Xen devel - Nov 2009 - [PATCH] x86/dom0: support bzip2 and lzma compressed bzImage payloads

This matches functionality in the tools already supporting the same for
DomU-s.

Code taken from Linux 2.6.32-rc and adjusted as little as possible to
be usable in Xen.

The question is whether, particularly for non-Linux Dom0-s, plain ELF
images compressed by bzip2 or lzma should also be supported.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

--- 2009-10-27.orig/xen/arch/x86/bzimage.c	2009-10-07 13:31:36.000000000 +0200
+++ 2009-10-27/xen/arch/x86/bzimage.c	2009-11-05 12:23:05.000000000 +0100
@@ -4,6 +4,7 @@
 #include <xen/mm.h>
 #include <xen/string.h>
 #include <xen/types.h>
+#include <xen/decompress.h>
 #include <asm/bzimage.h>
 
 #define HEAPORDER 3
@@ -93,28 +94,38 @@ static __init void flush_window(void)
     outcnt = 0;
 }
 
-static __init int gzip_length(char *image, unsigned long image_len)
+static __init unsigned long output_length(char *image, unsigned long image_len)
 {
     return *(uint32_t *)&image[image_len - 4];
 }
 
-static  __init int perform_gunzip(char *output, char **_image_start, unsigned
long *image_len)
+static __init int gzip_check(char *image, unsigned long image_len)
 {
-    char *image = *_image_start;
-    int rc;
-    unsigned char magic0 = (unsigned char)image[0];
-    unsigned char magic1 = (unsigned char)image[1];
+    unsigned char magic0, magic1;
 
-    if ( magic0 != 0x1f || ( (magic1 != 0x8b) && (magic1 != 0x9e) ) )
+    if ( image_len < 2 )
         return 0;
 
+    magic0 = (unsigned char)image[0];
+    magic1 = (unsigned char)image[1];
+
+    return (magic0 == 0x1f) && ((magic1 == 0x8b) || (magic1 == 0x9e));
+}
+
+static __init int perform_gunzip(char *output, char *image, unsigned long
image_len)
+{
+    int rc;
+
+    if ( !gzip_check(image, image_len) )
+        return 1;
+
     window = (unsigned char *)output;
 
     free_mem_ptr = (unsigned long)alloc_xenheap_pages(HEAPORDER, 0);
     free_mem_end_ptr = free_mem_ptr + (PAGE_SIZE << HEAPORDER);
 
     inbuf = (unsigned char *)image;
-    insize = *image_len;
+    insize = image_len;
     inptr = 0;
 
     makecrc();
@@ -125,8 +136,6 @@ static  __init int perform_gunzip(char *
     }
     else
     {
-        *_image_start = (char *)window;
-        *image_len = gzip_length(image, *image_len);
         rc = 0;
     }
 
@@ -203,9 +212,12 @@ int __init bzimage_headroom(char *image_
     img = image_start + (hdr->setup_sects+1) * 512;
     img += hdr->payload_offset;
 
-    headroom = gzip_length(img, hdr->payload_length);
-    headroom += headroom >> 12; /* Add 8 bytes for every 32K input block
*/
-    headroom += (32768 + 18); /* Add 32K + 18 bytes of extra headroom */
+    headroom = output_length(img, hdr->payload_length);
+    if (gzip_check(img, hdr->payload_length)) {
+        headroom += headroom >> 12; /* Add 8 bytes for every 32K input
block */
+        headroom += (32768 + 18); /* Add 32K + 18 bytes of extra headroom */
+    } else
+        headroom += hdr->payload_length;
     headroom = (headroom + 4095) & ~4095;
 
     return headroom;
@@ -215,6 +227,7 @@ int __init bzimage_parse(char *image_bas
 {
     struct setup_header *hdr = (struct setup_header *)(*image_start);
     int err = bzimage_check(hdr, *image_len);
+    unsigned long output_len;
 
     if (err < 1)
         return err;
@@ -224,11 +237,18 @@ int __init bzimage_parse(char *image_bas
     *image_start += (hdr->setup_sects+1) * 512;
     *image_start += hdr->payload_offset;
     *image_len = hdr->payload_length;
+    output_len = output_length(*image_start, *image_len);
 
-    if ( (err = perform_gunzip(image_base, image_start, image_len)) < 0 )
-        return err;
+    if ( (err = perform_gunzip(image_base, *image_start, *image_len)) > 0 )
+        err = decompress(*image_start, *image_len, image_base);
+
+    if ( !err )
+    {
+        *image_start = image_base;
+        *image_len = output_len;
+    }
 
-    return 0;
+    return err > 0 ? 0 : err;
 }
 
 /*
--- 2009-10-27.orig/xen/common/Makefile	2009-05-27 13:54:07.000000000 +0200
+++ 2009-10-27/xen/common/Makefile	2009-11-05 12:26:53.000000000 +0100
@@ -35,6 +35,8 @@ obj-y += radix-tree.o
 obj-y += rbtree.o
 obj-y += lzo.o
 
