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

1.1     ! root        1: /*
        !             2:  * QEMU Block driver for DMG 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 "bswap.h"
        !            27: #include "module.h"
        !            28: #include <zlib.h>
        !            29: 
        !            30: typedef struct BDRVDMGState {
        !            31:     int fd;
        !            32: 
        !            33:     /* each chunk contains a certain number of sectors,
        !            34:      * offsets[i] is the offset in the .dmg file,
        !            35:      * lengths[i] is the length of the compressed chunk,
        !            36:      * sectors[i] is the sector beginning at offsets[i],
        !            37:      * sectorcounts[i] is the number of sectors in that chunk,
        !            38:      * the sectors array is ordered
        !            39:      * 0<=i<n_chunks */
        !            40: 
        !            41:     uint32_t n_chunks;
        !            42:     uint32_t* types;
        !            43:     uint64_t* offsets;
        !            44:     uint64_t* lengths;
        !            45:     uint64_t* sectors;
        !            46:     uint64_t* sectorcounts;
        !            47:     uint32_t current_chunk;
        !            48:     uint8_t *compressed_chunk;
        !            49:     uint8_t *uncompressed_chunk;
        !            50:     z_stream zstream;
        !            51: } BDRVDMGState;
        !            52: 
        !            53: static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
        !            54: {
        !            55:     int len=strlen(filename);
        !            56:     if(len>4 && !strcmp(filename+len-4,".dmg"))
        !            57:        return 2;
        !            58:     return 0;
        !            59: }
        !            60: 
        !            61: static off_t read_off(int fd)
        !            62: {
        !            63:        uint64_t buffer;
        !            64:        if(read(fd,&buffer,8)<8)
        !            65:                return 0;
        !            66:        return be64_to_cpu(buffer);
        !            67: }
        !            68: 
        !            69: static off_t read_uint32(int fd)
        !            70: {
        !            71:        uint32_t buffer;
        !            72:        if(read(fd,&buffer,4)<4)
        !            73:                return 0;
        !            74:        return be32_to_cpu(buffer);
        !            75: }
        !            76: 
        !            77: static int dmg_open(BlockDriverState *bs, const char *filename, int flags)
        !            78: {
        !            79:     BDRVDMGState *s = bs->opaque;
        !            80:     off_t info_begin,info_end,last_in_offset,last_out_offset;
        !            81:     uint32_t count;
        !            82:     uint32_t max_compressed_size=1,max_sectors_per_chunk=1,i;
        !            83: 
        !            84:     s->fd = open(filename, O_RDONLY | O_BINARY);
        !            85:     if (s->fd < 0)
        !            86:         return -errno;
        !            87:     bs->read_only = 1;
        !            88:     s->n_chunks = 0;
        !            89:     s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
        !            90: 
        !            91:     /* read offset of info blocks */
        !            92:     if(lseek(s->fd,-0x1d8,SEEK_END)<0) {
        !            93: dmg_close:
        !            94:        close(s->fd);
        !            95:        /* open raw instead */
        !            96:        bs->drv=bdrv_find_format("raw");
        !            97:        return bs->drv->bdrv_open(bs, filename, flags);
        !            98:     }
        !            99:     info_begin=read_off(s->fd);
        !           100:     if(info_begin==0)
        !           101:        goto dmg_close;
        !           102:     if(lseek(s->fd,info_begin,SEEK_SET)<0)
        !           103:        goto dmg_close;
        !           104:     if(read_uint32(s->fd)!=0x100)
        !           105:        goto dmg_close;
        !           106:     if((count = read_uint32(s->fd))==0)
        !           107:        goto dmg_close;
        !           108:     info_end = info_begin+count;
        !           109:     if(lseek(s->fd,0xf8,SEEK_CUR)<0)
        !           110:        goto dmg_close;
        !           111: 
        !           112:     /* read offsets */
        !           113:     last_in_offset = last_out_offset = 0;
        !           114:     while(lseek(s->fd,0,SEEK_CUR)<info_end) {
        !           115:         uint32_t type;
        !           116: 
        !           117:        count = read_uint32(s->fd);
        !           118:        if(count==0)
        !           119:            goto dmg_close;
        !           120:        type = read_uint32(s->fd);
        !           121:        if(type!=0x6d697368 || count<244)
        !           122:            lseek(s->fd,count-4,SEEK_CUR);
