Patchwork [U-Boot,1/6,v2] Add support for XZ decompression algorithm.

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Submitter luigi.mantellini@idf-hit.com
Date Dec. 4, 2010, 1:23 p.m.
Message ID <1291469030-24984-2-git-send-email-luigi.mantellini@idf-hit.com>
Download mbox | patch
Permalink /patch/74275/
State Changes Requested
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Comments

luigi.mantellini@idf-hit.com - Dec. 4, 2010, 1:23 p.m.
From: Luigi 'Comio' Mantellini <luigi.mantellini@idf-hit.com>

The code is a cut-down version of XZ Embedded (2010/07/02) and supports only single-call API.

Signed-off-by: Luigi 'Comio' Mantellini <luigi.mantellini@idf-hit.com>
---
 Makefile                 |    1 +
 README                   |    9 +
 common/cmd_bootm.c       |   27 +-
 common/image.c           |    1 +
 include/image.h          |    1 +
 include/unxz.h           |   16 +
 include/xz.h             |  237 ++++++++++
 lib/xz/Makefile          |   51 ++
 lib/xz/decompress_unxz.c |  231 +++++++++
 lib/xz/xz_dec_bcj.c      |  564 ++++++++++++++++++++++
 lib/xz/xz_dec_lzma2.c    | 1175 ++++++++++++++++++++++++++++++++++++++++++++++
 lib/xz/xz_dec_stream.c   |  823 ++++++++++++++++++++++++++++++++
 lib/xz/xz_lzma2.h        |  204 ++++++++
 lib/xz/xz_private.h      |  154 ++++++
 lib/xz/xz_stream.h       |   50 ++
 15 files changed, 3542 insertions(+), 2 deletions(-)
 create mode 100644 include/unxz.h
 create mode 100644 include/xz.h
 create mode 100644 lib/xz/Makefile
 create mode 100644 lib/xz/decompress_unxz.c
 create mode 100644 lib/xz/xz_dec_bcj.c
 create mode 100644 lib/xz/xz_dec_lzma2.c
 create mode 100644 lib/xz/xz_dec_stream.c
 create mode 100644 lib/xz/xz_lzma2.h
 create mode 100644 lib/xz/xz_private.h
 create mode 100644 lib/xz/xz_stream.h
Wolfgang Denk - Dec. 4, 2010, 11:02 p.m.
Dear Luigi 'Comio' Mantellini,

In message <1291469030-24984-2-git-send-email-luigi.mantellini@idf-hit.com> you wrote:
> From: Luigi 'Comio' Mantellini <luigi.mantellini@idf-hit.com>
> 
> The code is a cut-down version of XZ Embedded (2010/07/02) and supports only single-call API.
> 
> Signed-off-by: Luigi 'Comio' Mantellini <luigi.mantellini@idf-hit.com>
> ---

Please read http://www.denx.de/wiki/U-Boot/Patches and especially
http://www.denx.de/wiki/view/U-Boot/Patches#Sending_updated_patch_versions

When reposting, please always describe what has been changed!!

So why are you reposting, and what did you change?

Best regards,

Wolfgang Denk

Patch

diff --git a/Makefile b/Makefile
index 87a383d..ba832a4 100644
--- a/Makefile
+++ b/Makefile
@@ -183,6 +183,7 @@  OBJS := $(addprefix $(obj),$(OBJS))
 LIBS  = lib/libgeneric.o
 LIBS += lib/lzma/liblzma.o
 LIBS += lib/lzo/liblzo.o
+LIBS += lib/xz/libxz.o
 LIBS += $(shell if [ -f board/$(VENDOR)/common/Makefile ]; then echo \
 	"board/$(VENDOR)/common/lib$(VENDOR).o"; fi)
 ifdef CONFIG_FSL_DIU_FB
diff --git a/README b/README
index 68f5fb0..90c19a9 100644
--- a/README
+++ b/README
@@ -220,6 +220,7 @@  Directory Hierarchy:
   /libfdt		Library files to support flattened device trees
   /lzma			Library files to support LZMA decompression
   /lzo			Library files to support LZO decompression
+  /xz			Library files to support XZ/LZMA2 decompression
 /net			Networking code
 /post			Power On Self Test
 /rtc			Real Time Clock drivers
@@ -1178,6 +1179,14 @@  The following options need to be configured:
 		then calculate the amount of needed dynamic memory (ensuring
 		the appropriate CONFIG_SYS_MALLOC_LEN value).
 
+		CONFIG_XZ
+
+		If this option is set, support for xz compresed
+		images is included.
+
+		XZ format is the next version of LZMA format. See also
+		the CONFIG_LZMA
+
 - MII/PHY support:
 		CONFIG_PHY_ADDR
 
diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c
index 1a024f1..066b908 100644
--- a/common/cmd_bootm.c
+++ b/common/cmd_bootm.c
@@ -61,6 +61,10 @@ 
 #include <linux/lzo.h>
 #endif /* CONFIG_LZO */
 
+#ifdef CONFIG_XZ
+#include <unxz.h>
+#endif /* CONFIG_XZ */
+
 DECLARE_GLOBAL_DATA_PTR;
 
 #ifndef CONFIG_SYS_BOOTM_LEN
@@ -338,9 +342,9 @@  static int bootm_load_os(image_info_t os, ulong *load_end, int boot_progress)
 	ulong image_start = os.image_start;
 	ulong image_len = os.image_len;
 	uint unc_len = CONFIG_SYS_BOOTM_LEN;
-#if defined(CONFIG_LZMA) || defined(CONFIG_LZO)
+#if defined(CONFIG_LZMA) || defined(CONFIG_LZO) || defined(CONFIG_XZ)
 	int ret;
-#endif /* defined(CONFIG_LZMA) || defined(CONFIG_LZO) */
+#endif /* defined(CONFIG_LZMA) || defined(CONFIG_LZO) || defined(CONFIG_XZ) */
 
 	const char *type_name = genimg_get_type_name (os.type);
 
