | |
| * @out_pos: Current position in the output buffer. This must not exceed | |
| * out_size. | |
| * @out_size: Size of the output buffer | |
| * | |
| * Only the contents of the output buffer from out[out_pos] onward, and | |
| * the variables in_pos and out_pos are modified by the XZ code. | |
| */ | |
| struct xz_buf { | |
| const uint8_t *in; | |
| size_t in_pos; | |
| size_t in_size; | |
| uint8_t *out; | |
| size_t out_pos; | |
| size_t out_size; | |
| }; | |
| /* | |
| * struct xz_dec - Opaque type to hold the XZ decoder state | |
| */ | |
| struct xz_dec; | |
| /** | |
| * xz_dec_init() - Allocate and initialize a XZ decoder state | |
| * @mode: Operation mode | |
| * @dict_max: Maximum size of the LZMA2 dictionary (history buffer) for | |
| * multi-call decoding. This is ignored in single-call mode | |
| * (mode == XZ_SINGLE). LZMA2 dictionary is always 2^n bytes | |
| * or 2^n + 2^(n-1) bytes (the latter sizes are less common | |
| * in practice), so other values for dict_max don't make sense. | |
| * In the kernel, dictionary sizes of 64 KiB, 128 KiB, 256 KiB, | |
| * 512 KiB, and 1 MiB are probably the only reasonable values, | |
| * except for kernel and initramfs images where a bigger | |
| * dictionary can be fine and useful. | |
| * | |
| * Single-call mode (XZ_SINGLE): xz_dec_run() decodes the whole stream at | |
| * once. The caller must provide enough output space or the decoding will | |
| * fail. The output space is used as the dictionary buffer, which is why | |
| * there is no need to allocate the dictionary as part of the decoder's | |
| * internal state. | |
| * | |
| * Because the output buffer is used as the workspace, streams encoded using | |
| * a big dictionary are not a problem in single-call mode. It is enough that | |
| * the output buffer is big enough to hold the actual uncompressed data; it | |
| * can be smaller than the dictionary size stored in the stream headers. | |
| * | |
| * Multi-call mode with preallocated dictionary (XZ_PREALLOC): dict_max bytes | |
| * of memory is preallocated for the LZMA2 dictionary. This way there is no | |
| * risk that xz_dec_run() could run out of memory, since xz_dec_run() will | |
| * never allocate any memory. Instead, if the preallocated dictionary is too | |
| * small for decoding the given input stream, xz_dec_run() will return | |
| * XZ_MEMLIMIT_ERROR. Thus, it is important to know what kind of data will be | |
| * decoded to avoid allocating excessive amount of memory for the dictionary. | |
| * | |
| * Multi-call mode with dynamically allocated dictionary (XZ_DYNALLOC): | |
| * dict_max specifies the maximum allowed dictionary size that xz_dec_run() | |
| * may allocate once it has parsed the dictionary size from the stream | |
| * headers. This way excessive allocations can be avoided while still | |
| * limiting the maximum memory usage to a sane value to prevent running the | |
| * system out of memory when decompressing streams from untrusted sources. | |
| * | |
| * On success, xz_dec_init() returns a pointer to struct xz_dec, which is | |
| * ready to be used with xz_dec_run(). If memory allocation fails, | |
| * xz_dec_init() returns NULL. | |
| */ | |
| XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max); | |
| /** | |
| * xz_dec_run() - Run the XZ decoder for a single XZ stream | |
| * @s: Decoder state allocated using xz_dec_init() | |
| * @b: Input and output buffers | |
| * | |
| * The possible return values depend on build options and operation mode. | |
| * See enum xz_ret for details. | |
| * | |
| * Note that if an error occurs in single-call mode (return value is not | |
| * XZ_STREAM_END), b->in_pos and b->out_pos are not modified and the | |
| * contents of the output buffer from b->out[b->out_pos] onward are | |
| * undefined. This is true even after XZ_BUF_ERROR, because with some filter | |
| * chains, there may be a second pass over the output buffer, and this pass | |
| * cannot be properly done if the output buffer is truncated. Thus, you | |
| * cannot give the single-call decoder a too small buffer and then expect to | |
| * get that amount valid data from the beginning of the stream. You must use | |
| * the multi-call decoder if you don't want to uncompress the whole stream. | |
| * | |
| * Use xz_dec_run() when XZ data is stored inside some other file format. | |
| * The decoding will stop after one XZ stream has been decompressed. To | |
| * decompress regular .xz files which might have multiple concatenated | |
| * streams, use xz_dec_catrun() instead. | |
| */ | |
| XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b); | |
| /** | |
| * xz_dec_catrun() - Run the XZ decoder with support for concatenated streams | |
| * @s: Decoder state allocated using xz_dec_init() | |
