Archipelago » qemu

/*

 * QEMU Block driver for DMG 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 "vl.h"

#include "block_int.h"

#include "bswap.h"

#include <zlib.h>

typedef struct BDRVDMGState {

    int fd;

    /* each chunk contains a certain number of sectors,

     * offsets[i] is the offset in the .dmg file,

     * lengths[i] is the length of the compressed chunk,

     * sectors[i] is the sector beginning at offsets[i],

     * sectorcounts[i] is the number of sectors in that chunk,

     * the sectors array is ordered

     * 0<=i<n_chunks */

    uint32_t n_chunks;

    uint32_t* types;

    uint64_t* offsets;

    uint64_t* lengths;

    uint64_t* sectors;

    uint64_t* sectorcounts;

    uint32_t current_chunk;

    char* compressed_chunk;

    char* uncompressed_chunk;

    z_stream zstream;

} BDRVDMGState;

static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)

{

    int len=strlen(filename);

    if(len>4 && !strcmp(filename+len-4,".dmg"))

        return 2;

    return 0;

}

static off_t read_off(int fd)

{

        uint64_t buffer;

        if(read(fd,&buffer,8)<8)

                return 0;

        return be64_to_cpu(buffer);

}

static off_t read_uint32(int fd)

{

        uint32_t buffer;

        if(read(fd,&buffer,4)<4)

                return 0;

        return be32_to_cpu(buffer);

}

static int dmg_open(BlockDriverState *bs, const char *filename)

{

    BDRVDMGState *s = bs->opaque;

    off_t info_begin,info_end,last_in_offset,last_out_offset;

    uint32_t count;

    uint32_t max_compressed_size=1,max_sectors_per_chunk=1,i;

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

    if (s->fd < 0)

        return -1;

    bs->read_only = 1;

    s->n_chunks = 0;

    s->offsets = s->lengths = s->sectors = s->sectorcounts = 0;

    /* read offset of info blocks */

    if(lseek(s->fd,-0x1d8,SEEK_END)<0) {

dmg_close:

        close(s->fd);

        return -1;

    }

    info_begin=read_off(s->fd);

    if(info_begin==0)

        goto dmg_close;

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

        goto dmg_close;

    if(read_uint32(s->fd)!=0x100)

        goto dmg_close;

    if((count = read_uint32(s->fd))==0)

        goto dmg_close;

    info_end = info_begin+count;

    if(lseek(s->fd,0xf8,SEEK_CUR)<0)

        goto dmg_close;

    /* read offsets */

    last_in_offset = last_out_offset = 0;

    while(lseek(s->fd,0,SEEK_CUR)<info_end) {

        uint32_t type;

        count = read_uint32(s->fd);

        if(count==0)

            goto dmg_close;

        type = read_uint32(s->fd);

        if(type!=0x6d697368 || count<244)

            lseek(s->fd,count-4,SEEK_CUR);

        else {

            int new_size, chunk_count;

            if(lseek(s->fd,200,SEEK_CUR)<0)

                goto dmg_close;

            chunk_count = (count-204)/40;

            new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);

            s->types = realloc(s->types, new_size/2);

            s->offsets = realloc(s->offsets, new_size);

            s->lengths = realloc(s->lengths, new_size);

            s->sectors = realloc(s->sectors, new_size);

            s->sectorcounts = realloc(s->sectorcounts, new_size);

            for(i=s->n_chunks;i<s->n_chunks+chunk_count;i++) {

                s->types[i] = read_uint32(s->fd);

                if(s->types[i]!=0x80000005 && s->types[i]!=1 && s->types[i]!=2) {

                    if(s->types[i]==0xffffffff) {

                        last_in_offset = s->offsets[i-1]+s->lengths[i-1];

                        last_out_offset = s->sectors[i-1]+s->sectorcounts[i-1];

                    }

                    chunk_count--;

                    i--;

                    if(lseek(s->fd,36,SEEK_CUR)<0)

                        goto dmg_close;

                    continue;

                }

                read_uint32(s->fd);

                s->sectors[i] = last_out_offset+read_off(s->fd);

                s->sectorcounts[i] = read_off(s->fd);

                s->offsets[i] = last_in_offset+read_off(s->fd);

                s->lengths[i] = read_off(s->fd);

                if(s->lengths[i]>max_compressed_size)

                    max_compressed_size = s->lengths[i];

                if(s->sectorcounts[i]>max_sectors_per_chunk)

                    max_sectors_per_chunk = s->sectorcounts[i];