+obj-$(CONFIG_X86) += decompress.o bunzip2.o unlzma.o
+
 obj-$(perfc)       += perfc.o
 obj-$(crash_debug) += gdbstub.o
 obj-$(xenoprof)    += xenoprof.o
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2009-10-27/xen/common/bunzip2.c	2009-11-05 12:44:51.000000000 +0100
@@ -0,0 +1,726 @@
+/* vi: set sw = 4 ts = 4: */
+/*	Small bzip2 deflate implementation, by Rob Landley (rob@landley.net).
+
+	Based on bzip2 decompression code by Julian R Seward (jseward@acm.org),
+	which also acknowledges contributions by Mike Burrows, David Wheeler,
+	Peter Fenwick, Alistair Moffat, Radford Neal, Ian H. Witten,
+	Robert Sedgewick, and Jon L. Bentley.
+
+	This code is licensed under the LGPLv2:
+		LGPL (http://www.gnu.org/copyleft/lgpl.html 
+*/
+
+/*
+	Size and speed optimizations by Manuel Novoa III  (mjn3@codepoet.org).
+
+	More efficient reading of Huffman codes, a streamlined read_bunzip()
+	function, and various other tweaks.  In (limited) tests, approximately
+	20% faster than bzcat on x86 and about 10% faster on arm.
+
+	Note that about 2/3 of the time is spent in read_unzip() reversing
+	the Burrows-Wheeler transformation.  Much of that time is delay
+	resulting from cache misses.
+
+	I would ask that anyone benefiting from this work, especially those
+	using it in commercial products, consider making a donation to my local
+	non-profit hospice organization in the name of the woman I loved, who
+	passed away Feb. 12, 2003.
+
+		In memory of Toni W. Hagan
+
+		Hospice of Acadiana, Inc.
+		2600 Johnston St., Suite 200
+		Lafayette, LA 70503-3240
+
+		Phone (337) 232-1234 or 1-800-738-2226
+		Fax   (337) 232-1297
+
+		http://www.hospiceacadiana.com/ 
+
+	Manuel
+ */
+
+/*
+	Made it fit for running in Linux Kernel by Alain Knaff (alain@knaff.lu)
+*/
+
+#include "decompress.h"
+
+#ifndef INT_MAX
+#define INT_MAX 0x7fffffff
+#endif
+
+/* Constants for Huffman coding */
+#define MAX_GROUPS		6
+#define GROUP_SIZE   		50	/* 64 would have been more efficient */
+#define MAX_HUFCODE_BITS 	20	/* Longest Huffman code allowed */
+#define MAX_SYMBOLS 		258	/* 256 literals + RUNA + RUNB */
+#define SYMBOL_RUNA		0
+#define SYMBOL_RUNB		1
+
+/* Status return values */
+#define RETVAL_OK			0
+#define RETVAL_LAST_BLOCK		(-1)
+#define RETVAL_NOT_BZIP_DATA		(-2)
+#define RETVAL_UNEXPECTED_INPUT_EOF	(-3)
+#define RETVAL_UNEXPECTED_OUTPUT_EOF	(-4)
+#define RETVAL_DATA_ERROR		(-5)
+#define RETVAL_OUT_OF_MEMORY		(-6)
+#define RETVAL_OBSOLETE_INPUT		(-7)
+
+/* Other housekeeping constants */
+#define BZIP2_IOBUF_SIZE		4096
+
+/* This is what we know about each Huffman coding group */
+struct group_data {
+	/* We have an extra slot at the end of limit[] for a sentinal value. */
+	int limit[MAX_HUFCODE_BITS+1];
+	int base[MAX_HUFCODE_BITS];
+	int permute[MAX_SYMBOLS];
+	int minLen, maxLen;
+};
+
+/* Structure holding all the housekeeping data, including IO buffers and
+   memory that persists between calls to bunzip */
+struct bunzip_data {
+	/* State for interrupting output loop */
+	int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent;
+	/* I/O tracking data (file handles, buffers, positions, etc.) */
+	int (*fill)(void*, unsigned int);
+	int inbufCount, inbufPos /*, outbufPos*/;
+	unsigned char *inbuf /*,*outbuf*/;
+	unsigned int inbufBitCount, inbufBits;
+	/* The CRC values stored in the block header and calculated from the
+	data */
+	unsigned int crc32Table[256], headerCRC, totalCRC, writeCRC;
+	/* Intermediate buffer and its size (in bytes) */
+	unsigned int *dbuf, dbufSize;
+	/* These things are a bit too big to go on the stack */
+	unsigned char selectors[32768];		/* nSelectors = 15 bits */
+	struct group_data groups[MAX_GROUPS];	/* Huffman coding tables */
+	int io_error;			/* non-zero if we have IO error */
+};
+
+
+/* Return the next nnn bits of input.  All reads from the compressed input
+   are done through this function.  All reads are big endian */
+static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted)
+{
+	unsigned int bits = 0;
+
+	/* If we need to get more data from the byte buffer, do so.
+	   (Loop getting one byte at a time to enforce endianness and avoid
+	   unaligned access.) */
+	while (bd->inbufBitCount < bits_wanted) {
+		/* If we need to read more data from file into byte buffer, do
+		   so */
+		if (bd->inbufPos == bd->inbufCount) {
+			if (bd->io_error)
+				return 0;
+			bd->inbufCount = bd->fill(bd->inbuf, BZIP2_IOBUF_SIZE);
+			if (bd->inbufCount <= 0) {
+				bd->io_error = RETVAL_UNEXPECTED_INPUT_EOF;
+				return 0;
+			}
+			bd->inbufPos = 0;
+		}
+		/* Avoid 32-bit overflow (dump bit buffer to top of output) */
+		if (bd->inbufBitCount >= 24) {
+			bits = bd->inbufBits&((1 << bd->inbufBitCount)-1);
+			bits_wanted -= bd->inbufBitCount;
+			bits <<= bits_wanted;
+			bd->inbufBitCount = 0;
+		}
+		/* Grab next 8 bits of input from buffer. */
+		bd->inbufBits = (bd->inbufBits <<
8)|bd->inbuf[bd->inbufPos++];
+		bd->inbufBitCount += 8;
+	}
+	/* Calculate result */
+	bd->inbufBitCount -= bits_wanted;
+	bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 <<
bits_wanted)-1);
+
+	return bits;
+}
+
+/* Unpacks the next block and sets up for the inverse burrows-wheeler step. */
+
+static int INIT get_next_block(struct bunzip_data *bd)
+{
+	struct group_data *hufGroup = NULL;
+	int *base = NULL;
+	int *limit = NULL;
+	int dbufCount, nextSym, dbufSize, groupCount, selector,
+		i, j, k, t, runPos, symCount, symTotal, nSelectors,
+		byteCount[256];
+	unsigned char uc, symToByte[256], mtfSymbol[256], *selectors;
+	unsigned int *dbuf, origPtr;
+
+	dbuf = bd->dbuf;
+	dbufSize = bd->dbufSize;
+	selectors = bd->selectors;
+
+	/* Read in header signature and CRC, then validate signature.
+	   (last block signature means CRC is for whole file, return now) */
+	i = get_bits(bd, 24);
+	j = get_bits(bd, 24);
+	bd->headerCRC = get_bits(bd, 32);
+	if ((i == 0x177245) && (j == 0x385090))
+		return RETVAL_LAST_BLOCK;
+	if ((i != 0x314159) || (j != 0x265359))
+		return RETVAL_NOT_BZIP_DATA;
+	/* We can add support for blockRandomised if anybody complains.
+	   There was some code for this in busybox 1.0.0-pre3, but nobody ever
+	   noticed that it didn''t actually work. */
+	if (get_bits(bd, 1))
+		return RETVAL_OBSOLETE_INPUT;
+	origPtr = get_bits(bd, 24);
+	if (origPtr > dbufSize)
+		return RETVAL_DATA_ERROR;
+	/* mapping table: if some byte values are never used (encoding things
+	   like ascii text), the compression code removes the gaps to have fewer
+	   symbols to deal with, and writes a sparse bitfield indicating which
+	   values were present.  We make a translation table to convert the
+	   symbols back to the corresponding bytes. */
+	t = get_bits(bd, 16);
+	symTotal = 0;
+	for (i = 0; i < 16; i++) {
+		if (t&(1 << (15-i))) {
+			k = get_bits(bd, 16);
+			for (j = 0; j < 16; j++)
+				if (k&(1 << (15-j)))
+					symToByte[symTotal++] = (16*i)+j;
+		}
+	}
+	/* How many different Huffman coding groups does this block use? */
+	groupCount = get_bits(bd, 3);
+	if (groupCount < 2 || groupCount > MAX_GROUPS)
+		return RETVAL_DATA_ERROR;
+	/* nSelectors: Every GROUP_SIZE many symbols we select a new
+	   Huffman coding group.  Read in the group selector list,
+	   which is stored as MTF encoded bit runs.  (MTF = Move To
+	   Front, as each value is used it''s moved to the start of the
+	   list.) */
+	nSelectors = get_bits(bd, 15);
+	if (!nSelectors)
+		return RETVAL_DATA_ERROR;
+	for (i = 0; i < groupCount; i++)
+		mtfSymbol[i] = i;
+	for (i = 0; i < nSelectors; i++) {
+		/* Get next value */
+		for (j = 0; get_bits(bd, 1); j++)
+			if (j >= groupCount)
+				return RETVAL_DATA_ERROR;
+		/* Decode MTF to get the next selector */
+		uc = mtfSymbol[j];
+		for (; j; j--)
+			mtfSymbol[j] = mtfSymbol[j-1];
+		mtfSymbol[0] = selectors[i] = uc;
+	}
+	/* Read the Huffman coding tables for each group, which code
+	   for symTotal literal symbols, plus two run symbols (RUNA,
+	   RUNB) */
+	symCount = symTotal+2;
+	for (j = 0; j < groupCount; j++) {
+		unsigned char length[MAX_SYMBOLS], temp[MAX_HUFCODE_BITS+1];
+		int	minLen,	maxLen, pp;
+		/* Read Huffman code lengths for each symbol.  They''re
+		   stored in a way similar to mtf; record a starting
+		   value for the first symbol, and an offset from the
+		   previous value for everys symbol after that.
+		   (Subtracting 1 before the loop and then adding it
+		   back at the end is an optimization that makes the
+		   test inside the loop simpler: symbol length 0
+		   becomes negative, so an unsigned inequality catches
+		   it.) */
+		t = get_bits(bd, 5)-1;
+		for (i = 0; i < symCount; i++) {
+			for (;;) {
+				if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
+					return RETVAL_DATA_ERROR;
+
+				/* If first bit is 0, stop.  Else
+				   second bit indicates whether to
+				   increment or decrement the value.
+				   Optimization: grab 2 bits and unget
+				   the second if the first was 0. */
+
+				k = get_bits(bd, 2);
+				if (k < 2) {
+					bd->inbufBitCount++;
+					break;
+				}
+				/* Add one if second bit 1, else
+				 * subtract 1.  Avoids if/else */
+				t += (((k+1)&2)-1);
+			}
+			/* Correct for the initial -1, to get the
+			 * final symbol length */
+			length[i] = t+1;
+		}
+		/* Find largest and smallest lengths in this group */
+		minLen = maxLen = length[0];
+
+		for (i = 1; i < symCount; i++) {
+			if (length[i] > maxLen)
+				maxLen = length[i];
+			else if (length[i] < minLen)
+				minLen = length[i];
+		}
+
+		/* Calculate permute[], base[], and limit[] tables from
+		 * length[].
+		 *
+		 * permute[] is the lookup table for converting
+		 * Huffman coded symbols into decoded symbols.  base[]
+		 * is the amount to subtract from the value of a
+		 * Huffman symbol of a given length when using
+		 * permute[].
+		 *
+		 * limit[] indicates the largest numerical value a
+		 * symbol with a given number of bits can have.  This
+		 * is how the Huffman codes can vary in length: each
+		 * code with a value > limit[length] needs another
+		 * bit.
+		 */
+		hufGroup = bd->groups+j;
+		hufGroup->minLen = minLen;
+		hufGroup->maxLen = maxLen;
+		/* Note that minLen can''t be smaller than 1, so we
+		   adjust the base and limit array pointers so we''re
+		   not always wasting the first entry.  We do this
+		   again when using them (during symbol decoding).*/
+		base = hufGroup->base-1;
+		limit = hufGroup->limit-1;
+		/* Calculate permute[].  Concurently, initialize
+		 * temp[] and limit[]. */
+		pp = 0;
+		for (i = minLen; i <= maxLen; i++) {
+			temp[i] = limit[i] = 0;
+			for (t = 0; t < symCount; t++)
+				if (length[t] == i)
+					hufGroup->permute[pp++] = t;
+		}
+		/* Count symbols coded for at each bit length */
+		for (i = 0; i < symCount; i++)
+			temp[length[i]]++;
+		/* Calculate limit[] (the largest symbol-coding value
+		 *at each bit length, which is (previous limit <<
+		 *1)+symbols at this level), and base[] (number of
+		 *symbols to ignore at each bit length, which is limit
+		 *minus the cumulative count of symbols coded for
+		 *already). */
+		pp = t = 0;
+		for (i = minLen; i < maxLen; i++) {
+			pp += temp[i];
+			/* We read the largest possible symbol size
+			   and then unget bits after determining how
+			   many we need, and those extra bits could be
+			   set to anything.  (They''re noise from
+			   future symbols.)  At each level we''re
+			   really only interested in the first few
+			   bits, so here we set all the trailing
+			   to-be-ignored bits to 1 so they don''t
+			   affect the value > limit[length]
+			   comparison. */
+			limit[i] = (pp << (maxLen - i)) - 1;
+			pp <<= 1;
+			base[i+1] = pp-(t += temp[i]);
+		}
+		limit[maxLen+1] = INT_MAX; /* Sentinal value for
+					    * reading next sym. */
+		limit[maxLen] = pp+temp[maxLen]-1;
+		base[minLen] = 0;
+	}
+	/* We''ve finished reading and digesting the block header.  Now
+	   read this block''s Huffman coded symbols from the file and
+	   undo the Huffman coding and run length encoding, saving the
+	   result into dbuf[dbufCount++] = uc */
+
+	/* Initialize symbol occurrence counters and symbol Move To
+	 * Front table */
+	for (i = 0; i < 256; i++) {
+		byteCount[i] = 0;
+		mtfSymbol[i] = (unsigned char)i;
+	}
+	/* Loop through compressed symbols. */
+	runPos = dbufCount = symCount = selector = 0;
+	for (;;) {
+		/* Determine which Huffman coding group to use. */
+		if (!(symCount--)) {
+			symCount = GROUP_SIZE-1;
+			if (selector >= nSelectors)
+				return RETVAL_DATA_ERROR;
+			hufGroup = bd->groups+selectors[selector++];
+			base = hufGroup->base-1;
+			limit = hufGroup->limit-1;
+		}
+		/* Read next Huffman-coded symbol. */
+		/* Note: It is far cheaper to read maxLen bits and
+		   back up than it is to read minLen bits and then an
+		   additional bit at a time, testing as we go.
+		   Because there is a trailing last block (with file
+		   CRC), there is no danger of the overread causing an
+		   unexpected EOF for a valid compressed file.  As a
+		   further optimization, we do the read inline
+		   (falling back to a call to get_bits if the buffer
+		   runs dry).  The following (up to got_huff_bits:) is
+		   equivalent to j = get_bits(bd, hufGroup->maxLen);
+		 */
+		while (bd->inbufBitCount < hufGroup->maxLen) {
+			if (bd->inbufPos == bd->inbufCount) {
+				j = get_bits(bd, hufGroup->maxLen);
+				goto got_huff_bits;
+			}
+			bd->inbufBits +				(bd->inbufBits <<
8)|bd->inbuf[bd->inbufPos++];
+			bd->inbufBitCount += 8;
+		};
+		bd->inbufBitCount -= hufGroup->maxLen;
+		j = (bd->inbufBits >> bd->inbufBitCount)&
+			((1 << hufGroup->maxLen)-1);
+got_huff_bits:
+		/* Figure how how many bits are in next symbol and
+		 * unget extras */
+		i = hufGroup->minLen;
+		while (j > limit[i])
+			++i;
+		bd->inbufBitCount += (hufGroup->maxLen - i);
+		/* Huffman decode value to get nextSym (with bounds checking) */
+		if ((i > hufGroup->maxLen)
+			|| (((unsigned)(j = (j>>(hufGroup->maxLen-i))-base[i]))
+				>= MAX_SYMBOLS))
+			return RETVAL_DATA_ERROR;
+		nextSym = hufGroup->permute[j];
+		/* We have now decoded the symbol, which indicates
+		   either a new literal byte, or a repeated run of the
+		   most recent literal byte.  First, check if nextSym
+		   indicates a repeated run, and if so loop collecting
+		   how many times to repeat the last literal. */
+		if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */
