[Skiboot] [PATCH v12 06/10] skiboot: Add a library for xz
Michael Neuling
mikey at neuling.org
Tue Jun 13 16:48:11 AEST 2017
On Sun, 2017-05-21 at 20:40 +0530, Madhavan Srinivasan wrote:
> From: Hemant Kumar <hemant at linux.vnet.ibm.com>
>
> This patch adds a library for compression/decompression using xz.
> The code comes from http://tukaani.org/xz/embedded.html.
>
> The codebase has been kept as-is with a new Makefile.inc.
>
> For libxz/Makefile.inc and Makefile.main :
> Signed-off-by: Hemant Kumar <hemant at linux.vnet.ibm.com>
>
> Signed-off-by: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
Acked-by: Michael Neuling <mikey at neuling.org>
As an aside, it might be nice to build the skiboot.lid.xz using this so we don't
have an external dependency on needing xz.
> ---
> Makefile.main | 5 +-
> libxz/Makefile.inc | 7 +
> libxz/xz.h | 304 +++++++++++++
> libxz/xz_config.h | 124 ++++++
> libxz/xz_crc32.c | 59 +++
> libxz/xz_dec_lzma2.c | 1171
> +++++++++++++++++++++++++++++++++++++++++++++++++
> libxz/xz_dec_stream.c | 847 +++++++++++++++++++++++++++++++++++
> libxz/xz_lzma2.h | 204 +++++++++
> libxz/xz_private.h | 156 +++++++
> libxz/xz_stream.h | 62 +++
> 10 files changed, 2937 insertions(+), 2 deletions(-)
> create mode 100644 libxz/Makefile.inc
> create mode 100644 libxz/xz.h
> create mode 100644 libxz/xz_config.h
> create mode 100644 libxz/xz_crc32.c
> create mode 100644 libxz/xz_dec_lzma2.c
> create mode 100644 libxz/xz_dec_stream.c
> create mode 100644 libxz/xz_lzma2.h
> create mode 100644 libxz/xz_private.h
> create mode 100644 libxz/xz_stream.h
>
> diff --git a/Makefile.main b/Makefile.main
> index 65eacb1554cf..b22925dac88a 100644
> --- a/Makefile.main
> +++ b/Makefile.main
> @@ -52,7 +52,7 @@ OPTS=-Os
> DBG=-g
>
> CPPFLAGS := -I$(SRC)/include -Iinclude -MMD -include $(SRC)/include/config.h
> -CPPFLAGS += -I$(SRC)/libfdt -I$(SRC)/libflash -I$(SRC)/libc/include -I$(SRC)
> +CPPFLAGS += -I$(SRC)/libfdt -I$(SRC)/libflash -I$(SRC)/libxz
> -I$(SRC)/libc/include -I$(SRC)
> CPPFLAGS += -I$(SRC)/libpore
> CPPFLAGS += -D__SKIBOOT__ -nostdinc
> CPPFLAGS += -isystem $(shell $(CC) -print-file-name=include)
> @@ -171,6 +171,7 @@ include $(SRC)/hw/Makefile.inc
> include $(SRC)/platforms/Makefile.inc
> include $(SRC)/libfdt/Makefile.inc
> include $(SRC)/libflash/Makefile.inc
> +include $(SRC)/libxz/Makefile.inc
> include $(SRC)/libpore/Makefile.inc
> include $(SRC)/libc/Makefile.inc
> include $(SRC)/ccan/Makefile.inc
> @@ -190,7 +191,7 @@ pflash-coverity:
> all: $(SUBDIRS) $(TARGET).lid $(TARGET).lid.xz $(TARGET).map extract-gcov
> all: $(TARGET).lid.stb $(TARGET).lid.xz.stb
>
> -OBJS := $(ASM) $(CORE) $(HW) $(PLATFORMS) $(LIBFDT) $(LIBFLASH) $(LIBSTB)
> +OBJS := $(ASM) $(CORE) $(HW) $(PLATFORMS) $(LIBFDT) $(LIBXZ) $(LIBFLASH)
> $(LIBSTB)
> OBJS += $(LIBC) $(CCAN) $(DEVSRC_OBJ) $(LIBPORE)
> OBJS_NO_VER = $(OBJS)
> ALL_OBJS = $(OBJS) version.o
> diff --git a/libxz/Makefile.inc b/libxz/Makefile.inc
> new file mode 100644
> index 000000000000..298732867b77
> --- /dev/null
> +++ b/libxz/Makefile.inc
> @@ -0,0 +1,7 @@
> +LIBXZ_SRCS = xz_dec_stream.c xz_dec_lzma2.c xz_crc32.c
> +LIBXZ_OBJS = $(LIBXZ_SRCS:%.c=%.o)
> +
> +SUBDIRS += libxz
> +LIBXZ = libxz/built-in.o
> +
> +$(LIBXZ): $(LIBXZ_OBJS:%=libxz/%)
> diff --git a/libxz/xz.h b/libxz/xz.h
> new file mode 100644
> index 000000000000..75df73e39e53
> --- /dev/null
> +++ b/libxz/xz.h
> @@ -0,0 +1,304 @@
> +/*
> + * XZ decompressor
> + *
> + * Authors: Lasse Collin <lasse.collin at 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
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#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 CRC64 support has been enabled with XZ_USE_CRC64, a CRC64
> + * implementation is needed too.
> + */
> +#ifndef XZ_USE_CRC64
> + #undef XZ_INTERNAL_CRC64
> + #define XZ_INTERNAL_CRC64 0
> +#endif
> +#ifndef XZ_INTERNAL_CRC64
> + #ifdef __KERNEL__
> + #error Using CRC64 in the kernel has not been implemented.
> + #else
> + #define XZ_INTERNAL_CRC64 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
> +
> +#if XZ_INTERNAL_CRC64
> +/*
> + * 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);
> +#endif
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif
> diff --git a/libxz/xz_config.h b/libxz/xz_config.h
> new file mode 100644
> index 000000000000..a380be02c143
> --- /dev/null
> +++ b/libxz/xz_config.h
> @@ -0,0 +1,124 @@
> +/*
> + * Private includes and definitions for userspace use of XZ Embedded
> + *
> + * Author: Lasse Collin <lasse.collin at tukaani.org>
> + *
> + * This file has been put into the public domain.
> + * You can do whatever you want with this file.
> + */
> +
> +#ifndef XZ_CONFIG_H
> +#define XZ_CONFIG_H
> +
> +/* Uncomment to enable CRC64 support. */
> +/* #define XZ_USE_CRC64 */
> +
> +/* Uncomment as needed to enable BCJ filter decoders. */
> +/* #define XZ_DEC_X86 */
> +/* #define XZ_DEC_POWERPC */
> +/* #define XZ_DEC_IA64 */
> +/* #define XZ_DEC_ARM */
> +/* #define XZ_DEC_ARMTHUMB */
> +/* #define XZ_DEC_SPARC */
> +
> +/*
> + * MSVC doesn't support modern C but XZ Embedded is mostly C89
> + * so these are enough.
> + */
> +#ifdef _MSC_VER
> +typedef unsigned char bool;
> + #define true 1
> + #define false 0
> + #define inline __inline
> +#else
> + #include <stdbool.h>
> +#endif
> +
> +#include <stdlib.h>
> +#include <string.h>
> +
> +#include "xz.h"
> +
> +#define kmalloc(size, flags) malloc(size)
> +#define kfree(ptr) free(ptr)
> +#define vmalloc(size) malloc(size)
> +#define vfree(ptr) free(ptr)
> +
> +#define memeq(a, b, size) (memcmp(a, b, size) == 0)
> +#define memzero(buf, size) memset(buf, 0, size)
> +
> +#ifndef min
> + #define min(x, y) ((x) < (y) ? (x) : (y))
> +#endif
> +#define min_t(type, x, y) min(x, y)
> +
> +/*
> + * Some functions have been marked with __always_inline to keep the
> + * performance reasonable even when the compiler is optimizing for
> + * small code size. You may be able to save a few bytes by #defining
> + * __always_inline to plain inline, but don't complain if the code
> + * becomes slow.
> + *
> + * NOTE: System headers on GNU/Linux may #define this macro already,
> + * so if you want to change it, you need to #undef it first.
> + */
> +#ifndef __always_inline
> + #ifdef __GNUC__
> + #define __always_inline \
> + inline __attribute__((__always_inline__))
> + #else
> + #define __always_inline inline
> + #endif
> +#endif
> +
> +/* Inline functions to access unaligned unsigned 32-bit integers */
> +#ifndef get_unaligned_le32
> +static inline uint32_t get_unaligned_le32(const uint8_t *buf)
> +{
> + return (uint32_t)buf[0]
> + | ((uint32_t)buf[1] << 8)
> + | ((uint32_t)buf[2] << 16)
> + | ((uint32_t)buf[3] << 24);
> +}
> +#endif
> +
> +#ifndef get_unaligned_be32
> +static inline uint32_t get_unaligned_be32(const uint8_t *buf)
> +{
> + return (uint32_t)(buf[0] << 24)
> + | ((uint32_t)buf[1] << 16)
> + | ((uint32_t)buf[2] << 8)
> + | (uint32_t)buf[3];
> +}
> +#endif
> +
> +#ifndef put_unaligned_le32
> +static inline void put_unaligned_le32(uint32_t val, uint8_t *buf)
> +{
> + buf[0] = (uint8_t)val;
> + buf[1] = (uint8_t)(val >> 8);
> + buf[2] = (uint8_t)(val >> 16);
> + buf[3] = (uint8_t)(val >> 24);
> +}
> +#endif
> +
> +#ifndef put_unaligned_be32
> +static inline void put_unaligned_be32(uint32_t val, uint8_t *buf)
> +{
> + buf[0] = (uint8_t)(val >> 24);
> + buf[1] = (uint8_t)(val >> 16);
> + buf[2] = (uint8_t)(val >> 8);
> + buf[3] = (uint8_t)val;
> +}
> +#endif
> +
> +/*
> + * Use get_unaligned_le32() also for aligned access for simplicity. On
> + * little endian systems, #define get_le32(ptr) (*(const uint32_t *)(ptr))
> + * could save a few bytes in code size.
> + */
> +#ifndef get_le32
> + #define get_le32 get_unaligned_le32
> +#endif
> +
> +#endif
> diff --git a/libxz/xz_crc32.c b/libxz/xz_crc32.c
> new file mode 100644
> index 000000000000..c9194ff9c1d5
> --- /dev/null
> +++ b/libxz/xz_crc32.c
> @@ -0,0 +1,59 @@
> +/*
> + * CRC32 using the polynomial from IEEE-802.3
> + *
> + * Authors: Lasse Collin <lasse.collin at 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.
> + */
> +
> +/*
> + * This is not the fastest implementation, but it is pretty compact.
> + * The fastest versions of xz_crc32() on modern CPUs without hardware
> + * accelerated CRC instruction are 3-5 times as fast as this version,
> + * but they are bigger and use more memory for the lookup table.
> + */
> +
> +#include "xz_private.h"
> +
> +/*
> + * STATIC_RW_DATA is used in the pre-boot environment on some architectures.
> + * See <linux/decompress/mm.h> for details.
> + */
> +#ifndef STATIC_RW_DATA
> + #define STATIC_RW_DATA static
> +#endif
> +
> +STATIC_RW_DATA uint32_t xz_crc32_table[256];
> +
> +XZ_EXTERN void xz_crc32_init(void)
> +{
> + const uint32_t poly = 0xEDB88320;
> +
> + uint32_t i;
> + uint32_t j;
> + uint32_t r;
> +
> + for (i = 0; i < 256; ++i) {
> + r = i;
> + for (j = 0; j < 8; ++j)
> + r = (r >> 1) ^ (poly & ~((r & 1) - 1));
> +
> + xz_crc32_table[i] = r;
> + }
> +
> + return;
> +}
> +
> +XZ_EXTERN uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc)
> +{
> + crc = ~crc;
> +
> + while (size != 0) {
> + crc = xz_crc32_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8);
> + --size;
> + }
> +
> + return ~crc;
> +}
> diff --git a/libxz/xz_dec_lzma2.c b/libxz/xz_dec_lzma2.c
> new file mode 100644
> index 000000000000..7ba6cdbf874e
> --- /dev/null
> +++ b/libxz/xz_dec_lzma2.c
> @@ -0,0 +1,1171 @@
> +/*
> + * LZMA2 decoder
> + *
> + * Authors: Lasse Collin <lasse.collin at 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.
