Adding upstream version 2.06.upstream/2.06upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 2662 insertions, 0 deletions

diff --git a/grub-core/io/bufio.c b/grub-core/io/bufio.c
new file mode 100644
index 0000000..a458c3a
--- /dev/null
+++ b/grub-core/io/bufio.c
@@ -0,0 +1,214 @@
+/* bufio.c - buffered io access */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2008  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/err.h>
+#include <grub/types.h>
+#include <grub/mm.h>
+#include <grub/misc.h>
+#include <grub/fs.h>
+#include <grub/bufio.h>
+#include <grub/dl.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+#define GRUB_BUFIO_DEF_SIZE	8192
+#define GRUB_BUFIO_MAX_SIZE	1048576
+
+struct grub_bufio
+{
+  grub_file_t file;
+  grub_size_t block_size;
+  grub_size_t buffer_len;
+  grub_off_t buffer_at;
+  char buffer[0];
+};
+typedef struct grub_bufio *grub_bufio_t;
+
+static struct grub_fs grub_bufio_fs;
+
+grub_file_t
+grub_bufio_open (grub_file_t io, grub_size_t size)
+{
+  grub_file_t file;
+  grub_bufio_t bufio = 0;
+
+  file = (grub_file_t) grub_zalloc (sizeof (*file));
+  if (! file)
+    return 0;
+
+  if (size == 0)
+    size = GRUB_BUFIO_DEF_SIZE;
+  else if (size > GRUB_BUFIO_MAX_SIZE)
+    size = GRUB_BUFIO_MAX_SIZE;
+
+  if (size > io->size)
+    size = ((io->size > GRUB_BUFIO_MAX_SIZE) ? GRUB_BUFIO_MAX_SIZE :
+            io->size);
+
+  /*
+   * Round up size to power of 2 which the binary math to
+   * calculate next_buf in grub_bufio_read() requires.
+   */
+  while (size & (size - 1))
+    size = (size | (size - 1)) + 1;
+
+  bufio = grub_zalloc (sizeof (struct grub_bufio) + size);
+  if (! bufio)
+    {
+      grub_free (file);
+      return 0;
+    }
+
+  bufio->file = io;
+  bufio->block_size = size;
+
+  file->device = io->device;
+  file->size = io->size;
+  file->data = bufio;
+  file->fs = &grub_bufio_fs;
+  file->not_easily_seekable = io->not_easily_seekable;
+
+  return file;
+}
+
+grub_file_t
+grub_buffile_open (const char *name, enum grub_file_type type, grub_size_t size)
+{
+  grub_file_t io, file;
+
+  io = grub_file_open (name, type);
+  if (! io)
+    return 0;
+
+  file = grub_bufio_open (io, size);
+  if (! file)
+    {
+      grub_file_close (io);
+      return 0;
+    }
+
+  return file;
+}
+
+static grub_ssize_t
+grub_bufio_read (grub_file_t file, char *buf, grub_size_t len)
+{
+  grub_size_t res = 0;
+  grub_off_t next_buf;
+  grub_bufio_t bufio = file->data;
+  grub_ssize_t really_read;
+
+  if (file->size == GRUB_FILE_SIZE_UNKNOWN)
+    file->size = bufio->file->size;
+
+  /* First part: use whatever we already have in the buffer.  */
+  if ((file->offset >= bufio->buffer_at) &&
+      (file->offset < bufio->buffer_at + bufio->buffer_len))
+    {
+      grub_size_t n;
+      grub_uint64_t pos;
+
+      pos = file->offset - bufio->buffer_at;
+      n = bufio->buffer_len - pos;
+      if (n > len)
+        n = len;
+
+      grub_memcpy (buf, &bufio->buffer[pos], n);
+      len -= n;
+      res += n;
+
+      buf += n;
+    }
+  if (len == 0)
+    return res;
+
+  /* Need to read some more.  */
+  next_buf = (file->offset + res + len - 1) & ~((grub_off_t) bufio->block_size - 1);
+  /* Now read between file->offset + res and bufio->buffer_at.  */
+  if (file->offset + res < next_buf)
+    {
+      grub_size_t read_now;
+      read_now = next_buf - (file->offset + res);
+      grub_file_seek (bufio->file, file->offset + res);
+      really_read = grub_file_read (bufio->file, buf, read_now);
+      if (really_read < 0)
+	return -1;
+      if (file->size == GRUB_FILE_SIZE_UNKNOWN)
+	file->size = bufio->file->size;
+      len -= really_read;
+      buf += really_read;
+      res += really_read;
+
+      /* Partial read. File ended unexpectedly. Save the last chunk in buffer.
+       */
+      if (really_read != (grub_ssize_t) read_now)
+	{
+	  bufio->buffer_len = really_read;
+	  if (bufio->buffer_len > bufio->block_size)
+	    bufio->buffer_len = bufio->block_size;
+	  bufio->buffer_at = file->offset + res - bufio->buffer_len;
+	  grub_memcpy (&bufio->buffer[0], buf - bufio->buffer_len,
+		       bufio->buffer_len);
+	  return res;
+	}
+    }
+
+  /* Read into buffer.  */
+  grub_file_seek (bufio->file, next_buf);
+  really_read = grub_file_read (bufio->file, bufio->buffer,
+				bufio->block_size);
+  if (really_read < 0)
+    return -1;
+  bufio->buffer_at = next_buf;
+  bufio->buffer_len = really_read;
+
+  if (file->size == GRUB_FILE_SIZE_UNKNOWN)
+    file->size = bufio->file->size;
+
+  if (len > bufio->buffer_len)
+    len = bufio->buffer_len;
+  grub_memcpy (buf, &bufio->buffer[file->offset + res - next_buf], len);
+  res += len;
+
+  return res;
+}
+
+static grub_err_t
+grub_bufio_close (grub_file_t file)
+{
+  grub_bufio_t bufio = file->data;
+
+  grub_file_close (bufio->file);
+  grub_free (bufio);
+
+  file->device = 0;
+
+  return grub_errno;
+}
+
+static struct grub_fs grub_bufio_fs =
+  {
+    .name = "bufio",
+    .fs_dir = 0,
+    .fs_open = 0,
+    .fs_read = grub_bufio_read,
+    .fs_close = grub_bufio_close,
+    .fs_label = 0,
+    .next = 0
+  };
diff --git a/grub-core/io/gzio.c b/grub-core/io/gzio.c
new file mode 100644
index 0000000..aea86a0
--- /dev/null
+++ b/grub-core/io/gzio.c
@@ -0,0 +1,1444 @@
+/* gzio.c - decompression support for gzip */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 1999,2005,2006,2007,2009  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * Most of this file was originally the source file "inflate.c", written
+ * by Mark Adler.  It has been very heavily modified.  In particular, the
+ * original would run through the whole file at once, and this version can
+ * be stopped and restarted on any boundary during the decompression process.
+ *
+ * The license and header comments that file are included here.
+ */
+
+/* inflate.c -- Not copyrighted 1992 by Mark Adler
+   version c10p1, 10 January 1993 */
+
+/* You can do whatever you like with this source file, though I would
+   prefer that if you modify it and redistribute it that you include
+   comments to that effect with your name and the date.  Thank you.
+ */
+
+#include <grub/err.h>
+#include <grub/types.h>
+#include <grub/mm.h>
+#include <grub/misc.h>
+#include <grub/fs.h>
+#include <grub/file.h>
+#include <grub/dl.h>
+#include <grub/deflate.h>
+#include <grub/i18n.h>
+#include <grub/crypto.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+/*
+ *  Window Size
+ *
+ *  This must be a power of two, and at least 32K for zip's deflate method
+ */
+
+#define WSIZE	0x8000
+
+
+#define INBUFSIZ  0x2000
+
+/* The state stored in filesystem-specific data.  */
+struct grub_gzio
+{
+  /* The underlying file object.  */
+  grub_file_t file;
+  /* If input is in memory following fields are used instead of file.  */
+  grub_size_t mem_input_size, mem_input_off;
+  grub_uint8_t *mem_input;
+  /* The offset at which the data starts in the underlying file.  */
+  grub_off_t data_offset;
+  /* The type of current block.  */
+  int block_type;
+  /* The length of current block.  */
+  int block_len;
+  /* The flag of the last block.  */
+  int last_block;
+  /* The flag of codes.  */
+  int code_state;
+  /* The length of a copy.  */
+  unsigned inflate_n;
+  /* The index of a copy.  */
+  unsigned inflate_d;
+  /* The input buffer.  */
+  grub_uint8_t inbuf[INBUFSIZ];
+  int inbuf_d;
+  /* The bit buffer.  */
+  unsigned long bb;
+  /* The bits in the bit buffer.  */
+  unsigned bk;
+  /* The sliding window in uncompressed data.  */
+  grub_uint8_t slide[WSIZE];
+  /* Current position in the slide.  */
+  unsigned wp;
+  /* The literal/length code table.  */
+  struct huft *tl;
+  /* The distance code table.  */
+  struct huft *td;
+  /* The checksum algorithm */
+  const gcry_md_spec_t *hdesc;
+  /* The wanted checksum */
+  grub_uint32_t orig_checksum;
+  /* The uncompressed length */
+  grub_size_t orig_len;
+  /* Context for checksum calculation */
+  grub_uint8_t *hcontext;
+  /* The lookup bits for the literal/length code table. */
+  int bl;
+  /* The lookup bits for the distance code table.  */
+  int bd;
+  /* The original offset value.  */
+  grub_off_t saved_offset;
+};
+typedef struct grub_gzio *grub_gzio_t;
+
+/* Declare the filesystem structure for grub_gzio_open.  */
+static struct grub_fs grub_gzio_fs;
+
+/* Function prototypes */
+static void initialize_tables (grub_gzio_t);
+
+/* Eat variable-length header fields.  */
+static int
+eat_field (grub_file_t file, int len)
+{
+  char ch = 1;
+  int not_retval = 1;
+
+  do
+    {
+      if (len >= 0)
+	{
+	  if (! (len--))
+	    break;
+	}
+      else
+	{
+	  if (! ch)
+	    break;
+	}
+    }
+  while ((not_retval = grub_file_read (file, &ch, 1)) == 1);
+
+  return ! not_retval;
+}
+
+
+/* Little-Endian defines for the 2-byte magic numbers for gzip files.  */
+#define GZIP_MAGIC	grub_le_to_cpu16 (0x8B1F)
+#define OLD_GZIP_MAGIC	grub_le_to_cpu16 (0x9E1F)
+
+/* Compression methods (see algorithm.doc) */
+#define GRUB_GZ_STORED      0
+#define GRUB_GZ_COMPRESSED  1
+#define GRUB_GZ_PACKED      2
+#define GRUB_GZ_LZHED       3
+/* methods 4 to 7 reserved */
+#define GRUB_GZ_DEFLATED    8
+#define GRUB_GZ_MAX_METHODS 9
+
+/* gzip flag byte */
+#define GRUB_GZ_ASCII_FLAG   0x01	/* bit 0 set: file probably ascii text */
+#define GRUB_GZ_CONTINUATION 0x02	/* bit 1 set: continuation of multi-part gzip file */
+#define GRUB_GZ_EXTRA_FIELD  0x04	/* bit 2 set: extra field present */
+#define GRUB_GZ_ORIG_NAME    0x08	/* bit 3 set: original file name present */
+#define GRUB_GZ_COMMENT      0x10	/* bit 4 set: file comment present */
+#define GRUB_GZ_ENCRYPTED    0x20	/* bit 5 set: file is encrypted */
+#define GRUB_GZ_RESERVED     0xC0	/* bit 6,7:   reserved */
+
+#define GRUB_GZ_UNSUPPORTED_FLAGS	(GRUB_GZ_CONTINUATION | GRUB_GZ_ENCRYPTED | GRUB_GZ_RESERVED)
+
+/* inflate block codes */
+#define INFLATE_STORED	0
+#define INFLATE_FIXED	1
+#define INFLATE_DYNAMIC	2
+
+typedef unsigned char uch;
+typedef unsigned short ush;
+typedef unsigned long ulg;
+
+static int
+test_gzip_header (grub_file_t file)
+{
+  struct {
+    grub_uint16_t magic;
+    grub_uint8_t method;
+    grub_uint8_t flags;
+    grub_uint32_t timestamp;
+    grub_uint8_t extra_flags;
+    grub_uint8_t os_type;
+  } hdr;
+  grub_uint16_t extra_len;
+  grub_uint32_t crc32;
+  grub_gzio_t gzio = file->data;
+
+  if (grub_file_tell (gzio->file) != 0)
+    grub_file_seek (gzio->file, 0);
+
+  /*
+   *  This checks if the file is gzipped.  If a problem occurs here
+   *  (other than a real error with the disk) then we don't think it
+   *  is a compressed file, and simply mark it as such.
