qemu

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/*
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 * QEMU Block driver for CLOOP images
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 *
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 * Copyright (c) 2004 Johannes E. Schindelin
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 *
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 * Permission is hereby granted, free of charge, to any person obtaining a copy
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 * of this software and associated documentation files (the "Software"), to deal
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 * in the Software without restriction, including without limitation the rights
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 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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 * copies of the Software, and to permit persons to whom the Software is
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 * furnished to do so, subject to the following conditions:
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 *
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 * The above copyright notice and this permission notice shall be included in
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 * all copies or substantial portions of the Software.
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 *
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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 * THE SOFTWARE.
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 */
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "qemu/error-report.h"
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#include "block/block-io.h"
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#include "block/block_int.h"
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#include "qemu/module.h"
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#include "qemu/bswap.h"
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#include <zlib.h>
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/* Maximum compressed block size */
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#define MAX_BLOCK_SIZE (64 * 1024 * 1024)
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typedef struct BDRVCloopState {
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    CoMutex lock;
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    uint32_t block_size;
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    uint32_t n_blocks;
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    uint64_t *offsets;
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    uint32_t sectors_per_block;
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    uint32_t current_block;
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    uint8_t *compressed_block;
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    uint8_t *uncompressed_block;
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    z_stream zstream;
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} BDRVCloopState;
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static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
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{
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    const char *magic_version_2_0 = "#!/bin/sh\n"
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        "#V2.0 Format\n"
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        "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
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    int length = strlen(magic_version_2_0);
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    if (length > buf_size) {
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        length = buf_size;
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    }
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    if (!memcmp(magic_version_2_0, buf, length)) {
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        return 2;
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    }
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    return 0;
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}
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static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
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                      Error **errp)
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{
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    BDRVCloopState *s = bs->opaque;
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    uint32_t offsets_size, max_compressed_block_size = 1, i;
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    int ret;
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    GLOBAL_STATE_CODE();
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    bdrv_graph_rdlock_main_loop();
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    ret = bdrv_apply_auto_read_only(bs, NULL, errp);
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    bdrv_graph_rdunlock_main_loop();
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    if (ret < 0) {
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        return ret;
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    }
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    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
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    if (ret < 0) {
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        return ret;
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    }
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    GRAPH_RDLOCK_GUARD_MAINLOOP();
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    /* read header */
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    ret = bdrv_pread(bs->file, 128, 4, &s->block_size, 0);
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    if (ret < 0) {
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        return ret;
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    }
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    s->block_size = be32_to_cpu(s->block_size);
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    if (s->block_size % 512) {
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        error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
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                   s->block_size);
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        return -EINVAL;
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    }
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    if (s->block_size == 0) {
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        error_setg(errp, "block_size cannot be zero");
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        return -EINVAL;
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    }
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    /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
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     * we can accept more.  Prevent ridiculous values like 4 GB - 1 since we
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     * need a buffer this big.
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     */
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    if (s->block_size > MAX_BLOCK_SIZE) {
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        error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
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                   s->block_size,
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                   MAX_BLOCK_SIZE / (1024 * 1024));
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        return -EINVAL;
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    }
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    ret = bdrv_pread(bs->file, 128 + 4, 4, &s->n_blocks, 0);
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    if (ret < 0) {
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        return ret;
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    }
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    s->n_blocks = be32_to_cpu(s->n_blocks);
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    /* read offsets */
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    if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
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        /* Prevent integer overflow */
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        error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
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                   s->n_blocks,
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                   (UINT32_MAX - 1) / sizeof(uint64_t));
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        return -EINVAL;
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    }
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    offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
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    if (offsets_size > 512 * 1024 * 1024) {
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        /* Prevent ridiculous offsets_size which causes memory allocation to
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         * fail or overflows bdrv_pread() size.  In practice the 512 MB
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         * offsets[] limit supports 16 TB images at 256 KB block size.
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         */
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        error_setg(errp, "image requires too many offsets, "
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                   "try increasing block size");
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        return -EINVAL;
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    }
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    s->offsets = g_try_malloc(offsets_size);
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    if (s->offsets == NULL) {
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        error_setg(errp, "Could not allocate offsets table");
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        return -ENOMEM;
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    }
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    ret = bdrv_pread(bs->file, 128 + 4 + 4, offsets_size, s->offsets, 0);
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    if (ret < 0) {
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        goto fail;
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    }
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    for (i = 0; i < s->n_blocks + 1; i++) {
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        uint64_t size;
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        s->offsets[i] = be64_to_cpu(s->offsets[i]);
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        if (i == 0) {
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            continue;
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        }
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        if (s->offsets[i] < s->offsets[i - 1]) {
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            error_setg(errp, "offsets not monotonically increasing at "
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                       "index %" PRIu32 ", image file is corrupt", i);
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            ret = -EINVAL;
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            goto fail;
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        }
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        size = s->offsets[i] - s->offsets[i - 1];
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        /* Compressed blocks should be smaller than the uncompressed block size
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         * but maybe compression performed poorly so the compressed block is
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         * actually bigger.  Clamp down on unrealistic values to prevent
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         * ridiculous s->compressed_block allocation.