| * @b: Input and output buffers | |
| * @finish: This is an int instead of bool to avoid requiring stdbool.h. | |
| * As long as more input might be coming, finish must be false. | |
| * When the caller knows that it has provided all the input to | |
| * the decoder (some possibly still in b->in), it must set finish | |
| * to true. Only when finish is true can this function return | |
| * XZ_STREAM_END to indicate successful decompression of the | |
| * file. In single-call mode (XZ_SINGLE) finish is assumed to | |
| * always be true; the caller-provided value is ignored. | |
| * | |
| * This is like xz_dec_run() except that this makes it easy to decode .xz | |
| * files with multiple streams (multiple .xz files concatenated as is). | |
| * The rarely-used Stream Padding feature is supported too, that is, there | |
| * can be null bytes after or between the streams. The number of null bytes | |
| * must be a multiple of four. | |
| * | |
| * When finish is false and b->in_pos == b->in_size, it is possible that | |
| * XZ_BUF_ERROR isn't returned even when no progress is possible (XZ_OK is | |
| * returned instead). This shouldn't matter because in this situation a | |
| * reasonable caller will attempt to provide more input or set finish to | |
| * true for the next xz_dec_catrun() call anyway. | |
| * | |
| * For any struct xz_dec that has been initialized for multi-call mode: | |
| * Once decoding has been started with xz_dec_run() or xz_dec_catrun(), | |
| * the same function must be used until xz_dec_reset() or xz_dec_end(). | |
| * Switching between the two decoding functions without resetting results | |
| * in undefined behavior. | |
| * | |
| * xz_dec_catrun() is only available if XZ_DEC_CONCATENATED was defined | |
| * at compile time. | |
| */ | |
| XZ_EXTERN enum xz_ret xz_dec_catrun(struct xz_dec *s, struct xz_buf *b, | |
| int finish); | |
| /** | |
| * xz_dec_reset() - Reset an already allocated decoder state | |
| * @s: Decoder state allocated using xz_dec_init() | |
| * | |
| * This function can be used to reset the multi-call decoder state without | |
| * freeing and reallocating memory with xz_dec_end() and xz_dec_init(). | |
| * | |
| * In single-call mode, xz_dec_reset() is always called in the beginning of | |
| * xz_dec_run(). Thus, explicit call to xz_dec_reset() is useful only in | |
| * multi-call mode. | |
| */ | |
| XZ_EXTERN void xz_dec_reset(struct xz_dec *s); | |
| /** | |
| * xz_dec_end() - Free the memory allocated for the decoder state | |
| * @s: Decoder state allocated using xz_dec_init(). If s is NULL, | |
| * this function does nothing. | |
| */ | |
| XZ_EXTERN void xz_dec_end(struct xz_dec *s); | |
| /** | |
| * DOC: MicroLZMA decompressor | |
| * | |
| * This MicroLZMA header format was created for use in EROFS but may be used | |
| * by others too. **In most cases one needs the XZ APIs above instead.** | |
| * | |
| * The compressed format supported by this decoder is a raw LZMA stream | |
| * whose first byte (always 0x00) has been replaced with bitwise-negation | |
| * of the LZMA properties (lc/lp/pb) byte. For example, if lc/lp/pb is | |
| * 3/0/2, the first byte is 0xA2. This way the first byte can never be 0x00. | |
| * Just like with LZMA2, lc + lp <= 4 must be true. The LZMA end-of-stream | |
| * marker must not be used. The unused values are reserved for future use. | |
| * | |
| * These functions aren't used or available in preboot code and thus aren't | |
| * marked with XZ_EXTERN. This avoids warnings about static functions that | |
| * are never defined. | |
| */ | |
| /* | |
| * struct xz_dec_microlzma - Opaque type to hold the MicroLZMA decoder state | |
| */ | |
| struct xz_dec_microlzma; | |
| /** | |
| * xz_dec_microlzma_alloc() - Allocate memory for the MicroLZMA decoder | |
| * @mode: XZ_SINGLE or XZ_PREALLOC | |
| * @dict_size: LZMA dictionary size. This must be at least 4 KiB and | |
| * at most 3 GiB. | |
| * | |
| * In contrast to xz_dec_init(), this function only allocates the memory | |
| * and remembers the dictionary size. xz_dec_microlzma_reset() must be used | |
| * before calling xz_dec_microlzma_run(). | |
| * | |
| * The amount of allocated memory is a little less than 30 KiB with XZ_SINGLE. | |
| * With XZ_PREALLOC also a dictionary buffer of dict_size bytes is allocated. | |
| * | |
| * On success, xz_dec_microlzma_alloc() returns a pointer to | |
| * struct xz_dec_microlzma. If memory allocation fails or | |
| * dict_size is invalid, NULL is returned. | |
| */ | |
| extern struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode, | |
| uint32_t dict_size); | |
| /** | |
| * xz_dec_microlzma_reset() - Reset the MicroLZMA decoder state | |
| * @s: Decoder state allocated using xz_dec_microlzma_alloc() | |