+			/* If this is the start of a new run, zero out
+			 * counter */
+			if (!runPos) {
+				runPos = 1;
+				t = 0;
+			}
+			/* Neat trick that saves 1 symbol: instead of
+			   or-ing 0 or 1 at each bit position, add 1
+			   or 2 instead.  For example, 1011 is 1 << 0
+			   + 1 << 1 + 2 << 2.  1010 is 2 << 0 + 2 << 1
+			   + 1 << 2.  You can make any bit pattern
+			   that way using 1 less symbol than the basic
+			   or 0/1 method (except all bits 0, which
+			   would use no symbols, but a run of length 0
+			   doesn''t mean anything in this context).
+			   Thus space is saved. */
+			t += (runPos << nextSym);
+			/* +runPos if RUNA; +2*runPos if RUNB */
+
+			runPos <<= 1;
+			continue;
+		}
+		/* When we hit the first non-run symbol after a run,
+		   we now know how many times to repeat the last
+		   literal, so append that many copies to our buffer
+		   of decoded symbols (dbuf) now.  (The last literal
+		   used is the one at the head of the mtfSymbol
+		   array.) */
+		if (runPos) {
+			runPos = 0;
+			if (dbufCount+t >= dbufSize)
+				return RETVAL_DATA_ERROR;
+
+			uc = symToByte[mtfSymbol[0]];
+			byteCount[uc] += t;
+			while (t--)
+				dbuf[dbufCount++] = uc;
+		}
+		/* Is this the terminating symbol? */
+		if (nextSym > symTotal)
+			break;
+		/* At this point, nextSym indicates a new literal
+		   character.  Subtract one to get the position in the
+		   MTF array at which this literal is currently to be
+		   found.  (Note that the result can''t be -1 or 0,
+		   because 0 and 1 are RUNA and RUNB.  But another
+		   instance of the first symbol in the mtf array,
+		   position 0, would have been handled as part of a
+		   run above.  Therefore 1 unused mtf position minus 2
+		   non-literal nextSym values equals -1.) */
+		if (dbufCount >= dbufSize)
+			return RETVAL_DATA_ERROR;
+		i = nextSym - 1;
+		uc = mtfSymbol[i];
+		/* Adjust the MTF array.  Since we typically expect to
+		 *move only a small number of symbols, and are bound
+		 *by 256 in any case, using memmove here would
+		 *typically be bigger and slower due to function call
+		 *overhead and other assorted setup costs. */
+		do {
+			mtfSymbol[i] = mtfSymbol[i-1];
+		} while (--i);
+		mtfSymbol[0] = uc;
+		uc = symToByte[uc];
+		/* We have our literal byte.  Save it into dbuf. */
+		byteCount[uc]++;
+		dbuf[dbufCount++] = (unsigned int)uc;
+	}
+	/* At this point, we''ve read all the Huffman-coded symbols
+	   (and repeated runs) for this block from the input stream,
+	   and decoded them into the intermediate buffer.  There are
+	   dbufCount many decoded bytes in dbuf[].  Now undo the
+	   Burrows-Wheeler transform on dbuf.  See
+	   http://dogma.net/markn/articles/bwt/bwt.htm 
+	 */
+	/* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
+	j = 0;
+	for (i = 0; i < 256; i++) {
+		k = j+byteCount[i];
+		byteCount[i] = j;
+		j = k;
+	}
+	/* Figure out what order dbuf would be in if we sorted it. */
+	for (i = 0; i < dbufCount; i++) {
+		uc = (unsigned char)(dbuf[i] & 0xff);
+		dbuf[byteCount[uc]] |= (i << 8);
+		byteCount[uc]++;
+	}
+	/* Decode first byte by hand to initialize "previous" byte.
+	   Note that it doesn''t get output, and if the first three
+	   characters are identical it doesn''t qualify as a run (hence
+	   writeRunCountdown = 5). */
+	if (dbufCount) {
+		if (origPtr >= dbufCount)
+			return RETVAL_DATA_ERROR;
+		bd->writePos = dbuf[origPtr];
+		bd->writeCurrent = (unsigned char)(bd->writePos&0xff);
+		bd->writePos >>= 8;
+		bd->writeRunCountdown = 5;
+	}
+	bd->writeCount = dbufCount;
+
+	return RETVAL_OK;
+}
+
+/* Undo burrows-wheeler transform on intermediate buffer to produce output.
+   If start_bunzip was initialized with out_fd =-1, then up to len bytes of
+   data are written to outbuf.  Return value is number of bytes written or
+   error (all errors are negative numbers).  If out_fd!=-1, outbuf and len
+   are ignored, data is written to out_fd and return is RETVAL_OK or error.
+*/
+
+static int INIT read_bunzip(struct bunzip_data *bd, unsigned char *outbuf, int
len)
+{
+	const unsigned int *dbuf;
+	int pos, xcurrent, previous, gotcount;
+
+	/* If last read was short due to end of file, return last block now */
+	if (bd->writeCount < 0)
+		return bd->writeCount;
+
+	gotcount = 0;
+	dbuf = bd->dbuf;
+	pos = bd->writePos;
+	xcurrent = bd->writeCurrent;
+
+	/* We will always have pending decoded data to write into the output
+	   buffer unless this is the very first call (in which case we
haven''t
+	   Huffman-decoded a block into the intermediate buffer yet). */
+
+	if (bd->writeCopies) {
+		/* Inside the loop, writeCopies means extra copies (beyond 1) */
+		--bd->writeCopies;
+		/* Loop outputting bytes */
+		for (;;) {
+			/* If the output buffer is full, snapshot
+			 * state and return */
+			if (gotcount >= len) {
+				bd->writePos = pos;
+				bd->writeCurrent = xcurrent;
+				bd->writeCopies++;
+				return len;
+			}
+			/* Write next byte into output buffer, updating CRC */
+			outbuf[gotcount++] = xcurrent;
+			bd->writeCRC = (((bd->writeCRC) << 8)
+				^bd->crc32Table[((bd->writeCRC) >> 24)
+				^xcurrent]);
+			/* Loop now if we''re outputting multiple
+			 * copies of this byte */
+			if (bd->writeCopies) {
+				--bd->writeCopies;
+				continue;
+			}
+decode_next_byte:
+			if (!bd->writeCount--)
+				break;
+			/* Follow sequence vector to undo
+			 * Burrows-Wheeler transform */
+			previous = xcurrent;
+			pos = dbuf[pos];
+			xcurrent = pos&0xff;
+			pos >>= 8;
+			/* After 3 consecutive copies of the same
+			   byte, the 4th is a repeat count.  We count
+			   down from 4 instead *of counting up because
+			   testing for non-zero is faster */
+			if (--bd->writeRunCountdown) {
+				if (xcurrent != previous)
+					bd->writeRunCountdown = 4;
+			} else {
+				/* We have a repeated run, this byte
+				 * indicates the count */
+				bd->writeCopies = xcurrent;
+				xcurrent = previous;
+				bd->writeRunCountdown = 5;
+				/* Sometimes there are just 3 bytes
+				 * (run length 0) */
+				if (!bd->writeCopies)
+					goto decode_next_byte;
+				/* Subtract the 1 copy we''d output
+				 * anyway to get extras */
+				--bd->writeCopies;
+			}
+		}
+		/* Decompression of this block completed successfully */
+		bd->writeCRC = ~bd->writeCRC;
+		bd->totalCRC = ((bd->totalCRC << 1) |
+				(bd->totalCRC >> 31)) ^ bd->writeCRC;
+		/* If this block had a CRC error, force file level CRC error. */
+		if (bd->writeCRC != bd->headerCRC) {
+			bd->totalCRC = bd->headerCRC+1;
+			return RETVAL_LAST_BLOCK;
+		}
+	}
+
+	/* Refill the intermediate buffer by Huffman-decoding next
+	 * block of input */
+	/* (previous is just a convenient unused temp variable here) */
+	previous = get_next_block(bd);
+	if (previous) {
+		bd->writeCount = previous;
+		return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount;
+	}
+	bd->writeCRC = 0xffffffffUL;
+	pos = bd->writePos;
+	xcurrent = bd->writeCurrent;
+	goto decode_next_byte;
+}
+
+static int INIT nofill(void *buf, unsigned int len)
+{
+	return -1;
+}
+
+/* Allocate the structure, read file header.  If in_fd ==-1, inbuf must contain
+   a complete bunzip file (len bytes long).  If in_fd!=-1, inbuf and len are
+   ignored, and data is read from file handle into temporary buffer. */
+static int INIT start_bunzip(struct bunzip_data **bdp, void *inbuf, int len,
+			     int (*fill)(void*, unsigned int))
+{
+	struct bunzip_data *bd;
+	unsigned int i, j, c;
+	const unsigned int BZh0 +		(((unsigned int)''B'') <<
24)+(((unsigned int)''Z'') << 16)
+		+(((unsigned int)''h'') << 8)+(unsigned
int)''0'';
+
+	/* Figure out how much data to allocate */
+	i = sizeof(struct bunzip_data);
+
+	/* Allocate bunzip_data.  Most fields initialize to zero. */
+	bd = *bdp = malloc(i);
+	memset(bd, 0, sizeof(struct bunzip_data));
+	/* Setup input buffer */
+	bd->inbuf = inbuf;
+	bd->inbufCount = len;
+	if (fill != NULL)
+		bd->fill = fill;
+	else
+		bd->fill = nofill;
+
+	/* Init the CRC32 table (big endian) */
+	for (i = 0; i < 256; i++) {
+		c = i << 24;
+		for (j = 8; j; j--)
+			c = c&0x80000000 ? (c << 1)^0x04c11db7 : (c << 1);
+		bd->crc32Table[i] = c;
+	}
+
+	/* Ensure that file starts with
"BZh[''1''-''9'']." */
+	i = get_bits(bd, 32);
+	if (((unsigned int)(i-BZh0-1)) >= 9)
+		return RETVAL_NOT_BZIP_DATA;
+
+	/* Fourth byte (ascii ''1''-''9''), indicates
block size in units of 100k of
+	   uncompressed data.  Allocate intermediate buffer for block. */
+	bd->dbufSize = 100000*(i-BZh0);
+
+	bd->dbuf = large_malloc(bd->dbufSize * sizeof(int));
+	return RETVAL_OK;
+}
+
+/* Example usage: decompress src_fd to dst_fd.  (Stops at end of bzip2 data,
+   not end of file.) */
+STATIC int INIT bunzip2(unsigned char *buf, unsigned int len,
+			int(*fill)(void*, unsigned int),
+			int(*flush)(void*, unsigned int),
+			unsigned char *outbuf,
+			unsigned int *pos,
+			void(*error_fn)(const char *x))
+{
+	struct bunzip_data *bd;
+	int i = -1;
+	unsigned char *inbuf;
+
+	set_error_fn(error_fn);
+	if (flush)
+		outbuf = malloc(BZIP2_IOBUF_SIZE);
+
+	if (!outbuf) {
+		error("Could not allocate output bufer");
+		return -1;
+	}
+	if (buf)
+		inbuf = buf;
+	else
+		inbuf = malloc(BZIP2_IOBUF_SIZE);
+	if (!inbuf) {
+		error("Could not allocate input bufer");
+		goto exit_0;
+	}
+	i = start_bunzip(&bd, inbuf, len, fill);
+	if (!i) {
+		for (;;) {
+			i = read_bunzip(bd, outbuf, BZIP2_IOBUF_SIZE);
+			if (i <= 0)
+				break;
+			if (!flush)
+				outbuf += i;
+			else
+				if (i != flush(outbuf, i)) {
+					i = RETVAL_UNEXPECTED_OUTPUT_EOF;
+					break;
+				}
+		}
+	}
+	/* Check CRC and release memory */
+	if (i == RETVAL_LAST_BLOCK) {
+		if (bd->headerCRC != bd->totalCRC)
+			error("Data integrity error when decompressing.");
+		else
+			i = RETVAL_OK;
+	} else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) {
+		error("Compressed file ends unexpectedly");
+	}
+	if (bd->dbuf)
+		large_free(bd->dbuf);
+	if (pos)
+		*pos = bd->inbufPos;
+	free(bd);
+	if (!buf)
+		free(inbuf);
+exit_0:
+	if (flush)
+		free(outbuf);
+	return i;
+}
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2009-10-27/xen/common/decompress.c	2009-11-05 12:27:10.000000000 +0100
@@ -0,0 +1,27 @@
+#include <xen/config.h>
+#include <xen/init.h>
+#include <xen/lib.h>
+#include <xen/string.h>
+#include <xen/decompress.h>
+
+static void __init error(const char *msg)
+{
+    printk("%s\n", msg);
+}
+
+int __init decompress(void *inbuf, unsigned int len, void *outbuf)
+{
+#if 0 /* Not needed here yet. */
+    if ( len >= 2 &&
+         (!memcmp(inbuf, "\037\213", 2) || !memcmp(inbuf,
"\037\236", 2)) )
+        return gunzip(inbuf, len, NULL, NULL, outbuf, NULL, error);
+#endif
+
+    if ( len >= 3 && !memcmp(inbuf, "\x42\x5a\x68", 3) )
+        return bunzip2(inbuf, len, NULL, NULL, outbuf, NULL, error);
+
+    if ( len >= 2 && !memcmp(inbuf, "\135\000", 2) )
+        return unlzma(inbuf, len, NULL, NULL, outbuf, NULL, error);
+
+    return 1;
+}
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2009-10-27/xen/common/decompress.h	2009-11-05 15:21:52.000000000 +0100
@@ -0,0 +1,19 @@
+#include <xen/config.h>
+#include <xen/cache.h>
+#include <xen/decompress.h>
+#include <xen/init.h>
+#include <xen/string.h>
+#include <xen/types.h>
+#include <xen/xmalloc.h>
+
+#define STATIC
+#define INIT __init
+
+static void(*__initdata error)(const char *);
+#define set_error_fn(x) error = x;
+
+#define malloc xmalloc_bytes
+#define free xfree
+
+#define large_malloc xmalloc_bytes
+#define large_free xfree
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2009-10-27/xen/common/unlzma.c	2009-11-05 12:45:37.000000000 +0100
@@ -0,0 +1,647 @@
+/* Lzma decompressor for Linux kernel. Shamelessly snarfed
+ * from busybox 1.1.1
+ *
+ * Linux kernel adaptation
+ * Copyright (C) 2006  Alain < alain@knaff.lu >
+ *
+ * Based on small lzma deflate implementation/Small range coder
+ * implementation for lzma.
+ * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
+ *
+ * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
+ * Copyright (C) 1999-2005  Igor Pavlov
+ *
+ * Copyrights of the parts, see headers below.
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "decompress.h"
+
+#define	MIN(a, b) (((a) < (b)) ? (a) : (b))
+
+static long long INIT read_int(unsigned char *ptr, int size)
+{
+	int i;
+	long long ret = 0;
+
+	for (i = 0; i < size; i++)
+		ret = (ret << 8) | ptr[size-i-1];
+	return ret;
+}
+
+#define ENDIAN_CONVERT(x) \
+  x = (typeof(x))read_int((unsigned char *)&x, sizeof(x))
+
+
+/* Small range coder implementation for lzma.
+ * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
+ *
+ * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
+ * Copyright (c) 1999-2005  Igor Pavlov
+ */
+
+#include <xen/compiler.h>
+
+#define LZMA_IOBUF_SIZE	0x10000
+
+struct rc {
+	int (*fill)(void*, unsigned int);
+	uint8_t *ptr;
+	uint8_t *buffer;
+	uint8_t *buffer_end;
+	int buffer_size;
+	uint32_t code;
+	uint32_t range;
+	uint32_t bound;
+};
+
+
+#define RC_TOP_BITS 24
+#define RC_MOVE_BITS 5
+#define RC_MODEL_TOTAL_BITS 11
+
+
+static int nofill(void *buffer, unsigned int len)
+{
+	return -1;
+}
+
+/* Called twice: once at startup and once in rc_normalize() */
+static void INIT rc_read(struct rc *rc)
+{
+	rc->buffer_size = rc->fill((char *)rc->buffer, LZMA_IOBUF_SIZE);
+	if (rc->buffer_size <= 0)
+		error("unexpected EOF");
+	rc->ptr = rc->buffer;
+	rc->buffer_end = rc->buffer + rc->buffer_size;
+}
+
+/* Called once */
+static inline void INIT rc_init(struct rc *rc,
+				       int (*fill)(void*, unsigned int),
+				       unsigned char *buffer, int buffer_size)
+{
+	if (fill)
+		rc->fill = fill;
+	else
+		rc->fill = nofill;
+	rc->buffer = (uint8_t *)buffer;
+	rc->buffer_size = buffer_size;
+	rc->buffer_end = rc->buffer + rc->buffer_size;
+	rc->ptr = rc->buffer;
+
+	rc->code = 0;
+	rc->range = 0xFFFFFFFF;
+}
+
+static inline void INIT rc_init_code(struct rc *rc)
+{
+	int i;
+
+	for (i = 0; i < 5; i++) {
+		if (rc->ptr >= rc->buffer_end)
+			rc_read(rc);
+		rc->code = (rc->code << 8) | *rc->ptr++;
+	}
+}
+
+
+/* Called once. TODO: bb_maybe_free() */
+static inline void INIT rc_free(struct rc *rc)
+{
+	free(rc->buffer);
+}
+
+/* Called twice, but one callsite is in inline''d rc_is_bit_0_helper()
*/
+static void INIT rc_do_normalize(struct rc *rc)
+{
+	if (rc->ptr >= rc->buffer_end)
+		rc_read(rc);
+	rc->range <<= 8;
+	rc->code = (rc->code << 8) | *rc->ptr++;
+}