> + */
> +
> +#include "xz_private.h"
> +#include "xz_lzma2.h"
> +
> +/*
> + * Range decoder initialization eats the first five bytes of each LZMA chunk.
> + */
> +#define RC_INIT_BYTES 5
> +
> +/*
> + * Minimum number of usable input buffer to safely decode one LZMA symbol.
> + * The worst case is that we decode 22 bits using probabilities and 26
> + * direct bits. This may decode at maximum of 20 bytes of input. However,
> + * lzma_main() does an extra normalization before returning, thus we
> + * need to put 21 here.
> + */
> +#define LZMA_IN_REQUIRED 21
> +
> +/*
> + * Dictionary (history buffer)
> + *
> + * These are always true:
> + * start <= pos <= full <= end
> + * pos <= limit <= end
> + *
> + * In multi-call mode, also these are true:
> + * end == size
> + * size <= size_max
> + * allocated <= size
> + *
> + * Most of these variables are size_t to support single-call mode,
> + * in which the dictionary variables address the actual output
> + * buffer directly.
> + */
> +struct dictionary {
> + /* Beginning of the history buffer */
> + uint8_t *buf;
> +
> + /* Old position in buf (before decoding more data) */
> + size_t start;
> +
> + /* Position in buf */
> + size_t pos;
> +
> + /*
> + * How full dictionary is. This is used to detect corrupt input that
> + * would read beyond the beginning of the uncompressed stream.
> + */
> + size_t full;
> +
> + /* Write limit; we don't write to buf[limit] or later bytes. */
> + size_t limit;
> +
> + /*
> + * End of the dictionary buffer. In multi-call mode, this is
> + * the same as the dictionary size. In single-call mode, this
> + * indicates the size of the output buffer.
> + */
> + size_t end;
> +
> + /*
> + * Size of the dictionary as specified in Block Header. This is used
> + * together with "full" to detect corrupt input that would make us
> + * read beyond the beginning of the uncompressed stream.
> + */
> + uint32_t size;
> +
> + /*
> + * Maximum allowed dictionary size in multi-call mode.
> + * This is ignored in single-call mode.
> + */
> + uint32_t size_max;
> +
> + /*
> + * Amount of memory currently allocated for the dictionary.
> + * This is used only with XZ_DYNALLOC. (With XZ_PREALLOC,
> + * size_max is always the same as the allocated size.)
> + */
> + uint32_t allocated;
> +
> + /* Operation mode */
> + enum xz_mode mode;
> +};
> +
> +/* Range decoder */
> +struct rc_dec {
> + uint32_t range;
> + uint32_t code;
> +
> + /*
> + * Number of initializing bytes remaining to be read
> + * by rc_read_init().
> + */
> + uint32_t init_bytes_left;
> +
> + /*
> + * Buffer from which we read our input. It can be either
> + * temp.buf or the caller-provided input buffer.
> + */
> + const uint8_t *in;
> + size_t in_pos;
> + size_t in_limit;
> +};
> +
> +/* Probabilities for a length decoder. */
> +struct lzma_len_dec {
> + /* Probability of match length being at least 10 */
> + uint16_t choice;
> +
> + /* Probability of match length being at least 18 */
> + uint16_t choice2;
> +
> + /* Probabilities for match lengths 2-9 */
> + uint16_t low[POS_STATES_MAX][LEN_LOW_SYMBOLS];
> +
> + /* Probabilities for match lengths 10-17 */
> + uint16_t mid[POS_STATES_MAX][LEN_MID_SYMBOLS];
> +
> + /* Probabilities for match lengths 18-273 */
> + uint16_t high[LEN_HIGH_SYMBOLS];
> +};
> +
> +struct lzma_dec {
> + /* Distances of latest four matches */
> + uint32_t rep0;
> + uint32_t rep1;
> + uint32_t rep2;
> + uint32_t rep3;
> +
> + /* Types of the most recently seen LZMA symbols */
> + enum lzma_state state;
> +
> + /*
> + * Length of a match. This is updated so that dict_repeat can
> + * be called again to finish repeating the whole match.
> + */
> + uint32_t len;
> +
> + /*
> + * LZMA properties or related bit masks (number of literal
> + * context bits, a mask dervied from the number of literal
> + * position bits, and a mask dervied from the number
> + * position bits)
> + */
> + uint32_t lc;
> + uint32_t literal_pos_mask; /* (1 << lp) - 1 */
> + uint32_t pos_mask; /* (1 << pb) - 1 */
> +
> + /* If 1, it's a match. Otherwise it's a single 8-bit literal. */
> + uint16_t is_match[STATES][POS_STATES_MAX];
> +
> + /* If 1, it's a repeated match. The distance is one of rep0 .. rep3. */
> + uint16_t is_rep[STATES];
> +
> + /*
> + * If 0, distance of a repeated match is rep0.
> + * Otherwise check is_rep1.
> + */
> + uint16_t is_rep0[STATES];
> +
> + /*
> + * If 0, distance of a repeated match is rep1.
> + * Otherwise check is_rep2.
> + */
> + uint16_t is_rep1[STATES];
> +
> + /* If 0, distance of a repeated match is rep2. Otherwise it is rep3. */
> + uint16_t is_rep2[STATES];
> +
> + /*
> + * If 1, the repeated match has length of one byte. Otherwise
> + * the length is decoded from rep_len_decoder.
> + */
> + uint16_t is_rep0_long[STATES][POS_STATES_MAX];
> +
> + /*
> + * Probability tree for the highest two bits of the match
> + * distance. There is a separate probability tree for match
> + * lengths of 2 (i.e. MATCH_LEN_MIN), 3, 4, and [5, 273].
> + */
> + uint16_t dist_slot[DIST_STATES][DIST_SLOTS];
> +
> + /*
> + * Probility trees for additional bits for match distance
> + * when the distance is in the range [4, 127].
> + */
> + uint16_t dist_special[FULL_DISTANCES - DIST_MODEL_END];
> +
> + /*
> + * Probability tree for the lowest four bits of a match
> + * distance that is equal to or greater than 128.
> + */
> + uint16_t dist_align[ALIGN_SIZE];
> +
> + /* Length of a normal match */
> + struct lzma_len_dec match_len_dec;
> +
> + /* Length of a repeated match */
> + struct lzma_len_dec rep_len_dec;
> +
> + /* Probabilities of literals */
> + uint16_t literal[LITERAL_CODERS_MAX][LITERAL_CODER_SIZE];
> +};
> +
> +struct lzma2_dec {
> + /* Position in xz_dec_lzma2_run(). */
> + enum lzma2_seq {
> + SEQ_CONTROL,
> + SEQ_UNCOMPRESSED_1,
> + SEQ_UNCOMPRESSED_2,
> + SEQ_COMPRESSED_0,
> + SEQ_COMPRESSED_1,
> + SEQ_PROPERTIES,
> + SEQ_LZMA_PREPARE,
> + SEQ_LZMA_RUN,
> + SEQ_COPY
> + } sequence;
> +
> + /* Next position after decoding the compressed size of the chunk. */
> + enum lzma2_seq next_sequence;
> +
> + /* Uncompressed size of LZMA chunk (2 MiB at maximum) */
> + uint32_t uncompressed;
> +
> + /*
> + * Compressed size of LZMA chunk or compressed/uncompressed
> + * size of uncompressed chunk (64 KiB at maximum)
> + */
> + uint32_t compressed;
> +
> + /*
> + * True if dictionary reset is needed. This is false before
> + * the first chunk (LZMA or uncompressed).
> + */
> + bool need_dict_reset;
> +
> + /*
> + * True if new LZMA properties are needed. This is false
> + * before the first LZMA chunk.
> + */
> + bool need_props;
> +};
> +
> +struct xz_dec_lzma2 {
> + /*
> + * The order below is important on x86 to reduce code size and
> + * it shouldn't hurt on other platforms. Everything up to and
> + * including lzma.pos_mask are in the first 128 bytes on x86-32,
> + * which allows using smaller instructions to access those
> + * variables. On x86-64, fewer variables fit into the first 128
> + * bytes, but this is still the best order without sacrificing
> + * the readability by splitting the structures.
> + */
> + struct rc_dec rc;
> + struct dictionary dict;
> + struct lzma2_dec lzma2;
> + struct lzma_dec lzma;
> +
> + /*
> + * Temporary buffer which holds small number of input bytes between
> + * decoder calls. See lzma2_lzma() for details.
> + */
> + struct {
> + uint32_t size;
> + uint8_t buf[3 * LZMA_IN_REQUIRED];
> + } temp;
> +};
> +
> +/**************
> + * Dictionary *
> + **************/
> +
> +/*
> + * Reset the dictionary state. When in single-call mode, set up the beginning
> + * of the dictionary to point to the actual output buffer.
> + */
> +static void dict_reset(struct dictionary *dict, struct xz_buf *b)
> +{
> + if (DEC_IS_SINGLE(dict->mode)) {
> + dict->buf = b->out + b->out_pos;
> + dict->end = b->out_size - b->out_pos;
> + }
> +
> + dict->start = 0;
> + dict->pos = 0;
> + dict->limit = 0;
> + dict->full = 0;
> +}
> +
> +/* Set dictionary write limit */
> +static void dict_limit(struct dictionary *dict, size_t out_max)
> +{
> + if (dict->end - dict->pos <= out_max)
> + dict->limit = dict->end;
> + else
> + dict->limit = dict->pos + out_max;
> +}
> +
> +/* Return true if at least one byte can be written into the dictionary. */
> +static inline bool dict_has_space(const struct dictionary *dict)
> +{
> + return dict->pos < dict->limit;
> +}
> +
> +/*
> + * Get a byte from the dictionary at the given distance. The distance is
> + * assumed to valid, or as a special case, zero when the dictionary is
> + * still empty. This special case is needed for single-call decoding to
> + * avoid writing a '\0' to the end of the destination buffer.
> + */
> +static inline uint32_t dict_get(const struct dictionary *dict, uint32_t dist)
> +{
> + size_t offset = dict->pos - dist - 1;
> +
> + if (dist >= dict->pos)
> + offset += dict->end;
> +
> + return dict->full > 0 ? dict->buf[offset] : 0;
> +}
> +
> +/*
> + * Put one byte into the dictionary. It is assumed that there is space for
> it.
> + */
> +static inline void dict_put(struct dictionary *dict, uint8_t byte)
> +{
> + dict->buf[dict->pos++] = byte;
> +
> + if (dict->full < dict->pos)
> + dict->full = dict->pos;
> +}
> +
> +/*
> + * Repeat given number of bytes from the given distance. If the distance is
> + * invalid, false is returned. On success, true is returned and *len is
> + * updated to indicate how many bytes were left to be repeated.
> + */
> +static bool dict_repeat(struct dictionary *dict, uint32_t *len, uint32_t
> dist)
> +{
> + size_t back;
> + uint32_t left;
> +
> + if (dist >= dict->full || dist >= dict->size)
> + return false;
> +
> + left = min_t(size_t, dict->limit - dict->pos, *len);
> + *len -= left;
> +
> + back = dict->pos - dist - 1;
> + if (dist >= dict->pos)
> + back += dict->end;
> +
> + do {
> + dict->buf[dict->pos++] = dict->buf[back++];
> + if (back == dict->end)
> + back = 0;
> + } while (--left > 0);
> +
> + if (dict->full < dict->pos)
> + dict->full = dict->pos;
> +
> + return true;
> +}
> +
> +/* Copy uncompressed data as is from input to dictionary and output buffers.
> */
> +static void dict_uncompressed(struct dictionary *dict, struct xz_buf *b,
> + uint32_t *left)
> +{
> + size_t copy_size;
> +
> + while (*left > 0 && b->in_pos < b->in_size
> + && b->out_pos < b->out_size) {
> + copy_size = min(b->in_size - b->in_pos,
> + b->out_size - b->out_pos);
> + if (copy_size > dict->end - dict->pos)
> + copy_size = dict->end - dict->pos;
> + if (copy_size > *left)
> + copy_size = *left;
> +
> + *left -= copy_size;
> +
> + memcpy(dict->buf + dict->pos, b->in + b->in_pos, copy_size);
> + dict->pos += copy_size;
> +
> + if (dict->full < dict->pos)
> + dict->full = dict->pos;
> +
> + if (DEC_IS_MULTI(dict->mode)) {
> + if (dict->pos == dict->end)
> + dict->pos = 0;
> +
> + memcpy(b->out + b->out_pos, b->in + b->in_pos,
> + copy_size);
> + }
> +
> + dict->start = dict->pos;
> +
> + b->out_pos += copy_size;
> + b->in_pos += copy_size;
> + }
> +}
> +
> +/*
> + * Flush pending data from dictionary to b->out. It is assumed that there is
> + * enough space in b->out. This is guaranteed because caller uses
> dict_limit()
> + * before decoding data into the dictionary.
