Archipelago » qemu

/*

 * QEMU Block driver for virtual VFAT (shadows a local directory)

 * 

 * 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 <sys/stat.h>

#include <dirent.h>

#include <assert.h>

#include "vl.h"

#include "block_int.h"

// TODO: new file

// TODO: delete file

// TODO: make root directory larger

// TODO: make directory clusters connected, so they are reserved anyway... add a member which tells how many clusters are reserved after a directory

// TODO: introduce another member in mapping_t which says where the directory resides in s->directory (for mkdir and rmdir) 

// in _read and _write, before treating direntries or file contents, get_mapping to know what it is.

// TODO: mkdir

// TODO: rmdir 

// TODO: when commit_data'ing a direntry and is_consistent, commit_remove

// TODO: reset MODE_MODIFIED when commit_remove'ing

#define DEBUG

/* dynamic array functions */

typedef struct array_t {

    char* pointer;

    unsigned int size,next,item_size;

} array_t;

static inline void array_init(array_t* array,unsigned int item_size)

{

    array->pointer=0;

    array->size=0;

    array->next=0;

    array->item_size=item_size;

}

static inline void array_free(array_t* array)

{

    if(array->pointer)

        free(array->pointer);

    array->size=array->next=0;

}

/* make sure that memory is reserved at pointer[index*item_size] */

static inline void* array_get(array_t* array,unsigned int index) {

    if((index+1)*array->item_size>array->size) {

        int new_size=(index+32)*array->item_size;

        array->pointer=realloc(array->pointer,new_size);

        if(!array->pointer)

            return 0;

        array->size=new_size;

        array->next=index+1;

    }

    return array->pointer+index*array->item_size;

}

static inline void* array_get_next(array_t* array) {

    unsigned int next=array->next;

    void* result=array_get(array,next);

    array->next=next+1;

    return result;

}

static inline void* array_insert(array_t* array,unsigned int index,unsigned int count) {

    if((array->next+count)*array->item_size>array->size) {

        int increment=count*array->item_size;

        array->pointer=realloc(array->pointer,array->size+increment);

        if(!array->pointer)

            return 0;

        array->size+=increment;

    }

    memmove(array->pointer+(index+count)*array->item_size,

                array->pointer+index*array->item_size,

                (array->next-index)*array->item_size);

    array->next+=count;

    return array->pointer+index*array->item_size;

}

/* this performs a "roll", so that the element which was at index_from becomes

 * index_to, but the order of all other elements is preserved. */

static inline int array_roll(array_t* array,int index_to,int index_from,int count)

{

    char* buf;

    char* from;

    char* to;

    int is;

    if(!array ||

            index_to<0 || index_to>=array->next ||

            index_from<0 || index_from>=array->next)

        return -1;

    if(index_to==index_from)

        return 0;

    is=array->item_size;

    from=array->pointer+index_from*is;

    to=array->pointer+index_to*is;

    buf=malloc(is*count);

    memcpy(buf,from,is*count);

    if(index_to<index_from)

        memmove(to+is*count,to,from-to);

    else

        memmove(from,from+is*count,to-from);

    memcpy(to,buf,is*count);

    free(buf);

    return 0;

}

int array_remove(array_t* array,int index)

{

    if(array_roll(array,array->next-1,index,1))

        return -1;

    array->next--;

    return 0;

}

/* These structures are used to fake a disk and the VFAT filesystem.

 * For this reason we need to use __attribute__((packed)). */

typedef struct bootsector_t {

    uint8_t jump[3];

    uint8_t name[8];

    uint16_t sector_size;

    uint8_t sectors_per_cluster;

    uint16_t reserved_sectors;

    uint8_t number_of_fats;

    uint16_t root_entries;

    uint16_t zero;

    uint8_t media_type;

    uint16_t sectors_per_fat;

    uint16_t sectors_per_track;

    uint16_t number_of_heads;

    uint32_t hidden_sectors;

    uint32_t total_sectors;

    union {

        struct {

            uint8_t drive_number;

            uint8_t current_head;

            uint8_t signature;

            uint32_t id;

            uint8_t volume_label[11];

        } __attribute__((packed)) fat16;

        struct {

            uint32_t sectors_per_fat;

            uint16_t flags;

            uint8_t major,minor;

            uint32_t first_cluster_of_root_directory;

            uint16_t info_sector;

            uint16_t backup_boot_sector;

            uint16_t ignored;

