block/cloop.c - qemu - Git at Google

 /*
  * QEMU Block driver for CLOOP images
  *
  * Copyright (c) 2004 Johannes E. Schindelin
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "qemu-common.h"
 #include "block/block_int.h"
 #include "qemu/module.h"
 #include "qemu/bswap.h"
 #include <zlib.h>

 /* Maximum compressed block size */
 #define MAX_BLOCK_SIZE (64 * 1024 * 1024)

 typedef struct BDRVCloopState {
     CoMutex lock;
     uint32_t block_size;
     uint32_t n_blocks;
     uint64_t *offsets;
     uint32_t sectors_per_block;
     uint32_t current_block;
     uint8_t *compressed_block;
     uint8_t *uncompressed_block;
     z_stream zstream;
 } BDRVCloopState;

 static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
 {
     const char *magic_version_2_0 = "#!/bin/sh\n"
         "#V2.0 Format\n"
         "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
     int length = strlen(magic_version_2_0);
     if (length > buf_size) {
         length = buf_size;
     }
     if (!memcmp(magic_version_2_0, buf, length)) {
         return 2;
     }
     return 0;
 }

 static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
                       Error **errp)
 {
     BDRVCloopState *s = bs->opaque;
     uint32_t offsets_size, max_compressed_block_size = 1, i;
     int ret;

     ret = bdrv_apply_auto_read_only(bs, NULL, errp);
     if (ret < 0) {
         return ret;
     }

     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
                                false, errp);
     if (!bs->file) {
         return -EINVAL;
     }

     /* read header */
     ret = bdrv_pread(bs->file, 128, &s->block_size, 4);
     if (ret < 0) {
         return ret;
     }
     s->block_size = be32_to_cpu(s->block_size);
     if (s->block_size % 512) {
         error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
                    s->block_size);
         return -EINVAL;
     }
     if (s->block_size == 0) {
         error_setg(errp, "block_size cannot be zero");
         return -EINVAL;
     }

     /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
      * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
      * need a buffer this big.
      */
     if (s->block_size > MAX_BLOCK_SIZE) {
         error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
                    s->block_size,
                    MAX_BLOCK_SIZE / (1024 * 1024));
         return -EINVAL;
     }

     ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);
     if (ret < 0) {
         return ret;
     }
     s->n_blocks = be32_to_cpu(s->n_blocks);

     /* read offsets */
     if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
         /* Prevent integer overflow */
         error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
                    s->n_blocks,
                    (UINT32_MAX - 1) / sizeof(uint64_t));
         return -EINVAL;
     }
     offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
     if (offsets_size > 512 * 1024 * 1024) {
         /* Prevent ridiculous offsets_size which causes memory allocation to
          * fail or overflows bdrv_pread() size.  In practice the 512 MB
          * offsets[] limit supports 16 TB images at 256 KB block size.
          */
         error_setg(errp, "image requires too many offsets, "
                    "try increasing block size");
         return -EINVAL;
     }

     s->offsets = g_try_malloc(offsets_size);
     if (s->offsets == NULL) {
         error_setg(errp, "Could not allocate offsets table");
         return -ENOMEM;
     }

     ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size);
     if (ret < 0) {
         goto fail;
     }

     for (i = 0; i < s->n_blocks + 1; i++) {
         uint64_t size;

         s->offsets[i] = be64_to_cpu(s->offsets[i]);
         if (i == 0) {
             continue;
         }

         if (s->offsets[i] < s->offsets[i - 1]) {
             error_setg(errp, "offsets not monotonically increasing at "
                        "index %" PRIu32 ", image file is corrupt", i);
             ret = -EINVAL;
             goto fail;
         }

         size = s->offsets[i] - s->offsets[i - 1];

         /* Compressed blocks should be smaller than the uncompressed block size
          * but maybe compression performed poorly so the compressed block is
          * actually bigger.  Clamp down on unrealistic values to prevent
          * ridiculous s->compressed_block allocation.
          */
         if (size > 2 * MAX_BLOCK_SIZE) {
             error_setg(errp, "invalid compressed block size at index %" PRIu32
                        ", image file is corrupt", i);
             ret = -EINVAL;
             goto fail;
         }

         if (size > max_compressed_block_size) {
             max_compressed_block_size = size;
         }
     }