> + */
> +static uint32_t dict_flush(struct dictionary *dict, struct xz_buf *b)
> +{
> + size_t copy_size = dict->pos - dict->start;
> +
> + if (DEC_IS_MULTI(dict->mode)) {
> + if (dict->pos == dict->end)
> + dict->pos = 0;
> +
> + memcpy(b->out + b->out_pos, dict->buf + dict->start,
> + copy_size);
> + }
> +
> + dict->start = dict->pos;
> + b->out_pos += copy_size;
> + return copy_size;
> +}
> +
> +/*****************
> + * Range decoder *
> + *****************/
> +
> +/* Reset the range decoder. */
> +static void rc_reset(struct rc_dec *rc)
> +{
> + rc->range = (uint32_t)-1;
> + rc->code = 0;
> + rc->init_bytes_left = RC_INIT_BYTES;
> +}
> +
> +/*
> + * Read the first five initial bytes into rc->code if they haven't been
> + * read already. (Yes, the first byte gets completely ignored.)
> + */
> +static bool rc_read_init(struct rc_dec *rc, struct xz_buf *b)
> +{
> + while (rc->init_bytes_left > 0) {
> + if (b->in_pos == b->in_size)
> + return false;
> +
> + rc->code = (rc->code << 8) + b->in[b->in_pos++];
> + --rc->init_bytes_left;
> + }
> +
> + return true;
> +}
> +
> +/* Return true if there may not be enough input for the next decoding loop.
> */
> +static inline bool rc_limit_exceeded(const struct rc_dec *rc)
> +{
> + return rc->in_pos > rc->in_limit;
> +}
> +
> +/*
> + * Return true if it is possible (from point of view of range decoder) that
> + * we have reached the end of the LZMA chunk.
> + */
> +static inline bool rc_is_finished(const struct rc_dec *rc)
> +{
> + return rc->code == 0;
> +}
> +
> +/* Read the next input byte if needed. */
> +static __always_inline void rc_normalize(struct rc_dec *rc)
> +{
> + if (rc->range < RC_TOP_VALUE) {
> + rc->range <<= RC_SHIFT_BITS;
> + rc->code = (rc->code << RC_SHIFT_BITS) + rc->in[rc->in_pos++];
> + }
> +}
> +
> +/*
> + * Decode one bit. In some versions, this function has been splitted in three
> + * functions so that the compiler is supposed to be able to more easily avoid
> + * an extra branch. In this particular version of the LZMA decoder, this
> + * doesn't seem to be a good idea (tested with GCC 3.3.6, 3.4.6, and 4.3.3
> + * on x86). Using a non-splitted version results in nicer looking code too.
> + *
> + * NOTE: This must return an int. Do not make it return a bool or the speed
> + * of the code generated by GCC 3.x decreases 10-15 %. (GCC 4.3 doesn't care,
> + * and it generates 10-20 % faster code than GCC 3.x from this file anyway.)
> + */
> +static __always_inline int rc_bit(struct rc_dec *rc, uint16_t *prob)
> +{
> + uint32_t bound;
> + int bit;
> +
> + rc_normalize(rc);
> + bound = (rc->range >> RC_BIT_MODEL_TOTAL_BITS) * *prob;
> + if (rc->code < bound) {
> + rc->range = bound;
> + *prob += (RC_BIT_MODEL_TOTAL - *prob) >> RC_MOVE_BITS;
> + bit = 0;
> + } else {
> + rc->range -= bound;
> + rc->code -= bound;
> + *prob -= *prob >> RC_MOVE_BITS;
> + bit = 1;
> + }
> +
> + return bit;
> +}
> +
> +/* Decode a bittree starting from the most significant bit. */
> +static __always_inline uint32_t rc_bittree(struct rc_dec *rc,
> + uint16_t *probs, uint32_t limit)
> +{
> + uint32_t symbol = 1;
> +
> + do {
> + if (rc_bit(rc, &probs[symbol]))
> + symbol = (symbol << 1) + 1;
> + else
> + symbol <<= 1;
> + } while (symbol < limit);
> +
> + return symbol;
> +}
> +
> +/* Decode a bittree starting from the least significant bit. */
> +static __always_inline void rc_bittree_reverse(struct rc_dec *rc,
> + uint16_t *probs,
> + uint32_t *dest, uint32_t limit)
> +{
> + uint32_t symbol = 1;
> + uint32_t i = 0;
> +
> + do {
> + if (rc_bit(rc, &probs[symbol])) {
> + symbol = (symbol << 1) + 1;
> + *dest += 1 << i;
> + } else {
> + symbol <<= 1;
> + }
> + } while (++i < limit);
> +}
> +
> +/* Decode direct bits (fixed fifty-fifty probability) */
> +static inline void rc_direct(struct rc_dec *rc, uint32_t *dest, uint32_t
> limit)
> +{
> + uint32_t mask;
> +
> + do {
> + rc_normalize(rc);
> + rc->range >>= 1;
> + rc->code -= rc->range;
> + mask = (uint32_t)0 - (rc->code >> 31);
> + rc->code += rc->range & mask;
> + *dest = (*dest << 1) + (mask + 1);
> + } while (--limit > 0);
> +}
> +
> +/********
> + * LZMA *
> + ********/
> +
> +/* Get pointer to literal coder probability array. */
> +static uint16_t *lzma_literal_probs(struct xz_dec_lzma2 *s)
> +{
> + uint32_t prev_byte = dict_get(&s->dict, 0);
> + uint32_t low = prev_byte >> (8 - s->lzma.lc);
> + uint32_t high = (s->dict.pos & s->lzma.literal_pos_mask) << s->lzma.lc;
> + return s->lzma.literal[low + high];
> +}
> +
> +/* Decode a literal (one 8-bit byte) */
> +static void lzma_literal(struct xz_dec_lzma2 *s)
> +{
> + uint16_t *probs;
> + uint32_t symbol;
> + uint32_t match_byte;
> + uint32_t match_bit;
> + uint32_t offset;
> + uint32_t i;
> +
> + probs = lzma_literal_probs(s);
> +
> + if (lzma_state_is_literal(s->lzma.state)) {
> + symbol = rc_bittree(&s->rc, probs, 0x100);
> + } else {
> + symbol = 1;
> + match_byte = dict_get(&s->dict, s->lzma.rep0) << 1;
> + offset = 0x100;
> +
> + do {
> + match_bit = match_byte & offset;
> + match_byte <<= 1;
> + i = offset + match_bit + symbol;
> +
> + if (rc_bit(&s->rc, &probs[i])) {
> + symbol = (symbol << 1) + 1;
> + offset &= match_bit;
> + } else {
> + symbol <<= 1;
> + offset &= ~match_bit;
> + }
> + } while (symbol < 0x100);
> + }
> +
> + dict_put(&s->dict, (uint8_t)symbol);
> + lzma_state_literal(&s->lzma.state);
> +}
> +
> +/* Decode the length of the match into s->lzma.len. */
> +static void lzma_len(struct xz_dec_lzma2 *s, struct lzma_len_dec *l,
> + uint32_t pos_state)
> +{
> + uint16_t *probs;
> + uint32_t limit;
> +
> + if (!rc_bit(&s->rc, &l->choice)) {
> + probs = l->low[pos_state];
> + limit = LEN_LOW_SYMBOLS;
> + s->lzma.len = MATCH_LEN_MIN;
> + } else {
> + if (!rc_bit(&s->rc, &l->choice2)) {
> + probs = l->mid[pos_state];
> + limit = LEN_MID_SYMBOLS;
> + s->lzma.len = MATCH_LEN_MIN + LEN_LOW_SYMBOLS;
> + } else {
> + probs = l->high;
> + limit = LEN_HIGH_SYMBOLS;
> + s->lzma.len = MATCH_LEN_MIN + LEN_LOW_SYMBOLS
> + + LEN_MID_SYMBOLS;
> + }
> + }
> +
> + s->lzma.len += rc_bittree(&s->rc, probs, limit) - limit;
> +}
> +
> +/* Decode a match. The distance will be stored in s->lzma.rep0. */
> +static void lzma_match(struct xz_dec_lzma2 *s, uint32_t pos_state)
> +{
> + uint16_t *probs;
> + uint32_t dist_slot;
> + uint32_t limit;
> +
> + lzma_state_match(&s->lzma.state);
> +
> + s->lzma.rep3 = s->lzma.rep2;
> + s->lzma.rep2 = s->lzma.rep1;
> + s->lzma.rep1 = s->lzma.rep0;
> +
> + lzma_len(s, &s->lzma.match_len_dec, pos_state);
> +
> + probs = s->lzma.dist_slot[lzma_get_dist_state(s->lzma.len)];
> + dist_slot = rc_bittree(&s->rc, probs, DIST_SLOTS) - DIST_SLOTS;
> +
> + if (dist_slot < DIST_MODEL_START) {
> + s->lzma.rep0 = dist_slot;
> + } else {
> + limit = (dist_slot >> 1) - 1;
> + s->lzma.rep0 = 2 + (dist_slot & 1);
> +
> + if (dist_slot < DIST_MODEL_END) {
> + s->lzma.rep0 <<= limit;
> + probs = s->lzma.dist_special + s->lzma.rep0
> + - dist_slot - 1;
> + rc_bittree_reverse(&s->rc, probs,
> + &s->lzma.rep0, limit);
> + } else {
> + rc_direct(&s->rc, &s->lzma.rep0, limit - ALIGN_BITS);
> + s->lzma.rep0 <<= ALIGN_BITS;
> + rc_bittree_reverse(&s->rc, s->lzma.dist_align,
> + &s->lzma.rep0, ALIGN_BITS);
> + }
> + }
> +}
> +
> +/*
> + * Decode a repeated match. The distance is one of the four most recently
> + * seen matches. The distance will be stored in s->lzma.rep0.
> + */
> +static void lzma_rep_match(struct xz_dec_lzma2 *s, uint32_t pos_state)
> +{
> + uint32_t tmp;
> +
> + if (!rc_bit(&s->rc, &s->lzma.is_rep0[s->lzma.state])) {
> + if (!rc_bit(&s->rc, &s->lzma.is_rep0_long[
> + s->lzma.state][pos_state])) {
> + lzma_state_short_rep(&s->lzma.state);
> + s->lzma.len = 1;
> + return;
> + }
> + } else {
> + if (!rc_bit(&s->rc, &s->lzma.is_rep1[s->lzma.state])) {
> + tmp = s->lzma.rep1;
> + } else {
> + if (!rc_bit(&s->rc, &s->lzma.is_rep2[s->lzma.state])) {
> + tmp = s->lzma.rep2;
> + } else {
> + tmp = s->lzma.rep3;
> + s->lzma.rep3 = s->lzma.rep2;
> + }
> +
> + s->lzma.rep2 = s->lzma.rep1;
> + }
> +
> + s->lzma.rep1 = s->lzma.rep0;
> + s->lzma.rep0 = tmp;
> + }
> +
> + lzma_state_long_rep(&s->lzma.state);
> + lzma_len(s, &s->lzma.rep_len_dec, pos_state);
> +}
> +
> +/* LZMA decoder core */
> +static bool lzma_main(struct xz_dec_lzma2 *s)
> +{
> + uint32_t pos_state;
> +
> + /*
> + * If the dictionary was reached during the previous call, try to
> + * finish the possibly pending repeat in the dictionary.
> + */
> + if (dict_has_space(&s->dict) && s->lzma.len > 0)
> + dict_repeat(&s->dict, &s->lzma.len, s->lzma.rep0);
> +
> + /*
> + * Decode more LZMA symbols. One iteration may consume up to
> + * LZMA_IN_REQUIRED - 1 bytes.