        } __attribute__((packed)) fat32;

    } u;

    uint8_t fat_type[8];

    uint8_t ignored[0x1c0];

    uint8_t magic[2];

} __attribute__((packed)) bootsector_t;

typedef struct partition_t {

    uint8_t attributes; /* 0x80 = bootable */

    uint8_t start_head;

    uint8_t start_sector;

    uint8_t start_cylinder;

    uint8_t fs_type; /* 0x6 = FAT16, 0xb = FAT32 */

    uint8_t end_head;

    uint8_t end_sector;

    uint8_t end_cylinder;

    uint32_t start_sector_long;

    uint32_t end_sector_long;

} __attribute__((packed)) partition_t;

typedef struct mbr_t {

    uint8_t ignored[0x1be];

    partition_t partition[4];

    uint8_t magic[2];

} __attribute__((packed)) mbr_t;

typedef struct direntry_t {

    uint8_t name[8];

    uint8_t extension[3];

    uint8_t attributes;

    uint8_t reserved[2];

    uint16_t ctime;

    uint16_t cdate;

    uint16_t adate;

    uint16_t begin_hi;

    uint16_t mtime;

    uint16_t mdate;

    uint16_t begin;

    uint32_t size;

} __attribute__((packed)) direntry_t;

/* this structure are used to transparently access the files */

typedef struct mapping_t {

    /* begin is the first cluster, end is the last+1,

     * offset is the offset in the file in clusters of this slice */

    off_t begin,end,offset;

    char* filename;

    /* as s->directory is growable, no pointer may be used here */

    unsigned int dir_index;

    enum { MODE_NORMAL,MODE_UNDEFINED,MODE_MODIFIED,MODE_DELETED,MODE_DIRECTORY } mode;

} mapping_t;

/* this structure is used to hold sectors which need to be written, but it's

 * not known yet where to write them. */

typedef struct commit_t {

    uint32_t cluster_num;

    uint8_t* buf;

} commit_t;

/* write support exists for fat, direntry and file contents */

typedef enum {

    WRITE_UNDEFINED,WRITE_FAT,WRITE_DIRENTRY,WRITE_DATA

} write_action_t;

/* here begins the real VVFAT driver */

typedef struct BDRVVVFATState {

    unsigned int first_sectors_number; /* 1 for a single partition, 0x40 for a disk with partition table */

    unsigned char first_sectors[0x40*0x200];

    int fat_type; /* 16 or 32 */

    array_t fat,directory,mapping;

    unsigned int cluster_size;

    unsigned int sectors_per_cluster;

    unsigned int sectors_per_fat;

    unsigned int sectors_of_root_directory;

    unsigned int sectors_for_directory;

    unsigned int faked_sectors; /* how many sectors are faked before file data */

    uint32_t sector_count; /* total number of sectors of the partition */

    uint32_t cluster_count; /* total number of clusters of this partition */

    unsigned int first_file_mapping; /* index of the first mapping which is not a directory, but a file */

    uint32_t max_fat_value;

    int current_fd;

    char current_fd_is_writable; /* =0 if read only, !=0 if read/writable */

    mapping_t* current_mapping;

    unsigned char* cluster;

    unsigned int current_cluster;

    /* write support */

    array_t commit;

    /* for each file, the file contents, the direntry, and the fat entries are

     * written, but not necessarily in that order */

    write_action_t action[3];

} BDRVVVFATState;

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

{

    if (strstart(filename, "fat:", NULL) ||

        strstart(filename, "fatrw:", NULL))

        return 100;

    return 0;

}

static void init_mbr(BDRVVVFATState* s)

{

    /* TODO: if the files mbr.img and bootsect.img exist, use them */

    mbr_t* real_mbr=(mbr_t*)s->first_sectors;

    partition_t* partition=&(real_mbr->partition[0]);

    memset(s->first_sectors,0,512);

    partition->attributes=0x80; /* bootable */

    partition->start_head=1;

    partition->start_sector=1;

    partition->start_cylinder=0;

    partition->fs_type=(s->fat_type==16?0x6:0xb); /* FAT16/FAT32 */

    partition->end_head=0xf;

    partition->end_sector=0xff; /* end sector & upper 2 bits of cylinder */;

    partition->end_cylinder=0xff; /* lower 8 bits of end cylinder */;

    partition->start_sector_long=cpu_to_le32(0x3f);

    partition->end_sector_long=cpu_to_le32(s->sector_count);

    real_mbr->magic[0]=0x55; real_mbr->magic[1]=0xaa;