+   */
+  if (grub_file_read (gzio->file, &hdr, 10) != 10
+      || ((hdr.magic != GZIP_MAGIC)
+	  && (hdr.magic != OLD_GZIP_MAGIC)))
+    return 0;
+
+  /*
+   *  This does consistency checking on the header data.  If a
+   *  problem occurs from here on, then we have corrupt or otherwise
+   *  bad data, and the error should be reported to the user.
+   */
+  if (hdr.method != GRUB_GZ_DEFLATED
+      || (hdr.flags & GRUB_GZ_UNSUPPORTED_FLAGS)
+      || ((hdr.flags & GRUB_GZ_EXTRA_FIELD)
+	  && (grub_file_read (gzio->file, &extra_len, 2) != 2
+	      || eat_field (gzio->file,
+			    grub_le_to_cpu16 (extra_len))))
+      || ((hdr.flags & GRUB_GZ_ORIG_NAME) && eat_field (gzio->file, -1))
+      || ((hdr.flags & GRUB_GZ_COMMENT) && eat_field (gzio->file, -1)))
+    return 0;
+
+  gzio->data_offset = grub_file_tell (gzio->file);
+
+  /* FIXME: don't do this on not easily seekable files.  */
+  {
+    grub_file_seek (gzio->file, grub_file_size (gzio->file) - 8);
+    if (grub_file_read (gzio->file, &crc32, 4) != 4)
+      return 0;
+    gzio->orig_checksum = grub_le_to_cpu32 (crc32);
+    if (grub_file_read (gzio->file, &gzio->orig_len, 4) != 4)
+      return 0;
+    /* FIXME: this does not handle files whose original size is over 4GB.
+       But how can we know the real original size?  */
+    file->size = grub_le_to_cpu32 (gzio->orig_len);
+  }
+
+  initialize_tables (gzio);
+
+  return 1;
+}
+
+
+/* Huffman code lookup table entry--this entry is four bytes for machines
+   that have 16-bit pointers (e.g. PC's in the small or medium model).
+   Valid extra bits are 0..13.  e == 15 is EOB (end of block), e == 16
+   means that v is a literal, 16 < e < 32 means that v is a pointer to
+   the next table, which codes e - 16 bits, and lastly e == 99 indicates
+   an unused code.  If a code with e == 99 is looked up, this implies an
+   error in the data. */
+struct huft
+{
+  uch e;			/* number of extra bits or operation */
+  uch b;			/* number of bits in this code or subcode */
+  union
+    {
+      ush n;			/* literal, length base, or distance base */
+      struct huft *t;		/* pointer to next level of table */
+    }
+  v;
+};
+
+
+/* The inflate algorithm uses a sliding 32K byte window on the uncompressed
+   stream to find repeated byte strings.  This is implemented here as a
+   circular buffer.  The index is updated simply by incrementing and then
+   and'ing with 0x7fff (32K-1). */
+/* It is left to other modules to supply the 32K area.  It is assumed
+   to be usable as if it were declared "uch slide[32768];" or as just
+   "uch *slide;" and then malloc'ed in the latter case.  The definition
+   must be in unzip.h, included above. */
+
+
+/* Tables for deflate from PKZIP's appnote.txt. */
+static unsigned bitorder[] =
+{				/* Order of the bit length code lengths */
+  16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
+static ush cplens[] =
+{				/* Copy lengths for literal codes 257..285 */
+  3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
+  35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
+	/* note: see note #13 above about the 258 in this list. */
+static ush cplext[] =
+{				/* Extra bits for literal codes 257..285 */
+  0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
+  3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99};	/* 99==invalid */
+static ush cpdist[] =
+{				/* Copy offsets for distance codes 0..29 */
+  1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
+  257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
+  8193, 12289, 16385, 24577};
+static ush cpdext[] =
+{				/* Extra bits for distance codes */
+  0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
+  7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
+  12, 12, 13, 13};
+
+
+/*
+   Huffman code decoding is performed using a multi-level table lookup.
+   The fastest way to decode is to simply build a lookup table whose
+   size is determined by the longest code.  However, the time it takes
+   to build this table can also be a factor if the data being decoded
+   is not very long.  The most common codes are necessarily the
+   shortest codes, so those codes dominate the decoding time, and hence
+   the speed.  The idea is you can have a shorter table that decodes the
+   shorter, more probable codes, and then point to subsidiary tables for
+   the longer codes.  The time it costs to decode the longer codes is
+   then traded against the time it takes to make longer tables.
+
+   This results of this trade are in the variables lbits and dbits
+   below.  lbits is the number of bits the first level table for literal/
+   length codes can decode in one step, and dbits is the same thing for
+   the distance codes.  Subsequent tables are also less than or equal to
+   those sizes.  These values may be adjusted either when all of the
+   codes are shorter than that, in which case the longest code length in
+   bits is used, or when the shortest code is *longer* than the requested
+   table size, in which case the length of the shortest code in bits is
+   used.
+
+   There are two different values for the two tables, since they code a
+   different number of possibilities each.  The literal/length table
+   codes 286 possible values, or in a flat code, a little over eight
+   bits.  The distance table codes 30 possible values, or a little less
+   than five bits, flat.  The optimum values for speed end up being
+   about one bit more than those, so lbits is 8+1 and dbits is 5+1.
+   The optimum values may differ though from machine to machine, and
+   possibly even between compilers.  Your mileage may vary.
+ */
+
+
+static int lbits = 9;		/* bits in base literal/length lookup table */
+static int dbits = 6;		/* bits in base distance lookup table */
+
+
+/* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
+#define BMAX 16			/* maximum bit length of any code (16 for explode) */
+#define N_MAX 288		/* maximum number of codes in any set */
+
+
+/* Macros for inflate() bit peeking and grabbing.
+   The usage is:
+
+        NEEDBITS(j)
+        x = b & mask_bits[j];
+        DUMPBITS(j)
+
+   where NEEDBITS makes sure that b has at least j bits in it, and
+   DUMPBITS removes the bits from b.  The macros use the variable k
+   for the number of bits in b.  Normally, b and k are register
+   variables for speed, and are initialized at the beginning of a
+   routine that uses these macros from a global bit buffer and count.
+
+   If we assume that EOB will be the longest code, then we will never
+   ask for bits with NEEDBITS that are beyond the end of the stream.
+   So, NEEDBITS should not read any more bytes than are needed to
+   meet the request.  Then no bytes need to be "returned" to the buffer
+   at the end of the last block.
+
+   However, this assumption is not true for fixed blocks--the EOB code
+   is 7 bits, but the other literal/length codes can be 8 or 9 bits.
+   (The EOB code is shorter than other codes because fixed blocks are
+   generally short.  So, while a block always has an EOB, many other
+   literal/length codes have a significantly lower probability of
+   showing up at all.)  However, by making the first table have a
+   lookup of seven bits, the EOB code will be found in that first
+   lookup, and so will not require that too many bits be pulled from
+   the stream.