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         */
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        if (size > 2 * MAX_BLOCK_SIZE) {
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            error_setg(errp, "invalid compressed block size at index %" PRIu32
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                       ", image file is corrupt", i);
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            ret = -EINVAL;
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            goto fail;
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        }
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        if (size > max_compressed_block_size) {
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            max_compressed_block_size = size;
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        }
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    }
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    /* initialize zlib engine */
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    s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
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    if (s->compressed_block == NULL) {
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        error_setg(errp, "Could not allocate compressed_block");
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        ret = -ENOMEM;
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        goto fail;
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    }
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    s->uncompressed_block = g_try_malloc(s->block_size);
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    if (s->uncompressed_block == NULL) {
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        error_setg(errp, "Could not allocate uncompressed_block");
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        ret = -ENOMEM;
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        goto fail;
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    }
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    if (inflateInit(&s->zstream) != Z_OK) {
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        ret = -EINVAL;
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        goto fail;
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    }
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    s->current_block = s->n_blocks;
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    s->sectors_per_block = s->block_size/512;
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    bs->total_sectors = s->n_blocks * s->sectors_per_block;
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    qemu_co_mutex_init(&s->lock);
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    return 0;
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fail:
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    g_free(s->offsets);
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    g_free(s->compressed_block);
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    g_free(s->uncompressed_block);
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    return ret;
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}
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static void cloop_refresh_limits(BlockDriverState *bs, Error **errp)
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{
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    bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
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}
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static int coroutine_fn GRAPH_RDLOCK
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cloop_read_block(BlockDriverState *bs, int block_num)
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{
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    BDRVCloopState *s = bs->opaque;
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    if (s->current_block != block_num) {
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        int ret;
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        uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
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        ret = bdrv_co_pread(bs->file, s->offsets[block_num], bytes,
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                            s->compressed_block, 0);
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        if (ret < 0) {
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            return -1;
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        }
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        s->zstream.next_in = s->compressed_block;
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        s->zstream.avail_in = bytes;
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        s->zstream.next_out = s->uncompressed_block;
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        s->zstream.avail_out = s->block_size;
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        ret = inflateReset(&s->zstream);
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        if (ret != Z_OK) {
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            return -1;
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        }
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        ret = inflate(&s->zstream, Z_FINISH);
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        if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
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            return -1;
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        }
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        s->current_block = block_num;
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    }
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    return 0;
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}
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static int coroutine_fn GRAPH_RDLOCK
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cloop_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
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                QEMUIOVector *qiov, BdrvRequestFlags flags)
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{
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    BDRVCloopState *s = bs->opaque;
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    uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
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    int nb_sectors = bytes >> BDRV_SECTOR_BITS;
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    int ret, i;
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    assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
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    assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
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    qemu_co_mutex_lock(&s->lock);
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    for (i = 0; i < nb_sectors; i++) {
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        void *data;
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        uint32_t sector_offset_in_block =
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            ((sector_num + i) % s->sectors_per_block),
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            block_num = (sector_num + i) / s->sectors_per_block;
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        if (cloop_read_block(bs, block_num) != 0) {
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            ret = -EIO;
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            goto fail;
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        }
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        data = s->uncompressed_block + sector_offset_in_block * 512;
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        qemu_iovec_from_buf(qiov, i * 512, data, 512);
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    }
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    ret = 0;
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fail:
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    qemu_co_mutex_unlock(&s->lock);
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    return ret;
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}
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static void cloop_close(BlockDriverState *bs)
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{
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    BDRVCloopState *s = bs->opaque;
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    g_free(s->offsets);
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    g_free(s->compressed_block);
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    g_free(s->uncompressed_block);
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    inflateEnd(&s->zstream);
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}
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static BlockDriver bdrv_cloop = {
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    .format_name    = "cloop",
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    .instance_size  = sizeof(BDRVCloopState),
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    .bdrv_probe     = cloop_probe,
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    .bdrv_open      = cloop_open,
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    .bdrv_child_perm     = bdrv_default_perms,
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    .bdrv_refresh_limits = cloop_refresh_limits,
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    .bdrv_co_preadv = cloop_co_preadv,
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    .bdrv_close     = cloop_close,
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    .is_format      = true,
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};
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static void bdrv_cloop_init(void)
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{
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    bdrv_register(&bdrv_cloop);
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}
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block_init(bdrv_cloop_init);
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