}

/* dest is assumed to hold 258 bytes, and pads with 0xffff up to next multiple of 26 */

static inline int short2long_name(unsigned char* dest,const char* src)

{

    int i;

    for(i=0;i<129 && src[i];i++) {

        dest[2*i]=src[i];

        dest[2*i+1]=0;

    }

    dest[2*i]=dest[2*i+1]=0;

    for(i=2*i+2;(i%26);i++)

        dest[i]=0xff;

    return i;

}

static inline direntry_t* create_long_filename(BDRVVVFATState* s,const char* filename)

{

    char buffer[258];

    int length=short2long_name(buffer,filename),

        number_of_entries=(length+25)/26,i;

    direntry_t* entry;

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

        entry=array_get_next(&(s->directory));

        entry->attributes=0xf;

        entry->reserved[0]=0;

        entry->begin=0;

        entry->name[0]=(number_of_entries-i)|(i==0?0x40:0);

    }

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

        int offset=(i%26);

        if(offset<10) offset=1+offset;

        else if(offset<22) offset=14+offset-10;

        else offset=28+offset-22;

        entry=array_get(&(s->directory),s->directory.next-1-(i/26));

        entry->name[offset]=buffer[i];

    }

    return array_get(&(s->directory),s->directory.next-number_of_entries);

}

/* fat functions */

static inline uint8_t fat_chksum(direntry_t* entry)

{

    uint8_t chksum=0;

    int i;

    for(i=0;i<11;i++)

        chksum=(((chksum&0xfe)>>1)|((chksum&0x01)?0x80:0))

            +(unsigned char)entry->name[i];

    return chksum;

}

/* if return_time==0, this returns the fat_date, else the fat_time */

static uint16_t fat_datetime(time_t time,int return_time) {

    struct tm* t;

#ifdef _WIN32

    t=localtime(&time); /* this is not thread safe */

#else

    struct tm t1;

    t=&t1;

    localtime_r(&time,t);

#endif

    if(return_time)

        return cpu_to_le16((t->tm_sec/2)|(t->tm_min<<5)|(t->tm_hour<<11));

    return cpu_to_le16((t->tm_mday)|((t->tm_mon+1)<<5)|((t->tm_year-80)<<9));

}

static inline void fat_set(BDRVVVFATState* s,unsigned int cluster,uint32_t value)

{

    if(s->fat_type==12) {

        assert(0); /* TODO */

    } else if(s->fat_type==16) {

        uint16_t* entry=array_get(&(s->fat),cluster);

        *entry=cpu_to_le16(value&0xffff);

    } else {

        uint32_t* entry=array_get(&(s->fat),cluster);

        *entry=cpu_to_le32(value);

    }

}

static inline uint32_t fat_get(BDRVVVFATState* s,unsigned int cluster)

{

    //fprintf(stderr,"want to get fat for cluster %d\n",cluster);

    if(s->fat_type==12) {

        const uint8_t* x=s->fat.pointer+cluster*3/2;

        return ((x[0]|(x[1]<<8))>>(cluster&1?4:0))&0x0fff;

    } else if(s->fat_type==16) {

        uint16_t* entry=array_get(&(s->fat),cluster);

        return le16_to_cpu(*entry);

    } else {

        uint32_t* entry=array_get(&(s->fat),cluster);

        return le32_to_cpu(*entry);

    }

}

static inline int fat_eof(BDRVVVFATState* s,uint32_t fat_entry)

{

    if(fat_entry>s->max_fat_value-8)

        return -1;

    return 0;

}

static inline void init_fat(BDRVVVFATState* s)