> + */
> + while (dict_has_space(&s->dict) && !rc_limit_exceeded(&s->rc)) {
> + pos_state = s->dict.pos & s->lzma.pos_mask;
> +
> + if (!rc_bit(&s->rc, &s->lzma.is_match[
> + s->lzma.state][pos_state])) {
> + lzma_literal(s);
> + } else {
> + if (rc_bit(&s->rc, &s->lzma.is_rep[s->lzma.state]))
> + lzma_rep_match(s, pos_state);
> + else
> + lzma_match(s, pos_state);
> +
> + if (!dict_repeat(&s->dict, &s->lzma.len, s->lzma.rep0))
> + return false;
> + }
> + }
> +
> + /*
> + * Having the range decoder always normalized when we are outside
> + * this function makes it easier to correctly handle end of the chunk.
> + */
> + rc_normalize(&s->rc);
> +
> + return true;
> +}
> +
> +/*
> + * Reset the LZMA decoder and range decoder state. Dictionary is nore reset
> + * here, because LZMA state may be reset without resetting the dictionary.
> + */
> +static void lzma_reset(struct xz_dec_lzma2 *s)
> +{
> + uint16_t *probs;
> + size_t i;
> +
> + s->lzma.state = STATE_LIT_LIT;
> + s->lzma.rep0 = 0;
> + s->lzma.rep1 = 0;
> + s->lzma.rep2 = 0;
> + s->lzma.rep3 = 0;
> +
> + /*
> + * All probabilities are initialized to the same value. This hack
> + * makes the code smaller by avoiding a separate loop for each
> + * probability array.
> + *
> + * This could be optimized so that only that part of literal
> + * probabilities that are actually required. In the common case
> + * we would write 12 KiB less.
> + */
> + probs = s->lzma.is_match[0];
> + for (i = 0; i < PROBS_TOTAL; ++i)
> + probs[i] = RC_BIT_MODEL_TOTAL / 2;
> +
> + rc_reset(&s->rc);
> +}
> +
> +/*
> + * Decode and validate LZMA properties (lc/lp/pb) and calculate the bit masks
> + * from the decoded lp and pb values. On success, the LZMA decoder state is
> + * reset and true is returned.
> + */
> +static bool lzma_props(struct xz_dec_lzma2 *s, uint8_t props)
> +{
> + if (props > (4 * 5 + 4) * 9 + 8)
> + return false;
> +
> + s->lzma.pos_mask = 0;
> + while (props >= 9 * 5) {
> + props -= 9 * 5;
> + ++s->lzma.pos_mask;
> + }
> +
> + s->lzma.pos_mask = (1 << s->lzma.pos_mask) - 1;
> +
> + s->lzma.literal_pos_mask = 0;
> + while (props >= 9) {
> + props -= 9;
> + ++s->lzma.literal_pos_mask;
> + }
> +
> + s->lzma.lc = props;
> +
> + if (s->lzma.lc + s->lzma.literal_pos_mask > 4)
> + return false;
> +
> + s->lzma.literal_pos_mask = (1 << s->lzma.literal_pos_mask) - 1;
> +
> + lzma_reset(s);
> +
> + return true;
> +}
> +
> +/*********
> + * LZMA2 *
> + *********/
> +
> +/*
> + * The LZMA decoder assumes that if the input limit (s->rc.in_limit) hasn't
> + * been exceeded, it is safe to read up to LZMA_IN_REQUIRED bytes. This
> + * wrapper function takes care of making the LZMA decoder's assumption safe.
> + *
> + * As long as there is plenty of input left to be decoded in the current LZMA
> + * chunk, we decode directly from the caller-supplied input buffer until
> + * there's LZMA_IN_REQUIRED bytes left. Those remaining bytes are copied into
> + * s->temp.buf, which (hopefully) gets filled on the next call to this
> + * function. We decode a few bytes from the temporary buffer so that we can
> + * continue decoding from the caller-supplied input buffer again.
> + */
> +static bool lzma2_lzma(struct xz_dec_lzma2 *s, struct xz_buf *b)
> +{
> + size_t in_avail;
> + uint32_t tmp;
> +
> + in_avail = b->in_size - b->in_pos;
> + if (s->temp.size > 0 || s->lzma2.compressed == 0) {
> + tmp = 2 * LZMA_IN_REQUIRED - s->temp.size;
> + if (tmp > s->lzma2.compressed - s->temp.size)
> + tmp = s->lzma2.compressed - s->temp.size;
> + if (tmp > in_avail)
> + tmp = in_avail;
> +
> + memcpy(s->temp.buf + s->temp.size, b->in + b->in_pos, tmp);
> +
> + if (s->temp.size + tmp == s->lzma2.compressed) {
> + memzero(s->temp.buf + s->temp.size + tmp,
> + sizeof(s->temp.buf)
> + - s->temp.size - tmp);
> + s->rc.in_limit = s->temp.size + tmp;
> + } else if (s->temp.size + tmp < LZMA_IN_REQUIRED) {
> + s->temp.size += tmp;
> + b->in_pos += tmp;
> + return true;
> + } else {
> + s->rc.in_limit = s->temp.size + tmp - LZMA_IN_REQUIRED;
> + }
> +
> + s->rc.in = s->temp.buf;
> + s->rc.in_pos = 0;
> +
> + if (!lzma_main(s) || s->rc.in_pos > s->temp.size + tmp)
> + return false;
> +
> + s->lzma2.compressed -= s->rc.in_pos;
> +
> + if (s->rc.in_pos < s->temp.size) {
> + s->temp.size -= s->rc.in_pos;
> + memmove(s->temp.buf, s->temp.buf + s->rc.in_pos,
> + s->temp.size);
> + return true;
> + }
> +
> + b->in_pos += s->rc.in_pos - s->temp.size;
> + s->temp.size = 0;
> + }
> +
> + in_avail = b->in_size - b->in_pos;
> + if (in_avail >= LZMA_IN_REQUIRED) {
> + s->rc.in = b->in;
> + s->rc.in_pos = b->in_pos;
> +
> + if (in_avail >= s->lzma2.compressed + LZMA_IN_REQUIRED)
> + s->rc.in_limit = b->in_pos + s->lzma2.compressed;
> + else
> + s->rc.in_limit = b->in_size - LZMA_IN_REQUIRED;
> +
> + if (!lzma_main(s))
> + return false;
> +
> + in_avail = s->rc.in_pos - b->in_pos;
> + if (in_avail > s->lzma2.compressed)
> + return false;
> +
> + s->lzma2.compressed -= in_avail;
> + b->in_pos = s->rc.in_pos;
> + }
> +
> + in_avail = b->in_size - b->in_pos;
> + if (in_avail < LZMA_IN_REQUIRED) {
> + if (in_avail > s->lzma2.compressed)
> + in_avail = s->lzma2.compressed;
> +
> + memcpy(s->temp.buf, b->in + b->in_pos, in_avail);
> + s->temp.size = in_avail;
> + b->in_pos += in_avail;
> + }
> +
> + return true;
> +}
> +
> +/*
> + * Take care of the LZMA2 control layer, and forward the job of actual LZMA
> + * decoding or copying of uncompressed chunks to other functions.
> + */
> +XZ_EXTERN enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
> + struct xz_buf *b)
> +{
> + uint32_t tmp;
> +
> + while (b->in_pos < b->in_size || s->lzma2.sequence == SEQ_LZMA_RUN) {
> + switch (s->lzma2.sequence) {
> + case SEQ_CONTROL:
> + /*
> + * LZMA2 control byte
> + *
> + * Exact values:
> + * 0x00 End marker
> + * 0x01 Dictionary reset followed by
> + * an uncompressed chunk
> + * 0x02 Uncompressed chunk (no dictionary reset)
> + *
> + * Highest three bits (s->control & 0xE0):
> + * 0xE0 Dictionary reset, new properties and state
> + * reset, followed by LZMA compressed chunk
> + * 0xC0 New properties and state reset, followed
> + * by LZMA compressed chunk (no dictionary
> + * reset)
> + * 0xA0 State reset using old properties,
> + * followed by LZMA compressed chunk (no
> + * dictionary reset)
> + * 0x80 LZMA chunk (no dictionary or state reset)
> + *
> + * For LZMA compressed chunks, the lowest five bits
> + * (s->control & 1F) are the highest bits of the
> + * uncompressed size (bits 16-20).
> + *
> + * A new LZMA2 stream must begin with a dictionary
> + * reset. The first LZMA chunk must set new
> + * properties and reset the LZMA state.
> + *
> + * Values that don't match anything described above
> + * are invalid and we return XZ_DATA_ERROR.
> + */
> + tmp = b->in[b->in_pos++];
> +
> + if (tmp == 0x00)
> + return XZ_STREAM_END;
> +
> + if (tmp >= 0xE0 || tmp == 0x01) {
> + s->lzma2.need_props = true;
> + s->lzma2.need_dict_reset = false;
> + dict_reset(&s->dict, b);
> + } else if (s->lzma2.need_dict_reset) {
> + return XZ_DATA_ERROR;
> + }
> +
> + if (tmp >= 0x80) {
> + s->lzma2.uncompressed = (tmp & 0x1F) << 16;
> + s->lzma2.sequence = SEQ_UNCOMPRESSED_1;
> +
> + if (tmp >= 0xC0) {
> + /*
> + * When there are new properties,
> + * state reset is done at
> + * SEQ_PROPERTIES.
> + */
> + s->lzma2.need_props = false;
> + s->lzma2.next_sequence
> + = SEQ_PROPERTIES;
> +
> + } else if (s->lzma2.need_props) {
> + return XZ_DATA_ERROR;
> +
> + } else {
> + s->lzma2.next_sequence
> + = SEQ_LZMA_PREPARE;
> + if (tmp >= 0xA0)
> + lzma_reset(s);
> + }
> + } else {
> + if (tmp > 0x02)
> + return XZ_DATA_ERROR;
> +
> + s->lzma2.sequence = SEQ_COMPRESSED_0;
> + s->lzma2.next_sequence = SEQ_COPY;
> + }
> +
> + break;
> +
> + case SEQ_UNCOMPRESSED_1:
> + s->lzma2.uncompressed
> + += (uint32_t)b->in[b->in_pos++] << 8;
> + s->lzma2.sequence = SEQ_UNCOMPRESSED_2;
> + break;
> +
> + case SEQ_UNCOMPRESSED_2:
> + s->lzma2.uncompressed
> + += (uint32_t)b->in[b->in_pos++] + 1;
> + s->lzma2.sequence = SEQ_COMPRESSED_0;
> + break;
> +
> + case SEQ_COMPRESSED_0:
> + s->lzma2.compressed
> + = (uint32_t)b->in[b->in_pos++] << 8;
> + s->lzma2.sequence = SEQ_COMPRESSED_1;
> + break;
> +
> + case SEQ_COMPRESSED_1:
> + s->lzma2.compressed
> + += (uint32_t)b->in[b->in_pos++] + 1;
> + s->lzma2.sequence = s->lzma2.next_sequence;
> + break;
> +
> + case SEQ_PROPERTIES:
> + if (!lzma_props(s, b->in[b->in_pos++]))
> + return XZ_DATA_ERROR;
> +
> + s->lzma2.sequence = SEQ_LZMA_PREPARE;
> +
> + case SEQ_LZMA_PREPARE:
> + if (s->lzma2.compressed < RC_INIT_BYTES)
> + return XZ_DATA_ERROR;
> +
> + if (!rc_read_init(&s->rc, b))
> + return XZ_OK;
> +
> + s->lzma2.compressed -= RC_INIT_BYTES;
> + s->lzma2.sequence = SEQ_LZMA_RUN;
> +
> + case SEQ_LZMA_RUN:
> + /*
> + * Set dictionary limit to indicate how much we want
> + * to be encoded at maximum. Decode new data into the
> + * dictionary. Flush the new data from dictionary to
> + * b->out. Check if we finished decoding this chunk.
> + * In case the dictionary got full but we didn't fill
> + * the output buffer yet, we may run this loop
> + * multiple times without changing s->lzma2.sequence.