+ */
+
+static ush mask_bits[] =
+{
+  0x0000,
+  0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
+  0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
+};
+
+#define NEEDBITS(n) do {while(k<(n)){b|=((ulg)get_byte(gzio))<<k;k+=8;}} while (0)
+#define DUMPBITS(n) do {b>>=(n);k-=(n);} while (0)
+
+static int
+get_byte (grub_gzio_t gzio)
+{
+  if (gzio->mem_input)
+    {
+      if (gzio->mem_input_off < gzio->mem_input_size)
+	return gzio->mem_input[gzio->mem_input_off++];
+      return 0;
+    }
+
+  if (gzio->file && (grub_file_tell (gzio->file)
+		     == (grub_off_t) gzio->data_offset
+		     || gzio->inbuf_d == INBUFSIZ))
+    {
+      gzio->inbuf_d = 0;
+      grub_file_read (gzio->file, gzio->inbuf, INBUFSIZ);
+    }
+
+  return gzio->inbuf[gzio->inbuf_d++];
+}
+
+static void
+gzio_seek (grub_gzio_t gzio, grub_off_t off)
+{
+  if (gzio->mem_input)
+    {
+      if (off > gzio->mem_input_size)
+	grub_error (GRUB_ERR_OUT_OF_RANGE,
+		    N_("attempt to seek outside of the file"));
+      else
+	gzio->mem_input_off = off;
+    }
+  else
+    grub_file_seek (gzio->file, off);
+}
+
+/* more function prototypes */
+static int huft_build (unsigned *, unsigned, unsigned, ush *, ush *,
+		       struct huft **, int *);
+static int huft_free (struct huft *);
+static int inflate_codes_in_window (grub_gzio_t);
+
+
+/* Given a list of code lengths and a maximum table size, make a set of
+   tables to decode that set of codes.  Return zero on success, one if
+   the given code set is incomplete (the tables are still built in this
+   case), two if the input is invalid (all zero length codes or an
+   oversubscribed set of lengths), and three if not enough memory. */
+
+static int
+huft_build (unsigned *b,	/* code lengths in bits (all assumed <= BMAX) */
+	    unsigned n,		/* number of codes (assumed <= N_MAX) */
+	    unsigned s,		/* number of simple-valued codes (0..s-1) */
+	    ush * d,		/* list of base values for non-simple codes */
+	    ush * e,		/* list of extra bits for non-simple codes */
+	    struct huft **t,	/* result: starting table */
+	    int *m)		/* maximum lookup bits, returns actual */
+{
+  unsigned a;			/* counter for codes of length k */
+  unsigned c[BMAX + 1];		/* bit length count table */
+  unsigned f;			/* i repeats in table every f entries */
+  int g;			/* maximum code length */
+  int h;			/* table level */
+  register unsigned i;		/* counter, current code */
+  register unsigned j;		/* counter */
+  register int k;		/* number of bits in current code */
+  int l;			/* bits per table (returned in m) */
+  register unsigned *p;		/* pointer into c[], b[], or v[] */
+  register struct huft *q;	/* points to current table */
+  struct huft r;		/* table entry for structure assignment */
+  struct huft *u[BMAX];		/* table stack */
+  unsigned v[N_MAX];		/* values in order of bit length */
+  register int w;		/* bits before this table == (l * h) */
+  unsigned x[BMAX + 1];		/* bit offsets, then code stack */
+  unsigned *xp;			/* pointer into x */
+  int y;			/* number of dummy codes added */
+  unsigned z;			/* number of entries in current table */
+
+  /* Generate counts for each bit length */
+  grub_memset ((char *) c, 0, sizeof (c));
+  p = b;
+  i = n;
+  do
+    {
+      c[*p]++;			/* assume all entries <= BMAX */
+      p++;			/* Can't combine with above line (Solaris bug) */
+    }
+  while (--i);
+  if (c[0] == n)		/* null input--all zero length codes */
+    {
+      *t = (struct huft *) NULL;
+      *m = 0;
+      return 0;
+    }
+
+  /* Find minimum and maximum length, bound *m by those */
+  l = *m;
+  for (j = 1; j <= BMAX; j++)
+    if (c[j])
+      break;
+  k = j;			/* minimum code length */
+  if ((unsigned) l < j)
+    l = j;
+  for (i = BMAX; i; i--)
+    if (c[i])
+      break;
+  g = i;			/* maximum code length */
+  if ((unsigned) l > i)
+    l = i;
+  *m = l;
+
+  /* Adjust last length count to fill out codes, if needed */
+  for (y = 1 << j; j < i; j++, y <<= 1)
+    if ((y -= c[j]) < 0)
+      return 2;			/* bad input: more codes than bits */
+  if ((y -= c[i]) < 0)
+    return 2;
+  c[i] += y;
+
+  /* Generate starting offsets into the value table for each length */
+  x[1] = j = 0;
+  p = c + 1;
+  xp = x + 2;
+  while (--i)
+    {				/* note that i == g from above */
+      *xp++ = (j += *p++);
+    }
+
+  /* Make a table of values in order of bit lengths */
+  grub_memset (v, N_MAX, ARRAY_SIZE (v));
+  p = b;
+  i = 0;
+  do
+    {
+      if ((j = *p++) != 0)
+	v[x[j]++] = i;
+    }
+  while (++i < n);
+
+  /* Generate the Huffman codes and for each, make the table entries */
+  x[0] = i = 0;			/* first Huffman code is zero */
+  p = v;			/* grab values in bit order */
+  h = -1;			/* no tables yet--level -1 */
+  w = -l;			/* bits decoded == (l * h) */
+  u[0] = (struct huft *) NULL;	/* just to keep compilers happy */
+  q = (struct huft *) NULL;	/* ditto */
+  z = 0;			/* ditto */
+
+  /* go through the bit lengths (k already is bits in shortest code) */
+  for (; k <= g; k++)
+    {
+      a = c[k];
+      while (a--)
+	{
+	  /* here i is the Huffman code of length k bits for value *p */
+	  /* make tables up to required level */
+	  while (k > w + l)
+	    {
+	      h++;
+	      w += l;		/* previous table always l bits */
+
+	      /* compute minimum size table less than or equal to l bits */
+	      z = (z = (unsigned) (g - w)) > (unsigned) l ? (unsigned) l : z;	/* upper limit on table size */
+	      if ((f = 1 << (j = k - w)) > a + 1)	/* try a k-w bit table */
+		{		/* too few codes for k-w bit table */
+		  f -= a + 1;	/* deduct codes from patterns left */
+		  xp = c + k;
+		  while (++j < z)	/* try smaller tables up to z bits */
+		    {
+		      if ((f <<= 1) <= *++xp)
+			break;	/* enough codes to use up j bits */
+		      f -= *xp;	/* else deduct codes from patterns */
+		    }
+		}
+	      z = 1 << j;	/* table entries for j-bit table */
+
+	      /* allocate and link in new table */
+	      q = (struct huft *) grub_calloc (z + 1, sizeof (struct huft));
+	      if (! q)
+		{
+		  if (h)
+		    huft_free (u[0]);
+		  return 3;
+		}
+
+	      *t = q + 1;	/* link to list for huft_free() */
+	      *(t = &(q->v.t)) = (struct huft *) NULL;
+	      u[h] = ++q;	/* table starts after link */
+
+	      /* connect to last table, if there is one */
+	      if (h)
+		{
+		  x[h] = i;	/* save pattern for backing up */
+		  r.b = (uch) l;	/* bits to dump before this table */
+		  r.e = (uch) (16 + j);		/* bits in this table */
+		  r.v.t = q;	/* pointer to this table */
+		  j = i >> (w - l);	/* (get around Turbo C bug) */
+		  u[h - 1][j] = r;	/* connect to last table */
+		}
+	    }
+
+	  /* set up table entry in r */
+	  r.b = (uch) (k - w);
+	  if (p >= v + n)
+	    r.e = 99;		/* out of values--invalid code */
+	  else if (*p < s)
+	    {
+	      r.e = (uch) (*p < 256 ? 16 : 15);		/* 256 is end-of-block code */
+	      r.v.n = (ush) (*p);	/* simple code is just the value */
+	      p++;		/* one compiler does not like *p++ */
+	    }
+	  else if (*p < N_MAX)
+	    {
+	      r.e = (uch) e[*p - s];	/* non-simple--look up in lists */
+	      r.v.n = d[*p++ - s];
+	    }
+	  else
+	    {
+	      /* Detected an uninitialised value, abort. */
+	      if (h)
+		huft_free (u[0]);
+	      return 2;
+	    }
+
+	  /* fill code-like entries with r */
+	  f = 1 << (k - w);
+	  for (j = i >> w; j < z; j += f)
+	    q[j] = r;
+
+	  /* backwards increment the k-bit code i */
+	  for (j = 1 << (k - 1); i & j; j >>= 1)
+	    i ^= j;
+	  i ^= j;
+
+	  /* backup over finished tables */
+	  while ((i & ((1 << w) - 1)) != x[h])
+	    {
+	      h--;		/* don't need to update q */
+	      w -= l;
+	    }
+	}
+    }
+
+  /* Return true (1) if we were given an incomplete table */
+  return y != 0 && g != 1;
+}
+
+
+/* Free the malloc'ed tables built by huft_build(), which makes a linked
+   list of the tables it made, with the links in a dummy first entry of
+   each table.  */
+static int
+huft_free (struct huft *t)
+{
+  register struct huft *p, *q;
+
+
+  /* Go through linked list, freeing from the malloced (t[-1]) address. */
+  p = t;
+  while (p != (struct huft *) NULL)
+    {
+      q = (--p)->v.t;
+      grub_free ((char *) p);
+      p = q;
+    }
+  return 0;
+}
+
+
+/*
+ *  inflate (decompress) the codes in a deflated (compressed) block.
+ *  Return an error code or zero if it all goes ok.