{

    int i;

    array_init(&(s->fat),(s->fat_type==32?4:2));

    array_get(&(s->fat),s->sectors_per_fat*0x200/s->fat.item_size-1);

    memset(s->fat.pointer,0,s->fat.size);

    fat_set(s,0,0x7ffffff8);

    for(i=1;i<s->sectors_for_directory/s->sectors_per_cluster-1;i++)

        fat_set(s,i,i+1);

    fat_set(s,i,0x7fffffff);

    switch(s->fat_type) {

        case 12: s->max_fat_value=0xfff; break;

        case 16: s->max_fat_value=0xffff; break;

        case 32: s->max_fat_value=0xfffffff; break;

        default: s->max_fat_value=0; /* error... */

    }

}

static inline int long2unix_name(unsigned char* dest,int dest_size,direntry_t* direntry_short) {

    int i=-1,j;

    int chksum=fat_chksum(direntry_short);

    while(1) {

        char* buf=(char*)(direntry_short+i);

        if((buf[0]&0x3f)!=-i || direntry_short[i].reserved[1]!=chksum ||

                direntry_short[i].attributes!=0xf) {

            if(i<-1)

                return -3;

            /* take short name */

            for(j=7;j>0 && direntry_short->name[j]==' ';j--);

            if(j+1>dest_size)

                return -1;

            strncpy(dest,direntry_short->name,j+1);

            dest+=j+1; dest_size-=j+1;

            for(j=2;j>=0 && direntry_short->extension[j]==' ';j--);

            if(j>=0) {

                if(j+2>dest_size)

                    return -1;

                dest[0]='.';

                strncpy(dest+1,direntry_short->extension,j+1);

            }

            return 0;

        }

        for(j=0;j<13;j++) {

            dest_size--;

            if(dest_size<0)

                return -2;

            dest[0]=buf[2*j+((j<5)?1:(j<11)?4:6)];

            if(dest[0]==0 && (buf[0]&0x40)!=0)

                return 0;

            dest++;

        }

        /* last entry, but no trailing \0? */

        if(buf[0]&0x40)

            return -3;

        i--;

    }

}

static inline direntry_t* create_short_filename(BDRVVVFATState* s,unsigned int directory_start,const char* filename,int is_dot)

{

    int i,long_index=s->directory.next;

    direntry_t* entry=0;

    direntry_t* entry_long=0;

    if(is_dot) {

        entry=array_get_next(&(s->directory));

        memset(entry->name,0x20,11);

        memcpy(entry->name,filename,strlen(filename));

        return entry;

    }

    for(i=1;i<8 && filename[i] && filename[i]!='.';i++);

    entry_long=create_long_filename(s,filename);

    entry=array_get_next(&(s->directory));

    memset(entry->name,0x20,11);

    strncpy(entry->name,filename,i);

    if(filename[i]) {

        int len=strlen(filename);

        for(i=len;i>0 && filename[i-1]!='.';i--);

        if(i>0)

            memcpy(entry->extension,filename+i,(len-i>3?3:len-i));

    }

    /* upcase & remove unwanted characters */

    for(i=10;i>=0;i--) {

        if(i==10 || i==7) for(;i>1 && entry->name[i]==' ';i--);

        if(entry->name[i]<=' ' || entry->name[i]>0x7f

                || strchr("*?<>|\":/\\[];,+='",entry->name[i]))

            entry->name[i]='_';

        else if(entry->name[i]>='a' && entry->name[i]<='z')

            entry->name[i]+='A'-'a';

    }

    /* mangle duplicates */

    while(1) {

        direntry_t* entry1=array_get(&(s->directory),directory_start);

        int j;

        for(;entry1<entry;entry1++)

            if(!(entry1->attributes&0xf) && !memcmp(entry1->name,entry->name,11))

                break; /* found dupe */

        if(entry1==entry) /* no dupe found */

            break;

        /* use all 8 characters of name */        

        if(entry->name[7]==' ') {

            int j;

            for(j=6;j>0 && entry->name[j]==' ';j--)

                entry->name[j]='~';

        }

        /* increment number */

        for(j=7;j>0 && entry->name[j]=='9';j--)

            entry->name[j]='0';

        if(j>0) {

            if(entry->name[j]<'0' || entry->name[j]>'9')

                entry->name[j]='0';

            else

                entry->name[j]++;

        }

    }

    /* calculate checksum; propagate to long name */

    if(entry_long) {

        uint8_t chksum=fat_chksum(entry);