> + */
> + dict_limit(&s->dict, min_t(size_t,
> + b->out_size - b->out_pos,
> + s->lzma2.uncompressed));
> + if (!lzma2_lzma(s, b))
> + return XZ_DATA_ERROR;
> +
> + s->lzma2.uncompressed -= dict_flush(&s->dict, b);
> +
> + if (s->lzma2.uncompressed == 0) {
> + if (s->lzma2.compressed > 0 || s->lzma.len > 0
> + || !rc_is_finished(&s->rc))
> + return XZ_DATA_ERROR;
> +
> + rc_reset(&s->rc);
> + s->lzma2.sequence = SEQ_CONTROL;
> +
> + } else if (b->out_pos == b->out_size
> + || (b->in_pos == b->in_size
> + && s->temp.size
> + < s->lzma2.compressed)) {
> + return XZ_OK;
> + }
> +
> + break;
> +
> + case SEQ_COPY:
> + dict_uncompressed(&s->dict, b, &s->lzma2.compressed);
> + if (s->lzma2.compressed > 0)
> + return XZ_OK;
> +
> + s->lzma2.sequence = SEQ_CONTROL;
> + break;
> + }
> + }
> +
> + return XZ_OK;
> +}
> +
> +XZ_EXTERN struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode,
> + uint32_t dict_max)
> +{
> + struct xz_dec_lzma2 *s = kmalloc(sizeof(*s), GFP_KERNEL);
> + if (s == NULL)
> + return NULL;
> +
> + s->dict.mode = mode;
> + s->dict.size_max = dict_max;
> +
> + if (DEC_IS_PREALLOC(mode)) {
> + s->dict.buf = vmalloc(dict_max);
> + if (s->dict.buf == NULL) {
> + kfree(s);
> + return NULL;
> + }
> + } else if (DEC_IS_DYNALLOC(mode)) {
> + s->dict.buf = NULL;
> + s->dict.allocated = 0;
> + }
> +
> + return s;
> +}
> +
> +XZ_EXTERN enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s, uint8_t
> props)
> +{
> + /* This limits dictionary size to 3 GiB to keep parsing simpler. */
> + if (props > 39)
> + return XZ_OPTIONS_ERROR;
> +
> + s->dict.size = 2 + (props & 1);
> + s->dict.size <<= (props >> 1) + 11;
> +
> + if (DEC_IS_MULTI(s->dict.mode)) {
> + if (s->dict.size > s->dict.size_max)
> + return XZ_MEMLIMIT_ERROR;
> +
> + s->dict.end = s->dict.size;
> +
> + if (DEC_IS_DYNALLOC(s->dict.mode)) {
> + if (s->dict.allocated < s->dict.size) {
> + vfree(s->dict.buf);
> + s->dict.buf = vmalloc(s->dict.size);
> + if (s->dict.buf == NULL) {
> + s->dict.allocated = 0;
> + return XZ_MEM_ERROR;
> + }
> + }
> + }
> + }
> +
> + s->lzma.len = 0;
> +
> + s->lzma2.sequence = SEQ_CONTROL;
> + s->lzma2.need_dict_reset = true;
> +
> + s->temp.size = 0;
> +
> + return XZ_OK;
> +}
> +
> +XZ_EXTERN void xz_dec_lzma2_end(struct xz_dec_lzma2 *s)
> +{
> + if (DEC_IS_MULTI(s->dict.mode))
> + vfree(s->dict.buf);
> +
> + kfree(s);
> +}
> diff --git a/libxz/xz_dec_stream.c b/libxz/xz_dec_stream.c
> new file mode 100644
> index 000000000000..08d26af18de3
> --- /dev/null
> +++ b/libxz/xz_dec_stream.c
> @@ -0,0 +1,847 @@
> +/*
> + * .xz Stream decoder
> + *
> + * Author: Lasse Collin <lasse.collin at tukaani.org>
> + *
> + * This file has been put into the public domain.
> + * You can do whatever you want with this file.
> + */
> +
> +#include "xz_private.h"
> +#include "xz_stream.h"
> +
> +#ifdef XZ_USE_CRC64
> + #define IS_CRC64(check_type) ((check_type) == XZ_CHECK_CRC64)
> +#else
> + #define IS_CRC64(check_type) false
> +#endif
> +
> +/* Hash used to validate the Index field */
> +struct xz_dec_hash {
> + vli_type unpadded;
> + vli_type uncompressed;
> + uint32_t crc32;
> +};
> +
> +struct xz_dec {
> + /* Position in dec_main() */
> + enum {
> + SEQ_STREAM_HEADER,
> + SEQ_BLOCK_START,
> + SEQ_BLOCK_HEADER,
> + SEQ_BLOCK_UNCOMPRESS,
> + SEQ_BLOCK_PADDING,
> + SEQ_BLOCK_CHECK,
> + SEQ_INDEX,
> + SEQ_INDEX_PADDING,
> + SEQ_INDEX_CRC32,
> + SEQ_STREAM_FOOTER
> + } sequence;
> +
> + /* Position in variable-length integers and Check fields */
> + uint32_t pos;
> +
> + /* Variable-length integer decoded by dec_vli() */
> + vli_type vli;
> +
> + /* Saved in_pos and out_pos */
> + size_t in_start;
> + size_t out_start;
> +
> +#ifdef XZ_USE_CRC64
> + /* CRC32 or CRC64 value in Block or CRC32 value in Index */
> + uint64_t crc;
> +#else
> + /* CRC32 value in Block or Index */
> + uint32_t crc;
> +#endif
> +
> + /* Type of the integrity check calculated from uncompressed data */
> + enum xz_check check_type;
> +
> + /* Operation mode */
> + enum xz_mode mode;
> +
> + /*
> + * True if the next call to xz_dec_run() is allowed to return
> + * XZ_BUF_ERROR.
> + */
> + bool allow_buf_error;
> +
> + /* Information stored in Block Header */
> + struct {
> + /*
> + * Value stored in the Compressed Size field, or
> + * VLI_UNKNOWN if Compressed Size is not present.
> + */
> + vli_type compressed;
> +
> + /*
> + * Value stored in the Uncompressed Size field, or
> + * VLI_UNKNOWN if Uncompressed Size is not present.
> + */
> + vli_type uncompressed;
> +
> + /* Size of the Block Header field */
> + uint32_t size;
> + } block_header;
> +
> + /* Information collected when decoding Blocks */
> + struct {
> + /* Observed compressed size of the current Block */
> + vli_type compressed;
> +
> + /* Observed uncompressed size of the current Block */
> + vli_type uncompressed;
> +
> + /* Number of Blocks decoded so far */
> + vli_type count;
> +
> + /*
> + * Hash calculated from the Block sizes. This is used to
> + * validate the Index field.
> + */
> + struct xz_dec_hash hash;
> + } block;
> +
> + /* Variables needed when verifying the Index field */
> + struct {
> + /* Position in dec_index() */
> + enum {
> + SEQ_INDEX_COUNT,
> + SEQ_INDEX_UNPADDED,
> + SEQ_INDEX_UNCOMPRESSED
> + } sequence;
> +
> + /* Size of the Index in bytes */
> + vli_type size;
> +
> + /* Number of Records (matches block.count in valid files) */
> + vli_type count;
> +
> + /*
> + * Hash calculated from the Records (matches block.hash in
> + * valid files).
> + */
> + struct xz_dec_hash hash;
> + } index;
> +
> + /*
> + * Temporary buffer needed to hold Stream Header, Block Header,
> + * and Stream Footer. The Block Header is the biggest (1 KiB)
> + * so we reserve space according to that. buf[] has to be aligned
> + * to a multiple of four bytes; the size_t variables before it
> + * should guarantee this.
> + */
> + struct {
> + size_t pos;
> + size_t size;
> + uint8_t buf[1024];
> + } temp;
> +
> + struct xz_dec_lzma2 *lzma2;
> +
> +#ifdef XZ_DEC_BCJ
> + struct xz_dec_bcj *bcj;
> + bool bcj_active;
> +#endif
> +};
> +
> +#ifdef XZ_DEC_ANY_CHECK
> +/* Sizes of the Check field with different Check IDs */
> +static const uint8_t check_sizes[16] = {
> + 0,
> + 4, 4, 4,
> + 8, 8, 8,
> + 16, 16, 16,
> + 32, 32, 32,
> + 64, 64, 64
> +};
> +#endif
> +
> +/*
> + * Fill s->temp by copying data starting from b->in[b->in_pos]. Caller
> + * must have set s->temp.pos to indicate how much data we are supposed
> + * to copy into s->temp.buf. Return true once s->temp.pos has reached
> + * s->temp.size.
> + */
> +static bool fill_temp(struct xz_dec *s, struct xz_buf *b)
> +{
> + size_t copy_size = min_t(size_t,
> + b->in_size - b->in_pos, s->temp.size - s->temp.pos);
> +
> + memcpy(s->temp.buf + s->temp.pos, b->in + b->in_pos, copy_size);
> + b->in_pos += copy_size;
> + s->temp.pos += copy_size;
> +
> + if (s->temp.pos == s->temp.size) {
> + s->temp.pos = 0;
> + return true;
> + }
> +
> + return false;
> +}
> +
> +/* Decode a variable-length integer (little-endian base-128 encoding) */
> +static enum xz_ret dec_vli(struct xz_dec *s, const uint8_t *in,
> + size_t *in_pos, size_t in_size)
> +{
> + uint8_t byte;
> +
> + if (s->pos == 0)
> + s->vli = 0;
> +
> + while (*in_pos < in_size) {
> + byte = in[*in_pos];
> + ++*in_pos;
> +
> + s->vli |= (vli_type)(byte & 0x7F) << s->pos;
> +
> + if ((byte & 0x80) == 0) {
> + /* Don't allow non-minimal encodings. */
> + if (byte == 0 && s->pos != 0)
> + return XZ_DATA_ERROR;
> +
> + s->pos = 0;
> + return XZ_STREAM_END;
> + }
> +
> + s->pos += 7;
> + if (s->pos == 7 * VLI_BYTES_MAX)
> + return XZ_DATA_ERROR;
> + }
> +
> + return XZ_OK;
> +}
> +
> +/*
> + * Decode the Compressed Data field from a Block. Update and validate
> + * the observed compressed and uncompressed sizes of the Block so that
> + * they don't exceed the values possibly stored in the Block Header
> + * (validation assumes that no integer overflow occurs, since vli_type
> + * is normally uint64_t). Update the CRC32 or CRC64 value if presence of
> + * the CRC32 or CRC64 field was indicated in Stream Header.
> + *
> + * Once the decoding is finished, validate that the observed sizes match
> + * the sizes possibly stored in the Block Header. Update the hash and
> + * Block count, which are later used to validate the Index field.
> + */
> +static enum xz_ret dec_block(struct xz_dec *s, struct xz_buf *b)
> +{
> + enum xz_ret ret;
> +
> + s->in_start = b->in_pos;
> + s->out_start = b->out_pos;
> +
> +#ifdef XZ_DEC_BCJ
> + if (s->bcj_active)
> + ret = xz_dec_bcj_run(s->bcj, s->lzma2, b);
> + else
> +#endif
> + ret = xz_dec_lzma2_run(s->lzma2, b);
> +
> + s->block.compressed += b->in_pos - s->in_start;
> + s->block.uncompressed += b->out_pos - s->out_start;
> +
> + /*
> + * There is no need to separately check for VLI_UNKNOWN, since
> + * the observed sizes are always smaller than VLI_UNKNOWN.
