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Annotation of qemu/block/cloop.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * QEMU Block driver for CLOOP images
        !             3:  *
        !             4:  * Copyright (c) 2004 Johannes E. Schindelin
        !             5:  *
        !             6:  * Permission is hereby granted, free of charge, to any person obtaining a copy
        !             7:  * of this software and associated documentation files (the "Software"), to deal
        !             8:  * in the Software without restriction, including without limitation the rights
        !             9:  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
        !            10:  * copies of the Software, and to permit persons to whom the Software is
        !            11:  * furnished to do so, subject to the following conditions:
        !            12:  *
        !            13:  * The above copyright notice and this permission notice shall be included in
        !            14:  * all copies or substantial portions of the Software.
        !            15:  *
        !            16:  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
        !            17:  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
        !            19:  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
        !            20:  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
        !            21:  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
        !            22:  * THE SOFTWARE.
        !            23:  */
        !            24: #include "qemu-common.h"
        !            25: #include "block_int.h"
        !            26: #include "module.h"
        !            27: #include <zlib.h>
        !            28: 
        !            29: typedef struct BDRVCloopState {
        !            30:     int fd;
        !            31:     uint32_t block_size;
        !            32:     uint32_t n_blocks;
        !            33:     uint64_t* offsets;
        !            34:     uint32_t sectors_per_block;
        !            35:     uint32_t current_block;
        !            36:     uint8_t *compressed_block;
        !            37:     uint8_t *uncompressed_block;
        !            38:     z_stream zstream;
        !            39: } BDRVCloopState;
        !            40: 
        !            41: static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
        !            42: {
        !            43:     const char* magic_version_2_0="#!/bin/sh\n"
        !            44:        "#V2.0 Format\n"
        !            45:        "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
        !            46:     int length=strlen(magic_version_2_0);
        !            47:     if(length>buf_size)
        !            48:        length=buf_size;
        !            49:     if(!memcmp(magic_version_2_0,buf,length))
        !            50:        return 2;
        !            51:     return 0;
        !            52: }
        !            53: 
        !            54: static int cloop_open(BlockDriverState *bs, const char *filename, int flags)
        !            55: {
        !            56:     BDRVCloopState *s = bs->opaque;
        !            57:     uint32_t offsets_size,max_compressed_block_size=1,i;
        !            58: 
        !            59:     s->fd = open(filename, O_RDONLY | O_BINARY);
        !            60:     if (s->fd < 0)
        !            61:         return -errno;
        !            62:     bs->read_only = 1;
        !            63: 
        !            64:     /* read header */
        !            65:     if(lseek(s->fd,128,SEEK_SET)<0) {
        !            66: cloop_close:
        !            67:        close(s->fd);
        !            68:        return -1;
        !            69:     }
        !            70:     if(read(s->fd,&s->block_size,4)<4)
        !            71:        goto cloop_close;
        !            72:     s->block_size=be32_to_cpu(s->block_size);
        !            73:     if(read(s->fd,&s->n_blocks,4)<4)
        !            74:        goto cloop_close;
        !            75:     s->n_blocks=be32_to_cpu(s->n_blocks);
        !            76: 
        !            77:     /* read offsets */
        !            78:     offsets_size=s->n_blocks*sizeof(uint64_t);
        !            79:     s->offsets=(uint64_t*)qemu_malloc(offsets_size);
        !            80:     if(read(s->fd,s->offsets,offsets_size)<offsets_size)
        !            81:        goto cloop_close;
        !            82:     for(i=0;i<s->n_blocks;i++) {
        !            83:        s->offsets[i]=be64_to_cpu(s->offsets[i]);
        !            84:        if(i>0) {
        !            85:            uint32_t size=s->offsets[i]-s->offsets[i-1];
        !            86:            if(size>max_compressed_block_size)
        !            87:                max_compressed_block_size=size;
        !            88:        }
        !            89:     }
        !            90: 
        !            91:     /* initialize zlib engine */
        !            92:     s->compressed_block = qemu_malloc(max_compressed_block_size+1);
        !            93:     s->uncompressed_block = qemu_malloc(s->block_size);
        !            94:     if(inflateInit(&s->zstream) != Z_OK)
        !            95:        goto cloop_close;
        !            96:     s->current_block=s->n_blocks;
        !            97: 
        !            98:     s->sectors_per_block = s->block_size/512;
        !            99:     bs->total_sectors = s->n_blocks*s->sectors_per_block;
        !           100:     return 0;
        !           101: }
        !           102: 
        !           103: static inline int cloop_read_block(BDRVCloopState *s,int block_num)
        !           104: {
        !           105:     if(s->current_block != block_num) {
        !           106:        int ret;
        !           107:         uint32_t bytes = s->offsets[block_num+1]-s->offsets[block_num];
        !           108: 
        !           109:        lseek(s->fd, s->offsets[block_num], SEEK_SET);
        !           110:         ret = read(s->fd, s->compressed_block, bytes);
        !           111:         if (ret != bytes)
        !           112:             return -1;
        !           113: 
        !           114:        s->zstream.next_in = s->compressed_block;
        !           115:        s->zstream.avail_in = bytes;
        !           116:        s->zstream.next_out = s->uncompressed_block;
        !           117:        s->zstream.avail_out = s->block_size;
        !           118:        ret = inflateReset(&s->zstream);
        !           119:        if(ret != Z_OK)
        !           120:            return -1;
        !           121:        ret = inflate(&s->zstream, Z_FINISH);
        !           122:        if(ret != Z_STREAM_END || s->zstream.total_out != s->block_size)
        !           123:            return -1;
        !           124: 
        !           125:        s->current_block = block_num;
        !           126:     }
        !           127:     return 0;
        !           128: }
        !           129: 
        !           130: static int cloop_read(BlockDriverState *bs, int64_t sector_num,
        !           131:                     uint8_t *buf, int nb_sectors)
        !           132: {
        !           133:     BDRVCloopState *s = bs->opaque;
        !           134:     int i;
        !           135: 
        !           136:     for(i=0;i<nb_sectors;i++) {
        !           137:        uint32_t sector_offset_in_block=((sector_num+i)%s->sectors_per_block),
        !           138:            block_num=(sector_num+i)/s->sectors_per_block;
        !           139:        if(cloop_read_block(s, block_num) != 0)
        !           140:            return -1;
        !           141:        memcpy(buf+i*512,s->uncompressed_block+sector_offset_in_block*512,512);
        !           142:     }
        !           143:     return 0;
        !           144: }
        !           145: 
        !           146: static void cloop_close(BlockDriverState *bs)
        !           147: {
        !           148:     BDRVCloopState *s = bs->opaque;
        !           149:     close(s->fd);
        !           150:     if(s->n_blocks>0)
        !           151:        free(s->offsets);
        !           152:     free(s->compressed_block);
        !           153:     free(s->uncompressed_block);
        !           154:     inflateEnd(&s->zstream);
        !           155: }
        !           156: 
        !           157: static BlockDriver bdrv_cloop = {
        !           158:     .format_name       = "cloop",
        !           159:     .instance_size     = sizeof(BDRVCloopState),
        !           160:     .bdrv_probe                = cloop_probe,
        !           161:     .bdrv_open         = cloop_open,
        !           162:     .bdrv_read         = cloop_read,
        !           163:     .bdrv_close                = cloop_close,
        !           164: };
        !           165: 
        !           166: static void bdrv_cloop_init(void)
        !           167: {
        !           168:     bdrv_register(&bdrv_cloop);
        !           169: }
        !           170: 
        !           171: block_init(bdrv_cloop_init);

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