+static inline void INIT rc_normalize(struct rc *rc)
+{
+	if (rc->range < (1 << RC_TOP_BITS))
+		rc_do_normalize(rc);
+}
+
+/* Called 9 times */
+/* Why rc_is_bit_0_helper exists?
+ *Because we want to always expose (rc->code < rc->bound) to optimizer
+ */
+static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p)
+{
+	rc_normalize(rc);
+	rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
+	return rc->bound;
+}
+static inline int INIT rc_is_bit_0(struct rc *rc, uint16_t *p)
+{
+	uint32_t t = rc_is_bit_0_helper(rc, p);
+	return rc->code < t;
+}
+
+/* Called ~10 times, but very small, thus inlined */
+static inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p)
+{
+	rc->range = rc->bound;
+	*p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
+}
+static inline void rc_update_bit_1(struct rc *rc, uint16_t *p)
+{
+	rc->range -= rc->bound;
+	rc->code -= rc->bound;
+	*p -= *p >> RC_MOVE_BITS;
+}
+
+/* Called 4 times in unlzma loop */
+static int INIT rc_get_bit(struct rc *rc, uint16_t *p, int *symbol)
+{
+	if (rc_is_bit_0(rc, p)) {
+		rc_update_bit_0(rc, p);
+		*symbol *= 2;
+		return 0;
+	} else {
+		rc_update_bit_1(rc, p);
+		*symbol = *symbol * 2 + 1;
+		return 1;
+	}
+}
+
+/* Called once */
+static inline int INIT rc_direct_bit(struct rc *rc)
+{
+	rc_normalize(rc);
+	rc->range >>= 1;
+	if (rc->code >= rc->range) {
+		rc->code -= rc->range;
+		return 1;
+	}
+	return 0;
+}
+
+/* Called twice */
+static inline void INIT
+rc_bit_tree_decode(struct rc *rc, uint16_t *p, int num_levels, int *symbol)
+{
+	int i = num_levels;
+
+	*symbol = 1;
+	while (i--)
+		rc_get_bit(rc, p + *symbol, symbol);
+	*symbol -= 1 << num_levels;
+}
+
+
+/*
+ * Small lzma deflate implementation.
+ * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
+ *
+ * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
+ * Copyright (C) 1999-2005  Igor Pavlov
+ */
+
+
+struct lzma_header {
+	uint8_t pos;
+	uint32_t dict_size;
+	uint64_t dst_size;
+} __attribute__ ((packed)) ;
+
+
+#define LZMA_BASE_SIZE 1846
+#define LZMA_LIT_SIZE 768
+
+#define LZMA_NUM_POS_BITS_MAX 4
+
+#define LZMA_LEN_NUM_LOW_BITS 3
+#define LZMA_LEN_NUM_MID_BITS 3
+#define LZMA_LEN_NUM_HIGH_BITS 8
+
+#define LZMA_LEN_CHOICE 0
+#define LZMA_LEN_CHOICE_2 (LZMA_LEN_CHOICE + 1)
+#define LZMA_LEN_LOW (LZMA_LEN_CHOICE_2 + 1)
+#define LZMA_LEN_MID (LZMA_LEN_LOW \
+		      + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS)))
+#define LZMA_LEN_HIGH (LZMA_LEN_MID \
+		       +(1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS)))
+#define LZMA_NUM_LEN_PROBS (LZMA_LEN_HIGH + (1 <<
LZMA_LEN_NUM_HIGH_BITS))
+
+#define LZMA_NUM_STATES 12
+#define LZMA_NUM_LIT_STATES 7
+
+#define LZMA_START_POS_MODEL_INDEX 4
+#define LZMA_END_POS_MODEL_INDEX 14
+#define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX >>
1))
+
+#define LZMA_NUM_POS_SLOT_BITS 6
+#define LZMA_NUM_LEN_TO_POS_STATES 4
+
+#define LZMA_NUM_ALIGN_BITS 4
+
+#define LZMA_MATCH_MIN_LEN 2
+
+#define LZMA_IS_MATCH 0
+#define LZMA_IS_REP (LZMA_IS_MATCH + (LZMA_NUM_STATES <<
LZMA_NUM_POS_BITS_MAX))
+#define LZMA_IS_REP_G0 (LZMA_IS_REP + LZMA_NUM_STATES)
+#define LZMA_IS_REP_G1 (LZMA_IS_REP_G0 + LZMA_NUM_STATES)
+#define LZMA_IS_REP_G2 (LZMA_IS_REP_G1 + LZMA_NUM_STATES)
+#define LZMA_IS_REP_0_LONG (LZMA_IS_REP_G2 + LZMA_NUM_STATES)
+#define LZMA_POS_SLOT (LZMA_IS_REP_0_LONG \
+		       + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
+#define LZMA_SPEC_POS (LZMA_POS_SLOT \
+		       +(LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS))
+#define LZMA_ALIGN (LZMA_SPEC_POS \
+		    + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX)
+#define LZMA_LEN_CODER (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS))
+#define LZMA_REP_LEN_CODER (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS)
+#define LZMA_LITERAL (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS)
+
+
+struct writer {
+	uint8_t *buffer;
+	uint8_t previous_byte;
+	size_t buffer_pos;
+	int bufsize;
+	size_t global_pos;
+	int(*flush)(void*, unsigned int);
+	struct lzma_header *header;
+};
+
+struct cstate {
+	int state;
+	uint32_t rep0, rep1, rep2, rep3;
+};
+
+static inline size_t INIT get_pos(struct writer *wr)
+{
+	return
+		wr->global_pos + wr->buffer_pos;
+}
+
+static inline uint8_t INIT peek_old_byte(struct writer *wr,
+						uint32_t offs)
+{
+	if (!wr->flush) {
+		int32_t pos;
+		while (offs > wr->header->dict_size)
+			offs -= wr->header->dict_size;
+		pos = wr->buffer_pos - offs;
+		return wr->buffer[pos];
+	} else {
+		uint32_t pos = wr->buffer_pos - offs;
+		while (pos >= wr->header->dict_size)
+			pos += wr->header->dict_size;
+		return wr->buffer[pos];
+	}
+
+}
+
+static inline void INIT write_byte(struct writer *wr, uint8_t byte)
+{
+	wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte;
+	if (wr->flush && wr->buffer_pos == wr->header->dict_size)
{
+		wr->buffer_pos = 0;
+		wr->global_pos += wr->header->dict_size;
+		wr->flush((char *)wr->buffer, wr->header->dict_size);
+	}
+}
+
+
+static inline void INIT copy_byte(struct writer *wr, uint32_t offs)
+{
+	write_byte(wr, peek_old_byte(wr, offs));
+}
+
+static inline void INIT copy_bytes(struct writer *wr,
+					 uint32_t rep0, int len)
+{
+	do {
+		copy_byte(wr, rep0);
+		len--;
+	} while (len != 0 && wr->buffer_pos <
wr->header->dst_size);
+}
+
+static inline void INIT process_bit0(struct writer *wr, struct rc *rc,
+				     struct cstate *cst, uint16_t *p,
+				     int pos_state, uint16_t *prob,
+				     int lc, uint32_t literal_pos_mask) {
+	int mi = 1;
+	rc_update_bit_0(rc, prob);
+	prob = (p + LZMA_LITERAL +
+		(LZMA_LIT_SIZE
+		 * (((get_pos(wr) & literal_pos_mask) << lc)
+		    + (wr->previous_byte >> (8 - lc))))
+		);
+
+	if (cst->state >= LZMA_NUM_LIT_STATES) {
+		int match_byte = peek_old_byte(wr, cst->rep0);
+		do {
+			int bit;
+			uint16_t *prob_lit;
+
+			match_byte <<= 1;
+			bit = match_byte & 0x100;
+			prob_lit = prob + 0x100 + bit + mi;
+			if (rc_get_bit(rc, prob_lit, &mi)) {
+				if (!bit)
+					break;
+			} else {
+				if (bit)
+					break;
+			}
+		} while (mi < 0x100);
+	}
+	while (mi < 0x100) {
+		uint16_t *prob_lit = prob + mi;
+		rc_get_bit(rc, prob_lit, &mi);
+	}
+	write_byte(wr, mi);
+	if (cst->state < 4)
+		cst->state = 0;
+	else if (cst->state < 10)
+		cst->state -= 3;
+	else
+		cst->state -= 6;
+}
+
+static inline void INIT process_bit1(struct writer *wr, struct rc *rc,
+					    struct cstate *cst, uint16_t *p,
+					    int pos_state, uint16_t *prob) {
+  int offset;
+	uint16_t *prob_len;
+	int num_bits;
+	int len;
+
+	rc_update_bit_1(rc, prob);
+	prob = p + LZMA_IS_REP + cst->state;
+	if (rc_is_bit_0(rc, prob)) {
+		rc_update_bit_0(rc, prob);
+		cst->rep3 = cst->rep2;
+		cst->rep2 = cst->rep1;
+		cst->rep1 = cst->rep0;
+		cst->state = cst->state < LZMA_NUM_LIT_STATES ? 0 : 3;
+		prob = p + LZMA_LEN_CODER;
+	} else {
+		rc_update_bit_1(rc, prob);
+		prob = p + LZMA_IS_REP_G0 + cst->state;
+		if (rc_is_bit_0(rc, prob)) {
+			rc_update_bit_0(rc, prob);
+			prob = (p + LZMA_IS_REP_0_LONG
+				+ (cst->state <<
+				   LZMA_NUM_POS_BITS_MAX) +
+				pos_state);
+			if (rc_is_bit_0(rc, prob)) {
+				rc_update_bit_0(rc, prob);
+
+				cst->state = cst->state < LZMA_NUM_LIT_STATES ?
+					9 : 11;
+				copy_byte(wr, cst->rep0);
+				return;
+			} else {
+				rc_update_bit_1(rc, prob);
+			}
+		} else {
+			uint32_t distance;
+
+			rc_update_bit_1(rc, prob);
+			prob = p + LZMA_IS_REP_G1 + cst->state;
+			if (rc_is_bit_0(rc, prob)) {
+				rc_update_bit_0(rc, prob);
+				distance = cst->rep1;
+			} else {
+				rc_update_bit_1(rc, prob);
+				prob = p + LZMA_IS_REP_G2 + cst->state;
+				if (rc_is_bit_0(rc, prob)) {
+					rc_update_bit_0(rc, prob);
+					distance = cst->rep2;
+				} else {
+					rc_update_bit_1(rc, prob);
+					distance = cst->rep3;
+					cst->rep3 = cst->rep2;
+				}
+				cst->rep2 = cst->rep1;
+			}
+			cst->rep1 = cst->rep0;
+			cst->rep0 = distance;
+		}
+		cst->state = cst->state < LZMA_NUM_LIT_STATES ? 8 : 11;
+		prob = p + LZMA_REP_LEN_CODER;
+	}
+
+	prob_len = prob + LZMA_LEN_CHOICE;
+	if (rc_is_bit_0(rc, prob_len)) {
+		rc_update_bit_0(rc, prob_len);
+		prob_len = (prob + LZMA_LEN_LOW
+			    + (pos_state <<
+			       LZMA_LEN_NUM_LOW_BITS));
+		offset = 0;
+		num_bits = LZMA_LEN_NUM_LOW_BITS;
+	} else {
+		rc_update_bit_1(rc, prob_len);
+		prob_len = prob + LZMA_LEN_CHOICE_2;
+		if (rc_is_bit_0(rc, prob_len)) {
+			rc_update_bit_0(rc, prob_len);
+			prob_len = (prob + LZMA_LEN_MID
+				    + (pos_state <<
+				       LZMA_LEN_NUM_MID_BITS));
+			offset = 1 << LZMA_LEN_NUM_LOW_BITS;
+			num_bits = LZMA_LEN_NUM_MID_BITS;
+		} else {
+			rc_update_bit_1(rc, prob_len);
+			prob_len = prob + LZMA_LEN_HIGH;
+			offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
+				  + (1 << LZMA_LEN_NUM_MID_BITS));
+			num_bits = LZMA_LEN_NUM_HIGH_BITS;
+		}
+	}
+
+	rc_bit_tree_decode(rc, prob_len, num_bits, &len);
+	len += offset;
+
+	if (cst->state < 4) {
+		int pos_slot;
+
+		cst->state += LZMA_NUM_LIT_STATES;
+		prob +			p + LZMA_POS_SLOT +
+			((len <
+			  LZMA_NUM_LEN_TO_POS_STATES ? len :
+			  LZMA_NUM_LEN_TO_POS_STATES - 1)
+			 << LZMA_NUM_POS_SLOT_BITS);
+		rc_bit_tree_decode(rc, prob,
+				   LZMA_NUM_POS_SLOT_BITS,
+				   &pos_slot);
+		if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
+			int i, mi;
+			num_bits = (pos_slot >> 1) - 1;
+			cst->rep0 = 2 | (pos_slot & 1);
+			if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
+				cst->rep0 <<= num_bits;
+				prob = p + LZMA_SPEC_POS +
+					cst->rep0 - pos_slot - 1;
+			} else {
+				num_bits -= LZMA_NUM_ALIGN_BITS;
+				while (num_bits--)
+					cst->rep0 = (cst->rep0 << 1) |
+						rc_direct_bit(rc);
+				prob = p + LZMA_ALIGN;
+				cst->rep0 <<= LZMA_NUM_ALIGN_BITS;
+				num_bits = LZMA_NUM_ALIGN_BITS;
+			}
+			i = 1;
+			mi = 1;
+			while (num_bits--) {
+				if (rc_get_bit(rc, prob + mi, &mi))
+					cst->rep0 |= i;
+				i <<= 1;
+			}
+		} else
+			cst->rep0 = pos_slot;
+		if (++(cst->rep0) == 0)
+			return;
+	}
+
+	len += LZMA_MATCH_MIN_LEN;
+
+	copy_bytes(wr, cst->rep0, len);
+}
+
+
+
+STATIC inline int INIT unlzma(unsigned char *buf, unsigned int in_len,
+			      int(*fill)(void*, unsigned int),
+			      int(*flush)(void*, unsigned int),
+			      unsigned char *output,
+			      unsigned int *posp,
+			      void(*error_fn)(const char *x)
+	)
+{
+	struct lzma_header header;
+	int lc, pb, lp;
+	uint32_t pos_state_mask;
+	uint32_t literal_pos_mask;
+	uint16_t *p;
+	int num_probs;
+	struct rc rc;
+	int i, mi;
+	struct writer wr;
+	struct cstate cst;
+	unsigned char *inbuf;
+	int ret = -1;
+
+	set_error_fn(error_fn);
+
+	if (buf)
+		inbuf = buf;
+	else
+		inbuf = malloc(LZMA_IOBUF_SIZE);
+	if (!inbuf) {
+		error("Could not allocate input bufer");
+		goto exit_0;
+	}
+
+	cst.state = 0;
+	cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1;
+
+	wr.header = &header;
+	wr.flush = flush;
+	wr.global_pos = 0;
+	wr.previous_byte = 0;
+	wr.buffer_pos = 0;
+
+	rc_init(&rc, fill, inbuf, in_len);
+
+	for (i = 0; i < sizeof(header); i++) {
+		if (rc.ptr >= rc.buffer_end)
+			rc_read(&rc);
+		((unsigned char *)&header)[i] = *rc.ptr++;
+	}
+
+	if (header.pos >= (9 * 5 * 5))
+		error("bad header");
+
+	mi = 0;
+	lc = header.pos;
+	while (lc >= 9) {
+		mi++;
+		lc -= 9;
+	}
+	pb = 0;
+	lp = mi;
+	while (lp >= 5) {
+		pb++;
+		lp -= 5;
+	}
+	pos_state_mask = (1 << pb) - 1;
+	literal_pos_mask = (1 << lp) - 1;
+
+	ENDIAN_CONVERT(header.dict_size);
+	ENDIAN_CONVERT(header.dst_size);
+
+	if (header.dict_size == 0)
+		header.dict_size = 1;
+
+	if (output)
+		wr.buffer = output;
+	else {
+		wr.bufsize = MIN(header.dst_size, header.dict_size);
+		wr.buffer = large_malloc(wr.bufsize);
+	}
+	if (wr.buffer == NULL)
+		goto exit_1;
+
+	num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
+	p = (uint16_t *) large_malloc(num_probs * sizeof(*p));
+	if (p == 0)
+		goto exit_2;
+	num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
+	for (i = 0; i < num_probs; i++)
+		p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
+
+	rc_init_code(&rc);
+
+	while (get_pos(&wr) < header.dst_size) {
+		int pos_state =	get_pos(&wr) & pos_state_mask;
+		uint16_t *prob = p + LZMA_IS_MATCH +
+			(cst.state << LZMA_NUM_POS_BITS_MAX) + pos_state;
+		if (rc_is_bit_0(&rc, prob))
+			process_bit0(&wr, &rc, &cst, p, pos_state, prob,
+				     lc, literal_pos_mask);
+		else {
+			process_bit1(&wr, &rc, &cst, p, pos_state, prob);
+			if (cst.rep0 == 0)
+				break;
+		}
+	}
+
+	if (posp)
+		*posp = rc.ptr-rc.buffer;
+	if (wr.flush)
+		wr.flush(wr.buffer, wr.buffer_pos);
+	ret = 0;
+	large_free(p);
+exit_2:
+	if (!output)
+		large_free(wr.buffer);
+exit_1:
+	if (!buf)
+		free(inbuf);
+exit_0:
+	return ret;
+}
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2009-10-27/xen/include/xen/decompress.h	2009-11-05 12:27:44.000000000 +0100
@@ -0,0 +1,38 @@
+#ifndef __XEN_GENERIC_H
+#define __XEN_GENERIC_H
+
+typedef int decompress_fn(unsigned char *inbuf, unsigned int len,
+                          int (*fill)(void*, unsigned int),
+                          int (*flush)(void*, unsigned int),
+                          unsigned char *outbuf, unsigned int *posp,
+                          void (*error)(const char *x));
+
+/* inbuf   - input buffer
+ * len     - len of pre-read data in inbuf
+ * fill    - function to fill inbuf when empty
+ * flush   - function to write out outbuf
+ * outbuf  - output buffer
+ * posp    - if non-null, input position (number of bytes read) will be
+ *           returned here
+ * error   - error reporting function
+ *
+ * If len != 0, inbuf should contain all the necessary input data, and fill
+ * should be NULL
+ * If len = 0, inbuf can be NULL, in which case the decompressor will allocate
+ * the input buffer.  If inbuf != NULL it must be at least XXX_IOBUF_SIZE
bytes.
+ * fill will be called (repeatedly...) to read data, at most XXX_IOBUF_SIZE
+ * bytes should be read per call.  Replace XXX with the appropriate
decompressor
+ * name, i.e. LZMA_IOBUF_SIZE.
+ *
+ * If flush = NULL, outbuf must be large enough to buffer all the expected
+ * output.  If flush != NULL, the output buffer will be allocated by the
+ * decompressor (outbuf = NULL), and the flush function will be called to
+ * flush the output buffer at the appropriate time (decompressor and stream
+ * dependent).
+ */
+
+decompress_fn bunzip2, unlzma;
+
+int decompress(void *inbuf, unsigned int len, void *outbuf);
+
+#endif