@@ -430,6 +434,25 @@  static int bootm_load_os(image_info_t os, ulong *load_end, int boot_progress)
 		*load_end = load + unc_len;
 		break;
 #endif /* CONFIG_LZO */
+#ifdef CONFIG_XZ
+	case IH_COMP_XZ: {
+		int in_used = unc_len;
+		printf ("   Uncompressing %s ... ", type_name);
+		ret = unxz(
+			(unsigned char *)image_start, image_len,
+			(unsigned char *)load, &in_used);
+		unc_len = in_used;
+		if (ret != 0) {
+			printf ("XZ: uncompress or overwrite error %d "
+				"- must RESET board to recover\n", ret);
+			show_boot_progress (-6);
+			return BOOTM_ERR_RESET;
+		}
+		*load_end = load + unc_len;
+		break;
+	}
+		break;
+#endif /* CONFIG_XZ */
 	default:
 		printf ("Unimplemented compression type %d\n", comp);
 		return BOOTM_ERR_UNIMPLEMENTED;
diff --git a/common/image.c b/common/image.c
index 42f5b79..4e31691 100644
--- a/common/image.c
+++ b/common/image.c
@@ -150,6 +150,7 @@  static table_entry_t uimage_comp[] = {
 	{	IH_COMP_GZIP,	"gzip",		"gzip compressed",	},
 	{	IH_COMP_LZMA,	"lzma",		"lzma compressed",	},
 	{	IH_COMP_LZO,	"lzo",		"lzo compressed",	},
+	{	IH_COMP_XZ,	"xz",		"xz compressed",	},
 	{	-1,		"",		"",			},
 };
 
diff --git a/include/image.h b/include/image.h
index 49d6280..5ba5afa 100644
--- a/include/image.h
+++ b/include/image.h
@@ -166,6 +166,7 @@ 
 #define IH_COMP_BZIP2		2	/* bzip2 Compression Used	*/
 #define IH_COMP_LZMA		3	/* lzma  Compression Used	*/
 #define IH_COMP_LZO		4	/* lzo   Compression Used	*/
+#define IH_COMP_XZ		5	/* xz    Compression Used       */
 
