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Diffstat (limited to 'grub-core/lib/xzembed/xz.h')
| -rw-r--r-- | grub-core/lib/xzembed/xz.h | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/grub-core/lib/xzembed/xz.h b/grub-core/lib/xzembed/xz.h new file mode 100644 index 0000000..f7b32d8 --- /dev/null +++ b/grub-core/lib/xzembed/xz.h @@ -0,0 +1,188 @@ +/* xz.h - XZ decompressor */ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2010 Free Software Foundation, Inc. + * + * GRUB is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * GRUB is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GRUB. If not, see <http://www.gnu.org/licenses/>. + */ +/* + * This file is based on code from XZ embedded project + * http://tukaani.org/xz/embedded.html + */ + +#ifndef XZ_H +#define XZ_H + +#include <config.h> +#include <stdint.h> +#include <unistd.h> +#include <string.h> +#include <grub/misc.h> + +#ifndef GRUB_POSIX_BOOL_DEFINED +typedef enum { false = 0, true = 1 } bool; +#endif + +/** + * enum xz_ret - Return codes + * @XZ_OK: Everything is OK so far. More input or more output + * space is required to continue. + * @XZ_STREAM_END: Operation finished successfully. + * @XZ_MEMLIMIT_ERROR: Not enough memory was preallocated at decoder + * initialization time. + * @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_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 + * @dict_max: Maximum size of the LZMA2 dictionary (history buffer) for + * multi-call decoding, or special value of zero to indicate + * single-call decoding mode. + * + * If dict_max > 0, the decoder is initialized to work in multi-call mode. + * dict_max number of 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. + * + * LZMA2 dictionary is always 2^n bytes or 2^n + 2^(n-1) bytes (the latter + * sizes are less common in practice). In the kernel, dictionary sizes of + * 64 KiB, 128 KiB, 256 KiB, 512 KiB, and 1 MiB are probably the only + * reasonable values. + * + * If dict_max == 0, the decoder is initialized to work in single-call mode. + * In single-call mode, 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. It is enough that the + * output buffer is is big enough to hold the actual uncompressed data; it + * can be smaller than the dictionary size stored in the stream headers. + * + * On success, xz_dec_init() returns a pointer to struct xz_dec, which is + * ready to be used with xz_dec_run(). On error, xz_dec_init() returns NULL. + */ +struct xz_dec * xz_dec_init(uint32_t dict_max); + +/** + * xz_dec_run() - Run the XZ decoder + * @s: Decoder state allocated using xz_dec_init() + * @b: Input and output buffers + * + * In multi-call mode, this function may return any of the values listed in + * enum xz_ret. + * + * In single-call mode, this function never returns XZ_OK. 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. + * + * NOTE: In single-call mode, the contents of the output buffer are undefined + * also after XZ_BUF_ERROR. This is 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. + */ +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. + */ +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. + */ +void xz_dec_end(struct xz_dec *s); + +#endif |