diff options
Diffstat (limited to 'include/linux/xz.h')
| -rw-r--r-- | include/linux/xz.h | 125 |
1 files changed, 110 insertions, 15 deletions
diff --git a/include/linux/xz.h b/include/linux/xz.h index 9884c8440188..58ae1d746c6f 100644 --- a/include/linux/xz.h +++ b/include/linux/xz.h @@ -1,11 +1,10 @@ +/* SPDX-License-Identifier: 0BSD */ + /* * XZ decompressor * * Authors: Lasse Collin <lasse.collin@tukaani.org> * Igor Pavlov <https://7-zip.org/> - * - * This file has been put into the public domain. - * You can do whatever you want with this file. */ #ifndef XZ_H @@ -19,11 +18,6 @@ # include <stdint.h> #endif -/* In Linux, this is used to make extern functions static when needed. */ -#ifndef XZ_EXTERN -# define XZ_EXTERN extern -#endif - /** * enum xz_mode - Operation mode * @@ -143,7 +137,7 @@ struct xz_buf { size_t out_size; }; -/** +/* * struct xz_dec - Opaque type to hold the XZ decoder state */ struct xz_dec; @@ -191,7 +185,7 @@ struct xz_dec; * 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); +struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max); /** * xz_dec_run() - Run the XZ decoder @@ -211,7 +205,7 @@ XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max); * 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. */ -XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b); +enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b); /** * xz_dec_reset() - Reset an already allocated decoder state @@ -224,14 +218,115 @@ XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b); * 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); +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); +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. + */ + +/* + * 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. + */ +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. + */ +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. + */ +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. + */ +void xz_dec_microlzma_end(struct xz_dec_microlzma *s); /* * Standalone build (userspace build or in-kernel build for boot time use) @@ -252,13 +347,13 @@ XZ_EXTERN void xz_dec_end(struct xz_dec *s); * This must be called before any other xz_* function to initialize * the CRC32 lookup table. */ -XZ_EXTERN void xz_crc32_init(void); +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); +uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc); #endif #endif |