_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

On Thu, 2009-11-05 at 14:24 +0000, Jan Beulich wrote:
> This matches functionality in the tools already supporting the same for
> DomU-s.
> 
> Code taken from Linux 2.6.32-rc and adjusted as little as possible to
> be usable in Xen.
Looks good to me. The new files FOO.c are based on lib/decompress_FOO.c
from Linux? Might be worth a comment in at least the changelog to aid
the next person to come along who wants to resync them. (and why rename
them?)
> The question is whether, particularly for non-Linux Dom0-s, plain ELF
> images compressed by bzip2 or lzma should also be supported.
It should be fairly low cost to do so, so why not?

Is there a reason to treat gzip differently to bzip2/lzma? i.e. why not
route it through decompress.c as well? Perhaps that would involve
updating xen/common/inflate.c but that is already just a fork of what is
now in lib/decompress_inflate.c in Linux so it should be pretty trivial.
> Signed-off-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
> 
> --- 2009-10-27.orig/xen/arch/x86/bzimage.c      2009-10-07
13:31:36.000000000 +0200
> +++ 2009-10-27/xen/arch/x86/bzimage.c   2009-11-05 12:23:05.000000000 +0100
> @@ -4,6 +4,7 @@
>  #include <xen/mm.h>
>  #include <xen/string.h>
>  #include <xen/types.h>
> +#include <xen/decompress.h>
>  #include <asm/bzimage.h>
> 
>  #define HEAPORDER 3
> @@ -93,28 +94,38 @@ static __init void flush_window(void)
>      outcnt = 0;
>  }
> 
> -static __init int gzip_length(char *image, unsigned long image_len)
> +static __init unsigned long output_length(char *image, unsigned long
image_len)
>  {
>      return *(uint32_t *)&image[image_len - 4];
>  }
> 
> -static  __init int perform_gunzip(char *output, char **_image_start,
unsigned long *image_len)
> +static __init int gzip_check(char *image, unsigned long image_len)
>  {
> -    char *image = *_image_start;
> -    int rc;
> -    unsigned char magic0 = (unsigned char)image[0];
> -    unsigned char magic1 = (unsigned char)image[1];
> +    unsigned char magic0, magic1;
> 
> -    if ( magic0 != 0x1f || ( (magic1 != 0x8b) && (magic1 != 0x9e)
) )
> +    if ( image_len < 2 )
>          return 0;
> 
> +    magic0 = (unsigned char)image[0];
> +    magic1 = (unsigned char)image[1];
> +
> +    return (magic0 == 0x1f) && ((magic1 == 0x8b) || (magic1 ==
0x9e));
> +}
> +
> +static __init int perform_gunzip(char *output, char *image, unsigned long
image_len)
> +{
> +    int rc;
> +
> +    if ( !gzip_check(image, image_len) )
> +        return 1;
> +
>      window = (unsigned char *)output;
> 
>      free_mem_ptr = (unsigned long)alloc_xenheap_pages(HEAPORDER, 0);
>      free_mem_end_ptr = free_mem_ptr + (PAGE_SIZE << HEAPORDER);
> 
>      inbuf = (unsigned char *)image;
> -    insize = *image_len;
> +    insize = image_len;
>      inptr = 0;
> 
>      makecrc();
> @@ -125,8 +136,6 @@ static  __init int perform_gunzip(char *
>      }
>      else
>      {
> -        *_image_start = (char *)window;
> -        *image_len = gzip_length(image, *image_len);
>          rc = 0;
>      }
> 
> @@ -203,9 +212,12 @@ int __init bzimage_headroom(char *image_
>      img = image_start + (hdr->setup_sects+1) * 512;
>      img += hdr->payload_offset;
> 
> -    headroom = gzip_length(img, hdr->payload_length);
> -    headroom += headroom >> 12; /* Add 8 bytes for every 32K input
block */
> -    headroom += (32768 + 18); /* Add 32K + 18 bytes of extra headroom */
> +    headroom = output_length(img, hdr->payload_length);
> +    if (gzip_check(img, hdr->payload_length)) {
> +        headroom += headroom >> 12; /* Add 8 bytes for every 32K
input block */
> +        headroom += (32768 + 18); /* Add 32K + 18 bytes of extra headroom
*/
> +    } else
> +        headroom += hdr->payload_length;
>      headroom = (headroom + 4095) & ~4095;
> 
>      return headroom;
> @@ -215,6 +227,7 @@ int __init bzimage_parse(char *image_bas
>  {
>      struct setup_header *hdr = (struct setup_header *)(*image_start);
>      int err = bzimage_check(hdr, *image_len);
> +    unsigned long output_len;
> 
>      if (err < 1)
>          return err;
> @@ -224,11 +237,18 @@ int __init bzimage_parse(char *image_bas
>      *image_start += (hdr->setup_sects+1) * 512;
>      *image_start += hdr->payload_offset;
>      *image_len = hdr->payload_length;
> +    output_len = output_length(*image_start, *image_len);
> 
> -    if ( (err = perform_gunzip(image_base, image_start, image_len)) < 0
)
> -        return err;
> +    if ( (err = perform_gunzip(image_base, *image_start, *image_len)) >
0 )
> +        err = decompress(*image_start, *image_len, image_base);
> +
> +    if ( !err )
> +    {
> +        *image_start = image_base;
> +        *image_len = output_len;
> +    }
> 
> -    return 0;
> +    return err > 0 ? 0 : err;
>  }
> 
>  /*
> --- 2009-10-27.orig/xen/common/Makefile 2009-05-27 13:54:07.000000000 +0200
> +++ 2009-10-27/xen/common/Makefile      2009-11-05 12:26:53.000000000 +0100
> @@ -35,6 +35,8 @@ obj-y += radix-tree.o
>  obj-y += rbtree.o
>  obj-y += lzo.o
> 
> +obj-$(CONFIG_X86) += decompress.o bunzip2.o unlzma.o
> +
>  obj-$(perfc)       += perfc.o
>  obj-$(crash_debug) += gdbstub.o
>  obj-$(xenoprof)    += xenoprof.o
> --- /dev/null   1970-01-01 00:00:00.000000000 +0000
> +++ 2009-10-27/xen/common/bunzip2.c     2009-11-05 12:44:51.000000000 +0100
> @@ -0,0 +1,726 @@
> +/* vi: set sw = 4 ts = 4: */
> +/*     Small bzip2 deflate implementation, by Rob Landley
(rob@landley.net).
> +
> +       Based on bzip2 decompression code by Julian R Seward
(jseward@acm.org),
> +       which also acknowledges contributions by Mike Burrows, David
Wheeler,
> +       Peter Fenwick, Alistair Moffat, Radford Neal, Ian H. Witten,
> +       Robert Sedgewick, and Jon L. Bentley.
> +
> +       This code is licensed under the LGPLv2:
> +               LGPL (http://www.gnu.org/copyleft/lgpl.html
> +*/
> +
> +/*
> +       Size and speed optimizations by Manuel Novoa III 
(mjn3@codepoet.org).
> +
> +       More efficient reading of Huffman codes, a streamlined
read_bunzip()
> +       function, and various other tweaks.  In (limited) tests,
approximately
> +       20% faster than bzcat on x86 and about 10% faster on arm.
> +
> +       Note that about 2/3 of the time is spent in read_unzip() reversing
> +       the Burrows-Wheeler transformation.  Much of that time is delay
> +       resulting from cache misses.
> +
> +       I would ask that anyone benefiting from this work, especially those
> +       using it in commercial products, consider making a donation to my
local
> +       non-profit hospice organization in the name of the woman I loved,
who
> +       passed away Feb. 12, 2003.
> +
> +               In memory of Toni W. Hagan
> +
> +               Hospice of Acadiana, Inc.
> +               2600 Johnston St., Suite 200
> +               Lafayette, LA 70503-3240
> +
> +               Phone (337) 232-1234 or 1-800-738-2226
> +               Fax   (337) 232-1297
> +
> +               http://www.hospiceacadiana.com/
> +
> +       Manuel
> + */
> +
> +/*
> +       Made it fit for running in Linux Kernel by Alain Knaff
(alain@knaff.lu)
> +*/
> +
> +#include "decompress.h"
> +
> +#ifndef INT_MAX
> +#define INT_MAX 0x7fffffff
> +#endif
> +
> +/* Constants for Huffman coding */
> +#define MAX_GROUPS             6
> +#define GROUP_SIZE             50      /* 64 would have been more
efficient */
> +#define MAX_HUFCODE_BITS       20      /* Longest Huffman code allowed */
> +#define MAX_SYMBOLS            258     /* 256 literals + RUNA + RUNB */
> +#define SYMBOL_RUNA            0
> +#define SYMBOL_RUNB            1
> +
> +/* Status return values */
> +#define RETVAL_OK                      0
> +#define RETVAL_LAST_BLOCK              (-1)
> +#define RETVAL_NOT_BZIP_DATA           (-2)
> +#define RETVAL_UNEXPECTED_INPUT_EOF    (-3)
> +#define RETVAL_UNEXPECTED_OUTPUT_EOF   (-4)
> +#define RETVAL_DATA_ERROR              (-5)
> +#define RETVAL_OUT_OF_MEMORY           (-6)
> +#define RETVAL_OBSOLETE_INPUT          (-7)
> +
> +/* Other housekeeping constants */
> +#define BZIP2_IOBUF_SIZE               4096
> +
> +/* This is what we know about each Huffman coding group */
> +struct group_data {
> +       /* We have an extra slot at the end of limit[] for a sentinal
value. */
> +       int limit[MAX_HUFCODE_BITS+1];
> +       int base[MAX_HUFCODE_BITS];
> +       int permute[MAX_SYMBOLS];
> +       int minLen, maxLen;
> +};
> +
> +/* Structure holding all the housekeeping data, including IO buffers and
> +   memory that persists between calls to bunzip */
> +struct bunzip_data {
> +       /* State for interrupting output loop */
> +       int writeCopies, writePos, writeRunCountdown, writeCount,
writeCurrent;
> +       /* I/O tracking data (file handles, buffers, positions, etc.) */
> +       int (*fill)(void*, unsigned int);
> +       int inbufCount, inbufPos /*, outbufPos*/;
> +       unsigned char *inbuf /*,*outbuf*/;
> +       unsigned int inbufBitCount, inbufBits;
> +       /* The CRC values stored in the block header and calculated from
the
> +       data */
> +       unsigned int crc32Table[256], headerCRC, totalCRC, writeCRC;
> +       /* Intermediate buffer and its size (in bytes) */
> +       unsigned int *dbuf, dbufSize;
> +       /* These things are a bit too big to go on the stack */
> +       unsigned char selectors[32768];         /* nSelectors = 15 bits */
> +       struct group_data groups[MAX_GROUPS];   /* Huffman coding tables */
> +       int io_error;                   /* non-zero if we have IO error */
> +};
> +
> +
> +/* Return the next nnn bits of input.  All reads from the compressed input
> +   are done through this function.  All reads are big endian */
> +static unsigned int INIT get_bits(struct bunzip_data *bd, char
bits_wanted)
> +{
> +       unsigned int bits = 0;
> +
> +       /* If we need to get more data from the byte buffer, do so.
> +          (Loop getting one byte at a time to enforce endianness and avoid
> +          unaligned access.) */
> +       while (bd->inbufBitCount < bits_wanted) {
> +               /* If we need to read more data from file into byte buffer,
do
> +                  so */
> +               if (bd->inbufPos == bd->inbufCount) {
> +                       if (bd->io_error)
> +                               return 0;
> +                       bd->inbufCount = bd->fill(bd->inbuf,
BZIP2_IOBUF_SIZE);
> +                       if (bd->inbufCount <= 0) {
> +                               bd->io_error =
RETVAL_UNEXPECTED_INPUT_EOF;
> +                               return 0;
> +                       }
> +                       bd->inbufPos = 0;
> +               }
> +               /* Avoid 32-bit overflow (dump bit buffer to top of output)
*/
> +               if (bd->inbufBitCount >= 24) {
> +                       bits = bd->inbufBits&((1 <<
bd->inbufBitCount)-1);
> +                       bits_wanted -= bd->inbufBitCount;
> +                       bits <<= bits_wanted;
> +                       bd->inbufBitCount = 0;
> +               }
> +               /* Grab next 8 bits of input from buffer. */
> +               bd->inbufBits = (bd->inbufBits <<
8)|bd->inbuf[bd->inbufPos++];
> +               bd->inbufBitCount += 8;
> +       }
> +       /* Calculate result */
> +       bd->inbufBitCount -= bits_wanted;
> +       bits |= (bd->inbufBits >> bd->inbufBitCount)&((1
<< bits_wanted)-1);
> +
> +       return bits;
> +}
> +
> +/* Unpacks the next block and sets up for the inverse burrows-wheeler
step. */
> +
> +static int INIT get_next_block(struct bunzip_data *bd)
> +{
> +       struct group_data *hufGroup = NULL;
> +       int *base = NULL;
> +       int *limit = NULL;
> +       int dbufCount, nextSym, dbufSize, groupCount, selector,
> +               i, j, k, t, runPos, symCount, symTotal, nSelectors,
> +               byteCount[256];
> +       unsigned char uc, symToByte[256], mtfSymbol[256], *selectors;
> +       unsigned int *dbuf, origPtr;
> +
> +       dbuf = bd->dbuf;
> +       dbufSize = bd->dbufSize;
> +       selectors = bd->selectors;
> +
> +       /* Read in header signature and CRC, then validate signature.
> +          (last block signature means CRC is for whole file, return now)
*/
> +       i = get_bits(bd, 24);
> +       j = get_bits(bd, 24);
> +       bd->headerCRC = get_bits(bd, 32);
> +       if ((i == 0x177245) && (j == 0x385090))
> +               return RETVAL_LAST_BLOCK;
> +       if ((i != 0x314159) || (j != 0x265359))
> +               return RETVAL_NOT_BZIP_DATA;
> +       /* We can add support for blockRandomised if anybody complains.
> +          There was some code for this in busybox 1.0.0-pre3, but nobody
ever
> +          noticed that it didn''t actually work. */
> +       if (get_bits(bd, 1))
> +               return RETVAL_OBSOLETE_INPUT;
> +       origPtr = get_bits(bd, 24);
> +       if (origPtr > dbufSize)
> +               return RETVAL_DATA_ERROR;
> +       /* mapping table: if some byte values are never used (encoding
things
> +          like ascii text), the compression code removes the gaps to have
fewer
> +          symbols to deal with, and writes a sparse bitfield indicating
which
> +          values were present.  We make a translation table to convert the
> +          symbols back to the corresponding bytes. */
> +       t = get_bits(bd, 16);
> +       symTotal = 0;
> +       for (i = 0; i < 16; i++) {
> +               if (t&(1 << (15-i))) {
> +                       k = get_bits(bd, 16);
> +                       for (j = 0; j < 16; j++)
> +                               if (k&(1 << (15-j)))
> +                                       symToByte[symTotal++] = (16*i)+j;
> +               }
> +       }
> +       /* How many different Huffman coding groups does this block use? */
> +       groupCount = get_bits(bd, 3);
> +       if (groupCount < 2 || groupCount > MAX_GROUPS)
> +               return RETVAL_DATA_ERROR;
> +       /* nSelectors: Every GROUP_SIZE many symbols we select a new
> +          Huffman coding group.  Read in the group selector list,
> +          which is stored as MTF encoded bit runs.  (MTF = Move To
> +          Front, as each value is used it''s moved to the start of
the
> +          list.) */
> +       nSelectors = get_bits(bd, 15);
> +       if (!nSelectors)
> +               return RETVAL_DATA_ERROR;
> +       for (i = 0; i < groupCount; i++)
> +               mtfSymbol[i] = i;
> +       for (i = 0; i < nSelectors; i++) {
> +               /* Get next value */
> +               for (j = 0; get_bits(bd, 1); j++)
> +                       if (j >= groupCount)
> +                               return RETVAL_DATA_ERROR;
> +               /* Decode MTF to get the next selector */
> +               uc = mtfSymbol[j];
> +               for (; j; j--)
> +                       mtfSymbol[j] = mtfSymbol[j-1];
> +               mtfSymbol[0] = selectors[i] = uc;
> +       }
> +       /* Read the Huffman coding tables for each group, which code
> +          for symTotal literal symbols, plus two run symbols (RUNA,
> +          RUNB) */
> +       symCount = symTotal+2;
> +       for (j = 0; j < groupCount; j++) {
> +               unsigned char length[MAX_SYMBOLS],
temp[MAX_HUFCODE_BITS+1];
> +               int     minLen, maxLen, pp;
> +               /* Read Huffman code lengths for each symbol. 
They''re
> +                  stored in a way similar to mtf; record a starting
> +                  value for the first symbol, and an offset from the
> +                  previous value for everys symbol after that.
> +                  (Subtracting 1 before the loop and then adding it
> +                  back at the end is an optimization that makes the
> +                  test inside the loop simpler: symbol length 0
> +                  becomes negative, so an unsigned inequality catches
> +                  it.) */
> +               t = get_bits(bd, 5)-1;
> +               for (i = 0; i < symCount; i++) {
> +                       for (;;) {
> +                               if (((unsigned)t) >
(MAX_HUFCODE_BITS-1))
> +                                       return RETVAL_DATA_ERROR;
> +
> +                               /* If first bit is 0, stop.  Else
> +                                  second bit indicates whether to
> +                                  increment or decrement the value.
> +                                  Optimization: grab 2 bits and unget
> +                                  the second if the first was 0. */
> +
> +                               k = get_bits(bd, 2);
> +                               if (k < 2) {
> +                                       bd->inbufBitCount++;
> +                                       break;
> +                               }
> +                               /* Add one if second bit 1, else
> +                                * subtract 1.  Avoids if/else */
> +                               t += (((k+1)&2)-1);
> +                       }
> +                       /* Correct for the initial -1, to get the
> +                        * final symbol length */
> +                       length[i] = t+1;
> +               }
> +               /* Find largest and smallest lengths in this group */
> +               minLen = maxLen = length[0];
> +
> +               for (i = 1; i < symCount; i++) {
> +                       if (length[i] > maxLen)
> +                               maxLen = length[i];
> +                       else if (length[i] < minLen)
> +                               minLen = length[i];
> +               }
> +
> +               /* Calculate permute[], base[], and limit[] tables from
> +                * length[].
> +                *
> +                * permute[] is the lookup table for converting
> +                * Huffman coded symbols into decoded symbols.  base[]
> +                * is the amount to subtract from the value of a
> +                * Huffman symbol of a given length when using
> +                * permute[].
> +                *
> +                * limit[] indicates the largest numerical value a
> +                * symbol with a given number of bits can have.  This
> +                * is how the Huffman codes can vary in length: each
> +                * code with a value > limit[length] needs another
> +                * bit.
> +                */
> +               hufGroup = bd->groups+j;
> +               hufGroup->minLen = minLen;
> +               hufGroup->maxLen = maxLen;
> +               /* Note that minLen can''t be smaller than 1, so we
> +                  adjust the base and limit array pointers so
we''re
> +                  not always wasting the first entry.  We do this
> +                  again when using them (during symbol decoding).*/
> +               base = hufGroup->base-1;
> +               limit = hufGroup->limit-1;
> +               /* Calculate permute[].  Concurently, initialize
> +                * temp[] and limit[]. */
> +               pp = 0;
> +               for (i = minLen; i <= maxLen; i++) {
> +                       temp[i] = limit[i] = 0;
> +                       for (t = 0; t < symCount; t++)
> +                               if (length[t] == i)
> +                                       hufGroup->permute[pp++] = t;
> +               }
> +               /* Count symbols coded for at each bit length */
> +               for (i = 0; i < symCount; i++)
> +                       temp[length[i]]++;
> +               /* Calculate limit[] (the largest symbol-coding value
> +                *at each bit length, which is (previous limit <<
> +                *1)+symbols at this level), and base[] (number of
> +                *symbols to ignore at each bit length, which is limit
> +                *minus the cumulative count of symbols coded for
> +                *already). */
> +               pp = t = 0;
> +               for (i = minLen; i < maxLen; i++) {
> +                       pp += temp[i];
> +                       /* We read the largest possible symbol size
> +                          and then unget bits after determining how
> +                          many we need, and those extra bits could be
> +                          set to anything.  (They''re noise from
> +                          future symbols.)  At each level we''re
> +                          really only interested in the first few
> +                          bits, so here we set all the trailing
> +                          to-be-ignored bits to 1 so they don''t
> +                          affect the value > limit[length]
> +                          comparison. */
> +                       limit[i] = (pp << (maxLen - i)) - 1;
> +                       pp <<= 1;
> +                       base[i+1] = pp-(t += temp[i]);
> +               }
> +               limit[maxLen+1] = INT_MAX; /* Sentinal value for
> +                                           * reading next sym. */
> +               limit[maxLen] = pp+temp[maxLen]-1;
> +               base[minLen] = 0;
> +       }
> +       /* We''ve finished reading and digesting the block header. 
Now
> +          read this block''s Huffman coded symbols from the file
and
> +          undo the Huffman coding and run length encoding, saving the
> +          result into dbuf[dbufCount++] = uc */
> +
> +       /* Initialize symbol occurrence counters and symbol Move To
> +        * Front table */
> +       for (i = 0; i < 256; i++) {
> +               byteCount[i] = 0;
> +               mtfSymbol[i] = (unsigned char)i;
> +       }
> +       /* Loop through compressed symbols. */