 #define IH_MAGIC	0x27051956	/* Image Magic Number		*/
 #define IH_NMLEN		32	/* Image Name Length		*/
diff --git a/include/unxz.h b/include/unxz.h
new file mode 100644
index 0000000..db4d58a
--- /dev/null
+++ b/include/unxz.h
@@ -0,0 +1,16 @@ 
+/*
+ * Wrapper for XZ decompressor to make it usable for kernel and initramfs
+ * decompression
+ *
+ * Author: Lasse Collin <lasse.collin@tukaani.org>
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+#ifndef DECOMPRESS_UNXZ_H
+#define DECOMPRESS_UNXZ_H
+
+int unxz(unsigned char *in, int in_size, unsigned char *out, int *in_used);
+
+#endif
diff --git a/include/xz.h b/include/xz.h
new file mode 100644
index 0000000..4f2dc12
--- /dev/null
+++ b/include/xz.h
@@ -0,0 +1,237 @@ 
+/*
+ * XZ decompressor
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <http://7-zip.org/>
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+#ifndef XZ_H
+#define XZ_H
+
+#include <linux/stddef.h>
+#include <linux/types.h>
+
+/* In Linux, this is used to make extern functions static when needed. */
+#ifndef XZ_EXTERN
+#	define XZ_EXTERN extern
+#endif
+
+/* In Linux, this is used to mark the functions with __init when needed. */
+#ifndef XZ_FUNC
+#	define XZ_FUNC
+#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: 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 = 0,
+	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_FUNC 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: 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_FUNC 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_FUNC 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_FUNC xz_dec_end(struct xz_dec *s);
+
+#endif
diff --git a/lib/xz/Makefile b/lib/xz/Makefile
new file mode 100644
index 0000000..3cfeab4
--- /dev/null
+++ b/lib/xz/Makefile
@@ -0,0 +1,51 @@ 
+#
+# Copyright (C) 2007-2008 Industrie Dial Face S.p.A.
+# Luigi 'Comio' Mantellini (luigi.mantellini@idf-hit.com)
+#
+# (C) Copyright 2003-2006
+# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+#
+# See file CREDITS for list of people who contributed to this
+# project.
+#
+# This program 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 2 of
+# the License, or (at your option) any later version.
+#
+# This program 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 this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+# MA 02111-1307 USA
+#
+
+include $(TOPDIR)/config.mk
+
+LIB	= $(obj)libxz.o
+
+SOBJS	=
+
+CFLAGS +=
+
+COBJS-$(CONFIG_XZ) += decompress_unxz.o
+
+COBJS	= $(COBJS-y)
+SRCS 	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
+OBJS	:= $(addprefix $(obj),$(SOBJS) $(COBJS))
+
+$(LIB):	$(obj).depend $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
+
+#########################################################################
+
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
+
+sinclude $(obj).depend
+
+#########################################################################
diff --git a/lib/xz/decompress_unxz.c b/lib/xz/decompress_unxz.c
new file mode 100644
index 0000000..f701c7f
--- /dev/null
+++ b/lib/xz/decompress_unxz.c
@@ -0,0 +1,231 @@ 
+/*
+ * XZ decoder as a single file for uncompressing the kernel and initramfs
+ *
+ * Author: Lasse Collin <lasse.collin@tukaani.org>
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+/*
+ * Important notes about in-place decompression
+ *
+ * At least on x86, the kernel is decompressed in place: the compressed data
+ * is placed to the end of the output buffer, and the decompressor overwrites
+ * most of the compressed data. There must be enough safety margin to
+ * guarantee that the write position is always behind the read position.
+ * The optimal safety margin for XZ with LZMA2 or BCJ+LZMA2 is calculated
+ * below. Note that the margin with XZ is bigger than with Deflate (gzip)!
+ *
+ * The worst case for in-place decompression is that the beginning of
+ * the file is compressed extremely well, and the rest of the file is
+ * uncompressible. Thus, we must look for worst-case expansion when the
+ * compressor is encoding uncompressible data.
+ *
+ * The structure of the .xz file in case of a compresed kernel is as follows.
+ * Sizes (as bytes) of the fields are in parenthesis.
+ *
+ *    Stream Header (12)
+ *    Block Header:
+ *      Block Header (8-12)
+ *      Compressed Data (N)
+ *      Block Padding (0-3)
+ *      CRC32 (4)
+ *    Index (8-20)
+ *    Stream Footer (12)
+ *
+ * Normally there is exactly one Block, but let's assume that there are
+ * 2-4 Blocks just in case. Because Stream Header and also Block Header
+ * of the first Block don't make the decompressor produce any uncompressed
+ * data, we can ignore them from our calculations. Block Headers of possible
+ * additional Blocks have to be taken into account still. With these
+ * assumptions, it is safe to assume that the total header overhead is
+ * less than 128 bytes.
+ *
+ * Compressed Data contains LZMA2 or BCJ+LZMA2 encoded data. Since BCJ
+ * doesn't change the size of the data, it is enough to calculate the
+ * safety margin for LZMA2.
+ *
+ * LZMA2 stores the data in chunks. Each chunk has a header whose size is
+ * at maximum of 6 bytes, but to get round 2^n numbers, let's assume that
+ * the maximum chunk header size is 8 bytes. After the chunk header, there
+ * may be up to 64 KiB of actual payload in the chunk. Often the payload is
+ * quite a bit smaller though; to be safe, let's assume that an average