        /* calculate anew, because realloc could have taken place */

        entry_long=array_get(&(s->directory),long_index);

        while(entry_long<entry

                    && entry_long->attributes==0xf) {

            entry_long->reserved[1]=chksum;

            entry_long++;

        }

    }

    return entry;

}

static int read_directory(BDRVVVFATState* s,const char* dirname,

                int first_cluster_of_parent)

{

    DIR* dir=opendir(dirname);

    struct dirent* entry;

    struct stat st;

    unsigned int start_of_directory=s->directory.next;

    /* mappings before first_file_mapping are directories */

    unsigned int first_directory_mapping=s->first_file_mapping;

    unsigned int first_cluster=(start_of_directory/0x10/s->sectors_per_cluster);

    int i;

    if(!dir)

        return -1;

    while((entry=readdir(dir))) {

        unsigned int length=strlen(dirname)+2+strlen(entry->d_name);

        char* buffer;

        direntry_t* direntry;

        int is_dot=!strcmp(entry->d_name,".");

        int is_dotdot=!strcmp(entry->d_name,"..");

        if(start_of_directory==1 && (is_dotdot || is_dot))

            continue;

        buffer=(char*)malloc(length);

        snprintf(buffer,length,"%s/%s",dirname,entry->d_name);

        if(stat(buffer,&st)<0) {

            free(buffer);

            continue;

        }

        /* create directory entry for this file */

        //fprintf(stderr,"create direntry at %d (cluster %d) for %s\n",s->directory.next,s->directory.next/0x10/s->sectors_per_cluster,entry->d_name);

        direntry=create_short_filename(s,start_of_directory,entry->d_name,is_dot||is_dotdot);

        direntry->attributes=(S_ISDIR(st.st_mode)?0x10:0x20);

        direntry->reserved[0]=direntry->reserved[1]=0;

        direntry->ctime=fat_datetime(st.st_ctime,1);

        direntry->cdate=fat_datetime(st.st_ctime,0);

        direntry->adate=fat_datetime(st.st_atime,0);

        direntry->begin_hi=0;

        direntry->mtime=fat_datetime(st.st_mtime,1);

        direntry->mdate=fat_datetime(st.st_mtime,0);

        if(is_dotdot)

            direntry->begin=cpu_to_le16(first_cluster_of_parent);

        else if(is_dot)

            direntry->begin=cpu_to_le16(first_cluster);

        else

            direntry->begin=cpu_to_le16(0); /* do that later */

        direntry->size=cpu_to_le32(st.st_size);

        /* create mapping for this file */

        if(!is_dot && !is_dotdot) {

            if(S_ISDIR(st.st_mode))

                s->current_mapping=(mapping_t*)array_insert(&(s->mapping),s->first_file_mapping++,1);

            else

                s->current_mapping=(mapping_t*)array_get_next(&(s->mapping));

            s->current_mapping->begin=0;

            s->current_mapping->end=st.st_size;

            s->current_mapping->offset=0;

            s->current_mapping->filename=buffer;

            s->current_mapping->dir_index=s->directory.next-1;

            s->current_mapping->mode=(S_ISDIR(st.st_mode)?MODE_DIRECTORY:MODE_UNDEFINED);

        }

    }

    closedir(dir);

    /* fill with zeroes up to the end of the cluster */

    while(s->directory.next%(0x10*s->sectors_per_cluster)) {

        direntry_t* direntry=array_get_next(&(s->directory));

        memset(direntry,0,sizeof(direntry_t));

    }

    /* reserve next cluster also (for new files) */

    for(i=0;i<0x10*s->sectors_per_cluster;i++) {

        direntry_t* direntry=array_get_next(&(s->directory));

        memset(direntry,0,sizeof(direntry_t));

    }

    /* was it the first directory? */

    if(start_of_directory==1) {

        mapping_t* mapping=array_insert(&(s->mapping),0,1);

        mapping->filename=strdup(dirname);

        mapping->mode=MODE_DIRECTORY;

        mapping->begin=0;

        mapping->end=1;

        mapping->offset=0;

        mapping->dir_index=0xffffffff;

        s->sectors_of_root_directory=s->directory.next/0x10;

    }

    /* recurse directories */

    {

        int i;