> +       runPos = dbufCount = symCount = selector = 0;
> +       for (;;) {
> +               /* Determine which Huffman coding group to use. */
> +               if (!(symCount--)) {
> +                       symCount = GROUP_SIZE-1;
> +                       if (selector >= nSelectors)
> +                               return RETVAL_DATA_ERROR;
> +                       hufGroup = bd->groups+selectors[selector++];
> +                       base = hufGroup->base-1;
> +                       limit = hufGroup->limit-1;
> +               }
> +               /* Read next Huffman-coded symbol. */
> +               /* Note: It is far cheaper to read maxLen bits and
> +                  back up than it is to read minLen bits and then an
> +                  additional bit at a time, testing as we go.
> +                  Because there is a trailing last block (with file
> +                  CRC), there is no danger of the overread causing an
> +                  unexpected EOF for a valid compressed file.  As a
> +                  further optimization, we do the read inline
> +                  (falling back to a call to get_bits if the buffer
> +                  runs dry).  The following (up to got_huff_bits:) is
> +                  equivalent to j = get_bits(bd, hufGroup->maxLen);
> +                */
> +               while (bd->inbufBitCount < hufGroup->maxLen) {
> +                       if (bd->inbufPos == bd->inbufCount) {
> +                               j = get_bits(bd, hufGroup->maxLen);
> +                               goto got_huff_bits;
> +                       }
> +                       bd->inbufBits > +                            
(bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
> +                       bd->inbufBitCount += 8;
> +               };
> +               bd->inbufBitCount -= hufGroup->maxLen;
> +               j = (bd->inbufBits >> bd->inbufBitCount)&
> +                       ((1 << hufGroup->maxLen)-1);
> +got_huff_bits:
> +               /* Figure how how many bits are in next symbol and
> +                * unget extras */
> +               i = hufGroup->minLen;
> +               while (j > limit[i])
> +                       ++i;
> +               bd->inbufBitCount += (hufGroup->maxLen - i);
> +               /* Huffman decode value to get nextSym (with bounds
checking) */
> +               if ((i > hufGroup->maxLen)
> +                       || (((unsigned)(j =
(j>>(hufGroup->maxLen-i))-base[i]))
> +                               >= MAX_SYMBOLS))
> +                       return RETVAL_DATA_ERROR;
> +               nextSym = hufGroup->permute[j];
> +               /* We have now decoded the symbol, which indicates
> +                  either a new literal byte, or a repeated run of the
> +                  most recent literal byte.  First, check if nextSym
> +                  indicates a repeated run, and if so loop collecting
> +                  how many times to repeat the last literal. */
> +               if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or
RUNB */
> +                       /* If this is the start of a new run, zero out
> +                        * counter */
> +                       if (!runPos) {
> +                               runPos = 1;
> +                               t = 0;
> +                       }
> +                       /* Neat trick that saves 1 symbol: instead of
> +                          or-ing 0 or 1 at each bit position, add 1
> +                          or 2 instead.  For example, 1011 is 1 << 0
> +                          + 1 << 1 + 2 << 2.  1010 is 2
<< 0 + 2 << 1
> +                          + 1 << 2.  You can make any bit pattern
> +                          that way using 1 less symbol than the basic
> +                          or 0/1 method (except all bits 0, which
> +                          would use no symbols, but a run of length 0
> +                          doesn''t mean anything in this context).
> +                          Thus space is saved. */
> +                       t += (runPos << nextSym);
> +                       /* +runPos if RUNA; +2*runPos if RUNB */
> +
> +                       runPos <<= 1;
> +                       continue;
> +               }
> +               /* When we hit the first non-run symbol after a run,
> +                  we now know how many times to repeat the last
> +                  literal, so append that many copies to our buffer
> +                  of decoded symbols (dbuf) now.  (The last literal
> +                  used is the one at the head of the mtfSymbol
> +                  array.) */
> +               if (runPos) {
> +                       runPos = 0;
> +                       if (dbufCount+t >= dbufSize)
> +                               return RETVAL_DATA_ERROR;
> +
> +                       uc = symToByte[mtfSymbol[0]];
> +                       byteCount[uc] += t;
> +                       while (t--)
> +                               dbuf[dbufCount++] = uc;
> +               }
> +               /* Is this the terminating symbol? */
> +               if (nextSym > symTotal)
> +                       break;
> +               /* At this point, nextSym indicates a new literal
> +                  character.  Subtract one to get the position in the
> +                  MTF array at which this literal is currently to be
> +                  found.  (Note that the result can''t be -1 or 0,
> +                  because 0 and 1 are RUNA and RUNB.  But another
> +                  instance of the first symbol in the mtf array,
> +                  position 0, would have been handled as part of a
> +                  run above.  Therefore 1 unused mtf position minus 2
> +                  non-literal nextSym values equals -1.) */
> +               if (dbufCount >= dbufSize)
> +                       return RETVAL_DATA_ERROR;
> +               i = nextSym - 1;
> +               uc = mtfSymbol[i];
> +               /* Adjust the MTF array.  Since we typically expect to
> +                *move only a small number of symbols, and are bound
> +                *by 256 in any case, using memmove here would
> +                *typically be bigger and slower due to function call
> +                *overhead and other assorted setup costs. */
> +               do {
> +                       mtfSymbol[i] = mtfSymbol[i-1];
> +               } while (--i);
> +               mtfSymbol[0] = uc;
> +               uc = symToByte[uc];
> +               /* We have our literal byte.  Save it into dbuf. */
> +               byteCount[uc]++;
> +               dbuf[dbufCount++] = (unsigned int)uc;
> +       }
> +       /* At this point, we''ve read all the Huffman-coded symbols
> +          (and repeated runs) for this block from the input stream,
> +          and decoded them into the intermediate buffer.  There are
> +          dbufCount many decoded bytes in dbuf[].  Now undo the
> +          Burrows-Wheeler transform on dbuf.  See
> +          http://dogma.net/markn/articles/bwt/bwt.htm
> +        */
> +       /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
> +       j = 0;
> +       for (i = 0; i < 256; i++) {
> +               k = j+byteCount[i];
> +               byteCount[i] = j;
> +               j = k;
> +       }
> +       /* Figure out what order dbuf would be in if we sorted it. */
> +       for (i = 0; i < dbufCount; i++) {
> +               uc = (unsigned char)(dbuf[i] & 0xff);
> +               dbuf[byteCount[uc]] |= (i << 8);
> +               byteCount[uc]++;
> +       }
> +       /* Decode first byte by hand to initialize "previous"
byte.
> +          Note that it doesn''t get output, and if the first three
> +          characters are identical it doesn''t qualify as a run
(hence
> +          writeRunCountdown = 5). */
> +       if (dbufCount) {
> +               if (origPtr >= dbufCount)
> +                       return RETVAL_DATA_ERROR;
> +               bd->writePos = dbuf[origPtr];
> +               bd->writeCurrent = (unsigned
char)(bd->writePos&0xff);
> +               bd->writePos >>= 8;
> +               bd->writeRunCountdown = 5;
> +       }
> +       bd->writeCount = dbufCount;
> +
> +       return RETVAL_OK;
> +}
> +
> +/* Undo burrows-wheeler transform on intermediate buffer to produce
output.
> +   If start_bunzip was initialized with out_fd =-1, then up to len bytes
of
> +   data are written to outbuf.  Return value is number of bytes written or
> +   error (all errors are negative numbers).  If out_fd!=-1, outbuf and len
> +   are ignored, data is written to out_fd and return is RETVAL_OK or
error.
> +*/
> +
> +static int INIT read_bunzip(struct bunzip_data *bd, unsigned char *outbuf,
int len)
> +{
> +       const unsigned int *dbuf;
> +       int pos, xcurrent, previous, gotcount;
> +
> +       /* If last read was short due to end of file, return last block now
*/
> +       if (bd->writeCount < 0)
> +               return bd->writeCount;
> +
> +       gotcount = 0;
> +       dbuf = bd->dbuf;
> +       pos = bd->writePos;
> +       xcurrent = bd->writeCurrent;
> +
> +       /* We will always have pending decoded data to write into the
output
> +          buffer unless this is the very first call (in which case we
haven''t
> +          Huffman-decoded a block into the intermediate buffer yet). */
> +
> +       if (bd->writeCopies) {
> +               /* Inside the loop, writeCopies means extra copies (beyond
1) */
> +               --bd->writeCopies;
> +               /* Loop outputting bytes */
> +               for (;;) {
> +                       /* If the output buffer is full, snapshot
> +                        * state and return */
> +                       if (gotcount >= len) {
> +                               bd->writePos = pos;
> +                               bd->writeCurrent = xcurrent;
> +                               bd->writeCopies++;
> +                               return len;
> +                       }
> +                       /* Write next byte into output buffer, updating CRC
*/
> +                       outbuf[gotcount++] = xcurrent;
> +                       bd->writeCRC = (((bd->writeCRC) << 8)
> +                               ^bd->crc32Table[((bd->writeCRC)
>> 24)
> +                               ^xcurrent]);
> +                       /* Loop now if we''re outputting multiple
> +                        * copies of this byte */
> +                       if (bd->writeCopies) {
> +                               --bd->writeCopies;
> +                               continue;
> +                       }
> +decode_next_byte:
> +                       if (!bd->writeCount--)
> +                               break;
> +                       /* Follow sequence vector to undo
> +                        * Burrows-Wheeler transform */
> +                       previous = xcurrent;
> +                       pos = dbuf[pos];
> +                       xcurrent = pos&0xff;
> +                       pos >>= 8;
> +                       /* After 3 consecutive copies of the same
> +                          byte, the 4th is a repeat count.  We count
> +                          down from 4 instead *of counting up because
> +                          testing for non-zero is faster */
> +                       if (--bd->writeRunCountdown) {
> +                               if (xcurrent != previous)
> +                                       bd->writeRunCountdown = 4;
> +                       } else {
> +                               /* We have a repeated run, this byte
> +                                * indicates the count */
> +                               bd->writeCopies = xcurrent;
> +                               xcurrent = previous;
> +                               bd->writeRunCountdown = 5;
> +                               /* Sometimes there are just 3 bytes
> +                                * (run length 0) */
> +                               if (!bd->writeCopies)
> +                                       goto decode_next_byte;
> +                               /* Subtract the 1 copy we''d output
> +                                * anyway to get extras */
> +                               --bd->writeCopies;
> +                       }
> +               }
> +               /* Decompression of this block completed successfully */
> +               bd->writeCRC = ~bd->writeCRC;
> +               bd->totalCRC = ((bd->totalCRC << 1) |
> +                               (bd->totalCRC >> 31)) ^
bd->writeCRC;
> +               /* If this block had a CRC error, force file level CRC
error. */
> +               if (bd->writeCRC != bd->headerCRC) {
> +                       bd->totalCRC = bd->headerCRC+1;
> +                       return RETVAL_LAST_BLOCK;
> +               }
> +       }
> +
> +       /* Refill the intermediate buffer by Huffman-decoding next
> +        * block of input */
> +       /* (previous is just a convenient unused temp variable here) */
> +       previous = get_next_block(bd);
> +       if (previous) {
> +               bd->writeCount = previous;
> +               return (previous != RETVAL_LAST_BLOCK) ? previous :
gotcount;
> +       }
> +       bd->writeCRC = 0xffffffffUL;
> +       pos = bd->writePos;
> +       xcurrent = bd->writeCurrent;
> +       goto decode_next_byte;
> +}
> +
> +static int INIT nofill(void *buf, unsigned int len)
> +{
> +       return -1;
> +}
> +
> +/* Allocate the structure, read file header.  If in_fd ==-1, inbuf must
contain
> +   a complete bunzip file (len bytes long).  If in_fd!=-1, inbuf and len
are
> +   ignored, and data is read from file handle into temporary buffer. */
> +static int INIT start_bunzip(struct bunzip_data **bdp, void *inbuf, int
len,
> +                            int (*fill)(void*, unsigned int))
> +{
> +       struct bunzip_data *bd;
> +       unsigned int i, j, c;
> +       const unsigned int BZh0 > +               (((unsigned
int)''B'') << 24)+(((unsigned int)''Z'')
<< 16)
> +               +(((unsigned int)''h'') <<
8)+(unsigned int)''0'';
> +
> +       /* Figure out how much data to allocate */
> +       i = sizeof(struct bunzip_data);
> +
> +       /* Allocate bunzip_data.  Most fields initialize to zero. */
> +       bd = *bdp = malloc(i);
> +       memset(bd, 0, sizeof(struct bunzip_data));
> +       /* Setup input buffer */
> +       bd->inbuf = inbuf;
> +       bd->inbufCount = len;
> +       if (fill != NULL)
> +               bd->fill = fill;
> +       else
> +               bd->fill = nofill;
> +
> +       /* Init the CRC32 table (big endian) */
> +       for (i = 0; i < 256; i++) {
> +               c = i << 24;
> +               for (j = 8; j; j--)
> +                       c = c&0x80000000 ? (c << 1)^0x04c11db7 :
(c << 1);
> +               bd->crc32Table[i] = c;
> +       }
> +
> +       /* Ensure that file starts with
"BZh[''1''-''9'']." */
> +       i = get_bits(bd, 32);
> +       if (((unsigned int)(i-BZh0-1)) >= 9)
> +               return RETVAL_NOT_BZIP_DATA;
> +
> +       /* Fourth byte (ascii ''1''-''9''),
indicates block size in units of 100k of
> +          uncompressed data.  Allocate intermediate buffer for block. */
> +       bd->dbufSize = 100000*(i-BZh0);
> +
> +       bd->dbuf = large_malloc(bd->dbufSize * sizeof(int));
> +       return RETVAL_OK;
> +}
> +
> +/* Example usage: decompress src_fd to dst_fd.  (Stops at end of bzip2
data,
> +   not end of file.) */
> +STATIC int INIT bunzip2(unsigned char *buf, unsigned int len,
> +                       int(*fill)(void*, unsigned int),
> +                       int(*flush)(void*, unsigned int),
> +                       unsigned char *outbuf,
> +                       unsigned int *pos,
> +                       void(*error_fn)(const char *x))
> +{
> +       struct bunzip_data *bd;
> +       int i = -1;
> +       unsigned char *inbuf;
> +
> +       set_error_fn(error_fn);
> +       if (flush)
> +               outbuf = malloc(BZIP2_IOBUF_SIZE);
> +
> +       if (!outbuf) {
> +               error("Could not allocate output bufer");
> +               return -1;
> +       }
> +       if (buf)
> +               inbuf = buf;
> +       else
> +               inbuf = malloc(BZIP2_IOBUF_SIZE);
> +       if (!inbuf) {
> +               error("Could not allocate input bufer");
> +               goto exit_0;
> +       }
> +       i = start_bunzip(&bd, inbuf, len, fill);
> +       if (!i) {
> +               for (;;) {
> +                       i = read_bunzip(bd, outbuf, BZIP2_IOBUF_SIZE);
> +                       if (i <= 0)
> +                               break;
> +                       if (!flush)
> +                               outbuf += i;
> +                       else
> +                               if (i != flush(outbuf, i)) {
> +                                       i = RETVAL_UNEXPECTED_OUTPUT_EOF;
> +                                       break;
> +                               }
> +               }
> +       }
> +       /* Check CRC and release memory */
> +       if (i == RETVAL_LAST_BLOCK) {
> +               if (bd->headerCRC != bd->totalCRC)
> +                       error("Data integrity error when
decompressing.");
> +               else
> +                       i = RETVAL_OK;
> +       } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) {
> +               error("Compressed file ends unexpectedly");
> +       }
> +       if (bd->dbuf)
> +               large_free(bd->dbuf);
> +       if (pos)
> +               *pos = bd->inbufPos;
> +       free(bd);
> +       if (!buf)
> +               free(inbuf);
> +exit_0:
> +       if (flush)
> +               free(outbuf);
> +       return i;
> +}
> --- /dev/null   1970-01-01 00:00:00.000000000 +0000
> +++ 2009-10-27/xen/common/decompress.c  2009-11-05 12:27:10.000000000 +0100
> @@ -0,0 +1,27 @@
> +#include <xen/config.h>
> +#include <xen/init.h>
> +#include <xen/lib.h>
> +#include <xen/string.h>
> +#include <xen/decompress.h>
> +
> +static void __init error(const char *msg)
> +{
> +    printk("%s\n", msg);
> +}
> +
> +int __init decompress(void *inbuf, unsigned int len, void *outbuf)
> +{
> +#if 0 /* Not needed here yet. */
> +    if ( len >= 2 &&
> +         (!memcmp(inbuf, "\037\213", 2) || !memcmp(inbuf,
"\037\236", 2)) )
> +        return gunzip(inbuf, len, NULL, NULL, outbuf, NULL, error);
> +#endif
> +
> +    if ( len >= 3 && !memcmp(inbuf, "\x42\x5a\x68",
3) )
> +        return bunzip2(inbuf, len, NULL, NULL, outbuf, NULL, error);
> +
> +    if ( len >= 2 && !memcmp(inbuf, "\135\000", 2) )
> +        return unlzma(inbuf, len, NULL, NULL, outbuf, NULL, error);
> +
> +    return 1;
> +}
> --- /dev/null   1970-01-01 00:00:00.000000000 +0000
> +++ 2009-10-27/xen/common/decompress.h  2009-11-05 15:21:52.000000000 +0100
> @@ -0,0 +1,19 @@
> +#include <xen/config.h>
> +#include <xen/cache.h>
> +#include <xen/decompress.h>
> +#include <xen/init.h>
> +#include <xen/string.h>
> +#include <xen/types.h>
> +#include <xen/xmalloc.h>
> +
> +#define STATIC
> +#define INIT __init
> +
> +static void(*__initdata error)(const char *);
> +#define set_error_fn(x) error = x;
> +
> +#define malloc xmalloc_bytes
> +#define free xfree
> +
> +#define large_malloc xmalloc_bytes
> +#define large_free xfree
> --- /dev/null   1970-01-01 00:00:00.000000000 +0000
> +++ 2009-10-27/xen/common/unlzma.c      2009-11-05 12:45:37.000000000 +0100
> @@ -0,0 +1,647 @@
> +/* Lzma decompressor for Linux kernel. Shamelessly snarfed
> + * from busybox 1.1.1
> + *
> + * Linux kernel adaptation
> + * Copyright (C) 2006  Alain < alain@knaff.lu >
> + *
> + * Based on small lzma deflate implementation/Small range coder
> + * implementation for lzma.
> + * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
> + *
> + * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
> + * Copyright (C) 1999-2005  Igor Pavlov
> + *
> + * Copyrights of the parts, see headers below.
> + *
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 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
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 
USA
> + */
> +
> +#include "decompress.h"
> +
> +#define        MIN(a, b) (((a) < (b)) ? (a) : (b))
> +
> +static long long INIT read_int(unsigned char *ptr, int size)
> +{
> +       int i;
> +       long long ret = 0;
> +
> +       for (i = 0; i < size; i++)
> +               ret = (ret << 8) | ptr[size-i-1];
> +       return ret;
> +}
> +
> +#define ENDIAN_CONVERT(x) \
> +  x = (typeof(x))read_int((unsigned char *)&x, sizeof(x))
> +
> +
> +/* Small range coder implementation for lzma.
> + * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
> + *
> + * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
> + * Copyright (c) 1999-2005  Igor Pavlov
> + */
> +
> +#include <xen/compiler.h>
> +
> +#define LZMA_IOBUF_SIZE        0x10000
> +
> +struct rc {
> +       int (*fill)(void*, unsigned int);
> +       uint8_t *ptr;
> +       uint8_t *buffer;
> +       uint8_t *buffer_end;
> +       int buffer_size;
> +       uint32_t code;
> +       uint32_t range;
> +       uint32_t bound;
> +};
> +
> +
> +#define RC_TOP_BITS 24
> +#define RC_MOVE_BITS 5
> +#define RC_MODEL_TOTAL_BITS 11
> +
> +
> +static int nofill(void *buffer, unsigned int len)
> +{
> +       return -1;
> +}
> +
> +/* Called twice: once at startup and once in rc_normalize() */
> +static void INIT rc_read(struct rc *rc)
> +{
> +       rc->buffer_size = rc->fill((char *)rc->buffer,
LZMA_IOBUF_SIZE);
> +       if (rc->buffer_size <= 0)
> +               error("unexpected EOF");
> +       rc->ptr = rc->buffer;
> +       rc->buffer_end = rc->buffer + rc->buffer_size;
> +}
> +