+ * chunk has only 32 KiB of payload.
+ *
+ * The maximum uncompressed size of the payload is 2 MiB. The minimum
+ * uncompressed size of the payload is in practice never less than the
+ * payload size itself. The LZMA2 format would allow uncompressed size
+ * to be less than the payload size, but no sane compressor creates such
+ * files. LZMA2 supports storing uncompressible data in uncompressed form,
+ * so there's never a need to create payloads whose uncompressed size is
+ * smaller than the compressed size.
+ *
+ * The assumption, that the uncompressed size of the payload is never
+ * smaller than the payload itself, is valid only when talking about
+ * the payload as a whole. It is possible that the payload has parts where
+ * the decompressor consumes more input than it produces output. Calculating
+ * the worst case for this would be tricky. Instead of trying to do that,
+ * let's simply make sure that the decompressor never overwrites any bytes
+ * of the payload which it is currently reading.
+ *
+ * Now we have enough information to calculate the safety margin. We need
+ *   - 128 bytes for the .xz file format headers;
+ *   - 8 bytes per every 32 KiB of uncompressed size (one LZMA2 chunk header
+ *     per chunk, each chunk having average payload size of 32 KiB); and
+ *   - 64 KiB (biggest possible LZMA2 chunk payload size) to make sure that
+ *     the decompressor never overwrites anything from the LZMA2 chunk
+ *     payload it is currently reading.
+ *
+ * We get the following formula:
+ *
+ *    safety_margin = 128 + uncompressed_size * 8 / 32768 + 65536
+ *                  = 128 + (uncompressed_size >> 12) + 65536
+ *
+ * For comparision, according to arch/x86/boot/compressed/misc.c, the
+ * equivalent formula for Deflate is this:
+ *
+ *    safety_margin = 18 + (uncompressed_size >> 12) + 32768
+ *
+ * Thus, when updating Deflate-only in-place kernel decompressor to
+ * support XZ, the fixed overhead has to be increased from 18+32768 bytes
+ * to 128+65536 bytes.
+ */
+
+/*
+ * STATIC is defined to "static" if we are being built for kernel
+ * decompression (pre-boot code). <linux/decompress/mm.h> below will
+ * define STATIC to empty if it wasn't already defined. Since we will
+ * need to know if we are being used for kernel decompression, we define
+ * XZ_PREBOOT here.
+ */
+
+#define XZ_PREBOOT
+
+#define STATIC static
+
+/*
+ * Set the linkage of normally extern functions to static. The only
+ * function that we might make extern is unxz(), and even that will
+ * depend on the STATIC macro.
+ */
+#define XZ_EXTERN static
+
+/*
+ * Use INIT defined in <linux/decompress/mm.h> to possibly add __init
+ * to every function.
+ */
+#define XZ_FUNC
+
+/*
+ * Use the internal CRC32 code instead of kernel's CRC32 module, which
+ * is not available in early phase of booting.
+ */
+#define XZ_INTERNAL_CRC32 1
+
+/*
+ * Ignore the configuration specified in the kernel config for the xz_dec
+ * module. For boot time use, we enable only the BCJ filter of the current
+ * architecture, or none if no BCJ filter is available for the architecture.
+ */
+#define XZ_IGNORE_KCONFIG
+#ifdef CONFIG_X86
+#	define XZ_DEC_X86
+#endif
+#ifdef CONFIG_PPC
+#	define XZ_DEC_POWERPC
+#endif
+#ifdef CONFIG_ARM
+#	define XZ_DEC_ARM
+#endif
+#ifdef CONFIG_IA64
+#	define XZ_DEC_IA64
+#endif
+#ifdef CONFIG_SPARC
+#	define XZ_DEC_SPARC
+#endif
+
+#include "xz_private.h"
+
+#ifdef XZ_PREBOOT
+/*
+ * Replace the normal allocation functions with the versions
+ * from <linux/decompress/mm.h>.
+ */
+#undef kmalloc
+#undef kfree
+#undef vmalloc
+#undef vfree
+#define kmalloc(size, flags) malloc(size)
+#define kfree(ptr) free(ptr)
+#define vmalloc(size) malloc(size)
+#define vfree(ptr) free(ptr)
+
+#endif /* XZ_PREBOOT */
+
+#include "xz_dec_stream.c"
+#include "xz_dec_lzma2.c"
+#include "xz_dec_bcj.c"
+
+/*
+ * Maximum LZMA2 dictionary size. This matters only in multi-call mode.
+ * If you change this, remember to update also the error message in
+ * "case XZ_MEMLIMIT_ERROR".
+ */
+#define DICT_MAX (1024 * 1024)
+
+/* Size of the input and output buffers in multi-call mode */
+#define XZ_IOBUF_SIZE 4096
+
+/*
+ * This function implements the API defined in <linux/decompress/generic.h>.
+ *
+ * This wrapper will automatically choose single-call or multi-call mode
+ * of the native XZ decoder API. The single-call mode can be used only when
+ * both input and output buffers are available as a single chunk, i.e. when
+ * fill() and flush() won't be used.
+ *
+ * This API doesn't provide a way to specify the maximum dictionary size
+ * for the multi-call mode of the native XZ decoder API. We will use
+ * DICT_MAX bytes, which will be allocated with vmalloc().
+ */
+int XZ_FUNC unxz(/*const*/ unsigned char *in, int in_size,
+		unsigned char *out, int *in_used)
+{
+	struct xz_buf b;
+	struct xz_dec *s;
+	enum xz_ret ret;
+
+	if (in != NULL && out != NULL)
+		s = xz_dec_init(XZ_SINGLE, 0);
+	else
+		return -1;
+
+	if (s == NULL)
+		return -1;
+
+	b.in = in;
+	b.in_pos = 0;
+	b.in_size = in_size;
+	b.out_pos = 0;
+
+	if (in_used != NULL)
+		*in_used = 0;
+
+	b.out = out;
+	b.out_size = (size_t)-1;
+	ret = xz_dec_run(s, &b);
+
+	if (in_used != NULL)
+		*in_used += b.in_pos;
+
+	xz_dec_end(s);
+
+	return ret==XZ_STREAM_END?0:ret;
+}
+
+/*
+ * This macro is used by architecture-specific files to decompress
+ * the kernel image.