> + */
> + if (s->block.compressed > s->block_header.compressed
> + || s->block.uncompressed
> + > s->block_header.uncompressed)
> + return XZ_DATA_ERROR;
> +
> + if (s->check_type == XZ_CHECK_CRC32)
> + s->crc = xz_crc32(b->out + s->out_start,
> + b->out_pos - s->out_start, s->crc);
> +#ifdef XZ_USE_CRC64
> + else if (s->check_type == XZ_CHECK_CRC64)
> + s->crc = xz_crc64(b->out + s->out_start,
> + b->out_pos - s->out_start, s->crc);
> +#endif
> +
> + if (ret == XZ_STREAM_END) {
> + if (s->block_header.compressed != VLI_UNKNOWN
> + && s->block_header.compressed
> + != s->block.compressed)
> + return XZ_DATA_ERROR;
> +
> + if (s->block_header.uncompressed != VLI_UNKNOWN
> + && s->block_header.uncompressed
> + != s->block.uncompressed)
> + return XZ_DATA_ERROR;
> +
> + s->block.hash.unpadded += s->block_header.size
> + + s->block.compressed;
> +
> +#ifdef XZ_DEC_ANY_CHECK
> + s->block.hash.unpadded += check_sizes[s->check_type];
> +#else
> + if (s->check_type == XZ_CHECK_CRC32)
> + s->block.hash.unpadded += 4;
> + else if (IS_CRC64(s->check_type))
> + s->block.hash.unpadded += 8;
> +#endif
> +
> + s->block.hash.uncompressed += s->block.uncompressed;
> + s->block.hash.crc32 = xz_crc32(
> + (const uint8_t *)&s->block.hash,
> + sizeof(s->block.hash), s->block.hash.crc32);
> +
> + ++s->block.count;
> + }
> +
> + return ret;
> +}
> +
> +/* Update the Index size and the CRC32 value. */
> +static void index_update(struct xz_dec *s, const struct xz_buf *b)
> +{
> + size_t in_used = b->in_pos - s->in_start;
> + s->index.size += in_used;
> + s->crc = xz_crc32(b->in + s->in_start, in_used, s->crc);
> +}
> +
> +/*
> + * Decode the Number of Records, Unpadded Size, and Uncompressed Size
> + * fields from the Index field. That is, Index Padding and CRC32 are not
> + * decoded by this function.
> + *
> + * This can return XZ_OK (more input needed), XZ_STREAM_END (everything
> + * successfully decoded), or XZ_DATA_ERROR (input is corrupt).
> + */
> +static enum xz_ret dec_index(struct xz_dec *s, struct xz_buf *b)
> +{
> + enum xz_ret ret;
> +
> + do {
> + ret = dec_vli(s, b->in, &b->in_pos, b->in_size);
> + if (ret != XZ_STREAM_END) {
> + index_update(s, b);
> + return ret;
> + }
> +
> + switch (s->index.sequence) {
> + case SEQ_INDEX_COUNT:
> + s->index.count = s->vli;
> +
> + /*
> + * Validate that the Number of Records field
> + * indicates the same number of Records as
> + * there were Blocks in the Stream.
> + */
> + if (s->index.count != s->block.count)
> + return XZ_DATA_ERROR;
> +
> + s->index.sequence = SEQ_INDEX_UNPADDED;
> + break;
> +
> + case SEQ_INDEX_UNPADDED:
> + s->index.hash.unpadded += s->vli;
> + s->index.sequence = SEQ_INDEX_UNCOMPRESSED;
> + break;
> +
> + case SEQ_INDEX_UNCOMPRESSED:
> + s->index.hash.uncompressed += s->vli;
> + s->index.hash.crc32 = xz_crc32(
> + (const uint8_t *)&s->index.hash,
> + sizeof(s->index.hash),
> + s->index.hash.crc32);
> + --s->index.count;
> + s->index.sequence = SEQ_INDEX_UNPADDED;
> + break;
> + }
> + } while (s->index.count > 0);
> +
> + return XZ_STREAM_END;
> +}
> +
> +/*
> + * Validate that the next four or eight input bytes match the value
> + * of s->crc. s->pos must be zero when starting to validate the first byte.
> + * The "bits" argument allows using the same code for both CRC32 and CRC64.
> + */
> +static enum xz_ret crc_validate(struct xz_dec *s, struct xz_buf *b,
> + uint32_t bits)
> +{
> + do {
> + if (b->in_pos == b->in_size)
> + return XZ_OK;
> +
> + if (((s->crc >> s->pos) & 0xFF) != b->in[b->in_pos++])
> + return XZ_DATA_ERROR;
> +
> + s->pos += 8;
> +
> + } while (s->pos < bits);
> +
> + s->crc = 0;
> + s->pos = 0;
> +
> + return XZ_STREAM_END;
> +}
> +
> +#ifdef XZ_DEC_ANY_CHECK
> +/*
> + * Skip over the Check field when the Check ID is not supported.
> + * Returns true once the whole Check field has been skipped over.
> + */
> +static bool check_skip(struct xz_dec *s, struct xz_buf *b)
> +{
> + while (s->pos < check_sizes[s->check_type]) {
> + if (b->in_pos == b->in_size)
> + return false;
> +
> + ++b->in_pos;
> + ++s->pos;
> + }
> +
> + s->pos = 0;
> +
> + return true;
> +}
> +#endif
> +
> +/* Decode the Stream Header field (the first 12 bytes of the .xz Stream). */
> +static enum xz_ret dec_stream_header(struct xz_dec *s)
> +{
> + if (!memeq(s->temp.buf, HEADER_MAGIC, HEADER_MAGIC_SIZE))
> + return XZ_FORMAT_ERROR;
> +
> + if (xz_crc32(s->temp.buf + HEADER_MAGIC_SIZE, 2, 0)
> + != get_le32(s->temp.buf + HEADER_MAGIC_SIZE + 2))
> + return XZ_DATA_ERROR;
> +
> + if (s->temp.buf[HEADER_MAGIC_SIZE] != 0)
> + return XZ_OPTIONS_ERROR;
> +
> + /*
> + * Of integrity checks, we support none (Check ID = 0),
> + * CRC32 (Check ID = 1), and optionally CRC64 (Check ID = 4).
> + * However, if XZ_DEC_ANY_CHECK is defined, we will accept other
> + * check types too, but then the check won't be verified and
> + * a warning (XZ_UNSUPPORTED_CHECK) will be given.
> + */
> + s->check_type = s->temp.buf[HEADER_MAGIC_SIZE + 1];
> +
> +#ifdef XZ_DEC_ANY_CHECK
> + if (s->check_type > XZ_CHECK_MAX)
> + return XZ_OPTIONS_ERROR;
> +
> + if (s->check_type > XZ_CHECK_CRC32 && !IS_CRC64(s->check_type))
> + return XZ_UNSUPPORTED_CHECK;
> +#else
> + if (s->check_type > XZ_CHECK_CRC32 && !IS_CRC64(s->check_type))
> + return XZ_OPTIONS_ERROR;
> +#endif
> +
> + return XZ_OK;
> +}
> +
> +/* Decode the Stream Footer field (the last 12 bytes of the .xz Stream) */
> +static enum xz_ret dec_stream_footer(struct xz_dec *s)
> +{
> + if (!memeq(s->temp.buf + 10, FOOTER_MAGIC, FOOTER_MAGIC_SIZE))
> + return XZ_DATA_ERROR;
> +
> + if (xz_crc32(s->temp.buf + 4, 6, 0) != get_le32(s->temp.buf))
> + return XZ_DATA_ERROR;
> +
> + /*
> + * Validate Backward Size. Note that we never added the size of the
> + * Index CRC32 field to s->index.size, thus we use s->index.size / 4
> + * instead of s->index.size / 4 - 1.
> + */
> + if ((s->index.size >> 2) != get_le32(s->temp.buf + 4))
> + return XZ_DATA_ERROR;
> +
> + if (s->temp.buf[8] != 0 || s->temp.buf[9] != s->check_type)
> + return XZ_DATA_ERROR;
> +
> + /*
> + * Use XZ_STREAM_END instead of XZ_OK to be more convenient
> + * for the caller.
> + */
> + return XZ_STREAM_END;
> +}
> +
> +/* Decode the Block Header and initialize the filter chain. */
> +static enum xz_ret dec_block_header(struct xz_dec *s)
> +{
> + enum xz_ret ret;
> +
> + /*
> + * Validate the CRC32. We know that the temp buffer is at least
> + * eight bytes so this is safe.
> + */
> + s->temp.size -= 4;
> + if (xz_crc32(s->temp.buf, s->temp.size, 0)
> + != get_le32(s->temp.buf + s->temp.size))
> + return XZ_DATA_ERROR;
> +
> + s->temp.pos = 2;
> +
> + /*
> + * Catch unsupported Block Flags. We support only one or two filters
> + * in the chain, so we catch that with the same test.
> + */
> +#ifdef XZ_DEC_BCJ
> + if (s->temp.buf[1] & 0x3E)
> +#else
> + if (s->temp.buf[1] & 0x3F)
> +#endif
> + return XZ_OPTIONS_ERROR;
> +
> + /* Compressed Size */
> + if (s->temp.buf[1] & 0x40) {
> + if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size)
> + != XZ_STREAM_END)
> + return XZ_DATA_ERROR;
> +
> + s->block_header.compressed = s->vli;
> + } else {
> + s->block_header.compressed = VLI_UNKNOWN;
> + }
> +
> + /* Uncompressed Size */
> + if (s->temp.buf[1] & 0x80) {
> + if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size)
> + != XZ_STREAM_END)
> + return XZ_DATA_ERROR;
> +
> + s->block_header.uncompressed = s->vli;
> + } else {
> + s->block_header.uncompressed = VLI_UNKNOWN;
> + }
> +
> +#ifdef XZ_DEC_BCJ
> + /* If there are two filters, the first one must be a BCJ filter. */
> + s->bcj_active = s->temp.buf[1] & 0x01;
> + if (s->bcj_active) {
> + if (s->temp.size - s->temp.pos < 2)
> + return XZ_OPTIONS_ERROR;
> +
> + ret = xz_dec_bcj_reset(s->bcj, s->temp.buf[s->temp.pos++]);
> + if (ret != XZ_OK)
> + return ret;
> +
> + /*
> + * We don't support custom start offset,
> + * so Size of Properties must be zero.
> + */
> + if (s->temp.buf[s->temp.pos++] != 0x00)
> + return XZ_OPTIONS_ERROR;
> + }
> +#endif
> +
> + /* Valid Filter Flags always take at least two bytes. */
> + if (s->temp.size - s->temp.pos < 2)
> + return XZ_DATA_ERROR;
> +
> + /* Filter ID = LZMA2 */
> + if (s->temp.buf[s->temp.pos++] != 0x21)
> + return XZ_OPTIONS_ERROR;
> +
> + /* Size of Properties = 1-byte Filter Properties */
> + if (s->temp.buf[s->temp.pos++] != 0x01)
> + return XZ_OPTIONS_ERROR;
> +
> + /* Filter Properties contains LZMA2 dictionary size. */
> + if (s->temp.size - s->temp.pos < 1)
> + return XZ_DATA_ERROR;
> +
> + ret = xz_dec_lzma2_reset(s->lzma2, s->temp.buf[s->temp.pos++]);
> + if (ret != XZ_OK)
> + return ret;
> +
> + /* The rest must be Header Padding. */
> + while (s->temp.pos < s->temp.size)
> + if (s->temp.buf[s->temp.pos++] != 0x00)
> + return XZ_OPTIONS_ERROR;
> +
> + s->temp.pos = 0;
> + s->block.compressed = 0;
> + s->block.uncompressed = 0;
> +
> + return XZ_OK;
> +}
> +
> +static enum xz_ret dec_main(struct xz_dec *s, struct xz_buf *b)
> +{
> + enum xz_ret ret;
> +
> + /*
> + * Store the start position for the case when we are in the middle
> + * of the Index field.
> + */
> + s->in_start = b->in_pos;
> +
> + while (true) {
> + switch (s->sequence) {
> + case SEQ_STREAM_HEADER:
> + /*
> + * Stream Header is copied to s->temp, and then
> + * decoded from there. This way if the caller
> + * gives us only little input at a time, we can
> + * still keep the Stream Header decoding code
> + * simple. Similar approach is used in many places
> + * in this file.
> + */
> + if (!fill_temp(s, b))
> + return XZ_OK;
> +
> + /*
> + * If dec_stream_header() returns
> + * XZ_UNSUPPORTED_CHECK, it is still possible
> + * to continue decoding if working in multi-call
> + * mode. Thus, update s->sequence before calling
> + * dec_stream_header().
> + */
> + s->sequence = SEQ_BLOCK_START;
> +
> + ret = dec_stream_header(s);
> + if (ret != XZ_OK)
> + return ret;
> +
> + case SEQ_BLOCK_START:
> + /* We need one byte of input to continue. */
> + if (b->in_pos == b->in_size)
> + return XZ_OK;
> +
> + /* See if this is the beginning of the Index field. */
> + if (b->in[b->in_pos] == 0) {
> + s->in_start = b->in_pos++;
> + s->sequence = SEQ_INDEX;
> + break;
> + }
> +
> + /*
> + * Calculate the size of the Block Header and
> + * prepare to decode it.