+ */
+
+static int
+inflate_codes_in_window (grub_gzio_t gzio)
+{
+  register unsigned e;		/* table entry flag/number of extra bits */
+  unsigned n, d;		/* length and index for copy */
+  unsigned w;			/* current window position */
+  struct huft *t;		/* pointer to table entry */
+  unsigned ml, md;		/* masks for bl and bd bits */
+  register ulg b;		/* bit buffer */
+  register unsigned k;		/* number of bits in bit buffer */
+
+  /* make local copies of globals */
+  d = gzio->inflate_d;
+  n = gzio->inflate_n;
+  b = gzio->bb;			/* initialize bit buffer */
+  k = gzio->bk;
+  w = gzio->wp;			/* initialize window position */
+
+  /* inflate the coded data */
+  ml = mask_bits[gzio->bl];		/* precompute masks for speed */
+  md = mask_bits[gzio->bd];
+  for (;;)			/* do until end of block */
+    {
+      if (! gzio->code_state)
+	{
+
+	  if (gzio->tl == NULL)
+	    {
+	      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "NULL gzio->tl");
+	      return 1;
+	    }
+
+	  NEEDBITS ((unsigned) gzio->bl);
+	  if ((e = (t = gzio->tl + ((unsigned) b & ml))->e) > 16)
+	    do
+	      {
+		if (e == 99)
+		  {
+		    grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+				"an unused code found");
+		    return 1;
+		  }
+		DUMPBITS (t->b);
+		e -= 16;
+		NEEDBITS (e);
+	      }
+	    while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
+	  DUMPBITS (t->b);
+
+	  if (e == 16)		/* then it's a literal */
+	    {
+	      gzio->slide[w++] = (uch) t->v.n;
+	      if (w == WSIZE)
+		break;
+	    }
+	  else
+	    /* it's an EOB or a length */
+	    {
+	      /* exit if end of block */
+	      if (e == 15)
+		{
+		  gzio->block_len = 0;
+		  break;
+		}
+
+	      /* get length of block to copy */
+	      NEEDBITS (e);
+	      n = t->v.n + ((unsigned) b & mask_bits[e]);
+	      DUMPBITS (e);
+
+	      if (gzio->td == NULL)
+		{
+		  grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "NULL gzio->td");
+		  return 1;
+		}
+
+	      /* decode distance of block to copy */
+	      NEEDBITS ((unsigned) gzio->bd);
+	      if ((e = (t = gzio->td + ((unsigned) b & md))->e) > 16)
+		do
+		  {
+		    if (e == 99)
+		      {
+			grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+				    "an unused code found");
+			return 1;
+		      }
+		    DUMPBITS (t->b);
+		    e -= 16;
+		    NEEDBITS (e);
+		  }
+		while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e)
+		       > 16);
+	      DUMPBITS (t->b);
+	      NEEDBITS (e);
+	      d = w - t->v.n - ((unsigned) b & mask_bits[e]);
+	      DUMPBITS (e);
+	      gzio->code_state++;
+	    }
+	}
+
+      if (gzio->code_state)
+	{
+	  /* do the copy */
+	  do
+	    {
+	      n -= (e = (e = WSIZE - ((d &= WSIZE - 1) > w ? d : w)) > n ? n
+		    : e);
+
+	      if (w - d >= e)
+		{
+		  grub_memmove (gzio->slide + w, gzio->slide + d, e);
+		  w += e;
+		  d += e;
+		}
+	      else
+		/* purposefully use the overlap for extra copies here!! */
+		{
+		  while (e--)
+		    gzio->slide[w++] = gzio->slide[d++];
+		}
+
+	      if (w == WSIZE)
+		break;
+	    }
+	  while (n);
+
+	  if (! n)
+	    gzio->code_state--;
+
+	  /* did we break from the loop too soon? */
+	  if (w == WSIZE)
+	    break;
+	}
+    }
+
+  /* restore the globals from the locals */
+  gzio->inflate_d = d;
+  gzio->inflate_n = n;
+  gzio->wp = w;			/* restore global window pointer */
+  gzio->bb = b;			/* restore global bit buffer */
+  gzio->bk = k;
+
+  return ! gzio->block_len;
+}
+
+
+/* get header for an inflated type 0 (stored) block. */
+
+static void
+init_stored_block (grub_gzio_t gzio)
+{
+  register ulg b;		/* bit buffer */
+  register unsigned k;		/* number of bits in bit buffer */
+
+  /* make local copies of globals */
+  b = gzio->bb;			/* initialize bit buffer */
+  k = gzio->bk;
+
+  /* go to byte boundary */
+  DUMPBITS (k & 7);
+
+  /* get the length and its complement */
+  NEEDBITS (16);
+  gzio->block_len = ((unsigned) b & 0xffff);
+  DUMPBITS (16);
+  NEEDBITS (16);
+  if (gzio->block_len != (int) ((~b) & 0xffff))
+    grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+		"the length of a stored block does not match");
+  DUMPBITS (16);
+
+  /* restore global variables */
+  gzio->bb = b;
+  gzio->bk = k;
+}
+
+
+/* get header for an inflated type 1 (fixed Huffman codes) block.  We should
+   either replace this with a custom decoder, or at least precompute the
+   Huffman tables. */
+
+static void
+init_fixed_block (grub_gzio_t gzio)
+{
+  int i;			/* temporary variable */
+  unsigned l[288];		/* length list for huft_build */
+
+  /* set up literal table */
+  for (i = 0; i < 144; i++)
+    l[i] = 8;
+  for (; i < 256; i++)
+    l[i] = 9;
+  for (; i < 280; i++)
+    l[i] = 7;
+  for (; i < 288; i++)		/* make a complete, but wrong code set */
+    l[i] = 8;
+  gzio->bl = 7;
+  if (huft_build (l, 288, 257, cplens, cplext, &gzio->tl, &gzio->bl) != 0)
+    {
+      if (grub_errno == GRUB_ERR_NONE)
+	grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+		    "failed in building a Huffman code table");
+      return;
+    }
+
+  /* set up distance table */
+  for (i = 0; i < 30; i++)	/* make an incomplete code set */
+    l[i] = 5;
+  gzio->bd = 5;
+  if (huft_build (l, 30, 0, cpdist, cpdext, &gzio->td, &gzio->bd) > 1)
+    {
+      if (grub_errno == GRUB_ERR_NONE)
+	grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+		    "failed in building a Huffman code table");
+      huft_free (gzio->tl);
+      gzio->tl = 0;
+      return;
+    }
+
+  /* indicate we're now working on a block */
+  gzio->code_state = 0;
+  gzio->block_len++;
+}
+
+
+/* get header for an inflated type 2 (dynamic Huffman codes) block. */
+
+static void
+init_dynamic_block (grub_gzio_t gzio)
+{
+  int i;			/* temporary variables */
+  unsigned j;
+  unsigned l;			/* last length */
+  unsigned m;			/* mask for bit lengths table */
+  unsigned n;			/* number of lengths to get */
+  unsigned nb;			/* number of bit length codes */
+  unsigned nl;			/* number of literal/length codes */
+  unsigned nd;			/* number of distance codes */
+  unsigned ll[286 + 30];	/* literal/length and distance code lengths */
+  register ulg b;		/* bit buffer */
+  register unsigned k;		/* number of bits in bit buffer */
+
+  /* make local bit buffer */
+  b = gzio->bb;
+  k = gzio->bk;
+
+  /* read in table lengths */
+  NEEDBITS (5);
+  nl = 257 + ((unsigned) b & 0x1f);	/* number of literal/length codes */
+  DUMPBITS (5);
+  NEEDBITS (5);
+  nd = 1 + ((unsigned) b & 0x1f);	/* number of distance codes */
+  DUMPBITS (5);
+  NEEDBITS (4);
+  nb = 4 + ((unsigned) b & 0xf);	/* number of bit length codes */
+  DUMPBITS (4);
+  if (nl > 286 || nd > 30)
+    {
+      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too much data");
+      return;
+    }
+
+  /* read in bit-length-code lengths */
+  for (j = 0; j < nb; j++)
+    {
+      NEEDBITS (3);
+      ll[bitorder[j]] = (unsigned) b & 7;
+      DUMPBITS (3);
+    }
+  for (; j < 19; j++)
+    ll[bitorder[j]] = 0;
+
+  /* build decoding table for trees--single level, 7 bit lookup */
+  gzio->bl = 7;
+  if (huft_build (ll, 19, 19, NULL, NULL, &gzio->tl, &gzio->bl) != 0)
+    {
+      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+		  "failed in building a Huffman code table");
+      return;
+    }
+
+  /* read in literal and distance code lengths */
+  n = nl + nd;
+  m = mask_bits[gzio->bl];
+  i = l = 0;
+
+  if (gzio->tl == NULL)
+    {
+      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "NULL gzio->tl");
+      return;
+    }
+
+  while ((unsigned) i < n)
+    {
+      NEEDBITS ((unsigned) gzio->bl);
+      j = (gzio->td = gzio->tl + ((unsigned) b & m))->b;
+      DUMPBITS (j);
+      j = gzio->td->v.n;
+      if (j < 16)		/* length of code in bits (0..15) */
+	ll[i++] = l = j;	/* save last length in l */
+      else if (j == 16)		/* repeat last length 3 to 6 times */
+	{
+	  NEEDBITS (2);
+	  j = 3 + ((unsigned) b & 3);
+	  DUMPBITS (2);
+	  if ((unsigned) i + j > n)
+	    {
+	      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too many codes found");
+	      goto fail;
+	    }
+	  while (j--)
+	    ll[i++] = l;
+	}
+      else if (j == 17)		/* 3 to 10 zero length codes */
+	{
+	  NEEDBITS (3);
+	  j = 3 + ((unsigned) b & 7);
+	  DUMPBITS (3);
+	  if ((unsigned) i + j > n)
+	    {
+	      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too many codes found");
+	      goto fail;
+	    }
+	  while (j--)
+	    ll[i++] = 0;
+	  l = 0;
+	}
+      else
+	/* j == 18: 11 to 138 zero length codes */
+	{
+	  NEEDBITS (7);
+	  j = 11 + ((unsigned) b & 0x7f);
+	  DUMPBITS (7);
+	  if ((unsigned) i + j > n)
+	    {
+	      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too many codes found");
+	      goto fail;
+	    }
+	  while (j--)
+	    ll[i++] = 0;
+	  l = 0;
+	}
+    }
+
+  /* free decoding table for trees */
+  huft_free (gzio->tl);
+  gzio->td = 0;
+  gzio->tl = 0;
+
+  /* restore the global bit buffer */
+  gzio->bb = b;
+  gzio->bk = k;
+
+  /* build the decoding tables for literal/length and distance codes */
+  gzio->bl = lbits;
+  if (huft_build (ll, nl, 257, cplens, cplext, &gzio->tl, &gzio->bl) != 0)
+    {
+      gzio->tl = 0;
+      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+		  "failed in building a Huffman code table");
+      return;
+    }
+  gzio->bd = dbits;
+  if (huft_build (ll + nl, nd, 0, cpdist, cpdext, &gzio->td, &gzio->bd) != 0)
+    {
+      huft_free (gzio->tl);
+      gzio->tl = 0;
+      gzio->td = 0;
+      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+		  "failed in building a Huffman code table");
+      return;
+    }
+
+  /* indicate we're now working on a block */
+  gzio->code_state = 0;
+  gzio->block_len++;
+  return;
+
+ fail:
+  huft_free (gzio->tl);
+  gzio->td = NULL;
+  gzio->tl = NULL;
+}
+
+
+static void
+get_new_block (grub_gzio_t gzio)
+{
+  register ulg b;		/* bit buffer */
+  register unsigned k;		/* number of bits in bit buffer */
+
+  /* make local bit buffer */
+  b = gzio->bb;
+  k = gzio->bk;
+
+  /* read in last block bit */
+  NEEDBITS (1);
+  gzio->last_block = (int) b & 1;
+  DUMPBITS (1);
+
+  /* read in block type */
+  NEEDBITS (2);
+  gzio->block_type = (unsigned) b & 3;
+  DUMPBITS (2);
+
+  /* restore the global bit buffer */
+  gzio->bb = b;
+  gzio->bk = k;
+
+  switch (gzio->block_type)
+    {
+    case INFLATE_STORED:
+      init_stored_block (gzio);
+      break;
+    case INFLATE_FIXED:
+      init_fixed_block (gzio);
+      break;
+    case INFLATE_DYNAMIC:
+      init_dynamic_block (gzio);
+      break;
+    default:
+      break;
+    }
+}
+
+
+static void
+inflate_window (grub_gzio_t gzio)
+{
+  /* initialize window */
+  gzio->wp = 0;
+
+  /*
+   *  Main decompression loop.