+ */
+#define decompress unxz
diff --git a/lib/xz/xz_dec_bcj.c b/lib/xz/xz_dec_bcj.c
new file mode 100644
index 0000000..09162b5
--- /dev/null
+++ b/lib/xz/xz_dec_bcj.c
@@ -0,0 +1,564 @@ 
+/*
+ * Branch/Call/Jump (BCJ) filter decoders
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <http://7-zip.org/>
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+#include "xz_private.h"
+
+/*
+ * The rest of the file is inside this ifdef. It makes things a little more
+ * convenient when building without support for any BCJ filters.
+ */
+#ifdef XZ_DEC_BCJ
+
+struct xz_dec_bcj {
+	/* Type of the BCJ filter being used */
+	enum {
+		BCJ_X86 = 4,        /* x86 or x86-64 */
+		BCJ_POWERPC = 5,    /* Big endian only */
+		BCJ_IA64 = 6,       /* Big or little endian */
+		BCJ_ARM = 7,        /* Little endian only */
+		BCJ_ARMTHUMB = 8,   /* Little endian only */
+		BCJ_SPARC = 9       /* Big or little endian */
+	} type;
+
+	/*
+	 * Return value of the next filter in the chain. We need to preserve
+	 * this information across calls, because we must not call the next
+	 * filter anymore once it has returned XZ_STREAM_END.
+	 */
+	enum xz_ret ret;
+
+	/* True if we are operating in single-call mode. */
+	bool single_call;
+
+	/*
+	 * Absolute position relative to the beginning of the uncompressed
+	 * data (in a single .xz Block). We care only about the lowest 32
+	 * bits so this doesn't need to be uint64_t even with big files.
+	 */
+	uint32_t pos;
+
+	/* x86 filter state */
+	uint32_t x86_prev_mask;
+
+	/* Temporary space to hold the variables from struct xz_buf */
+	uint8_t *out;
+	size_t out_pos;
+	size_t out_size;
+
+	struct {
+		/* Amount of already filtered data in the beginning of buf */
+		size_t filtered;
+
+		/* Total amount of data currently stored in buf  */
+		size_t size;
+
+		/*
+		 * Buffer to hold a mix of filtered and unfiltered data. This
+		 * needs to be big enough to hold Alignment + 2 * Look-ahead:
+		 *
+		 * Type         Alignment   Look-ahead
+		 * x86              1           4
+		 * PowerPC          4           0
+		 * IA-64           16           0
+		 * ARM              4           0
+		 * ARM-Thumb        2           2
+		 * SPARC            4           0
+		 */
+		uint8_t buf[16];
+	} temp;
+};
+
+#ifdef XZ_DEC_X86
+/*
+ * This is macro used to test the most significant byte of a memory address
+ * in an x86 instruction.
+ */
+#define bcj_x86_test_msbyte(b) ((b) == 0x00 || (b) == 0xFF)
+
+static noinline_for_stack size_t XZ_FUNC bcj_x86(
+		struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	static const bool mask_to_allowed_status[8]
+		= { true, true, true, false, true, false, false, false };
+
+	static const uint8_t mask_to_bit_num[8] = { 0, 1, 2, 2, 3, 3, 3, 3 };
+
+	size_t i;
+	size_t prev_pos = (size_t)-1;
+	uint32_t prev_mask = s->x86_prev_mask;
+	uint32_t src;
+	uint32_t dest;
+	uint32_t j;
+	uint8_t b;
+
+	if (size <= 4)
+		return 0;
+
+	size -= 4;
+	for (i = 0; i < size; ++i) {
+		if ((buf[i] & 0xFE) != 0xE8)
+			continue;
+
+		prev_pos = i - prev_pos;
+		if (prev_pos > 3) {
+			prev_mask = 0;
+		} else {
+			prev_mask = (prev_mask << (prev_pos - 1)) & 7;
+			if (prev_mask != 0) {
+				b = buf[i + 4 - mask_to_bit_num[prev_mask]];
+				if (!mask_to_allowed_status[prev_mask]
+						|| bcj_x86_test_msbyte(b)) {
+					prev_pos = i;
+					prev_mask = (prev_mask << 1) | 1;
+					continue;
+				}
+			}
+		}
+
+		prev_pos = i;
+
+		if (bcj_x86_test_msbyte(buf[i + 4])) {
+			src = get_unaligned_le32(buf + i + 1);
+			while (true) {
+				dest = src - (s->pos + (uint32_t)i + 5);
+				if (prev_mask == 0)
+					break;
+
+				j = mask_to_bit_num[prev_mask] * 8;
+				b = (uint8_t)(dest >> (24 - j));
+				if (!bcj_x86_test_msbyte(b))
+					break;
+
+				src = dest ^ (((uint32_t)1 << (32 - j)) - 1);
+			}
+
+			dest &= 0x01FFFFFF;
+			dest |= (uint32_t)0 - (dest & 0x01000000);
+			put_unaligned_le32(dest, buf + i + 1);
+			i += 4;
+		} else {
+			prev_mask = (prev_mask << 1) | 1;
+		}
+	}
+
+	prev_pos = i - prev_pos;
+	s->x86_prev_mask = prev_pos > 3 ? 0 : prev_mask << (prev_pos - 1);
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_POWERPC
+static noinline_for_stack size_t XZ_FUNC bcj_powerpc(
+		struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t instr;
+
+	for (i = 0; i + 4 <= size; i += 4) {
+		instr = get_unaligned_be32(buf + i);
+		if ((instr & 0xFC000003) == 0x48000001) {
+			instr &= 0x03FFFFFC;
+			instr -= s->pos + (uint32_t)i;
+			instr &= 0x03FFFFFC;
+			instr |= 0x48000001;
+			put_unaligned_be32(instr, buf + i);
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_IA64
+static noinline_for_stack size_t XZ_FUNC bcj_ia64(
+		struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	static const uint8_t branch_table[32] = {
+		0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0,
+		4, 4, 6, 6, 0, 0, 7, 7,
+		4, 4, 0, 0, 4, 4, 0, 0
+	};
+
+	/*
+	 * The local variables take a little bit stack space, but it's less
+	 * than what LZMA2 decoder takes, so it doesn't make sense to reduce
+	 * stack usage here without doing that for the LZMA2 decoder too.
+	 */
+
+	/* Loop counters */
+	size_t i;
+	size_t j;
+
+	/* Instruction slot (0, 1, or 2) in the 128-bit instruction word */
+	uint32_t slot;
+
+	/* Bitwise offset of the instruction indicated by slot */
+	uint32_t bit_pos;
+
+	/* bit_pos split into byte and bit parts */
+	uint32_t byte_pos;
+	uint32_t bit_res;
+