> + */
> + s->block_header.size
> + = ((uint32_t)b->in[b->in_pos] + 1) * 4;
> +
> + s->temp.size = s->block_header.size;
> + s->temp.pos = 0;
> + s->sequence = SEQ_BLOCK_HEADER;
> +
> + case SEQ_BLOCK_HEADER:
> + if (!fill_temp(s, b))
> + return XZ_OK;
> +
> + ret = dec_block_header(s);
> + if (ret != XZ_OK)
> + return ret;
> +
> + s->sequence = SEQ_BLOCK_UNCOMPRESS;
> +
> + case SEQ_BLOCK_UNCOMPRESS:
> + ret = dec_block(s, b);
> + if (ret != XZ_STREAM_END)
> + return ret;
> +
> + s->sequence = SEQ_BLOCK_PADDING;
> +
> + case SEQ_BLOCK_PADDING:
> + /*
> + * Size of Compressed Data + Block Padding
> + * must be a multiple of four. We don't need
> + * s->block.compressed for anything else
> + * anymore, so we use it here to test the size
> + * of the Block Padding field.
> + */
> + while (s->block.compressed & 3) {
> + if (b->in_pos == b->in_size)
> + return XZ_OK;
> +
> + if (b->in[b->in_pos++] != 0)
> + return XZ_DATA_ERROR;
> +
> + ++s->block.compressed;
> + }
> +
> + s->sequence = SEQ_BLOCK_CHECK;
> +
> + case SEQ_BLOCK_CHECK:
> + if (s->check_type == XZ_CHECK_CRC32) {
> + ret = crc_validate(s, b, 32);
> + if (ret != XZ_STREAM_END)
> + return ret;
> + }
> + else if (IS_CRC64(s->check_type)) {
> + ret = crc_validate(s, b, 64);
> + if (ret != XZ_STREAM_END)
> + return ret;
> + }
> +#ifdef XZ_DEC_ANY_CHECK
> + else if (!check_skip(s, b)) {
> + return XZ_OK;
> + }
> +#endif
> +
> + s->sequence = SEQ_BLOCK_START;
> + break;
> +
> + case SEQ_INDEX:
> + ret = dec_index(s, b);
> + if (ret != XZ_STREAM_END)
> + return ret;
> +
> + s->sequence = SEQ_INDEX_PADDING;
> +
> + case SEQ_INDEX_PADDING:
> + while ((s->index.size + (b->in_pos - s->in_start))
> + & 3) {
> + if (b->in_pos == b->in_size) {
> + index_update(s, b);
> + return XZ_OK;
> + }
> +
> + if (b->in[b->in_pos++] != 0)
> + return XZ_DATA_ERROR;
> + }
> +
> + /* Finish the CRC32 value and Index size. */
> + index_update(s, b);
> +
> + /* Compare the hashes to validate the Index field. */
> + if (!memeq(&s->block.hash, &s->index.hash,
> + sizeof(s->block.hash)))
> + return XZ_DATA_ERROR;
> +
> + s->sequence = SEQ_INDEX_CRC32;
> +
> + case SEQ_INDEX_CRC32:
> + ret = crc_validate(s, b, 32);
> + if (ret != XZ_STREAM_END)
> + return ret;
> +
> + s->temp.size = STREAM_HEADER_SIZE;
> + s->sequence = SEQ_STREAM_FOOTER;
> +
> + case SEQ_STREAM_FOOTER:
> + if (!fill_temp(s, b))
> + return XZ_OK;
> +
> + return dec_stream_footer(s);
> + }
> + }
> +
> + /* Never reached */
> +}
> +
> +/*
> + * xz_dec_run() is a wrapper for dec_main() to handle some special cases in
> + * multi-call and single-call decoding.
> + *
> + * In multi-call mode, we must return XZ_BUF_ERROR when it seems clear that
> we
> + * are not going to make any progress anymore. This is to prevent the caller
> + * from calling us infinitely when the input file is truncated or otherwise
> + * corrupt. Since zlib-style API allows that the caller fills the input
> buffer
> + * only when the decoder doesn't produce any new output, we have to be
> careful
> + * to avoid returning XZ_BUF_ERROR too easily: XZ_BUF_ERROR is returned only
> + * after the second consecutive call to xz_dec_run() that makes no progress.
> + *
> + * In single-call mode, if we couldn't decode everything and no error
> + * occurred, either the input is truncated or the output buffer is too small.
> + * Since we know that the last input byte never produces any output, we know
> + * that if all the input was consumed and decoding wasn't finished, the file
> + * must be corrupt. Otherwise the output buffer has to be too small or the
> + * file is corrupt in a way that decoding it produces too big output.
> + *
> + * If single-call decoding fails, we reset b->in_pos and b->out_pos back to
> + * their original values. This is because with some filter chains there won't
> + * be any valid uncompressed data in the output buffer unless the decoding
> + * actually succeeds (that's the price to pay of using the output buffer as
> + * the workspace).
> + */
> +XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b)
> +{
> + size_t in_start;
> + size_t out_start;
> + enum xz_ret ret;
> +
> + if (DEC_IS_SINGLE(s->mode))
> + xz_dec_reset(s);
> +
> + in_start = b->in_pos;
> + out_start = b->out_pos;
> + ret = dec_main(s, b);
> +
> + if (DEC_IS_SINGLE(s->mode)) {
> + if (ret == XZ_OK)
> + ret = b->in_pos == b->in_size
> + ? XZ_DATA_ERROR : XZ_BUF_ERROR;
> +
> + if (ret != XZ_STREAM_END) {
> + b->in_pos = in_start;
> + b->out_pos = out_start;
> + }
> +
> + } else if (ret == XZ_OK && in_start == b->in_pos
> + && out_start == b->out_pos) {
> + if (s->allow_buf_error)
> + ret = XZ_BUF_ERROR;
> +
> + s->allow_buf_error = true;
> + } else {
> + s->allow_buf_error = false;
> + }
> +
> + return ret;
> +}
> +
> +XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max)
> +{
> + struct xz_dec *s = kmalloc(sizeof(*s), GFP_KERNEL);
> + if (s == NULL)
> + return NULL;
> +
> + s->mode = mode;
> +
> +#ifdef XZ_DEC_BCJ
> + s->bcj = xz_dec_bcj_create(DEC_IS_SINGLE(mode));
> + if (s->bcj == NULL)
> + goto error_bcj;
> +#endif
> +
> + s->lzma2 = xz_dec_lzma2_create(mode, dict_max);
> + if (s->lzma2 == NULL)
> + goto error_lzma2;
> +
> + xz_dec_reset(s);
> + return s;
> +
> +error_lzma2:
> +#ifdef XZ_DEC_BCJ
> + xz_dec_bcj_end(s->bcj);
> +error_bcj:
> +#endif
> + kfree(s);
> + return NULL;
> +}
> +
> +XZ_EXTERN void xz_dec_reset(struct xz_dec *s)
> +{
> + s->sequence = SEQ_STREAM_HEADER;
> + s->allow_buf_error = false;
> + s->pos = 0;
> + s->crc = 0;
> + memzero(&s->block, sizeof(s->block));
> + memzero(&s->index, sizeof(s->index));
> + s->temp.pos = 0;
> + s->temp.size = STREAM_HEADER_SIZE;
> +}
> +
> +XZ_EXTERN void xz_dec_end(struct xz_dec *s)
> +{
> + if (s != NULL) {
> + xz_dec_lzma2_end(s->lzma2);
> +#ifdef XZ_DEC_BCJ
> + xz_dec_bcj_end(s->bcj);
> +#endif
> + kfree(s);
> + }
> +}
> diff --git a/libxz/xz_lzma2.h b/libxz/xz_lzma2.h
> new file mode 100644
> index 000000000000..aa05d956319e
> --- /dev/null
> +++ b/libxz/xz_lzma2.h
> @@ -0,0 +1,204 @@
> +/*
> + * LZMA2 definitions
> + *
> + * Authors: Lasse Collin <lasse.collin at 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_LZMA2_H
> +#define XZ_LZMA2_H
> +
> +/* Range coder constants */
> +#define RC_SHIFT_BITS 8
> +#define RC_TOP_BITS 24
> +#define RC_TOP_VALUE (1 << RC_TOP_BITS)
> +#define RC_BIT_MODEL_TOTAL_BITS 11
> +#define RC_BIT_MODEL_TOTAL (1 << RC_BIT_MODEL_TOTAL_BITS)
> +#define RC_MOVE_BITS 5
> +
> +/*
> + * Maximum number of position states. A position state is the lowest pb
> + * number of bits of the current uncompressed offset. In some places there
> + * are different sets of probabilities for different position states.
> + */
> +#define POS_STATES_MAX (1 << 4)
> +
> +/*
> + * This enum is used to track which LZMA symbols have occurred most recently
> + * and in which order. This information is used to predict the next symbol.
> + *
> + * Symbols:
> + * - Literal: One 8-bit byte
> + * - Match: Repeat a chunk of data at some distance
> + * - Long repeat: Multi-byte match at a recently seen distance
> + * - Short repeat: One-byte repeat at a recently seen distance
> + *
> + * The symbol names are in from STATE_oldest_older_previous. REP means
> + * either short or long repeated match, and NONLIT means any non-literal.
> + */
> +enum lzma_state {
> + STATE_LIT_LIT,
> + STATE_MATCH_LIT_LIT,
> + STATE_REP_LIT_LIT,
> + STATE_SHORTREP_LIT_LIT,
> + STATE_MATCH_LIT,
> + STATE_REP_LIT,
> + STATE_SHORTREP_LIT,
> + STATE_LIT_MATCH,
> + STATE_LIT_LONGREP,
> + STATE_LIT_SHORTREP,
> + STATE_NONLIT_MATCH,
> + STATE_NONLIT_REP
> +};
> +
> +/* Total number of states */
> +#define STATES 12
> +
> +/* The lowest 7 states indicate that the previous state was a literal. */
> +#define LIT_STATES 7
> +
> +/* Indicate that the latest symbol was a literal. */
> +static inline void lzma_state_literal(enum lzma_state *state)
> +{
> + if (*state <= STATE_SHORTREP_LIT_LIT)
> + *state = STATE_LIT_LIT;
> + else if (*state <= STATE_LIT_SHORTREP)
> + *state -= 3;
> + else
> + *state -= 6;
> +}
> +
> +/* Indicate that the latest symbol was a match. */
> +static inline void lzma_state_match(enum lzma_state *state)
> +{
> + *state = *state < LIT_STATES ? STATE_LIT_MATCH : STATE_NONLIT_MATCH;
> +}
> +
> +/* Indicate that the latest state was a long repeated match. */
> +static inline void lzma_state_long_rep(enum lzma_state *state)
> +{
> + *state = *state < LIT_STATES ? STATE_LIT_LONGREP : STATE_NONLIT_REP;
> +}
> +
> +/* Indicate that the latest symbol was a short match. */
> +static inline void lzma_state_short_rep(enum lzma_state *state)
> +{
> + *state = *state < LIT_STATES ? STATE_LIT_SHORTREP : STATE_NONLIT_REP;
> +}
> +
> +/* Test if the previous symbol was a literal. */
> +static inline bool lzma_state_is_literal(enum lzma_state state)
> +{
> + return state < LIT_STATES;
> +}
> +
> +/* Each literal coder is divided in three sections:
> + * - 0x001-0x0FF: Without match byte
> + * - 0x101-0x1FF: With match byte; match bit is 0
> + * - 0x201-0x2FF: With match byte; match bit is 1
> + *
> + * Match byte is used when the previous LZMA symbol was something else than
> + * a literal (that is, it was some kind of match).
> + */
> +#define LITERAL_CODER_SIZE 0x300
> +
> +/* Maximum number of literal coders */
> +#define LITERAL_CODERS_MAX (1 << 4)
> +
> +/* Minimum length of a match is two bytes. */
> +#define MATCH_LEN_MIN 2
> +
> +/* Match length is encoded with 4, 5, or 10 bits.
> + *
> + * Length Bits
> + * 2-9 4 = Choice=0 + 3 bits
> + * 10-17 5 = Choice=1 + Choice2=0 + 3 bits
> + * 18-273 10 = Choice=1 + Choice2=1 + 8 bits
> + */
> +#define LEN_LOW_BITS 3
> +#define LEN_LOW_SYMBOLS (1 << LEN_LOW_BITS)
> +#define LEN_MID_BITS 3
> +#define LEN_MID_SYMBOLS (1 << LEN_MID_BITS)
> +#define LEN_HIGH_BITS 8
> +#define LEN_HIGH_SYMBOLS (1 << LEN_HIGH_BITS)
> +#define LEN_SYMBOLS (LEN_LOW_SYMBOLS + LEN_MID_SYMBOLS + LEN_HIGH_SYMBOLS)
> +
> +/*
> + * Maximum length of a match is 273 which is a result of the encoding
> + * described above.