> +/* Called once */
> +static inline void INIT rc_init(struct rc *rc,
> +                                      int (*fill)(void*, unsigned int),
> +                                      unsigned char *buffer, int
buffer_size)
> +{
> +       if (fill)
> +               rc->fill = fill;
> +       else
> +               rc->fill = nofill;
> +       rc->buffer = (uint8_t *)buffer;
> +       rc->buffer_size = buffer_size;
> +       rc->buffer_end = rc->buffer + rc->buffer_size;
> +       rc->ptr = rc->buffer;
> +
> +       rc->code = 0;
> +       rc->range = 0xFFFFFFFF;
> +}
> +
> +static inline void INIT rc_init_code(struct rc *rc)
> +{
> +       int i;
> +
> +       for (i = 0; i < 5; i++) {
> +               if (rc->ptr >= rc->buffer_end)
> +                       rc_read(rc);
> +               rc->code = (rc->code << 8) | *rc->ptr++;
> +       }
> +}
> +
> +
> +/* Called once. TODO: bb_maybe_free() */
> +static inline void INIT rc_free(struct rc *rc)
> +{
> +       free(rc->buffer);
> +}
> +
> +/* Called twice, but one callsite is in inline''d
rc_is_bit_0_helper() */
> +static void INIT rc_do_normalize(struct rc *rc)
> +{
> +       if (rc->ptr >= rc->buffer_end)
> +               rc_read(rc);
> +       rc->range <<= 8;
> +       rc->code = (rc->code << 8) | *rc->ptr++;
> +}
> +static inline void INIT rc_normalize(struct rc *rc)
> +{
> +       if (rc->range < (1 << RC_TOP_BITS))
> +               rc_do_normalize(rc);
> +}
> +
> +/* Called 9 times */
> +/* Why rc_is_bit_0_helper exists?
> + *Because we want to always expose (rc->code < rc->bound) to
optimizer
> + */
> +static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p)
> +{
> +       rc_normalize(rc);
> +       rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
> +       return rc->bound;
> +}
> +static inline int INIT rc_is_bit_0(struct rc *rc, uint16_t *p)
> +{
> +       uint32_t t = rc_is_bit_0_helper(rc, p);
> +       return rc->code < t;
> +}
> +
> +/* Called ~10 times, but very small, thus inlined */
> +static inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p)
> +{
> +       rc->range = rc->bound;
> +       *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >>
RC_MOVE_BITS;
> +}
> +static inline void rc_update_bit_1(struct rc *rc, uint16_t *p)
> +{
> +       rc->range -= rc->bound;
> +       rc->code -= rc->bound;
> +       *p -= *p >> RC_MOVE_BITS;
> +}
> +
> +/* Called 4 times in unlzma loop */
> +static int INIT rc_get_bit(struct rc *rc, uint16_t *p, int *symbol)
> +{
> +       if (rc_is_bit_0(rc, p)) {
> +               rc_update_bit_0(rc, p);
> +               *symbol *= 2;
> +               return 0;
> +       } else {
> +               rc_update_bit_1(rc, p);
> +               *symbol = *symbol * 2 + 1;
> +               return 1;
> +       }
> +}
> +
> +/* Called once */
> +static inline int INIT rc_direct_bit(struct rc *rc)
> +{
> +       rc_normalize(rc);
> +       rc->range >>= 1;
> +       if (rc->code >= rc->range) {
> +               rc->code -= rc->range;
> +               return 1;
> +       }
> +       return 0;
> +}
> +
> +/* Called twice */
> +static inline void INIT
> +rc_bit_tree_decode(struct rc *rc, uint16_t *p, int num_levels, int
*symbol)
> +{
> +       int i = num_levels;
> +
> +       *symbol = 1;
> +       while (i--)
> +               rc_get_bit(rc, p + *symbol, symbol);
> +       *symbol -= 1 << num_levels;
> +}
> +
> +
> +/*
> + * Small lzma deflate implementation.
> + * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
> + *
> + * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
> + * Copyright (C) 1999-2005  Igor Pavlov
> + */
> +
> +
> +struct lzma_header {
> +       uint8_t pos;
> +       uint32_t dict_size;
> +       uint64_t dst_size;
> +} __attribute__ ((packed)) ;
> +
> +
> +#define LZMA_BASE_SIZE 1846
> +#define LZMA_LIT_SIZE 768
> +
> +#define LZMA_NUM_POS_BITS_MAX 4
> +
> +#define LZMA_LEN_NUM_LOW_BITS 3
> +#define LZMA_LEN_NUM_MID_BITS 3
> +#define LZMA_LEN_NUM_HIGH_BITS 8
> +
> +#define LZMA_LEN_CHOICE 0
> +#define LZMA_LEN_CHOICE_2 (LZMA_LEN_CHOICE + 1)
> +#define LZMA_LEN_LOW (LZMA_LEN_CHOICE_2 + 1)
> +#define LZMA_LEN_MID (LZMA_LEN_LOW \
> +                     + (1 << (LZMA_NUM_POS_BITS_MAX +
LZMA_LEN_NUM_LOW_BITS)))
> +#define LZMA_LEN_HIGH (LZMA_LEN_MID \
> +                      +(1 << (LZMA_NUM_POS_BITS_MAX +
LZMA_LEN_NUM_MID_BITS)))
> +#define LZMA_NUM_LEN_PROBS (LZMA_LEN_HIGH + (1 <<
LZMA_LEN_NUM_HIGH_BITS))
> +
> +#define LZMA_NUM_STATES 12
> +#define LZMA_NUM_LIT_STATES 7
> +
> +#define LZMA_START_POS_MODEL_INDEX 4
> +#define LZMA_END_POS_MODEL_INDEX 14
> +#define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX
>> 1))
> +
> +#define LZMA_NUM_POS_SLOT_BITS 6
> +#define LZMA_NUM_LEN_TO_POS_STATES 4
> +
> +#define LZMA_NUM_ALIGN_BITS 4
> +
> +#define LZMA_MATCH_MIN_LEN 2
> +
> +#define LZMA_IS_MATCH 0
> +#define LZMA_IS_REP (LZMA_IS_MATCH + (LZMA_NUM_STATES <<
LZMA_NUM_POS_BITS_MAX))
> +#define LZMA_IS_REP_G0 (LZMA_IS_REP + LZMA_NUM_STATES)
> +#define LZMA_IS_REP_G1 (LZMA_IS_REP_G0 + LZMA_NUM_STATES)
> +#define LZMA_IS_REP_G2 (LZMA_IS_REP_G1 + LZMA_NUM_STATES)
> +#define LZMA_IS_REP_0_LONG (LZMA_IS_REP_G2 + LZMA_NUM_STATES)
> +#define LZMA_POS_SLOT (LZMA_IS_REP_0_LONG \
> +                      + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
> +#define LZMA_SPEC_POS (LZMA_POS_SLOT \
> +                      +(LZMA_NUM_LEN_TO_POS_STATES <<
LZMA_NUM_POS_SLOT_BITS))
> +#define LZMA_ALIGN (LZMA_SPEC_POS \
> +                   + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX)
> +#define LZMA_LEN_CODER (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS))
> +#define LZMA_REP_LEN_CODER (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS)
> +#define LZMA_LITERAL (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS)
> +
> +
> +struct writer {
> +       uint8_t *buffer;
> +       uint8_t previous_byte;
> +       size_t buffer_pos;
> +       int bufsize;
> +       size_t global_pos;
> +       int(*flush)(void*, unsigned int);
> +       struct lzma_header *header;
> +};
> +
> +struct cstate {
> +       int state;
> +       uint32_t rep0, rep1, rep2, rep3;
> +};
> +
> +static inline size_t INIT get_pos(struct writer *wr)
> +{
> +       return
> +               wr->global_pos + wr->buffer_pos;
> +}
> +
> +static inline uint8_t INIT peek_old_byte(struct writer *wr,
> +                                               uint32_t offs)
> +{
> +       if (!wr->flush) {
> +               int32_t pos;
> +               while (offs > wr->header->dict_size)
> +                       offs -= wr->header->dict_size;
> +               pos = wr->buffer_pos - offs;
> +               return wr->buffer[pos];
> +       } else {
> +               uint32_t pos = wr->buffer_pos - offs;
> +               while (pos >= wr->header->dict_size)
> +                       pos += wr->header->dict_size;
> +               return wr->buffer[pos];
> +       }
> +
> +}
> +
> +static inline void INIT write_byte(struct writer *wr, uint8_t byte)
> +{
> +       wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte;
> +       if (wr->flush && wr->buffer_pos ==
wr->header->dict_size) {
> +               wr->buffer_pos = 0;
> +               wr->global_pos += wr->header->dict_size;
> +               wr->flush((char *)wr->buffer,
wr->header->dict_size);
> +       }
> +}
> +
> +
> +static inline void INIT copy_byte(struct writer *wr, uint32_t offs)
> +{
> +       write_byte(wr, peek_old_byte(wr, offs));
> +}
> +
> +static inline void INIT copy_bytes(struct writer *wr,
> +                                        uint32_t rep0, int len)
> +{
> +       do {
> +               copy_byte(wr, rep0);
> +               len--;
> +       } while (len != 0 && wr->buffer_pos <
wr->header->dst_size);
> +}
> +
> +static inline void INIT process_bit0(struct writer *wr, struct rc *rc,
> +                                    struct cstate *cst, uint16_t *p,
> +                                    int pos_state, uint16_t *prob,
> +                                    int lc, uint32_t literal_pos_mask) {
> +       int mi = 1;
> +       rc_update_bit_0(rc, prob);
> +       prob = (p + LZMA_LITERAL +
> +               (LZMA_LIT_SIZE
> +                * (((get_pos(wr) & literal_pos_mask) << lc)
> +                   + (wr->previous_byte >> (8 - lc))))
> +               );
> +
> +       if (cst->state >= LZMA_NUM_LIT_STATES) {
> +               int match_byte = peek_old_byte(wr, cst->rep0);
> +               do {
> +                       int bit;
> +                       uint16_t *prob_lit;
> +
> +                       match_byte <<= 1;
> +                       bit = match_byte & 0x100;
> +                       prob_lit = prob + 0x100 + bit + mi;
> +                       if (rc_get_bit(rc, prob_lit, &mi)) {
> +                               if (!bit)
> +                                       break;
> +                       } else {
> +                               if (bit)
> +                                       break;
> +                       }
> +               } while (mi < 0x100);
> +       }
> +       while (mi < 0x100) {
> +               uint16_t *prob_lit = prob + mi;
> +               rc_get_bit(rc, prob_lit, &mi);
> +       }
> +       write_byte(wr, mi);
> +       if (cst->state < 4)
> +               cst->state = 0;
> +       else if (cst->state < 10)
> +               cst->state -= 3;
> +       else
> +               cst->state -= 6;
> +}
> +
> +static inline void INIT process_bit1(struct writer *wr, struct rc *rc,
> +                                           struct cstate *cst, uint16_t
*p,
> +                                           int pos_state, uint16_t *prob)
{
> +  int offset;
> +       uint16_t *prob_len;
> +       int num_bits;
> +       int len;
> +
> +       rc_update_bit_1(rc, prob);
> +       prob = p + LZMA_IS_REP + cst->state;
> +       if (rc_is_bit_0(rc, prob)) {
> +               rc_update_bit_0(rc, prob);
> +               cst->rep3 = cst->rep2;
> +               cst->rep2 = cst->rep1;
> +               cst->rep1 = cst->rep0;
> +               cst->state = cst->state < LZMA_NUM_LIT_STATES ? 0
: 3;
> +               prob = p + LZMA_LEN_CODER;
> +       } else {
> +               rc_update_bit_1(rc, prob);
> +               prob = p + LZMA_IS_REP_G0 + cst->state;
> +               if (rc_is_bit_0(rc, prob)) {
> +                       rc_update_bit_0(rc, prob);
> +                       prob = (p + LZMA_IS_REP_0_LONG
> +                               + (cst->state <<
> +                                  LZMA_NUM_POS_BITS_MAX) +
> +                               pos_state);
> +                       if (rc_is_bit_0(rc, prob)) {
> +                               rc_update_bit_0(rc, prob);
> +
> +                               cst->state = cst->state <
LZMA_NUM_LIT_STATES ?
> +                                       9 : 11;
> +                               copy_byte(wr, cst->rep0);
> +                               return;
> +                       } else {
> +                               rc_update_bit_1(rc, prob);
> +                       }
> +               } else {
> +                       uint32_t distance;
> +
> +                       rc_update_bit_1(rc, prob);
> +                       prob = p + LZMA_IS_REP_G1 + cst->state;
> +                       if (rc_is_bit_0(rc, prob)) {
> +                               rc_update_bit_0(rc, prob);
> +                               distance = cst->rep1;
> +                       } else {
> +                               rc_update_bit_1(rc, prob);
> +                               prob = p + LZMA_IS_REP_G2 + cst->state;
> +                               if (rc_is_bit_0(rc, prob)) {
> +                                       rc_update_bit_0(rc, prob);
> +                                       distance = cst->rep2;
> +                               } else {
> +                                       rc_update_bit_1(rc, prob);
> +                                       distance = cst->rep3;
> +                                       cst->rep3 = cst->rep2;
> +                               }
> +                               cst->rep2 = cst->rep1;
> +                       }
> +                       cst->rep1 = cst->rep0;
> +                       cst->rep0 = distance;
> +               }
> +               cst->state = cst->state < LZMA_NUM_LIT_STATES ? 8
: 11;
> +               prob = p + LZMA_REP_LEN_CODER;
> +       }
> +
> +       prob_len = prob + LZMA_LEN_CHOICE;
> +       if (rc_is_bit_0(rc, prob_len)) {
> +               rc_update_bit_0(rc, prob_len);
> +               prob_len = (prob + LZMA_LEN_LOW
> +                           + (pos_state <<
> +                              LZMA_LEN_NUM_LOW_BITS));
> +               offset = 0;
> +               num_bits = LZMA_LEN_NUM_LOW_BITS;
> +       } else {
> +               rc_update_bit_1(rc, prob_len);
> +               prob_len = prob + LZMA_LEN_CHOICE_2;
> +               if (rc_is_bit_0(rc, prob_len)) {
> +                       rc_update_bit_0(rc, prob_len);
> +                       prob_len = (prob + LZMA_LEN_MID
> +                                   + (pos_state <<
> +                                      LZMA_LEN_NUM_MID_BITS));
> +                       offset = 1 << LZMA_LEN_NUM_LOW_BITS;
> +                       num_bits = LZMA_LEN_NUM_MID_BITS;
> +               } else {
> +                       rc_update_bit_1(rc, prob_len);
> +                       prob_len = prob + LZMA_LEN_HIGH;
> +                       offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
> +                                 + (1 << LZMA_LEN_NUM_MID_BITS));
> +                       num_bits = LZMA_LEN_NUM_HIGH_BITS;
> +               }
> +       }
> +
> +       rc_bit_tree_decode(rc, prob_len, num_bits, &len);
> +       len += offset;
> +
> +       if (cst->state < 4) {
> +               int pos_slot;
> +
> +               cst->state += LZMA_NUM_LIT_STATES;
> +               prob > +                       p + LZMA_POS_SLOT +
> +                       ((len <
> +                         LZMA_NUM_LEN_TO_POS_STATES ? len :
> +                         LZMA_NUM_LEN_TO_POS_STATES - 1)
> +                        << LZMA_NUM_POS_SLOT_BITS);
> +               rc_bit_tree_decode(rc, prob,
> +                                  LZMA_NUM_POS_SLOT_BITS,
> +                                  &pos_slot);
> +               if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
> +                       int i, mi;
> +                       num_bits = (pos_slot >> 1) - 1;
> +                       cst->rep0 = 2 | (pos_slot & 1);
> +                       if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
> +                               cst->rep0 <<= num_bits;
> +                               prob = p + LZMA_SPEC_POS +
> +                                       cst->rep0 - pos_slot - 1;
> +                       } else {
> +                               num_bits -= LZMA_NUM_ALIGN_BITS;
> +                               while (num_bits--)
> +                                       cst->rep0 = (cst->rep0
<< 1) |
> +                                               rc_direct_bit(rc);
> +                               prob = p + LZMA_ALIGN;
> +                               cst->rep0 <<= LZMA_NUM_ALIGN_BITS;
> +                               num_bits = LZMA_NUM_ALIGN_BITS;
> +                       }
> +                       i = 1;
> +                       mi = 1;
> +                       while (num_bits--) {
> +                               if (rc_get_bit(rc, prob + mi, &mi))
> +                                       cst->rep0 |= i;
> +                               i <<= 1;
> +                       }
> +               } else
> +                       cst->rep0 = pos_slot;
> +               if (++(cst->rep0) == 0)
> +                       return;
> +       }
> +
> +       len += LZMA_MATCH_MIN_LEN;
> +
> +       copy_bytes(wr, cst->rep0, len);
> +}
> +
> +
> +
> +STATIC inline int INIT unlzma(unsigned char *buf, unsigned int in_len,
> +                             int(*fill)(void*, unsigned int),
> +                             int(*flush)(void*, unsigned int),
> +                             unsigned char *output,
> +                             unsigned int *posp,
> +                             void(*error_fn)(const char *x)
> +       )
> +{
> +       struct lzma_header header;
> +       int lc, pb, lp;
> +       uint32_t pos_state_mask;
> +       uint32_t literal_pos_mask;
> +       uint16_t *p;
> +       int num_probs;
> +       struct rc rc;
> +       int i, mi;
> +       struct writer wr;
> +       struct cstate cst;
> +       unsigned char *inbuf;
> +       int ret = -1;
> +
> +       set_error_fn(error_fn);
> +
> +       if (buf)
> +               inbuf = buf;
> +       else
> +               inbuf = malloc(LZMA_IOBUF_SIZE);
> +       if (!inbuf) {
> +               error("Could not allocate input bufer");
> +               goto exit_0;
> +       }
> +
> +       cst.state = 0;
> +       cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1;
> +
> +       wr.header = &header;
> +       wr.flush = flush;
> +       wr.global_pos = 0;
> +       wr.previous_byte = 0;
> +       wr.buffer_pos = 0;
> +
> +       rc_init(&rc, fill, inbuf, in_len);
> +
> +       for (i = 0; i < sizeof(header); i++) {
> +               if (rc.ptr >= rc.buffer_end)
> +                       rc_read(&rc);
> +               ((unsigned char *)&header)[i] = *rc.ptr++;
> +       }
> +
> +       if (header.pos >= (9 * 5 * 5))
> +               error("bad header");
> +
> +       mi = 0;
> +       lc = header.pos;
> +       while (lc >= 9) {
> +               mi++;
> +               lc -= 9;
> +       }
> +       pb = 0;
> +       lp = mi;
> +       while (lp >= 5) {
> +               pb++;
> +               lp -= 5;
> +       }
> +       pos_state_mask = (1 << pb) - 1;
> +       literal_pos_mask = (1 << lp) - 1;
> +
> +       ENDIAN_CONVERT(header.dict_size);
> +       ENDIAN_CONVERT(header.dst_size);
> +
> +       if (header.dict_size == 0)
> +               header.dict_size = 1;
> +
> +       if (output)
> +               wr.buffer = output;
> +       else {
> +               wr.bufsize = MIN(header.dst_size, header.dict_size);
> +               wr.buffer = large_malloc(wr.bufsize);
> +       }
> +       if (wr.buffer == NULL)
> +               goto exit_1;
> +
> +       num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
> +       p = (uint16_t *) large_malloc(num_probs * sizeof(*p));
> +       if (p == 0)
> +               goto exit_2;
> +       num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
> +       for (i = 0; i < num_probs; i++)
> +               p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
> +
> +       rc_init_code(&rc);
> +
> +       while (get_pos(&wr) < header.dst_size) {
> +               int pos_state = get_pos(&wr) & pos_state_mask;
> +               uint16_t *prob = p + LZMA_IS_MATCH +
> +                       (cst.state << LZMA_NUM_POS_BITS_MAX) +
pos_state;
> +               if (rc_is_bit_0(&rc, prob))
> +                       process_bit0(&wr, &rc, &cst, p,
pos_state, prob,
> +                                    lc, literal_pos_mask);
> +               else {
> +                       process_bit1(&wr, &rc, &cst, p,
pos_state, prob);
> +                       if (cst.rep0 == 0)
> +                               break;
> +               }
> +       }
> +
> +       if (posp)
> +               *posp = rc.ptr-rc.buffer;
> +       if (wr.flush)
> +               wr.flush(wr.buffer, wr.buffer_pos);
> +       ret = 0;
> +       large_free(p);
> +exit_2:
> +       if (!output)
> +               large_free(wr.buffer);
> +exit_1:
> +       if (!buf)
> +               free(inbuf);
> +exit_0:
> +       return ret;
> +}
> --- /dev/null   1970-01-01 00:00:00.000000000 +0000
> +++ 2009-10-27/xen/include/xen/decompress.h     2009-11-05
12:27:44.000000000 +0100
> @@ -0,0 +1,38 @@
> +#ifndef __XEN_GENERIC_H
> +#define __XEN_GENERIC_H
> +
> +typedef int decompress_fn(unsigned char *inbuf, unsigned int len,
> +                          int (*fill)(void*, unsigned int),
> +                          int (*flush)(void*, unsigned int),
> +                          unsigned char *outbuf, unsigned int *posp,
> +                          void (*error)(const char *x));
> +
> +/* inbuf   - input buffer
> + * len     - len of pre-read data in inbuf
> + * fill    - function to fill inbuf when empty
> + * flush   - function to write out outbuf
> + * outbuf  - output buffer
> + * posp    - if non-null, input position (number of bytes read) will be
> + *           returned here
> + * error   - error reporting function
> + *
> + * If len != 0, inbuf should contain all the necessary input data, and
fill
> + * should be NULL
> + * If len = 0, inbuf can be NULL, in which case the decompressor will
allocate
> + * the input buffer.  If inbuf != NULL it must be at least XXX_IOBUF_SIZE
bytes.
> + * fill will be called (repeatedly...) to read data, at most
XXX_IOBUF_SIZE
> + * bytes should be read per call.  Replace XXX with the appropriate
decompressor
> + * name, i.e. LZMA_IOBUF_SIZE.
> + *
> + * If flush = NULL, outbuf must be large enough to buffer all the expected
> + * output.  If flush != NULL, the output buffer will be allocated by the
> + * decompressor (outbuf = NULL), and the flush function will be called to
> + * flush the output buffer at the appropriate time (decompressor and
stream
> + * dependent).
> + */
> +
> +decompress_fn bunzip2, unlzma;
> +
> +int decompress(void *inbuf, unsigned int len, void *outbuf);
> +
> +#endif
> 