+	/* Address part of an instruction */
+	uint32_t addr;
+
+	/* Mask used to detect which instructions to convert */
+	uint32_t mask;
+
+	/* 41-bit instruction stored somewhere in the lowest 48 bits */
+	uint64_t instr;
+
+	/* Instruction normalized with bit_res for easier manipulation */
+	uint64_t norm;
+
+	for (i = 0; i + 16 <= size; i += 16) {
+		mask = branch_table[buf[i] & 0x1F];
+		for (slot = 0, bit_pos = 5; slot < 3; ++slot, bit_pos += 41) {
+			if (((mask >> slot) & 1) == 0)
+				continue;
+
+			byte_pos = bit_pos >> 3;
+			bit_res = bit_pos & 7;
+			instr = 0;
+			for (j = 0; j < 6; ++j)
+				instr |= (uint64_t)(buf[i + j + byte_pos])
+						<< (8 * j);
+
+			norm = instr >> bit_res;
+
+			if (((norm >> 37) & 0x0F) == 0x05
+					&& ((norm >> 9) & 0x07) == 0) {
+				addr = (norm >> 13) & 0x0FFFFF;
+				addr |= ((uint32_t)(norm >> 36) & 1) << 20;
+				addr <<= 4;
+				addr -= s->pos + (uint32_t)i;
+				addr >>= 4;
+
+				norm &= ~((uint64_t)0x8FFFFF << 13);
+				norm |= (uint64_t)(addr & 0x0FFFFF) << 13;
+				norm |= (uint64_t)(addr & 0x100000)
+						<< (36 - 20);
+
+				instr &= (1 << bit_res) - 1;
+				instr |= norm << bit_res;
+
+				for (j = 0; j < 6; j++)
+					buf[i + j + byte_pos]
+						= (uint8_t)(instr >> (8 * j));
+			}
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_ARM
+static noinline_for_stack size_t XZ_FUNC bcj_arm(
+		struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t addr;
+
+	for (i = 0; i + 4 <= size; i += 4) {
+		if (buf[i + 3] == 0xEB) {
+			addr = (uint32_t)buf[i] | ((uint32_t)buf[i + 1] << 8)
+					| ((uint32_t)buf[i + 2] << 16);
+			addr <<= 2;
+			addr -= s->pos + (uint32_t)i + 8;
+			addr >>= 2;
+			buf[i] = (uint8_t)addr;
+			buf[i + 1] = (uint8_t)(addr >> 8);
+			buf[i + 2] = (uint8_t)(addr >> 16);
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_ARMTHUMB
+static noinline_for_stack size_t XZ_FUNC bcj_armthumb(
+		struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t addr;
+
+	for (i = 0; i + 4 <= size; i += 2) {
+		if ((buf[i + 1] & 0xF8) == 0xF0
+				&& (buf[i + 3] & 0xF8) == 0xF8) {
+			addr = (((uint32_t)buf[i + 1] & 0x07) << 19)
+					| ((uint32_t)buf[i] << 11)
+					| (((uint32_t)buf[i + 3] & 0x07) << 8)
+					| (uint32_t)buf[i + 2];
+			addr <<= 1;
+			addr -= s->pos + (uint32_t)i + 4;
+			addr >>= 1;
+			buf[i + 1] = (uint8_t)(0xF0 | ((addr >> 19) & 0x07));
+			buf[i] = (uint8_t)(addr >> 11);
+			buf[i + 3] = (uint8_t)(0xF8 | ((addr >> 8) & 0x07));
+			buf[i + 2] = (uint8_t)addr;
+			i += 2;
+		}
+	}
+
+	return i;
+}
+#endif
+
+#ifdef XZ_DEC_SPARC
+static noinline_for_stack size_t XZ_FUNC bcj_sparc(
+		struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t instr;
+
+	for (i = 0; i + 4 <= size; i += 4) {
+		instr = get_unaligned_be32(buf + i);
+		if ((instr >> 22) == 0x100 || (instr >> 22) == 0x1FF) {
+			instr <<= 2;
+			instr -= s->pos + (uint32_t)i;
+			instr >>= 2;
+			instr = ((uint32_t)0x40000000 - (instr & 0x400000))
+					| 0x40000000 | (instr & 0x3FFFFF);
+			put_unaligned_be32(instr, buf + i);
+		}
+	}
+
+	return i;
+}
+#endif
+
+/*
+ * Apply the selected BCJ filter. Update *pos and s->pos to match the amount
+ * of data that got filtered.
+ *
+ * NOTE: This is implemented as a switch statement to avoid using function
+ * pointers, which could be problematic in the kernel boot code, which must
+ * avoid pointers to static data (at least on x86).
+ */
+static void XZ_FUNC bcj_apply(struct xz_dec_bcj *s,
+		uint8_t *buf, size_t *pos, size_t size)
+{
+	size_t filtered;
+
+	buf += *pos;
+	size -= *pos;
+
+	switch (s->type) {
+#ifdef XZ_DEC_X86
+	case BCJ_X86:
+		filtered = bcj_x86(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_POWERPC
+	case BCJ_POWERPC:
+		filtered = bcj_powerpc(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_IA64
+	case BCJ_IA64:
+		filtered = bcj_ia64(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_ARM
+	case BCJ_ARM:
+		filtered = bcj_arm(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_ARMTHUMB
+	case BCJ_ARMTHUMB:
+		filtered = bcj_armthumb(s, buf, size);
+		break;
+#endif
+#ifdef XZ_DEC_SPARC
+	case BCJ_SPARC:
+		filtered = bcj_sparc(s, buf, size);
+		break;
+#endif
+	default:
+		/* Never reached but silence compiler warnings. */
+		filtered = 0;
+		break;
+	}
+
+	*pos += filtered;
+	s->pos += filtered;
+}
+
+/*
+ * Flush pending filtered data from temp to the output buffer.
+ * Move the remaining mixture of possibly filtered and unfiltered
+ * data to the beginning of temp.
+ */
+static void XZ_FUNC bcj_flush(struct xz_dec_bcj *s, struct xz_buf *b)
+{
+	size_t copy_size;
+
+	copy_size = min_t(size_t, s->temp.filtered, b->out_size - b->out_pos);
+	memcpy(b->out + b->out_pos, s->temp.buf, copy_size);
+	b->out_pos += copy_size;
+
+	s->temp.filtered -= copy_size;
+	s->temp.size -= copy_size;
+	memmove(s->temp.buf, s->temp.buf + copy_size, s->temp.size);
+}
+
+/*
+ * The BCJ filter functions are primitive in sense that they process the
+ * data in chunks of 1-16 bytes. To hide this issue, this function does
+ * some buffering.
+ */
+XZ_EXTERN enum xz_ret XZ_FUNC xz_dec_bcj_run(struct xz_dec_bcj *s,
+		struct xz_dec_lzma2 *lzma2, struct xz_buf *b)
+{
+	size_t out_start;
+
+	/*
+	 * Flush pending already filtered data to the output buffer. Return
+	 * immediatelly if we couldn't flush everything, or if the next
+	 * filter in the chain had already returned XZ_STREAM_END.
+	 */
+	if (s->temp.filtered > 0) {