        //fprintf(stderr,"iterating subdirectories of %s (first cluster %d): %d to %d\n",dirname,first_cluster,first_directory_mapping,last_directory_mapping);

        for(i=first_directory_mapping;i<s->first_file_mapping;i++) {

            mapping_t* mapping=array_get(&(s->mapping),i);

            direntry_t* direntry=array_get(&(s->directory),mapping->dir_index);

            /* the directory to be read can add more subdirectories */

            int last_dir_mapping=s->first_file_mapping;

            assert(mapping->mode==MODE_DIRECTORY);

            /* first, tell the mapping where the directory will start */

            mapping->begin=s->directory.next/0x10/s->sectors_per_cluster;

            if(i>0) {

                mapping[-1].end=mapping->begin;

                assert(mapping[-1].begin<mapping->begin);

            }

            /* then tell the direntry */

            direntry->begin=cpu_to_le16(mapping->begin);

            //fprintf(stderr,"read directory %s (begin %d)\n",mapping->filename,(int)mapping->begin);

            /* then read it */

            if(read_directory(s,mapping->filename,first_cluster))

                return -1;

            if(last_dir_mapping!=s->first_file_mapping) {

                int diff=s->first_file_mapping-last_dir_mapping;

                assert(diff>0);

                if(last_dir_mapping!=i+1) {

                    int count=last_dir_mapping-i-1;

                    int to=s->first_file_mapping-count;

                    assert(count>0);

                    assert(to>i+1);

                    array_roll(&(s->mapping),to,i+1,count);

                    /* could have changed due to realloc */

                    mapping=array_get(&(s->mapping),i);

                    mapping->end=mapping[1].begin;

                }

                i+=diff;

            }

        }

    }

    return 0;

}

static int init_directory(BDRVVVFATState* s,const char* dirname)

{

    bootsector_t* bootsector=(bootsector_t*)&(s->first_sectors[(s->first_sectors_number-1)*0x200]);

    unsigned int i;

    unsigned int cluster;

    memset(&(s->first_sectors[0]),0,0x40*0x200);

    /* TODO: if FAT32, this is probably wrong */

    s->sectors_per_fat=0xfc;

    s->sectors_per_cluster=0x10;

    s->cluster_size=s->sectors_per_cluster*0x200;

    s->cluster=malloc(s->cluster_size);

    array_init(&(s->mapping),sizeof(mapping_t));

    array_init(&(s->directory),sizeof(direntry_t));

    array_init(&(s->commit),sizeof(commit_t));

    /* add volume label */

    {

        direntry_t* entry=array_get_next(&(s->directory));

        entry->attributes=0x28; /* archive | volume label */

        snprintf(entry->name,11,"QEMU VVFAT");

    }

    if(read_directory(s,dirname,0))

        return -1;

    /* make sure that the number of directory entries is multiple of 0x200/0x20 (to fit the last sector exactly) */

    s->sectors_for_directory=s->directory.next/0x10;

    s->faked_sectors=s->first_sectors_number+s->sectors_per_fat*2+s->sectors_for_directory;

    s->cluster_count=(s->sector_count-s->faked_sectors)/s->sectors_per_cluster;

    /* Now build FAT, and write back information into directory */

    init_fat(s);

    cluster=s->sectors_for_directory/s->sectors_per_cluster;

    assert(s->sectors_for_directory%s->sectors_per_cluster==0);

    /* set the end of the last read directory */

    if(s->first_file_mapping>0) {

        mapping_t* mapping=array_get(&(s->mapping),s->first_file_mapping-1);

        mapping->end=cluster;

    }

    for(i=1;i<s->mapping.next;i++) {

        mapping_t* mapping=array_get(&(s->mapping),i);

        direntry_t* direntry=array_get(&(s->directory),mapping->dir_index);

        if(mapping->mode==MODE_DIRECTORY) {

            /* directory */

            int i;

#ifdef DEBUG

            fprintf(stderr,"assert: %s %d < %d\n",mapping->filename,(int)mapping->begin,(int)mapping->end);

#endif

            assert(mapping->begin<mapping->end);

            for(i=mapping->begin;i<mapping->end-1;i++)

                fat_set(s,i,i+1);

            fat_set(s,i,0x7fffffff);