+   */
+
+  while (gzio->wp < WSIZE && grub_errno == GRUB_ERR_NONE)
+    {
+      if (! gzio->block_len)
+	{
+	  if (gzio->last_block)
+	    break;
+
+	  get_new_block (gzio);
+	}
+
+      if (gzio->block_type > INFLATE_DYNAMIC)
+	grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+		    "unknown block type %d", gzio->block_type);
+
+      if (grub_errno != GRUB_ERR_NONE)
+	return;
+
+      /*
+       *  Expand stored block here.
+       */
+      if (gzio->block_type == INFLATE_STORED)
+	{
+	  int w = gzio->wp;
+
+	  /*
+	   *  This is basically a glorified pass-through
+	   */
+
+	  while (gzio->block_len && w < WSIZE && grub_errno == GRUB_ERR_NONE)
+	    {
+	      gzio->slide[w++] = get_byte (gzio);
+	      gzio->block_len--;
+	    }
+
+	  gzio->wp = w;
+
+	  continue;
+	}
+
+      /*
+       *  Expand other kind of block.
+       */
+
+      if (inflate_codes_in_window (gzio))
+	{
+	  huft_free (gzio->tl);
+	  huft_free (gzio->td);
+	  gzio->tl = 0;
+	  gzio->td = 0;
+	}
+    }
+
+  gzio->saved_offset += gzio->wp;
+
+  if (gzio->hcontext)
+    {
+      gzio->hdesc->write (gzio->hcontext, gzio->slide, gzio->wp);
+
+      if (gzio->saved_offset == gzio->orig_len)
+	{
+	  grub_uint32_t csum;
+
+	  gzio->hdesc->final (gzio->hcontext);
+	  csum = grub_get_unaligned32 (gzio->hdesc->read (gzio->hcontext));
+	  csum = grub_be_to_cpu32 (csum);
+	  if (csum != gzio->orig_checksum)
+	    grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+			"checksum mismatch %08x/%08x",
+			gzio->orig_checksum, csum);
+	}
+    }
+}
+
+
+static void
+initialize_tables (grub_gzio_t gzio)
+{
+  gzio->saved_offset = 0;
+  gzio_seek (gzio, gzio->data_offset);
+
+  /* Initialize the bit buffer.  */
+  gzio->bk = 0;
+  gzio->bb = 0;
+
+  /* Reset partial decompression code.  */
+  gzio->last_block = 0;
+  gzio->block_len = 0;
+
+  /* Reset memory allocation stuff.  */
+  huft_free (gzio->tl);
+  huft_free (gzio->td);
+  gzio->tl = NULL;
+  gzio->td = NULL;
+
+  if (gzio->hcontext)
+    gzio->hdesc->init(gzio->hcontext);
+}
+
+
+/* Open a new decompressing object on the top of IO. If TRANSPARENT is true,
+   even if IO does not contain data compressed by gzip, return a valid file
+   object. Note that this function won't close IO, even if an error occurs.  */
+static grub_file_t
+grub_gzio_open (grub_file_t io, enum grub_file_type type)
+{
+  grub_file_t file;
+  grub_gzio_t gzio = 0;
+
+  if (type & GRUB_FILE_TYPE_NO_DECOMPRESS)
+    return io;
+
+  file = (grub_file_t) grub_zalloc (sizeof (*file));
+  if (! file)
+    return 0;
+
+  gzio = grub_zalloc (sizeof (*gzio));
+  if (! gzio)
+    {
+      grub_free (file);
+      return 0;
+    }
+
+  gzio->file = io;
+
+  gzio->hdesc = GRUB_MD_CRC32;
+  gzio->hcontext = grub_malloc(gzio->hdesc->contextsize);
+
+  file->device = io->device;
+  file->data = gzio;
+  file->fs = &grub_gzio_fs;
+  file->not_easily_seekable = 1;
+
+  if (! test_gzip_header (file))
+    {
+      grub_errno = GRUB_ERR_NONE;
+      grub_free (gzio->hcontext);
+      grub_free (gzio);
+      grub_free (file);
+      grub_file_seek (io, 0);
+
+      return io;
+    }
+
+  return file;
+}
+
+static grub_uint8_t
+mod_31 (grub_uint16_t v)
+{
+  /* At most 2 iterations for any number that
+     we can get here.
+     In any case faster than real division.  */
+  while (v > 0x1f)
+    v = (v & 0x1f) + (v >> 5);
+  if (v == 0x1f)
+    return 0;
+  return v;
+}
+
+static int
+test_zlib_header (grub_gzio_t gzio)
+{
+  grub_uint8_t cmf, flg;
+  
+  cmf = get_byte (gzio);
+  flg = get_byte (gzio);
+
+  /* Check that compression method is DEFLATE.  */
+  if ((cmf & 0xf) != GRUB_GZ_DEFLATED)
+    {
+      /* TRANSLATORS: It's about given file having some strange format, not
+	 complete lack of gzip support.  */
+      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, N_("unsupported gzip format"));
+      return 0;
+    }
+
+  /* Usually it would be: (cmf * 256 + flg) % 31 != 0.  */
+  /* But 256 == 8 (31).  */
+  /* By multiplying by 4 and using 32 == 1 (31). We get our formula.  */
+  if (mod_31 (cmf + flg * 4) != 0)
+    {
+      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, N_("unsupported gzip format"));
+      return 0;
+    }
+
+  /* Dictionary isn't supported.  */
+  if (flg & 0x20)
+    {
+      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, N_("unsupported gzip format"));
+      return 0;
+    }
+
+  gzio->data_offset = 2;
+  initialize_tables (gzio);
+
+  return 1;
+}
+
+static grub_ssize_t
+grub_gzio_read_real (grub_gzio_t gzio, grub_off_t offset,
+		     char *buf, grub_size_t len)
+{
+  grub_ssize_t ret = 0;
+
+  /* Do we reset decompression to the beginning of the file?  */
+  if (gzio->saved_offset > offset + WSIZE)
+    initialize_tables (gzio);
+
+  /*
+   *  This loop operates upon uncompressed data only.  The only
+   *  special thing it does is to make sure the decompression
+   *  window is within the range of data it needs.
+   */
+
+  while (len > 0 && grub_errno == GRUB_ERR_NONE)
+    {
+      register grub_size_t size;
+      register char *srcaddr;
+
+      while (offset >= gzio->saved_offset)
+	{
+	  inflate_window (gzio);
+	  if (gzio->wp == 0)
+	    goto out;
+	}
+
+      if (gzio->wp == 0)
+	goto out;
+
+      srcaddr = (char *) ((offset & (WSIZE - 1)) + gzio->slide);
+      size = gzio->saved_offset - offset;
+      if (size > len)
+	size = len;
+
+      grub_memmove (buf, srcaddr, size);
+
+      buf += size;
+      len -= size;
+      ret += size;
+      offset += size;
+    }
+
+ out:
+  if (grub_errno != GRUB_ERR_NONE)
+    ret = -1;
+
+  return ret;
+}
+
+static grub_ssize_t
+grub_gzio_read (grub_file_t file, char *buf, grub_size_t len)
+{
+  grub_ssize_t ret;
+  ret = grub_gzio_read_real (file->data, file->offset, buf, len);
+
+  if (!grub_errno && ret != (grub_ssize_t) len)
+    {
+      grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "premature end of compressed");
+      ret = -1;
+    }
+  return ret;
+}
+
+/* Release everything, including the underlying file object.  */
+static grub_err_t
+grub_gzio_close (grub_file_t file)
+{
+  grub_gzio_t gzio = file->data;
+
+  grub_file_close (gzio->file);
+  huft_free (gzio->tl);
+  huft_free (gzio->td);
+  grub_free (gzio->hcontext);
+  grub_free (gzio);
+
+  /* No need to close the same device twice.  */
+  file->device = 0;
+  file->name = 0;
+
+  return grub_errno;
+}
+
+grub_ssize_t
+grub_zlib_decompress (char *inbuf, grub_size_t insize, grub_off_t off,
+		      char *outbuf, grub_size_t outsize)
+{
+  grub_gzio_t gzio = 0;
+  grub_ssize_t ret;
+
+  gzio = grub_zalloc (sizeof (*gzio));
+  if (! gzio)
+    return -1;
+  gzio->mem_input = (grub_uint8_t *) inbuf;
+  gzio->mem_input_size = insize;
+  gzio->mem_input_off = 0;
+
+  if (!test_zlib_header (gzio))
+    {
+      grub_free (gzio);
+      return -1;
+    }
+
+  ret = grub_gzio_read_real (gzio, off, outbuf, outsize);
+  grub_free (gzio);
+
+  /* FIXME: Check Adler.  */
+  return ret;
+}
+
+grub_ssize_t
+grub_deflate_decompress (char *inbuf, grub_size_t insize, grub_off_t off,
+			 char *outbuf, grub_size_t outsize)
+{
+  grub_gzio_t gzio = 0;
+  grub_ssize_t ret;
+
+  gzio = grub_zalloc (sizeof (*gzio));
+  if (! gzio)
+    return -1;
+  gzio->mem_input = (grub_uint8_t *) inbuf;
+  gzio->mem_input_size = insize;
+  gzio->mem_input_off = 0;
+
+  initialize_tables (gzio);
+
+  ret = grub_gzio_read_real (gzio, off, outbuf, outsize);
+  grub_free (gzio);
+
+  return ret;
+}
+
+
+
+static struct grub_fs grub_gzio_fs =
+  {
+    .name = "gzio",
+    .fs_dir = 0,
+    .fs_open = 0,
+    .fs_read = grub_gzio_read,
+    .fs_close = grub_gzio_close,
+    .fs_label = 0,
+    .next = 0
+  };
+
+GRUB_MOD_INIT(gzio)
+{
+  grub_file_filter_register (GRUB_FILE_FILTER_GZIO, grub_gzio_open);
+}
+
+GRUB_MOD_FINI(gzio)
+{
+  grub_file_filter_unregister (GRUB_FILE_FILTER_GZIO);
+}
diff --git a/grub-core/io/lzopio.c b/grub-core/io/lzopio.c