        !           123:        else {
        !           124:            int new_size, chunk_count;
        !           125:            if(lseek(s->fd,200,SEEK_CUR)<0)
        !           126:                goto dmg_close;
        !           127:            chunk_count = (count-204)/40;
        !           128:            new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
        !           129:            s->types = qemu_realloc(s->types, new_size/2);
        !           130:            s->offsets = qemu_realloc(s->offsets, new_size);
        !           131:            s->lengths = qemu_realloc(s->lengths, new_size);
        !           132:            s->sectors = qemu_realloc(s->sectors, new_size);
        !           133:            s->sectorcounts = qemu_realloc(s->sectorcounts, new_size);
        !           134: 
        !           135:            for(i=s->n_chunks;i<s->n_chunks+chunk_count;i++) {
        !           136:                s->types[i] = read_uint32(s->fd);
        !           137:                if(s->types[i]!=0x80000005 && s->types[i]!=1 && s->types[i]!=2) {
        !           138:                    if(s->types[i]==0xffffffff) {
        !           139:                        last_in_offset = s->offsets[i-1]+s->lengths[i-1];
        !           140:                        last_out_offset = s->sectors[i-1]+s->sectorcounts[i-1];
        !           141:                    }
        !           142:                    chunk_count--;
        !           143:                    i--;
        !           144:                    if(lseek(s->fd,36,SEEK_CUR)<0)
        !           145:                        goto dmg_close;
        !           146:                    continue;
        !           147:                }
        !           148:                read_uint32(s->fd);
        !           149:                s->sectors[i] = last_out_offset+read_off(s->fd);
        !           150:                s->sectorcounts[i] = read_off(s->fd);
        !           151:                s->offsets[i] = last_in_offset+read_off(s->fd);
        !           152:                s->lengths[i] = read_off(s->fd);
        !           153:                if(s->lengths[i]>max_compressed_size)
        !           154:                    max_compressed_size = s->lengths[i];
        !           155:                if(s->sectorcounts[i]>max_sectors_per_chunk)
        !           156:                    max_sectors_per_chunk = s->sectorcounts[i];
        !           157:            }
        !           158:            s->n_chunks+=chunk_count;
        !           159:        }
        !           160:     }
        !           161: 
        !           162:     /* initialize zlib engine */
        !           163:     s->compressed_chunk = qemu_malloc(max_compressed_size+1);
        !           164:     s->uncompressed_chunk = qemu_malloc(512*max_sectors_per_chunk);
        !           165:     if(inflateInit(&s->zstream) != Z_OK)
        !           166:        goto dmg_close;
        !           167: 
        !           168:     s->current_chunk = s->n_chunks;
        !           169: 
        !           170:     return 0;
        !           171: }
        !           172: 
        !           173: static inline int is_sector_in_chunk(BDRVDMGState* s,
        !           174:                uint32_t chunk_num,int sector_num)
        !           175: {
        !           176:     if(chunk_num>=s->n_chunks || s->sectors[chunk_num]>sector_num ||
        !           177:            s->sectors[chunk_num]+s->sectorcounts[chunk_num]<=sector_num)
        !           178:        return 0;
        !           179:     else
        !           180:        return -1;
        !           181: }
        !           182: 
        !           183: static inline uint32_t search_chunk(BDRVDMGState* s,int sector_num)
        !           184: {
        !           185:     /* binary search */
        !           186:     uint32_t chunk1=0,chunk2=s->n_chunks,chunk3;
        !           187:     while(chunk1!=chunk2) {
        !           188:        chunk3 = (chunk1+chunk2)/2;
        !           189:        if(s->sectors[chunk3]>sector_num)
        !           190:            chunk2 = chunk3;
        !           191:        else if(s->sectors[chunk3]+s->sectorcounts[chunk3]>sector_num)
        !           192:            return chunk3;
        !           193:        else
        !           194:            chunk1 = chunk3;
        !           195:     }
        !           196:     return s->n_chunks; /* error */
        !           197: }
        !           198: 
        !           199: static inline int dmg_read_chunk(BDRVDMGState *s,int sector_num)
        !           200: {
        !           201:     if(!is_sector_in_chunk(s,s->current_chunk,sector_num)) {
        !           202:        int ret;
        !           203:        uint32_t chunk = search_chunk(s,sector_num);
        !           204: 
        !           205:        if(chunk>=s->n_chunks)
        !           206:            return -1;
        !           207: 
