Signed-off-by: Phillip Lougher <phillip@xxxxxxxxxxxxxxxxxxx>
---
fs/squashfs/block.c | 256 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 256 insertions(+), 0 deletions(-)
diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
new file mode 100644
index 0000000..da5f88b
--- /dev/null
+++ b/fs/squashfs/block.c
@@ -0,0 +1,256 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@xxxxxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * block.c
+ */
+
+/*
+ * This file implements the low-level routines to read and decompress
+ * datablocks and metadata blocks.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/string.h>
+#include <linux/buffer_head.h>
+#include <linux/zlib.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Read the metadata block length, this is stored in the first two
+ * bytes of the metadata block.
+ */
+static struct buffer_head *get_block_length(struct super_block *sb,
+ long long *cur_index, int *offset, int *length)
+{
+ struct squashfs_sb_info *msblk = sb->s_fs_info;
+ struct buffer_head *bh;
+
+ bh = sb_bread(sb, *cur_index);
+ if (bh == NULL)
+ return NULL;
+
+ if (msblk->devblksize - *offset == 1) {
+ *length = (unsigned char) bh->b_data[*offset];
+ brelse(bh);
+ bh = sb_bread(sb, ++(*cur_index));
+ if (bh == NULL)
+ return NULL;
+ *length |= (unsigned char) bh->b_data[0] << 8;
+ *offset = 1;
+ } else {
+ *length = (unsigned char) bh->b_data[*offset] |
+ (unsigned char) bh->b_data[*offset + 1] << 8;
+ *offset += 2;
+ }
+
+ return bh;
+}
+
+
+/*
+ * Read and decompress a metadata block or datablock. Length is non-zero
+ * if a datablock is being read (the size is stored elsewhere in the
+ * filesystem), otherwise the length is obtained from the first two bytes of
+ * the metadata block. A bit in the length field indicates if the block
+ * is stored uncompressed in the filesystem (usually because compression
+ * generated a larger block - this does occasionally happen with zlib).
+ */
+int squashfs_read_data(struct super_block *sb, void *buffer,
+ long long index, int length, long long *next_index,
+ int srclength)
+{
+ struct squashfs_sb_info *msblk = sb->s_fs_info;
+ struct buffer_head **bh;
+ int offset = index & ((1 << msblk->devblksize_log2) - 1);
+ long long cur_index = index >> msblk->devblksize_log2;
+ int avail, bytes, compressed, b = 0, k = 0;
+ int c_byte = length;
+
+ bh = kcalloc((msblk->block_size >> msblk->devblksize_log2) + 1,
+ sizeof(*bh), GFP_KERNEL);
+ if (bh == NULL)
+ return -ENOMEM;
+
+ if (c_byte) {
+ /*
+ * Datablock.
+ */
+ bytes = -offset;
+ compressed = SQUASHFS_COMPRESSED_BLOCK(c_byte);
+ c_byte = SQUASHFS_COMPRESSED_SIZE_BLOCK(c_byte);
+
+ TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",
+ index, compressed ? "" : "un", c_byte, srclength);
+
+ if (c_byte < 0 || c_byte > srclength || index < 0 ||
+ (index + c_byte) > msblk->bytes_used)
+ goto read_failure;
+
+ for (b = 0; bytes < c_byte; b++, cur_index++) {
+ bh[b] = sb_getblk(sb, cur_index);
+ if (bh[b] == NULL)
+ goto block_release;
+ bytes += msblk->devblksize;
+ }
+ ll_rw_block(READ, b, bh);
+ } else {
+ /*
+ * Metadata block.