     /* initialize zlib engine */
     s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
     if (s->compressed_block == NULL) {
         error_setg(errp, "Could not allocate compressed_block");
         ret = -ENOMEM;
         goto fail;
     }

     s->uncompressed_block = g_try_malloc(s->block_size);
     if (s->uncompressed_block == NULL) {
         error_setg(errp, "Could not allocate uncompressed_block");
         ret = -ENOMEM;
         goto fail;
     }

     if (inflateInit(&s->zstream) != Z_OK) {
         ret = -EINVAL;
         goto fail;
     }
     s->current_block = s->n_blocks;

     s->sectors_per_block = s->block_size/512;
     bs->total_sectors = s->n_blocks * s->sectors_per_block;
     qemu_co_mutex_init(&s->lock);
     return 0;

 fail:
     g_free(s->offsets);
     g_free(s->compressed_block);
     g_free(s->uncompressed_block);
     return ret;
 }

 static void cloop_refresh_limits(BlockDriverState *bs, Error **errp)
 {
     bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
 }

 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 {
     BDRVCloopState *s = bs->opaque;

     if (s->current_block != block_num) {
         int ret;
         uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];

         ret = bdrv_pread(bs->file, s->offsets[block_num],
                          s->compressed_block, bytes);
         if (ret != bytes) {
             return -1;
         }

         s->zstream.next_in = s->compressed_block;
         s->zstream.avail_in = bytes;
         s->zstream.next_out = s->uncompressed_block;
         s->zstream.avail_out = s->block_size;
         ret = inflateReset(&s->zstream);
         if (ret != Z_OK) {
             return -1;
         }
         ret = inflate(&s->zstream, Z_FINISH);
         if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
             return -1;
         }

         s->current_block = block_num;
     }
     return 0;
 }

 static int coroutine_fn
 cloop_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
                 QEMUIOVector *qiov, int flags)
 {
     BDRVCloopState *s = bs->opaque;
     uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
     int nb_sectors = bytes >> BDRV_SECTOR_BITS;
     int ret, i;

     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);

     qemu_co_mutex_lock(&s->lock);

     for (i = 0; i < nb_sectors; i++) {
         void *data;
         uint32_t sector_offset_in_block =
             ((sector_num + i) % s->sectors_per_block),
             block_num = (sector_num + i) / s->sectors_per_block;
         if (cloop_read_block(bs, block_num) != 0) {
             ret = -EIO;
             goto fail;
         }

         data = s->uncompressed_block + sector_offset_in_block * 512;
         qemu_iovec_from_buf(qiov, i * 512, data, 512);
     }

     ret = 0;
 fail:
     qemu_co_mutex_unlock(&s->lock);

     return ret;
 }

 static void cloop_close(BlockDriverState *bs)
 {
     BDRVCloopState *s = bs->opaque;
     g_free(s->offsets);
     g_free(s->compressed_block);
     g_free(s->uncompressed_block);
     inflateEnd(&s->zstream);
 }

 static BlockDriver bdrv_cloop = {
     .format_name    = "cloop",
     .instance_size  = sizeof(BDRVCloopState),
     .bdrv_probe     = cloop_probe,
     .bdrv_open      = cloop_open,
     .bdrv_child_perm     = bdrv_format_default_perms,
     .bdrv_refresh_limits = cloop_refresh_limits,
     .bdrv_co_preadv = cloop_co_preadv,
     .bdrv_close     = cloop_close,
 };

 static void bdrv_cloop_init(void)
 {
     bdrv_register(&bdrv_cloop);
 }

 block_init(bdrv_cloop_init);
	/*
	* QEMU Block driver for CLOOP images
	*
	* Copyright (c) 2004 Johannes E. Schindelin
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/
	#include "qemu/osdep.h"
	#include "qapi/error.h"
	#include "qemu/error-report.h"
	#include "qemu-common.h"
	#include "block/block_int.h"
	#include "qemu/module.h"
	#include "qemu/bswap.h"
	#include <zlib.h>