new file mode 100644
index 0000000..a7d4425
--- /dev/null
+++ b/grub-core/io/lzopio.c
@@ -0,0 +1,546 @@
+/* lzopio.c - decompression support for lzop */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2011  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/err.h>
+#include <grub/mm.h>
+#include <grub/file.h>
+#include <grub/fs.h>
+#include <grub/dl.h>
+#include <grub/crypto.h>
+#include <minilzo.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+#define LZOP_MAGIC "\x89\x4c\x5a\x4f\x00\x0d\x0a\x1a\x0a"
+#define LZOP_MAGIC_SIZE 9
+#define LZOP_CHECK_SIZE 4
+#define LZOP_NEW_LIB 0x0940
+
+/* Header flags - copied from conf.h of LZOP source code.  */
+#define F_ADLER32_D	0x00000001L
+#define F_ADLER32_C	0x00000002L
+#define F_STDIN		0x00000004L
+#define F_STDOUT	0x00000008L
+#define F_NAME_DEFAULT	0x00000010L
+#define F_DOSISH	0x00000020L
+#define F_H_EXTRA_FIELD	0x00000040L
+#define F_H_GMTDIFF	0x00000080L
+#define F_CRC32_D	0x00000100L
+#define F_CRC32_C	0x00000200L
+#define F_MULTIPART	0x00000400L
+#define F_H_FILTER	0x00000800L
+#define F_H_CRC32	0x00001000L
+#define F_H_PATH	0x00002000L
+#define F_MASK		0x00003FFFL
+
+struct block_header
+{
+  grub_uint32_t usize;
+  grub_uint32_t csize;
+  grub_uint32_t ucheck;
+  grub_uint32_t ccheck;
+  unsigned char *cdata;
+  unsigned char *udata;
+};
+
+struct grub_lzopio
+{
+  grub_file_t file;
+  int has_ccheck;
+  int has_ucheck;
+  const gcry_md_spec_t *ucheck_fun;
+  const gcry_md_spec_t *ccheck_fun;
+  grub_off_t saved_off;		/* Rounded down to block boundary.  */
+  grub_off_t start_block_off;
+  struct block_header block;
+};
+
+typedef struct grub_lzopio *grub_lzopio_t;
+static struct grub_fs grub_lzopio_fs;
+
+/* Some helper functions. On errors memory allocated by those function is free
+ * either on close() so no risk of leaks. This makes functions simpler.  */
+
+/* Read block header from file, after successful exit file points to
+ * beginning of block data.  */
+static int
+read_block_header (struct grub_lzopio *lzopio)
+{
+  lzopio->saved_off += lzopio->block.usize;
+
+  /* Free cached block data if any.  */
+  grub_free (lzopio->block.udata);
+  grub_free (lzopio->block.cdata);
+  lzopio->block.udata = NULL;
+  lzopio->block.cdata = NULL;
+
+  if (grub_file_read (lzopio->file, &lzopio->block.usize,
+		      sizeof (lzopio->block.usize)) !=
+      sizeof (lzopio->block.usize))
+    return -1;
+
+  lzopio->block.usize = grub_be_to_cpu32 (lzopio->block.usize);
+
+  /* Last block has uncompressed data size == 0 and no other fields.  */
+  if (lzopio->block.usize == 0)
+    {
+      if (grub_file_tell (lzopio->file) == grub_file_size (lzopio->file))
+	return 0;
+      else
+	return -1;
+    }
+
+  /* Read compressed data block size.  */
+  if (grub_file_read (lzopio->file, &lzopio->block.csize,
+		      sizeof (lzopio->block.csize)) !=
+      sizeof (lzopio->block.csize))
+    return -1;
+
+  lzopio->block.csize = grub_be_to_cpu32 (lzopio->block.csize);
+
+  /* Corrupted.  */
+  if (lzopio->block.csize > lzopio->block.usize)
+    return -1;
+
+  /* Read checksum of uncompressed data.  */
+  if (lzopio->has_ucheck)
+    {
+      if (grub_file_read (lzopio->file, &lzopio->block.ucheck,
+			  sizeof (lzopio->block.ucheck)) !=
+	  sizeof (lzopio->block.ucheck))
+	return -1;
+    }
+
+  /* Read checksum of compressed data.  */
+  if (lzopio->has_ccheck)
+    {
+      /* Incompressible data block.  */
+      if (lzopio->block.csize == lzopio->block.usize)
+	{
+	  lzopio->block.ccheck = lzopio->block.ucheck;
+	}
+      else
+	{
+	  if (grub_file_read (lzopio->file, &lzopio->block.ccheck,
+			      sizeof (lzopio->block.ccheck)) !=
+	      sizeof (lzopio->block.ccheck))
+	    return -1;
+	}
+    }
+
+  return 0;
+}
+
+/* Read block data into memory. File must be set to beginning of block data.
+ * Can't be called on last block.  */
+static int
+read_block_data (struct grub_lzopio *lzopio)
+{
+  lzopio->block.cdata = grub_malloc (lzopio->block.csize);
+  if (!lzopio->block.cdata)
+    return -1;
+
+  if (grub_file_read (lzopio->file, lzopio->block.cdata, lzopio->block.csize)
+      != (grub_ssize_t) lzopio->block.csize)
+    return -1;
+
+  if (lzopio->ccheck_fun)
+    {
+      grub_uint8_t computed_hash[GRUB_CRYPTO_MAX_MDLEN];
+
+      if (lzopio->ccheck_fun->mdlen > GRUB_CRYPTO_MAX_MDLEN)
+	return -1;
+
+      grub_crypto_hash (lzopio->ccheck_fun, computed_hash,
+			lzopio->block.cdata,
+			lzopio->block.csize);
+
+      if (grub_memcmp
+	  (computed_hash, &lzopio->block.ccheck,
+	   sizeof (lzopio->block.ccheck)) != 0)
+	return -1;
+    }
+
+  return 0;
+}
+
+/* Read block data, uncompressed and also store it in memory.  */
+/* XXX Investigate possibility of in-place decompression to reduce memory
+ * footprint. Or try to uncompress directly to buf if possible.  */
+static int
+uncompress_block (struct grub_lzopio *lzopio)
+{
+  lzo_uint usize = lzopio->block.usize;
+
+  if (read_block_data (lzopio) < 0)
+    return -1;
+
+  /* Incompressible data. */
+  if (lzopio->block.csize == lzopio->block.usize)
+    {
+      lzopio->block.udata = lzopio->block.cdata;
+      lzopio->block.cdata = NULL;
+    }
+  else
+    {
+      lzopio->block.udata = grub_malloc (lzopio->block.usize);
+      if (!lzopio->block.udata)
+	return -1;
+
+      if (lzo1x_decompress_safe (lzopio->block.cdata, lzopio->block.csize,
+				 lzopio->block.udata, &usize, NULL)
+	  != LZO_E_OK)
+	return -1;
+
+      if (lzopio->ucheck_fun)
+	{
+	  grub_uint8_t computed_hash[GRUB_CRYPTO_MAX_MDLEN];
+
+	  if (lzopio->ucheck_fun->mdlen > GRUB_CRYPTO_MAX_MDLEN)
+	    return -1;
+
+	  grub_crypto_hash (lzopio->ucheck_fun, computed_hash,
+			    lzopio->block.udata,
+			    lzopio->block.usize);
+
+	  if (grub_memcmp
+	      (computed_hash, &lzopio->block.ucheck,
+	       sizeof (lzopio->block.ucheck)) != 0)
+	    return -1;
+	}
+
+      /* Compressed data can be free now.  */
+      grub_free (lzopio->block.cdata);
+      lzopio->block.cdata = NULL;
+    }
+
+  return 0;
+}
+
+/* Jump to next block and read its header.  */
+static int
+jump_block (struct grub_lzopio *lzopio)
+{
+  /* only jump if block was not decompressed (and read from disk) */
+  if (!lzopio->block.udata)
+    {
+      grub_off_t off = grub_file_tell (lzopio->file) + lzopio->block.csize;
+
+      if (grub_file_seek (lzopio->file, off) == ((grub_off_t) - 1))
+	return -1;
+    }
+
+  return read_block_header (lzopio);
+}
+
+static int
+calculate_uncompressed_size (grub_file_t file)
+{
+  grub_lzopio_t lzopio = file->data;
+  grub_off_t usize_total = 0;
+
+  if (read_block_header (lzopio) < 0)
+    return -1;
+
+  /* FIXME: Don't do this for not easily seekable files.  */
+  while (lzopio->block.usize != 0)
+    {
+      usize_total += lzopio->block.usize;
+
+      if (jump_block (lzopio) < 0)
+	return -1;
+    }
+
+  file->size = usize_total;
+
+  return 0;
+}
+
+struct lzop_header
+{
+  grub_uint8_t magic[LZOP_MAGIC_SIZE];
+  grub_uint16_t lzop_version;
+  grub_uint16_t lib_version;
+  grub_uint16_t lib_version_ext;
+  grub_uint8_t method;
+  grub_uint8_t level;
+  grub_uint32_t flags;
+  /* grub_uint32_t filter; */ /* No filters support. Rarely used anyway.  */
+  grub_uint32_t mode;
+  grub_uint32_t mtime_lo;
+  grub_uint32_t mtime_hi;
+  grub_uint8_t name_len;
+} GRUB_PACKED;
+
+static int
+test_header (grub_file_t file)
+{
+  grub_lzopio_t lzopio = file->data;
+  struct lzop_header header;
+  grub_uint32_t flags, checksum;
+  const gcry_md_spec_t *hcheck;
+  grub_uint8_t *context = NULL;
+  grub_uint8_t *name = NULL;
+
+  if (grub_file_read (lzopio->file, &header, sizeof (header)) != sizeof (header))
+    return 0;
+
+  if (grub_memcmp (header.magic, LZOP_MAGIC, LZOP_MAGIC_SIZE) != 0)
+    return 0;
+
+  if (grub_be_to_cpu16(header.lib_version) < LZOP_NEW_LIB)
+    return 0;
+
+  /* Too new version, should upgrade minilzo?  */
+  if (grub_be_to_cpu16 (header.lib_version_ext) > MINILZO_VERSION)