> + */
> +#define MATCH_LEN_MAX (MATCH_LEN_MIN + LEN_SYMBOLS - 1)
> +
> +/*
> + * Different sets of probabilities are used for match distances that have
> + * very short match length: Lengths of 2, 3, and 4 bytes have a separate
> + * set of probabilities for each length. The matches with longer length
> + * use a shared set of probabilities.
> + */
> +#define DIST_STATES 4
> +
> +/*
> + * Get the index of the appropriate probability array for decoding
> + * the distance slot.
> + */
> +static inline uint32_t lzma_get_dist_state(uint32_t len)
> +{
> + return len < DIST_STATES + MATCH_LEN_MIN
> + ? len - MATCH_LEN_MIN : DIST_STATES - 1;
> +}
> +
> +/*
> + * The highest two bits of a 32-bit match distance are encoded using six
> bits.
> + * This six-bit value is called a distance slot. This way encoding a 32-bit
> + * value takes 6-36 bits, larger values taking more bits.
> + */
> +#define DIST_SLOT_BITS 6
> +#define DIST_SLOTS (1 << DIST_SLOT_BITS)
> +
> +/* Match distances up to 127 are fully encoded using probabilities. Since
> + * the highest two bits (distance slot) are always encoded using six bits,
> + * the distances 0-3 don't need any additional bits to encode, since the
> + * distance slot itself is the same as the actual distance. DIST_MODEL_START
> + * indicates the first distance slot where at least one additional bit is
> + * needed.
> + */
> +#define DIST_MODEL_START 4
> +
> +/*
> + * Match distances greater than 127 are encoded in three pieces:
> + * - distance slot: the highest two bits
> + * - direct bits: 2-26 bits below the highest two bits
> + * - alignment bits: four lowest bits
> + *
> + * Direct bits don't use any probabilities.
> + *
> + * The distance slot value of 14 is for distances 128-191.
> + */
> +#define DIST_MODEL_END 14
> +
> +/* Distance slots that indicate a distance <= 127. */
> +#define FULL_DISTANCES_BITS (DIST_MODEL_END / 2)
> +#define FULL_DISTANCES (1 << FULL_DISTANCES_BITS)
> +
> +/*
> + * For match distances greater than 127, only the highest two bits and the
> + * lowest four bits (alignment) is encoded using probabilities.
> + */
> +#define ALIGN_BITS 4
> +#define ALIGN_SIZE (1 << ALIGN_BITS)
> +#define ALIGN_MASK (ALIGN_SIZE - 1)
> +
> +/* Total number of all probability variables */
> +#define PROBS_TOTAL (1846 + LITERAL_CODERS_MAX * LITERAL_CODER_SIZE)
> +
> +/*
> + * LZMA remembers the four most recent match distances. Reusing these
> + * distances tends to take less space than re-encoding the actual
> + * distance value.
> + */
> +#define REPS 4
> +
> +#endif
> diff --git a/libxz/xz_private.h b/libxz/xz_private.h
> new file mode 100644
> index 000000000000..49c366554086
> --- /dev/null
> +++ b/libxz/xz_private.h
> @@ -0,0 +1,156 @@
> +/*
> + * Private includes and definitions
> + *
> + * Author: Lasse Collin <lasse.collin at tukaani.org>
> + *
> + * This file has been put into the public domain.
> + * You can do whatever you want with this file.
> + */
> +
> +#ifndef XZ_PRIVATE_H
> +#define XZ_PRIVATE_H
> +
> +#ifdef __KERNEL__
> + #include <linux/xz.h>
> + #include <linux/kernel.h>
> + #include <asm/unaligned.h>
> + /* XZ_PREBOOT may be defined only via decompress_unxz.c. */
> + #ifndef XZ_PREBOOT
> + #include <linux/slab.h>
> + #include <linux/vmalloc.h>
> + #include <linux/string.h>
> + #ifdef CONFIG_XZ_DEC_X86
> + #define XZ_DEC_X86
> + #endif
> + #ifdef CONFIG_XZ_DEC_POWERPC
> + #define XZ_DEC_POWERPC
> + #endif
> + #ifdef CONFIG_XZ_DEC_IA64
> + #define XZ_DEC_IA64
> + #endif
> + #ifdef CONFIG_XZ_DEC_ARM
> + #define XZ_DEC_ARM
> + #endif
> + #ifdef CONFIG_XZ_DEC_ARMTHUMB
> + #define XZ_DEC_ARMTHUMB
> + #endif
> + #ifdef CONFIG_XZ_DEC_SPARC
> + #define XZ_DEC_SPARC
> + #endif
> + #define memeq(a, b, size) (memcmp(a, b, size) == 0)
> + #define memzero(buf, size) memset(buf, 0, size)
> + #endif
> + #define get_le32(p) le32_to_cpup((const uint32_t *)(p))
> +#else
> + /*
> + * For userspace builds, use a separate header to define the required
> + * macros and functions. This makes it easier to adapt the code into
> + * different environments and avoids clutter in the Linux kernel tree.
> + */
> + #include "xz_config.h"
> +#endif
> +
> +/* If no specific decoding mode is requested, enable support for all modes.
> */
> +#if !defined(XZ_DEC_SINGLE) && !defined(XZ_DEC_PREALLOC) \
> + && !defined(XZ_DEC_DYNALLOC)
> + #define XZ_DEC_SINGLE
> + #define XZ_DEC_PREALLOC
> + #define XZ_DEC_DYNALLOC
> +#endif
> +
> +/*
> + * The DEC_IS_foo(mode) macros are used in "if" statements. If only some
> + * of the supported modes are enabled, these macros will evaluate to true or
> + * false at compile time and thus allow the compiler to omit unneeded code.
> + */
> +#ifdef XZ_DEC_SINGLE
> + #define DEC_IS_SINGLE(mode) ((mode) == XZ_SINGLE)
> +#else
> + #define DEC_IS_SINGLE(mode) (false)
> +#endif
> +
> +#ifdef XZ_DEC_PREALLOC
> + #define DEC_IS_PREALLOC(mode) ((mode) == XZ_PREALLOC)
> +#else
> + #define DEC_IS_PREALLOC(mode) (false)
> +#endif
> +
> +#ifdef XZ_DEC_DYNALLOC
> + #define DEC_IS_DYNALLOC(mode) ((mode) == XZ_DYNALLOC)
> +#else
> + #define DEC_IS_DYNALLOC(mode) (false)
> +#endif
> +
> +#if !defined(XZ_DEC_SINGLE)
> + #define DEC_IS_MULTI(mode) (true)
> +#elif defined(XZ_DEC_PREALLOC) || defined(XZ_DEC_DYNALLOC)
> + #define DEC_IS_MULTI(mode) ((mode) != XZ_SINGLE)
> +#else
> + #define DEC_IS_MULTI(mode) (false)
> +#endif
> +
> +/*
> + * If any of the BCJ filter decoders are wanted, define XZ_DEC_BCJ.
> + * XZ_DEC_BCJ is used to enable generic support for BCJ decoders.
> + */
> +#ifndef XZ_DEC_BCJ
> + #if defined(XZ_DEC_X86) || defined(XZ_DEC_POWERPC) \
> + || defined(XZ_DEC_IA64) || defined(XZ_DEC_ARM) \
> + || defined(XZ_DEC_ARM) || defined(XZ_DEC_ARMTHUMB) \
> + || defined(XZ_DEC_SPARC)
> + #define XZ_DEC_BCJ
> + #endif
> +#endif
> +
> +/*
> + * Allocate memory for LZMA2 decoder. xz_dec_lzma2_reset() must be used
> + * before calling xz_dec_lzma2_run().
> + */
> +XZ_EXTERN struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode,
> + uint32_t dict_max);
> +
> +/*
> + * Decode the LZMA2 properties (one byte) and reset the decoder. Return
> + * XZ_OK on success, XZ_MEMLIMIT_ERROR if the preallocated dictionary is not
> + * big enough, and XZ_OPTIONS_ERROR if props indicates something that this
> + * decoder doesn't support.
> + */
> +XZ_EXTERN enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s,
> + uint8_t props);
> +
> +/* Decode raw LZMA2 stream from b->in to b->out. */
> +XZ_EXTERN enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
> + struct xz_buf *b);
> +
> +/* Free the memory allocated for the LZMA2 decoder. */
> +XZ_EXTERN void xz_dec_lzma2_end(struct xz_dec_lzma2 *s);
> +
> +#ifdef XZ_DEC_BCJ
> +/*
> + * Allocate memory for BCJ decoders. xz_dec_bcj_reset() must be used before
> + * calling xz_dec_bcj_run().
> + */
> +XZ_EXTERN struct xz_dec_bcj *xz_dec_bcj_create(bool single_call);
> +
> +/*
> + * Decode the Filter ID of a BCJ filter. This implementation doesn't
> + * support custom start offsets, so no decoding of Filter Properties
> + * is needed. Returns XZ_OK if the given Filter ID is supported.
> + * Otherwise XZ_OPTIONS_ERROR is returned.
> + */
> +XZ_EXTERN enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id);
> +
> +/*
> + * Decode raw BCJ + LZMA2 stream. This must be used only if there actually is
> + * a BCJ filter in the chain. If the chain has only LZMA2, xz_dec_lzma2_run()
> + * must be called directly.
> + */
> +XZ_EXTERN enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
> + struct xz_dec_lzma2 *lzma2,
> + struct xz_buf *b);
> +
> +/* Free the memory allocated for the BCJ filters. */
> +#define xz_dec_bcj_end(s) kfree(s)
> +#endif
> +
> +#endif
> diff --git a/libxz/xz_stream.h b/libxz/xz_stream.h
> new file mode 100644
> index 000000000000..c0fcd5857b7b
> --- /dev/null
> +++ b/libxz/xz_stream.h
> @@ -0,0 +1,62 @@
> +/*
> + * Definitions for handling the .xz file format
> + *
> + * Author: Lasse Collin <lasse.collin at tukaani.org>
> + *
> + * This file has been put into the public domain.
> + * You can do whatever you want with this file.
> + */
> +
> +#ifndef XZ_STREAM_H
> +#define XZ_STREAM_H
> +
> +#if defined(__KERNEL__) && !XZ_INTERNAL_CRC32
> + #include <linux/crc32.h>
> + #undef crc32
> + #define xz_crc32(buf, size, crc) \
> + (~crc32_le(~(uint32_t)(crc), buf, size))
> +#endif
> +
> +/*
> + * See the .xz file format specification at
> + * http://tukaani.org/xz/xz-file-format.txt
> + * to understand the container format.
> + */
> +
> +#define STREAM_HEADER_SIZE 12
> +
> +#define HEADER_MAGIC "\3757zXZ"
> +#define HEADER_MAGIC_SIZE 6
> +
> +#define FOOTER_MAGIC "YZ"
> +#define FOOTER_MAGIC_SIZE 2
> +
> +/*
> + * Variable-length integer can hold a 63-bit unsigned integer or a special
> + * value indicating that the value is unknown.
> + *
> + * Experimental: vli_type can be defined to uint32_t to save a few bytes
> + * in code size (no effect on speed). Doing so limits the uncompressed and
> + * compressed size of the file to less than 256 MiB and may also weaken
> + * error detection slightly.
> + */
> +typedef uint64_t vli_type;
> +
> +#define VLI_MAX ((vli_type)-1 / 2)
> +#define VLI_UNKNOWN ((vli_type)-1)
> +
> +/* Maximum encoded size of a VLI */
> +#define VLI_BYTES_MAX (sizeof(vli_type) * 8 / 7)
> +
> +/* Integrity Check types */
> +enum xz_check {
> + XZ_CHECK_NONE = 0,
> + XZ_CHECK_CRC32 = 1,
> + XZ_CHECK_CRC64 = 4,
> + XZ_CHECK_SHA256 = 10
> +};
> +
> +/* Maximum possible Check ID */
> +#define XZ_CHECK_MAX 15
> +
> +#endif
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