+ */
+ if (index < 0 || (index + 2) > msblk->bytes_used)
+ goto read_failure;
+
+ bh[0] = get_block_length(sb, &cur_index, &offset, &c_byte);
+ if (bh[0] == NULL)
+ goto read_failure;
+ b = 1;
+
+ bytes = msblk->devblksize - offset;
+ compressed = SQUASHFS_COMPRESSED(c_byte);
+ c_byte = SQUASHFS_COMPRESSED_SIZE(c_byte);
+
+ TRACE("Block @ 0x%llx, %scompressed size %d\n", index,
+ compressed ? "" : "un", c_byte);
+
+ if (c_byte < 0 || c_byte > srclength ||
+ (index + c_byte) > msblk->bytes_used)
+ goto block_release;
+
+ for (; bytes < c_byte; b++) {
+ bh[b] = sb_getblk(sb, ++cur_index);
+ if (bh[b] == NULL)
+ goto block_release;
+ bytes += msblk->devblksize;
+ }
+ ll_rw_block(READ, b - 1, bh + 1);
+ }
+
+ if (compressed) {
+ int zlib_err = 0;
+
+ /*
+ * Uncompress block.
+ */
+
+ mutex_lock(&msblk->read_data_mutex);
+
+ msblk->stream.next_out = buffer;
+ msblk->stream.avail_out = srclength;
+
+ for (bytes = 0; k < b; k++) {
+ avail = min(c_byte - bytes, msblk->devblksize - offset);
+
+ wait_on_buffer(bh[k]);
+ if (!buffer_uptodate(bh[k]))
+ goto release_mutex;
+
+ msblk->stream.next_in = bh[k]->b_data + offset;
+ msblk->stream.avail_in = avail;
+
+ if (k == 0) {
+ zlib_err = zlib_inflateInit(&msblk->stream);
+ if (zlib_err != Z_OK) {
+ ERROR("zlib_inflateInit returned"
+ " unexpected result 0x%x,"
+ " srclength %d\n", zlib_err,
+ srclength);
+ goto release_mutex;
+ }
+
+ if (avail == 0) {
+ offset = 0;
+ brelse(bh[k]);
+ continue;
+ }
+ }
+
+ zlib_err = zlib_inflate(&msblk->stream, Z_NO_FLUSH);
+ if (zlib_err != Z_OK && zlib_err != Z_STREAM_END) {
+ ERROR("zlib_inflate returned unexpected result"
+ " 0x%x, srclength %d, avail_in %d,"
+ " avail_out %d\n", zlib_err, srclength,
+ msblk->stream.avail_in,
+ msblk->stream.avail_out);
+ goto release_mutex;
+ }
+
+ bytes += avail;
+ offset = 0;
+ brelse(bh[k]);
+ }
+
+ if (zlib_err != Z_STREAM_END)
+ goto release_mutex;
+
+ zlib_err = zlib_inflateEnd(&msblk->stream);
+ if (zlib_err != Z_OK) {
+ ERROR("zlib_inflateEnd returned unexpected result 0x%x,"
+ " srclength %d\n", zlib_err, srclength);
+ goto release_mutex;
+ }
+ bytes = msblk->stream.total_out;
+ mutex_unlock(&msblk->read_data_mutex);
+ } else {
+ /*
+ * Block is uncompressed.
+ */
+ int i;
+
+ for (i = 0; i < b; i++) {
+ wait_on_buffer(bh[i]);
+ if (!buffer_uptodate(bh[i]))
+ goto block_release;
+ }
+
+ for (bytes = 0; k < b; k++) {
+ avail = min(c_byte - bytes, msblk->devblksize - offset);
+
+ memcpy(buffer + bytes, bh[k]->b_data + offset, avail);
+ bytes += avail;
+ offset = 0;
+ brelse(bh[k]);
+ }
+ }
+
+ if (next_index)
+ *next_index = index + c_byte + (length ? 0 : 2);
+
+ kfree(bh);
+ return bytes;
+
+release_mutex:
+ mutex_unlock(&msblk->read_data_mutex);
+
+block_release:
+ for (; k < b; k++)
+ brelse(bh[k]);
+
+read_failure:
+ ERROR("sb_bread failed reading block 0x%llx\n", cur_index);
+ kfree(bh);
+ return -EIO;
+}
--
1.5.2.5
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