+    return 0;
+
+  flags = grub_be_to_cpu32 (header.flags);
+
+  if (flags & F_CRC32_D)
+    {
+      lzopio->has_ucheck = 1;
+      lzopio->ucheck_fun = grub_crypto_lookup_md_by_name ("crc32");
+    }
+  else if (flags & F_ADLER32_D)
+    {
+      lzopio->has_ucheck = 1;
+      lzopio->ucheck_fun = grub_crypto_lookup_md_by_name ("adler32");
+    }
+
+  if (flags & F_CRC32_C)
+    {
+      lzopio->has_ccheck = 1;
+      lzopio->ccheck_fun = grub_crypto_lookup_md_by_name ("crc32");
+    }
+  else if (flags & F_ADLER32_C)
+    {
+      lzopio->has_ccheck = 1;
+      lzopio->ccheck_fun = grub_crypto_lookup_md_by_name ("adler32");
+    }
+
+  if (flags & F_H_CRC32)
+    hcheck = grub_crypto_lookup_md_by_name ("crc32");
+  else
+    hcheck = grub_crypto_lookup_md_by_name ("adler32");
+
+  if (hcheck) {
+    context = grub_malloc(hcheck->contextsize);
+    if (! context)
+      return 0;
+
+    hcheck->init(context);
+
+    /* MAGIC is not included in check calculation.  */
+    hcheck->write(context, &header.lzop_version, sizeof(header)- LZOP_MAGIC_SIZE);
+  }
+
+  if (header.name_len != 0)
+    {
+      name = grub_malloc (header.name_len);
+      if (! name)
+	{
+	  grub_free (context);
+	  return 0;
+	}
+
+      if (grub_file_read (lzopio->file, name, header.name_len) !=
+	  header.name_len)
+	{
+	  grub_free(name);
+	  goto CORRUPTED;
+	}
+
+      if (hcheck)
+	hcheck->write(context, name, header.name_len);
+
+      grub_free(name);
+    }
+
+  if (hcheck)
+    hcheck->final(context);
+
+  if (grub_file_read (lzopio->file, &checksum, sizeof (checksum)) !=
+      sizeof (checksum))
+    goto CORRUPTED;
+
+  if (hcheck && grub_memcmp (&checksum, hcheck->read(context), sizeof(checksum)) != 0)
+    goto CORRUPTED;
+
+  lzopio->start_block_off = grub_file_tell (lzopio->file);
+
+  if (calculate_uncompressed_size (file) < 0)
+    goto CORRUPTED;
+
+  /* Get back to start block.  */
+  grub_file_seek (lzopio->file, lzopio->start_block_off);
+
+  /* Read first block - grub_lzopio_read() expects valid block.  */
+  if (read_block_header (lzopio) < 0)
+    goto CORRUPTED;
+
+  lzopio->saved_off = 0;
+  return 1;
+
+CORRUPTED:
+  return 0;
+}
+
+static grub_file_t
+grub_lzopio_open (grub_file_t io, enum grub_file_type type)
+{
+  grub_file_t file;
+  grub_lzopio_t lzopio;
+
+  if (type & GRUB_FILE_TYPE_NO_DECOMPRESS)
+    return io;
+
+  file = (grub_file_t) grub_zalloc (sizeof (*file));
+  if (!file)
+    return 0;
+
+  lzopio = grub_zalloc (sizeof (*lzopio));
+  if (!lzopio)
+    {
+      grub_free (file);
+      return 0;
+    }
+
+  lzopio->file = io;
+
+  file->device = io->device;
+  file->data = lzopio;
+  file->fs = &grub_lzopio_fs;
+  file->size = GRUB_FILE_SIZE_UNKNOWN;
+  file->not_easily_seekable = 1;
+
+  if (grub_file_tell (lzopio->file) != 0)
+    grub_file_seek (lzopio->file, 0);
+
+  if (!test_header (file))
+    {
+      grub_errno = GRUB_ERR_NONE;
+      grub_file_seek (io, 0);
+      grub_free (lzopio);
+      grub_free (file);
+
+      return io;
+    }
+
+  return file;
+}
+
+static grub_ssize_t
+grub_lzopio_read (grub_file_t file, char *buf, grub_size_t len)
+{
+  grub_lzopio_t lzopio = file->data;
+  grub_ssize_t ret = 0;
+  grub_off_t off;
+
+  /* Backward seek before last read block.  */
+  if (lzopio->saved_off > grub_file_tell (file))
+    {
+      grub_file_seek (lzopio->file, lzopio->start_block_off);
+
+      if (read_block_header (lzopio) < 0)
+	goto CORRUPTED;
+
+      lzopio->saved_off = 0;
+    }
+
+  /* Forward to first block with requested data.  */
+  while (lzopio->saved_off + lzopio->block.usize <= grub_file_tell (file))
+    {
+      /* EOF, could be possible files with unknown size.  */
+      if (lzopio->block.usize == 0)
+	return 0;
+
+      if (jump_block (lzopio) < 0)
+	goto CORRUPTED;
+    }
+
+  off = grub_file_tell (file) - lzopio->saved_off;
+
+  while (len != 0 && lzopio->block.usize != 0)
+    {
+      grub_size_t to_copy;
+
+      /* Block not decompressed yet.  */
+      if (!lzopio->block.udata && uncompress_block (lzopio) < 0)
+	goto CORRUPTED;
+
+      /* Copy requested data into buffer.  */
+      to_copy = lzopio->block.usize - off;
+      if (to_copy > len)
+	to_copy = len;
+      grub_memcpy (buf, lzopio->block.udata + off, to_copy);
+
+      len -= to_copy;
+      buf += to_copy;
+      ret += to_copy;
+      off = 0;
+
+      /* Read next block if needed.  */
+      if (len > 0 && read_block_header (lzopio) < 0)
+	goto CORRUPTED;
+    }
+
+  return ret;
+
+CORRUPTED:
+  grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, N_("lzop file corrupted"));
+  return -1;
+}
+
+/* Release everything, including the underlying file object.  */
+static grub_err_t
+grub_lzopio_close (grub_file_t file)
+{
+  grub_lzopio_t lzopio = file->data;
+
+  grub_file_close (lzopio->file);
+  grub_free (lzopio->block.cdata);
+  grub_free (lzopio->block.udata);
+  grub_free (lzopio);
+
+  /* Device must not be closed twice.  */
+  file->device = 0;
+  file->name = 0;
+  return grub_errno;
+}
+
+static struct grub_fs grub_lzopio_fs = {
+  .name = "lzopio",
+  .fs_dir = 0,
+  .fs_open = 0,
+  .fs_read = grub_lzopio_read,
+  .fs_close = grub_lzopio_close,
+  .fs_label = 0,
+  .next = 0
+};
+
+GRUB_MOD_INIT (lzopio)
+{
+  grub_file_filter_register (GRUB_FILE_FILTER_LZOPIO, grub_lzopio_open);
+}
+
+GRUB_MOD_FINI (lzopio)
+{
+  grub_file_filter_unregister (GRUB_FILE_FILTER_LZOPIO);
+}
diff --git a/grub-core/io/offset.c b/grub-core/io/offset.c
new file mode 100644
index 0000000..7e2db4a
--- /dev/null
+++ b/grub-core/io/offset.c
@@ -0,0 +1,112 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2013  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/file.h>
+#include <grub/dl.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+struct grub_offset_file
+{
+  grub_file_t parent;
+  grub_off_t off;
+};
+
+static grub_ssize_t
+grub_offset_read (grub_file_t file, char *buf, grub_size_t len)
+{
+  struct grub_offset_file *data = file->data;
+  if (grub_file_seek (data->parent, data->off + file->offset) == (grub_off_t) -1)
+    return -1;
+  return grub_file_read (data->parent, buf, len);
+}
+
+static grub_err_t
+grub_offset_close (grub_file_t file)
+{
+  struct grub_offset_file *data = file->data;
+
+  if (data->parent)
+    grub_file_close (data->parent);
+
+  /* No need to close the same device twice.  */
+  file->device = 0;
+
+  return 0;
+}
+
+static struct grub_fs grub_offset_fs = {
+  .name = "offset",
+  .fs_dir = 0,
+  .fs_open = 0,
+  .fs_read = grub_offset_read,
+  .fs_close = grub_offset_close,
+  .fs_label = 0,
+  .next = 0
+};
+
+void
+grub_file_offset_close (grub_file_t file)
+{
+  struct grub_offset_file *off_data = file->data;
+  off_data->parent = NULL;
+  grub_file_close (file);
+}
+
+grub_file_t
+grub_file_offset_open (grub_file_t parent, enum grub_file_type type,
+		       grub_off_t start, grub_off_t size)
+{
+  struct grub_offset_file *off_data;
+  grub_file_t off_file, last_off_file;
+  grub_file_filter_id_t filter;
+
+  off_file = grub_zalloc (sizeof (*off_file));
+  off_data = grub_zalloc (sizeof (*off_data));
+  if (!off_file || !off_data)
+    {
+      grub_free (off_file);
+      grub_free (off_data);
+      return 0;
+    }
+
+  off_data->off = start;
+  off_data->parent = parent;
+
+  off_file->device = parent->device;
+  off_file->data = off_data;
+  off_file->fs = &grub_offset_fs;
+  off_file->size = size;
+
+  last_off_file = NULL;
+  for (filter = GRUB_FILE_FILTER_COMPRESSION_FIRST;
+       off_file && filter <= GRUB_FILE_FILTER_COMPRESSION_LAST; filter++)
+    if (grub_file_filters[filter])
+      {
+	last_off_file = off_file;
+	off_file = grub_file_filters[filter] (off_file, type);
+      }
+
+  if (!off_file)
+    {
+      off_data->parent = NULL;
+      grub_file_close (last_off_file);
+      return 0;
+    }
+  return off_file;
+}
diff --git a/grub-core/io/xzio.c b/grub-core/io/xzio.c
new file mode 100644