+		bcj_flush(s, b);
+		if (s->temp.filtered > 0)
+			return XZ_OK;
+
+		if (s->ret == XZ_STREAM_END)
+			return XZ_STREAM_END;
+	}
+
+	/*
+	 * If we have more output space than what is currently pending in
+	 * temp, copy the unfiltered data from temp to the output buffer
+	 * and try to fill the output buffer by decoding more data from the
+	 * next filter in the chain. Apply the BCJ filter on the new data
+	 * in the output buffer. If everything cannot be filtered, copy it
+	 * to temp and rewind the output buffer position accordingly.
+	 */
+	if (s->temp.size < b->out_size - b->out_pos) {
+		out_start = b->out_pos;
+		memcpy(b->out + b->out_pos, s->temp.buf, s->temp.size);
+		b->out_pos += s->temp.size;
+
+		s->ret = xz_dec_lzma2_run(lzma2, b);
+		if (s->ret != XZ_STREAM_END
+				&& (s->ret != XZ_OK || s->single_call))
+			return s->ret;
+
+		bcj_apply(s, b->out, &out_start, b->out_pos);
+
+		/*
+		 * As an exception, if the next filter returned XZ_STREAM_END,
+		 * we can do that too, since the last few bytes that remain
+		 * unfiltered are meant to remain unfiltered.
+		 */
+		if (s->ret == XZ_STREAM_END)
+			return XZ_STREAM_END;
+
+		s->temp.size = b->out_pos - out_start;
+		b->out_pos -= s->temp.size;
+		memcpy(s->temp.buf, b->out + b->out_pos, s->temp.size);
+	}
+
+	/*
+	 * If we have unfiltered data in temp, try to fill by decoding more
+	 * data from the next filter. Apply the BCJ filter on temp. Then we
+	 * hopefully can fill the actual output buffer by copying filtered
+	 * data from temp. A mix of filtered and unfiltered data may be left
+	 * in temp; it will be taken care on the next call to this function.
+	 */
+	if (s->temp.size > 0) {
+		/* Make b->out{,_pos,_size} temporarily point to s->temp. */
+		s->out = b->out;
+		s->out_pos = b->out_pos;
+		s->out_size = b->out_size;
+		b->out = s->temp.buf;
+		b->out_pos = s->temp.size;
+		b->out_size = sizeof(s->temp.buf);
+
+		s->ret = xz_dec_lzma2_run(lzma2, b);
+
+		s->temp.size = b->out_pos;
+		b->out = s->out;
+		b->out_pos = s->out_pos;
+		b->out_size = s->out_size;
+
+		if (s->ret != XZ_OK && s->ret != XZ_STREAM_END)
+			return s->ret;
+
+		bcj_apply(s, s->temp.buf, &s->temp.filtered, s->temp.size);
+
+		/*
+		 * If the next filter returned XZ_STREAM_END, we mark that
+		 * everything is filtered, since the last unfiltered bytes
+		 * of the stream are meant to be left as is.
+		 */
+		if (s->ret == XZ_STREAM_END)
+			s->temp.filtered = s->temp.size;
+
+		bcj_flush(s, b);
+		if (s->temp.filtered > 0)
+			return XZ_OK;
+	}
+
+	return s->ret;
+}
+
+XZ_EXTERN struct xz_dec_bcj * XZ_FUNC xz_dec_bcj_create(bool single_call)
+{
+	struct xz_dec_bcj *s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (s != NULL)
+		s->single_call = single_call;
+
+	return s;
+}
+
+XZ_EXTERN enum xz_ret XZ_FUNC xz_dec_bcj_reset(
+		struct xz_dec_bcj *s, uint8_t id)
+{
+	switch (id) {
+#ifdef XZ_DEC_X86
+	case BCJ_X86:
+#endif
+#ifdef XZ_DEC_POWERPC
+	case BCJ_POWERPC:
+#endif
+#ifdef XZ_DEC_IA64
+	case BCJ_IA64:
+#endif
+#ifdef XZ_DEC_ARM
+	case BCJ_ARM:
+#endif
+#ifdef XZ_DEC_ARMTHUMB
+	case BCJ_ARMTHUMB:
+#endif
+#ifdef XZ_DEC_SPARC
+	case BCJ_SPARC:
+#endif
+		break;
+
+	default:
+		/* Unsupported Filter ID */
+		return XZ_OPTIONS_ERROR;
+	}
+
+	s->type = id;
+	s->ret = XZ_OK;
+	s->pos = 0;
+	s->x86_prev_mask = 0;
+	s->temp.filtered = 0;
+	s->temp.size = 0;
+
+	return XZ_OK;
+}
+
+#endif
diff --git a/lib/xz/xz_dec_lzma2.c b/lib/xz/xz_dec_lzma2.c
new file mode 100644
index 0000000..16aea7d
--- /dev/null
+++ b/lib/xz/xz_dec_lzma2.c
@@ -0,0 +1,1175 @@ 
+/*
+ * LZMA2 decoder
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <http://7-zip.org/>
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+#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 XZ_FUNC 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 XZ_FUNC 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 bool XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC rc_is_finished(const struct rc_dec *rc)
+{
+	return rc->code == 0;
+}
+
+/* Read the next input byte if needed. */
+static __always_inline void XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 * XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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_FUNC 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 >= 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 == 0x00)
+					return XZ_STREAM_END;
+
+				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_FUNC 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_FUNC 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_FUNC 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/lib/xz/xz_dec_stream.c b/lib/xz/xz_dec_stream.c
new file mode 100644
index 0000000..c789245
--- /dev/null
+++ b/lib/xz/xz_dec_stream.c
@@ -0,0 +1,823 @@ 
+/*
+ * .xz Stream decoder
+ *
+ * Author: Lasse Collin <lasse.collin@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"
+
+/* 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;
+
+	/* CRC32 value in Block or Index */
+	uint32_t crc32;
+
+	/* 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 XZ_FUNC 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 XZ_FUNC 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 if presence of the CRC32
+ * 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 XZ_FUNC 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->crc32 = crc32(
