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grub/grub-core/io/xzio.c
Vladimir 'phcoder' Serbinenko 0b2db94300 Handling of files of unknown size is currently limited. They can't be 
used e.g. for initrd or modules. Moreover gzip handling of not
	easily seekable files is buggy. Disable unknown file size for now. May
	be inefficient but works.

	* grub-core/io/gzio.c (test_header): Always retrieve the file size.
	* grub-core/io/xzio.c (grub_xzio_open): Likewise.
2010-12-26 21:15:31 +01:00

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/* 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>
#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;
grub_size_t dec;
read = grub_file_read (file, buf, VLI_MAX_DIGITS);
if (read < 0)
return -1;
dec = decode_vli (buf, read, num);
grub_file_seek (file, file->offset - (read - 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;
xzio->buf.in_size = grub_file_read (xzio->file, xzio->inbuf,
STREAM_HEADER_SIZE);
if (xzio->buf.in_size != STREAM_HEADER_SIZE)
{
grub_error (GRUB_ERR_BAD_FILE_TYPE, "no xz magic found");
return 0;
}
enum xz_ret ret = xz_dec_run (xzio->dec, &xzio->buf);
if (ret == XZ_FORMAT_ERROR)
{
grub_error (GRUB_ERR_BAD_FILE_TYPE, "no xz magic found");
return 0;
}
if (ret != XZ_OK)
{
grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "not supported xz options");
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:
grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "bad footer magic");
return 0;
}
static grub_file_t
grub_xzio_open (grub_file_t io)
{
grub_file_t file;
grub_xzio_t xzio;
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;
xzio->saved_offset = 0;
file->device = io->device;
file->offset = 0;
file->data = xzio;
file->read_hook = 0;
file->fs = &grub_xzio_fs;
file->size = GRUB_FILE_SIZE_UNKNOWN;
file->not_easly_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.in_pos = 0;
xzio->buf.in_size = 0;
xzio->buf.out = xzio->outbuf;
xzio->buf.out_pos = 0;
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 = grub_min (file->offset + ret + len - current_offset,
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,
"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;
return grub_errno;
}
static struct grub_fs grub_xzio_fs = {
.name = "xzio",
.dir = 0,
.open = 0,
.read = grub_xzio_read,
.close = grub_xzio_close,
.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);
}
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