index 0000000..516c4df
--- /dev/null
+++ b/grub-core/io/xzio.c
@@ -0,0 +1,346 @@
+/* xzio.c - decompression support for xz */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2010  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/err.h>
+#include <grub/mm.h>
+#include <grub/misc.h>
+#include <grub/file.h>
+#include <grub/fs.h>
+#include <grub/dl.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+#include "xz.h"
+#include "xz_stream.h"
+
+#define XZBUFSIZ 0x2000
+#define VLI_MAX_DIGITS 9
+#define XZ_STREAM_FOOTER_SIZE 12
+
+struct grub_xzio
+{
+  grub_file_t file;
+  struct xz_buf buf;
+  struct xz_dec *dec;
+  grub_uint8_t inbuf[XZBUFSIZ];
+  grub_uint8_t outbuf[XZBUFSIZ];
+  grub_off_t saved_offset;
+};
+
+typedef struct grub_xzio *grub_xzio_t;
+static struct grub_fs grub_xzio_fs;
+
+static grub_size_t
+decode_vli (const grub_uint8_t buf[], grub_size_t size_max,
+	    grub_uint64_t *num)
+{
+  if (size_max == 0)
+    return 0;
+
+  if (size_max > VLI_MAX_DIGITS)
+    size_max = VLI_MAX_DIGITS;
+
+  *num = buf[0] & 0x7F;
+  grub_size_t i = 0;
+
+  while (buf[i++] & 0x80)
+    {
+      if (i >= size_max || buf[i] == 0x00)
+	return 0;
+
+      *num |= (uint64_t) (buf[i] & 0x7F) << (i * 7);
+    }
+
+  return i;
+}
+
+static grub_ssize_t
+read_vli (grub_file_t file, grub_uint64_t *num)
+{
+  grub_uint8_t buf[VLI_MAX_DIGITS];
+  grub_ssize_t read_bytes;
+  grub_size_t dec;
+
+  read_bytes = grub_file_read (file, buf, VLI_MAX_DIGITS);
+  if (read_bytes < 0)
+    return -1;
+
+  dec = decode_vli (buf, read_bytes, num);
+  grub_file_seek (file, file->offset - (read_bytes - dec));
+  return dec;
+}
+
+/* Function xz_dec_run() should consume header and ask for more (XZ_OK)
+ * else file is corrupted (or options not supported) or not xz.  */
+static int
+test_header (grub_file_t file)
+{
+  grub_xzio_t xzio = file->data;
+  enum xz_ret ret;
+
+  xzio->buf.in_size = grub_file_read (xzio->file, xzio->inbuf,
+				      STREAM_HEADER_SIZE);
+
+  if (xzio->buf.in_size != STREAM_HEADER_SIZE)
+    return 0;
+
+  ret = xz_dec_run (xzio->dec, &xzio->buf);
+
+  if (ret == XZ_FORMAT_ERROR)
+    return 0;
+
+  if (ret != XZ_OK)
+    return 0;
+
+  return 1;
+}
+
+/* Try to find out size of uncompressed data,
+ * also do some footer sanity checks.  */
+static int
+test_footer (grub_file_t file)
+{
+  grub_xzio_t xzio = file->data;
+  grub_uint8_t footer[FOOTER_MAGIC_SIZE];
+  grub_uint32_t backsize;
+  grub_uint8_t imarker;
+  grub_uint64_t uncompressed_size_total = 0;
+  grub_uint64_t uncompressed_size;
+  grub_uint64_t records;
+
+  grub_file_seek (xzio->file, xzio->file->size - FOOTER_MAGIC_SIZE);
+  if (grub_file_read (xzio->file, footer, FOOTER_MAGIC_SIZE)
+      != FOOTER_MAGIC_SIZE
+      || grub_memcmp (footer, FOOTER_MAGIC, FOOTER_MAGIC_SIZE) != 0)
+    goto ERROR;
+
+  grub_file_seek (xzio->file, xzio->file->size - 8);
+  if (grub_file_read (xzio->file, &backsize, sizeof (backsize))
+      != sizeof (backsize))
+    goto ERROR;
+
+  /* Calculate real backward size.  */
+  backsize = (grub_le_to_cpu32 (backsize) + 1) * 4;
+
+  /* Set file to the beginning of stream index.  */
+  grub_file_seek (xzio->file,
+		  xzio->file->size - XZ_STREAM_FOOTER_SIZE - backsize);
+
+  /* Test index marker.  */
+  if (grub_file_read (xzio->file, &imarker, sizeof (imarker))
+      != sizeof (imarker) && imarker != 0x00)
+    goto ERROR;
+
+  if (read_vli (xzio->file, &records) <= 0)
+    goto ERROR;
+
+  for (; records != 0; records--)
+    {
+      if (read_vli (xzio->file, &uncompressed_size) <= 0)	/* Ignore unpadded.  */
+	goto ERROR;
+      if (read_vli (xzio->file, &uncompressed_size) <= 0)	/* Uncompressed.  */
+	goto ERROR;
+
+      uncompressed_size_total += uncompressed_size;
+    }
+
+  file->size = uncompressed_size_total;
+  grub_file_seek (xzio->file, STREAM_HEADER_SIZE);
+  return 1;
+
+ERROR:
+  return 0;
+}
+
+static grub_file_t
+grub_xzio_open (grub_file_t io, enum grub_file_type type)
+{
+  grub_file_t file;
+  grub_xzio_t xzio;
+
+  if (type & GRUB_FILE_TYPE_NO_DECOMPRESS)
+    return io;
+
+  file = (grub_file_t) grub_zalloc (sizeof (*file));
+  if (!file)
+    return 0;
+
+  xzio = grub_zalloc (sizeof (*xzio));
+  if (!xzio)
+    {
+      grub_free (file);
+      return 0;
+    }
+
+  xzio->file = io;
+
+  file->device = io->device;
+  file->data = xzio;
+  file->fs = &grub_xzio_fs;
+  file->size = GRUB_FILE_SIZE_UNKNOWN;
+  file->not_easily_seekable = 1;
+
+  if (grub_file_tell (xzio->file) != 0)
+    grub_file_seek (xzio->file, 0);
+
+  /* Allocated 64KiB for dictionary.
+   * Decoder will relocate if bigger is needed.  */
+  xzio->dec = xz_dec_init (1 << 16);
+  if (!xzio->dec)
+    {
+      grub_free (file);
+      grub_free (xzio);
+      return 0;
+    }
+
+  xzio->buf.in = xzio->inbuf;
+  xzio->buf.out = xzio->outbuf;
+  xzio->buf.out_size = XZBUFSIZ;
+
+  /* FIXME: don't test footer on not easily seekable files.  */
+  if (!test_header (file) || !test_footer (file))
+    {
+      grub_errno = GRUB_ERR_NONE;
+      grub_file_seek (io, 0);
+      xz_dec_end (xzio->dec);
+      grub_free (xzio);
+      grub_free (file);
+
+      return io;
+    }
+
+  return file;
+}
+
+static grub_ssize_t
+grub_xzio_read (grub_file_t file, char *buf, grub_size_t len)
+{
+  grub_ssize_t ret = 0;
+  grub_ssize_t readret;
+  enum xz_ret xzret;
+  grub_xzio_t xzio = file->data;
+  grub_off_t current_offset;
+
+  /* If seek backward need to reset decoder and start from beginning of file.
+     TODO Possible improvement by jumping blocks.  */
+  if (file->offset < xzio->saved_offset)
+    {
+      xz_dec_reset (xzio->dec);
+      xzio->saved_offset = 0;
+      xzio->buf.out_pos = 0;
+      xzio->buf.in_pos = 0;
+      xzio->buf.in_size = 0;
+      grub_file_seek (xzio->file, 0);
+    }
+
+  current_offset = xzio->saved_offset;
+
+  while (len > 0)
+    {
+      xzio->buf.out_size = file->offset + ret + len - current_offset;
+      if (xzio->buf.out_size > XZBUFSIZ)
+	xzio->buf.out_size = XZBUFSIZ;
+      /* Feed input.  */
+      if (xzio->buf.in_pos == xzio->buf.in_size)
+	{
+	  readret = grub_file_read (xzio->file, xzio->inbuf, XZBUFSIZ);
+	  if (readret < 0)
+	    return -1;
+	  xzio->buf.in_size = readret;
+	  xzio->buf.in_pos = 0;
+	}
+
+      xzret = xz_dec_run (xzio->dec, &xzio->buf);
+      switch (xzret)
+	{
+	case XZ_MEMLIMIT_ERROR:
+	case XZ_FORMAT_ERROR:
+	case XZ_OPTIONS_ERROR:
+	case XZ_DATA_ERROR:
+	case XZ_BUF_ERROR:
+	  grub_error (GRUB_ERR_BAD_COMPRESSED_DATA,
+		      N_("xz file corrupted or unsupported block options"));
+	  return -1;
+	default:
+	  break;
+	}
+
+      {
+	grub_off_t new_offset = current_offset + xzio->buf.out_pos;
+	
+	if (file->offset <= new_offset)
+	  /* Store first chunk of data in buffer.  */
+	  {
+	    grub_size_t delta = new_offset - (file->offset + ret);
+	    grub_memmove (buf, xzio->buf.out + (xzio->buf.out_pos - delta),
+			  delta);
+	    len -= delta;
+	    buf += delta;
+	    ret += delta;
+	  }
+	current_offset = new_offset;
+      }
+      xzio->buf.out_pos = 0;
+
+      if (xzret == XZ_STREAM_END)	/* Stream end, EOF.  */
+	break;
+    }
+
+  if (ret >= 0)
+    xzio->saved_offset = file->offset + ret;
+
+  return ret;
+}
+
+/* Release everything, including the underlying file object.  */
+static grub_err_t
+grub_xzio_close (grub_file_t file)
+{
+  grub_xzio_t xzio = file->data;
+
+  xz_dec_end (xzio->dec);
+
+  grub_file_close (xzio->file);
+  grub_free (xzio);
+
+  /* Device must not be closed twice.  */
+  file->device = 0;
+  file->name = 0;
+  return grub_errno;
+}
+
+static struct grub_fs grub_xzio_fs = {
+  .name = "xzio",
+  .fs_dir = 0,
+  .fs_open = 0,
+  .fs_read = grub_xzio_read,
+  .fs_close = grub_xzio_close,
+  .fs_label = 0,
+  .next = 0
+};
+
+GRUB_MOD_INIT (xzio)
+{
+  grub_file_filter_register (GRUB_FILE_FILTER_XZIO, grub_xzio_open);
+}
+
+GRUB_MOD_FINI (xzio)
+{
+  grub_file_filter_unregister (GRUB_FILE_FILTER_XZIO);
+}