+		    s->crc32, b->out + s->out_start, b->out_pos - s->out_start);
+
+	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;
+#endif
+
+		s->block.hash.uncompressed += s->block.uncompressed;
+		s->block.hash.crc32 = crc32(
+					s->block.hash.crc32,
+					(const uint8_t *)&s->block.hash,
+					sizeof(s->block.hash));
+
+		++s->block.count;
+	}
+
+	return ret;
+}
+
+/* Update the Index size and the CRC32 value. */
+static void XZ_FUNC 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->crc32 = crc32(s->crc32, b->in + s->in_start, in_used);
+}
+
+/*
+ * 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 XZ_FUNC 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 = crc32(
+					s->index.hash.crc32,
+					(const uint8_t *)&s->index.hash,
+					sizeof(s->index.hash));
+			--s->index.count;
+			s->index.sequence = SEQ_INDEX_UNPADDED;
+			break;
+		}
+	} while (s->index.count > 0);
+
+	return XZ_STREAM_END;
+}
+
+/*
+ * Validate that the next four input bytes match the value of s->crc32.
+ * s->pos must be zero when starting to validate the first byte.
+ */
+static enum xz_ret XZ_FUNC crc32_validate(struct xz_dec *s, struct xz_buf *b)
+{
+	do {
+		if (b->in_pos == b->in_size)
+			return XZ_OK;
+
+		if (((s->crc32 >> s->pos) & 0xFF) != b->in[b->in_pos++])
+			return XZ_DATA_ERROR;
+
+		s->pos += 8;
+
+	} while (s->pos < 32);
+
+	s->crc32 = 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 XZ_FUNC 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 XZ_FUNC dec_stream_header(struct xz_dec *s)
+{
+	if (!memeq(s->temp.buf, HEADER_MAGIC, HEADER_MAGIC_SIZE))
+		return XZ_FORMAT_ERROR;
+
+	if (crc32(0, s->temp.buf + HEADER_MAGIC_SIZE, 2)
+			!= 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 only none (Check ID = 0) and
+	 * CRC32 (Check ID = 1). 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)
+		return XZ_UNSUPPORTED_CHECK;
+#else
+	if (s->check_type > XZ_CHECK_CRC32)
+		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 XZ_FUNC dec_stream_footer(struct xz_dec *s)
+{
+	if (!memeq(s->temp.buf + 10, FOOTER_MAGIC, FOOTER_MAGIC_SIZE))
+		return XZ_DATA_ERROR;
+
+	if (crc32(0, s->temp.buf + 4, 6) != 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 XZ_FUNC 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 (crc32(0, s->temp.buf, s->temp.size)
+			!= 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 XZ_FUNC 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 = crc32_validate(s, b);
+				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 = crc32_validate(s, b);
+			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_FUNC 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_FUNC 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_FUNC xz_dec_reset(struct xz_dec *s)
+{
+	s->sequence = SEQ_STREAM_HEADER;
+	s->allow_buf_error = false;
+	s->pos = 0;
+	s->crc32 = 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_FUNC 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/lib/xz/xz_lzma2.h b/lib/xz/xz_lzma2.h
new file mode 100644
index 0000000..47f21af
--- /dev/null
+++ b/lib/xz/xz_lzma2.h
@@ -0,0 +1,204 @@ 
+/*
+ * LZMA2 definitions
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <http://7-zip.org/>
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+#ifndef XZ_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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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 XZ_FUNC 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/lib/xz/xz_private.h b/lib/xz/xz_private.h
new file mode 100644
index 0000000..8f4b24c
--- /dev/null
+++ b/lib/xz/xz_private.h
@@ -0,0 +1,154 @@ 
+/*
+ * Private includes and definitions
+ *
+ * Author: Lasse Collin <lasse.collin@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
+
+#include <common.h>
+#include <linux/types.h>
+#include <asm/byteorder.h>
+#include <asm/unaligned.h>
+#include <malloc.h>
+#include <xz.h>
+
+#ifndef __always_inline
+#define __always_inline inline
+#endif
+
+#ifndef memzero
+#define memzero(ptr, len) memset(ptr, 0, len)
+#endif
+
+#ifndef memeq
+#define memeq(s1, s2, n) (memcmp(s1, s2, n) == 0)
+#endif
+
+#ifndef get_le32
+#define get_le32(x) get_unaligned_le32(x)
+#endif
+
+#ifndef bool
+typedef unsigned int bool;
+#define false	(0)
+#define true	(!false)
+#endif
+
+#ifndef min_t
+#define min_t(type,x,y) \
+	({ type __x = (x); type __y = (y); __x < __y ? __x: __y; })
+#endif
+#ifndef max_t
+#define max_t(type,x,y) \
+	({ type __x = (x); type __y = (y); __x > __y ? __x: __y; })
+#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_FUNC 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_FUNC 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_FUNC 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_FUNC 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_FUNC 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_FUNC 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_FUNC 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/lib/xz/xz_stream.h b/lib/xz/xz_stream.h
new file mode 100644
index 0000000..07c0383
--- /dev/null
+++ b/lib/xz/xz_stream.h
@@ -0,0 +1,50 @@ 
+/*
+ * Definitions for handling the .xz file format
+ *
+ * Author: Lasse Collin <lasse.collin@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
+
+/*
+ * 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 to indicate that the value is unknown.
+ */
+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