| * @comp_size: Compressed size of the input stream | |
| * @uncomp_size: Uncompressed size of the input stream. A value smaller | |
| * than the real uncompressed size of the input stream can | |
| * be specified if uncomp_size_is_exact is set to false. | |
| * uncomp_size can never be set to a value larger than the | |
| * expected real uncompressed size because it would eventually | |
| * result in XZ_DATA_ERROR. | |
| * @uncomp_size_is_exact: This is an int instead of bool to avoid | |
| * requiring stdbool.h. This should normally be set to true. | |
| * When this is set to false, error detection is weaker. | |
| */ | |
| extern void xz_dec_microlzma_reset(struct xz_dec_microlzma *s, | |
| uint32_t comp_size, uint32_t uncomp_size, | |
| int uncomp_size_is_exact); | |
| /** | |
| * xz_dec_microlzma_run() - Run the MicroLZMA decoder | |
| * @s: Decoder state initialized using xz_dec_microlzma_reset() | |
| * @b: Input and output buffers | |
| * | |
| * This works similarly to xz_dec_run() with a few important differences. | |
| * Only the differences are documented here. | |
| * | |
| * The only possible return values are XZ_OK, XZ_STREAM_END, and | |
| * XZ_DATA_ERROR. This function cannot return XZ_BUF_ERROR: if no progress | |
| * is possible due to lack of input data or output space, this function will | |
| * keep returning XZ_OK. Thus, the calling code must be written so that it | |
| * will eventually provide input and output space matching (or exceeding) | |
| * comp_size and uncomp_size arguments given to xz_dec_microlzma_reset(). | |
| * If the caller cannot do this (for example, if the input file is truncated | |
| * or otherwise corrupt), the caller must detect this error by itself to | |
| * avoid an infinite loop. | |
| * | |
| * If the compressed data seems to be corrupt, XZ_DATA_ERROR is returned. | |
| * This can happen also when incorrect dictionary, uncompressed, or | |
| * compressed sizes have been specified. | |
| * | |
| * With XZ_PREALLOC only: As an extra feature, b->out may be NULL to skip over | |
| * uncompressed data. This way the caller doesn't need to provide a temporary | |
| * output buffer for the bytes that will be ignored. | |
| * | |
| * With XZ_SINGLE only: In contrast to xz_dec_run(), the return value XZ_OK | |
| * is also possible and thus XZ_SINGLE is actually a limited multi-call mode. | |
| * After XZ_OK the bytes decoded so far may be read from the output buffer. | |
| * It is possible to continue decoding but the variables b->out and b->out_pos | |
| * MUST NOT be changed by the caller. Increasing the value of b->out_size is | |
| * allowed to make more output space available; one doesn't need to provide | |
| * space for the whole uncompressed data on the first call. The input buffer | |
| * may be changed normally like with XZ_PREALLOC. This way input data can be | |
| * provided from non-contiguous memory. | |
| */ | |
| extern enum xz_ret xz_dec_microlzma_run(struct xz_dec_microlzma *s, | |
| struct xz_buf *b); | |
| /** | |
| * xz_dec_microlzma_end() - Free the memory allocated for the decoder state | |
| * @s: Decoder state allocated using xz_dec_microlzma_alloc(). | |
| * If s is NULL, this function does nothing. | |
| */ | |
| extern void xz_dec_microlzma_end(struct xz_dec_microlzma *s); | |
| /* | |
| * Standalone build (userspace build or in-kernel build for boot time use) | |
| * needs a CRC32 implementation. For normal in-kernel use, kernel's own | |
| * CRC32 module is used instead, and users of this module don't need to | |
| * care about the functions below. | |
| */ | |
| /* | |
| * If CRC64 support has been enabled with XZ_USE_CRC64, a CRC64 | |
| * implementation is needed too. | |
| */ | |
| /* | |
| * This must be called before any other xz_* function to initialize | |
| * the CRC32 lookup table. | |
| */ | |
| XZ_EXTERN void xz_crc32_init(void); | |
| /* | |
| * Update CRC32 value using the polynomial from IEEE-802.3. To start a new | |
| * calculation, the third argument must be zero. To continue the calculation, | |
| * the previously returned value is passed as the third argument. | |
| */ | |
| XZ_EXTERN uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc); | |
| /* | |
| * This must be called before any other xz_* function (except xz_crc32_init()) | |
| * to initialize the CRC64 lookup table. | |
| */ | |
| XZ_EXTERN void xz_crc64_init(void); | |
| /* | |
| * Update CRC64 value using the polynomial from ECMA-182. To start a new | |
| * calculation, the third argument must be zero. To continue the calculation, | |
| * the previously returned value is passed as the third argument. | |
| */ | |
| XZ_EXTERN uint64_t xz_crc64(const uint8_t *buf, size_t size, uint64_t crc); | |
| } | |