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>>> Ian Campbell <Ian.Campbell@citrix.com> 06.11.09 09:56
>>>
>On Thu, 2009-11-05 at 14:24 +0000, Jan Beulich wrote:
>> This matches functionality in the tools already supporting the same for
>> DomU-s.
>> 
>> Code taken from Linux 2.6.32-rc and adjusted as little as possible to
>> be usable in Xen.
>
>Looks good to me. The new files FOO.c are based on lib/decompress_FOO.c
>from Linux? Might be worth a comment in at least the changelog to aid
Yes.
>the next person to come along who wants to resync them. (and why rename
>them?)
The decompress_* prefix seemed pointless to me.
>> The question is whether, particularly for non-Linux Dom0-s, plain ELF
>> images compressed by bzip2 or lzma should also be supported.
>
>It should be fairly low cost to do so, so why not?
>
>Is there a reason to treat gzip differently to bzip2/lzma? i.e. why not
>route it through decompress.c as well? Perhaps that would involve
>updating xen/common/inflate.c but that is already just a fork of what is
>now in lib/decompress_inflate.c in Linux so it should be pretty trivial.
Yes, I had considered that, but didn''t want the patch to become bigger
than necessary. I''m certainly planning on cleaning this up as a
subsequent
(though lower priority) patch.

Jan


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On Fri, 2009-11-06 at 09:02 +0000, Jan Beulich wrote:
> >>> Ian Campbell <Ian.Campbell@citrix.com> 06.11.09 09:56
>>>
> >On Thu, 2009-11-05 at 14:24 +0000, Jan Beulich wrote:
> >the next person to come along who wants to resync them. (and why rename
> >them?)
> 
> The decompress_* prefix seemed pointless to me.
I guess it just highlights all those files as being part of the same
"subsystem".
> >> The question is whether, particularly for non-Linux Dom0-s, plain
ELF
> >> images compressed by bzip2 or lzma should also be supported.
> >
> >It should be fairly low cost to do so, so why not?
> >
> >Is there a reason to treat gzip differently to bzip2/lzma? i.e. why not
> >route it through decompress.c as well? Perhaps that would involve
> >updating xen/common/inflate.c but that is already just a fork of what
is
> >now in lib/decompress_inflate.c in Linux so it should be pretty
trivial.
> 
> Yes, I had considered that, but didn''t want the patch to become
bigger
> than necessary. I''m certainly planning on cleaning this up as a
subsequent
> (though lower priority) patch.
Great, thanks!

Ian.


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