	/* Maximum compressed block size */
	#define MAX_BLOCK_SIZE (64 * 1024 * 1024)

	typedef struct BDRVCloopState {
	CoMutex lock;
	uint32_t block_size;
	uint32_t n_blocks;
	uint64_t *offsets;
	uint32_t sectors_per_block;
	uint32_t current_block;
	uint8_t *compressed_block;
	uint8_t *uncompressed_block;
	z_stream zstream;
	} BDRVCloopState;

	static int cloop_probe(const uint8_t buf, int buf_size, const char filename)
	{
	const char *magic_version_2_0 = "#!/bin/sh\n"
	"#V2.0 Format\n"
	"modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
	int length = strlen(magic_version_2_0);
	if (length > buf_size) {
	length = buf_size;
	}
	if (!memcmp(magic_version_2_0, buf, length)) {
	return 2;
	}
	return 0;
	}

	static int cloop_open(BlockDriverState bs, QDict options, int flags,
	Error **errp)
	{
	BDRVCloopState *s = bs->opaque;
	uint32_t offsets_size, max_compressed_block_size = 1, i;
	int ret;

	ret = bdrv_apply_auto_read_only(bs, NULL, errp);
	if (ret < 0) {
	return ret;
	}

	bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
	false, errp);
	if (!bs->file) {
	return -EINVAL;
	}

	/* read header */
	ret = bdrv_pread(bs->file, 128, &s->block_size, 4);
	if (ret < 0) {
	return ret;
	}
	s->block_size = be32_to_cpu(s->block_size);
	if (s->block_size % 512) {
	error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
	s->block_size);
	return -EINVAL;
	}
	if (s->block_size == 0) {
	error_setg(errp, "block_size cannot be zero");
	return -EINVAL;
	}

	/* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
	* we can accept more. Prevent ridiculous values like 4 GB - 1 since we
	* need a buffer this big.
	*/
	if (s->block_size > MAX_BLOCK_SIZE) {
	error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
	s->block_size,
	MAX_BLOCK_SIZE / (1024 * 1024));
	return -EINVAL;
	}

	ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4);
	if (ret < 0) {
	return ret;
	}
	s->n_blocks = be32_to_cpu(s->n_blocks);

	/* read offsets */
	if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
	/* Prevent integer overflow */
	error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
	s->n_blocks,
	(UINT32_MAX - 1) / sizeof(uint64_t));
	return -EINVAL;
	}
	offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
	if (offsets_size > 512 * 1024 * 1024) {
	/* Prevent ridiculous offsets_size which causes memory allocation to
	* fail or overflows bdrv_pread() size. In practice the 512 MB
	* offsets[] limit supports 16 TB images at 256 KB block size.
	*/
	error_setg(errp, "image requires too many offsets, "
	"try increasing block size");
	return -EINVAL;
	}

	s->offsets = g_try_malloc(offsets_size);
	if (s->offsets == NULL) {
	error_setg(errp, "Could not allocate offsets table");
	return -ENOMEM;
	}

	ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size);
	if (ret < 0) {
	goto fail;
	}

	for (i = 0; i < s->n_blocks + 1; i++) {
	uint64_t size;

	s->offsets[i] = be64_to_cpu(s->offsets[i]);
	if (i == 0) {
	continue;
	}

	if (s->offsets[i] < s->offsets[i - 1]) {
	error_setg(errp, "offsets not monotonically increasing at "
	"index %" PRIu32 ", image file is corrupt", i);
	ret = -EINVAL;
	goto fail;
	}

	size = s->offsets[i] - s->offsets[i - 1];