        !           208:        s->current_chunk = s->n_chunks;
        !           209:        switch(s->types[chunk]) {
        !           210:        case 0x80000005: { /* zlib compressed */
        !           211:            int i;
        !           212: 
        !           213:            ret = lseek(s->fd, s->offsets[chunk], SEEK_SET);
        !           214:            if(ret<0)
        !           215:                return -1;
        !           216: 
        !           217:            /* we need to buffer, because only the chunk as whole can be
        !           218:             * inflated. */
        !           219:            i=0;
        !           220:            do {
        !           221:                ret = read(s->fd, s->compressed_chunk+i, s->lengths[chunk]-i);
        !           222:                if(ret<0 && errno==EINTR)
        !           223:                    ret=0;
        !           224:                i+=ret;
        !           225:            } while(ret>=0 && ret+i<s->lengths[chunk]);
        !           226: 
        !           227:            if (ret != s->lengths[chunk])
        !           228:                return -1;
        !           229: 
        !           230:            s->zstream.next_in = s->compressed_chunk;
        !           231:            s->zstream.avail_in = s->lengths[chunk];
        !           232:            s->zstream.next_out = s->uncompressed_chunk;
        !           233:            s->zstream.avail_out = 512*s->sectorcounts[chunk];
        !           234:            ret = inflateReset(&s->zstream);
        !           235:            if(ret != Z_OK)
        !           236:                return -1;
        !           237:            ret = inflate(&s->zstream, Z_FINISH);
        !           238:            if(ret != Z_STREAM_END || s->zstream.total_out != 512*s->sectorcounts[chunk])
        !           239:                return -1;
        !           240:            break; }
        !           241:        case 1: /* copy */
        !           242:            ret = read(s->fd, s->uncompressed_chunk, s->lengths[chunk]);
        !           243:            if (ret != s->lengths[chunk])
        !           244:                return -1;
        !           245:            break;
        !           246:        case 2: /* zero */
        !           247:            memset(s->uncompressed_chunk, 0, 512*s->sectorcounts[chunk]);
        !           248:            break;
        !           249:        }
        !           250:        s->current_chunk = chunk;
        !           251:     }
        !           252:     return 0;
        !           253: }
        !           254: 
        !           255: static int dmg_read(BlockDriverState *bs, int64_t sector_num,
        !           256:                     uint8_t *buf, int nb_sectors)
        !           257: {
        !           258:     BDRVDMGState *s = bs->opaque;
        !           259:     int i;
        !           260: 
        !           261:     for(i=0;i<nb_sectors;i++) {
        !           262:        uint32_t sector_offset_in_chunk;
        !           263:        if(dmg_read_chunk(s, sector_num+i) != 0)
        !           264:            return -1;
        !           265:        sector_offset_in_chunk = sector_num+i-s->sectors[s->current_chunk];
        !           266:        memcpy(buf+i*512,s->uncompressed_chunk+sector_offset_in_chunk*512,512);
        !           267:     }
        !           268:     return 0;
        !           269: }
        !           270: 
        !           271: static void dmg_close(BlockDriverState *bs)
        !           272: {
        !           273:     BDRVDMGState *s = bs->opaque;
        !           274:     close(s->fd);
        !           275:     if(s->n_chunks>0) {
        !           276:        free(s->types);
        !           277:        free(s->offsets);
        !           278:        free(s->lengths);
        !           279:        free(s->sectors);
        !           280:        free(s->sectorcounts);
        !           281:     }
        !           282:     free(s->compressed_chunk);
        !           283:     free(s->uncompressed_chunk);
        !           284:     inflateEnd(&s->zstream);
        !           285: }
        !           286: 
        !           287: static BlockDriver bdrv_dmg = {
        !           288:     .format_name       = "dmg",
        !           289:     .instance_size     = sizeof(BDRVDMGState),
        !           290:     .bdrv_probe                = dmg_probe,
        !           291:     .bdrv_open         = dmg_open,
        !           292:     .bdrv_read         = dmg_read,
        !           293:     .bdrv_close                = dmg_close,
        !           294: };
        !           295: 
        !           296: static void bdrv_dmg_init(void)
        !           297: {
        !           298:     bdrv_register(&bdrv_dmg);
        !           299: }
        !           300: 
        !           301: block_init(bdrv_dmg_init);

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