            }

            s->n_chunks+=chunk_count;

        }

    }

    /* initialize zlib engine */

    if(!(s->compressed_chunk=(char*)malloc(max_compressed_size+1)))

        goto dmg_close;

    if(!(s->uncompressed_chunk=(char*)malloc(512*max_sectors_per_chunk)))

        goto dmg_close;

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

        goto dmg_close;

    s->current_chunk = s->n_chunks;

    return 0;

}

static inline int is_sector_in_chunk(BDRVDMGState* s,

                uint32_t chunk_num,int sector_num)

{

    if(chunk_num>=s->n_chunks || s->sectors[chunk_num]>sector_num ||

            s->sectors[chunk_num]+s->sectorcounts[chunk_num]<=sector_num)

        return 0;

    else

        return -1;

}

static inline uint32_t search_chunk(BDRVDMGState* s,int sector_num)

{

    /* binary search */

    uint32_t chunk1=0,chunk2=s->n_chunks,chunk3;

    while(chunk1!=chunk2) {

        chunk3 = (chunk1+chunk2)/2;

        if(s->sectors[chunk3]>sector_num)

            chunk2 = chunk3;

        else if(s->sectors[chunk3]+s->sectorcounts[chunk3]>sector_num)

            return chunk3;

        else

            chunk1 = chunk3;

    }

    return s->n_chunks; /* error */

}

static inline int dmg_read_chunk(BDRVDMGState *s,int sector_num)

{

    if(!is_sector_in_chunk(s,s->current_chunk,sector_num)) {

        int ret;

        uint32_t chunk = search_chunk(s,sector_num);

        if(chunk>=s->n_chunks)

            return -1;

        s->current_chunk = s->n_chunks;

        switch(s->types[chunk]) {

        case 0x80000005: { /* zlib compressed */

            int i;

            ret = lseek(s->fd, s->offsets[chunk], SEEK_SET);

            if(ret<0)

                return -1;

            /* we need to buffer, because only the chunk as whole can be

             * inflated. */

            i=0;

            do {

                ret = read(s->fd, s->compressed_chunk+i, s->lengths[chunk]-i);

                if(ret<0 && errno==EINTR)

                    ret=0;

                i+=ret;

            } while(ret>=0 && ret+i<s->lengths[chunk]);

            if (ret != s->lengths[chunk])

                return -1;

            s->zstream.next_in = s->compressed_chunk;

            s->zstream.avail_in = s->lengths[chunk];

            s->zstream.next_out = s->uncompressed_chunk;

            s->zstream.avail_out = 512*s->sectorcounts[chunk];

            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 != 512*s->sectorcounts[chunk])

                return -1;

            break; }

        case 1: /* copy */

            ret = read(s->fd, s->uncompressed_chunk, s->lengths[chunk]);

            if (ret != s->lengths[chunk])

                return -1;

            break;

        case 2: /* zero */

            memset(s->uncompressed_chunk, 0, 512*s->sectorcounts[chunk]);

            break;

        }

        s->current_chunk = chunk;

    }

    return 0;

}

static int dmg_read(BlockDriverState *bs, int64_t sector_num, 

                    uint8_t *buf, int nb_sectors)

{

    BDRVDMGState *s = bs->opaque;

    int i;

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

        uint32_t sector_offset_in_chunk;

        if(dmg_read_chunk(s, sector_num+i) != 0)

            return -1;

        sector_offset_in_chunk = sector_num+i-s->sectors[s->current_chunk];

        memcpy(buf+i*512,s->uncompressed_chunk+sector_offset_in_chunk*512,512);

    }

    return 0;

}

static void dmg_close(BlockDriverState *bs)

{

    BDRVDMGState *s = bs->opaque;

    close(s->fd);

    if(s->n_chunks>0) {

        free(s->types);

        free(s->offsets);

        free(s->lengths);

        free(s->sectors);

        free(s->sectorcounts);

    }

    free(s->compressed_chunk);

    free(s->uncompressed_chunk);

    inflateEnd(&s->zstream);

}

BlockDriver bdrv_dmg = {

    "dmg",

    sizeof(BDRVDMGState),

    dmg_probe,

    dmg_open,

    dmg_read,

    NULL,

    dmg_close,

};