	/* Compressed blocks should be smaller than the uncompressed block size
	* but maybe compression performed poorly so the compressed block is
	* actually bigger. Clamp down on unrealistic values to prevent
	* ridiculous s->compressed_block allocation.
	*/
	if (size > 2 * MAX_BLOCK_SIZE) {
	error_setg(errp, "invalid compressed block size at index %" PRIu32
	", image file is corrupt", i);
	ret = -EINVAL;
	goto fail;
	}

	if (size > max_compressed_block_size) {
	max_compressed_block_size = size;
	}
	}

	/* initialize zlib engine */
	s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
	if (s->compressed_block == NULL) {
	error_setg(errp, "Could not allocate compressed_block");
	ret = -ENOMEM;
	goto fail;
	}

	s->uncompressed_block = g_try_malloc(s->block_size);
	if (s->uncompressed_block == NULL) {
	error_setg(errp, "Could not allocate uncompressed_block");
	ret = -ENOMEM;
	goto fail;
	}

	if (inflateInit(&s->zstream) != Z_OK) {
	ret = -EINVAL;
	goto fail;
	}
	s->current_block = s->n_blocks;

	s->sectors_per_block = s->block_size/512;
	bs->total_sectors = s->n_blocks * s->sectors_per_block;
	qemu_co_mutex_init(&s->lock);
	return 0;

	fail:
	g_free(s->offsets);
	g_free(s->compressed_block);
	g_free(s->uncompressed_block);
	return ret;
	}

	static void cloop_refresh_limits(BlockDriverState bs, Error *errp)
	{
	bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
	}

	static inline int cloop_read_block(BlockDriverState *bs, int block_num)
	{
	BDRVCloopState *s = bs->opaque;

	if (s->current_block != block_num) {
	int ret;
	uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];

	ret = bdrv_pread(bs->file, s->offsets[block_num],
	s->compressed_block, bytes);
	if (ret != bytes) {
	return -1;
	}

	s->zstream.next_in = s->compressed_block;
	s->zstream.avail_in = bytes;
	s->zstream.next_out = s->uncompressed_block;
	s->zstream.avail_out = s->block_size;
	ret = inflateReset(&s->zstream);
	if (ret != Z_OK) {
	return -1;
	}
	ret = inflate(&s->zstream, Z_FINISH);
	if (ret != Z_STREAM_END \|\| s->zstream.total_out != s->block_size) {
	return -1;
	}

	s->current_block = block_num;
	}
	return 0;
	}

	static int coroutine_fn
	cloop_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
	QEMUIOVector *qiov, int flags)
	{
	BDRVCloopState *s = bs->opaque;
	uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
	int nb_sectors = bytes >> BDRV_SECTOR_BITS;
	int ret, i;

	assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
	assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);

	qemu_co_mutex_lock(&s->lock);

	for (i = 0; i < nb_sectors; i++) {
	void *data;
	uint32_t sector_offset_in_block =
	((sector_num + i) % s->sectors_per_block),
	block_num = (sector_num + i) / s->sectors_per_block;
	if (cloop_read_block(bs, block_num) != 0) {
	ret = -EIO;
	goto fail;
	}

	data = s->uncompressed_block + sector_offset_in_block * 512;
	qemu_iovec_from_buf(qiov, i * 512, data, 512);
	}

	ret = 0;
	fail:
	qemu_co_mutex_unlock(&s->lock);

	return ret;
	}

	static void cloop_close(BlockDriverState *bs)
	{
	BDRVCloopState *s = bs->opaque;
	g_free(s->offsets);
	g_free(s->compressed_block);
	g_free(s->uncompressed_block);
	inflateEnd(&s->zstream);
	}

	static BlockDriver bdrv_cloop = {
	.format_name = "cloop",
	.instance_size = sizeof(BDRVCloopState),
	.bdrv_probe = cloop_probe,
	.bdrv_open = cloop_open,
	.bdrv_child_perm = bdrv_format_default_perms,
	.bdrv_refresh_limits = cloop_refresh_limits,
	.bdrv_co_preadv = cloop_co_preadv,
	.bdrv_close = cloop_close,
	};

	static void bdrv_cloop_init(void)
	{
	bdrv_register(&bdrv_cloop);
	}

	block_init(bdrv_cloop_init);