| /* |
| * XZ decompressor |
| * |
| * Authors: Lasse Collin <lasse.collin@tukaani.org> |
| * Igor Pavlov <http://7-zip.org/> |
| * |
| * This file has been put into the public domain. |
| * You can do whatever you want with this file. |
| */ |
| |
| #ifndef XZ_H |
| #define XZ_H |
| |
| #ifdef __KERNEL__ |
| # include <linux/stddef.h> |
| # include <linux/types.h> |
| #else |
| # include <stddef.h> |
| # 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 |
| * |
| * @XZ_SINGLE: Single-call mode. This uses less RAM than |
| * 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 |
| * @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. |
| */ |
| XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b); |
| |
| /** |
| * 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); |
| |
| /* |
| * 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. |
| */ |
| #ifndef XZ_INTERNAL_CRC32 |
| # ifdef __KERNEL__ |
| # define XZ_INTERNAL_CRC32 0 |
| # else |
| # define XZ_INTERNAL_CRC32 1 |
| # endif |
| #endif |
| |
| #if XZ_INTERNAL_CRC32 |
| /* |
| * 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); |
| #endif |
| #endif |
