Archipelago » qemu

/*

 * 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-common.h"

#include "block_int.h"

#include <zlib.h>

typedef struct BDRVCloopState {

    int fd;

    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, const char *filename, int flags)

{

    BDRVCloopState *s = bs->opaque;

    uint32_t offsets_size,max_compressed_block_size=1,i;

    s->fd = open(filename, O_RDONLY | O_BINARY);

    if (s->fd < 0)

        return -errno;

    bs->read_only = 1;

    /* read header */

    if(lseek(s->fd,128,SEEK_SET)<0) {

cloop_close:

        close(s->fd);

        return -1;

    }

    if(read(s->fd,&s->block_size,4)<4)

        goto cloop_close;

    s->block_size=be32_to_cpu(s->block_size);

    if(read(s->fd,&s->n_blocks,4)<4)

        goto cloop_close;

    s->n_blocks=be32_to_cpu(s->n_blocks);

    /* read offsets */

    offsets_size=s->n_blocks*sizeof(uint64_t);

    s->offsets=(uint64_t*)qemu_malloc(offsets_size);

    if(read(s->fd,s->offsets,offsets_size)<offsets_size)

        goto cloop_close;

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

        s->offsets[i]=be64_to_cpu(s->offsets[i]);

        if(i>0) {

            uint32_t size=s->offsets[i]-s->offsets[i-1];

            if(size>max_compressed_block_size)

                max_compressed_block_size=size;

        }

    }

    /* initialize zlib engine */

    s->compressed_block = qemu_malloc(max_compressed_block_size+1);

    s->uncompressed_block = qemu_malloc(s->block_size);

    if(inflateInit(&s->zstream) != Z_OK)

        goto cloop_close;

    s->current_block=s->n_blocks;

    s->sectors_per_block = s->block_size/512;

    bs->total_sectors = s->n_blocks*s->sectors_per_block;

    return 0;

}

static inline int cloop_read_block(BDRVCloopState *s,int block_num)

{

    if(s->current_block != block_num) {

        int ret;

        uint32_t bytes = s->offsets[block_num+1]-s->offsets[block_num];

        lseek(s->fd, s->offsets[block_num], SEEK_SET);

        ret = read(s->fd, 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 cloop_read(BlockDriverState *bs, int64_t sector_num,

                    uint8_t *buf, int nb_sectors)

{

    BDRVCloopState *s = bs->opaque;

    int i;

    for(i=0;i<nb_sectors;i++) {

        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(s, block_num) != 0)

            return -1;

        memcpy(buf+i*512,s->uncompressed_block+sector_offset_in_block*512,512);

    }

    return 0;

}

static void cloop_close(BlockDriverState *bs)

{

    BDRVCloopState *s = bs->opaque;

    close(s->fd);

    if(s->n_blocks>0)

        free(s->offsets);

    free(s->compressed_block);

    free(s->uncompressed_block);

    inflateEnd(&s->zstream);

}

BlockDriver bdrv_cloop = {

    .format_name        = "cloop",

    .instance_size        = sizeof(BDRVCloopState),

    .bdrv_probe                = cloop_probe,

    .bdrv_open                = cloop_open,

    .bdrv_read                = cloop_read,

    .bdrv_close                = cloop_close,

};