        } else {

            /* as the space is virtual, we can be sloppy about it */

            unsigned int end_cluster=cluster+mapping->end/s->cluster_size;

            if(end_cluster>=s->cluster_count) {

                fprintf(stderr,"Directory does not fit in FAT%d\n",s->fat_type);

                return -1;

            }

            mapping->begin=cluster;

            mapping->mode=MODE_NORMAL;

            mapping->offset=0;

            direntry->size=cpu_to_le32(mapping->end);

            if(direntry->size==0) {

                direntry->begin=0;

                mapping->end=cluster;

                continue;

            }

            direntry->begin=cpu_to_le16(cluster);

            mapping->end=end_cluster+1;

            for(;cluster<end_cluster;cluster++)

                fat_set(s,cluster,cluster+1);

            fat_set(s,cluster,0x7fffffff);

            cluster++;

        }

    }

    s->current_mapping=0;

    bootsector->jump[0]=0xeb;

    bootsector->jump[1]=0x3e;

    bootsector->jump[2]=0x90;

    memcpy(bootsector->name,"QEMU    ",8);

    bootsector->sector_size=cpu_to_le16(0x200);

    bootsector->sectors_per_cluster=s->sectors_per_cluster;

    bootsector->reserved_sectors=cpu_to_le16(1);

    bootsector->number_of_fats=0x2; /* number of FATs */

    bootsector->root_entries=cpu_to_le16(s->sectors_of_root_directory*0x10);

    bootsector->zero=0;

    bootsector->media_type=(s->first_sectors_number==1?0xf0:0xf8); /* media descriptor */

    bootsector->sectors_per_fat=cpu_to_le16(s->sectors_per_fat);

    bootsector->sectors_per_track=cpu_to_le16(0x3f);

    bootsector->number_of_heads=cpu_to_le16(0x10);

    bootsector->hidden_sectors=cpu_to_le32(s->first_sectors_number==1?0:0x3f);

    /* TODO: if FAT32, adjust */

    bootsector->total_sectors=cpu_to_le32(s->sector_count);

    /* TODO: if FAT32, this is wrong */

    bootsector->u.fat16.drive_number=0x80; /* assume this is hda (TODO) */

    bootsector->u.fat16.current_head=0;

    bootsector->u.fat16.signature=0x29;

    bootsector->u.fat16.id=cpu_to_le32(0xfabe1afd);

    memcpy(bootsector->u.fat16.volume_label,"QEMU VVFAT ",11);

    memcpy(bootsector->fat_type,(s->fat_type==12?"FAT12   ":s->fat_type==16?"FAT16   ":"FAT32   "),8);

    bootsector->magic[0]=0x55; bootsector->magic[1]=0xaa;

    return 0;

}

static int vvfat_open(BlockDriverState *bs, const char* dirname)

{

    BDRVVVFATState *s = bs->opaque;

    int i;

    /* TODO: automatically determine which FAT type */

    s->fat_type=16;

    s->sector_count=0xec04f;

    s->current_cluster=0xffffffff;

    s->first_file_mapping=0;

    /* TODO: if simulating a floppy, this is 1, because there is no partition table */

    s->first_sectors_number=0x40;

    if (strstart(dirname, "fat:", &dirname)) {

        /* read only is the default for safety */

        bs->read_only = 1;

    } else if (strstart(dirname, "fatrw:", &dirname)) {

        /* development only for now */

        bs->read_only = 0;

    } else {

        return -1;

    }

    if(init_directory(s,dirname))

        return -1;

    if(s->first_sectors_number==0x40)

        init_mbr(s);

    /* TODO: this could be wrong for FAT32 */

    bs->cyls=1023; bs->heads=15; bs->secs=63;

    bs->total_sectors=bs->cyls*bs->heads*bs->secs;

    /* write support */

    for(i=0;i<3;i++)

        s->action[i]=WRITE_UNDEFINED;

    return 0;

}

static inline void vvfat_close_current_file(BDRVVVFATState *s)

{

    if(s->current_mapping) {

        s->current_mapping = 0;

        close(s->current_fd);

    }

}

/* mappings between index1 and index2-1 are supposed to be ordered

 * return value is the index of the last mapping for which end>cluster_num

 */

static inline int find_mapping_for_cluster_aux(BDRVVVFATState* s,int cluster_num,int index1,int index2)

{

    int index3=index1+1;

    //fprintf(stderr,"find_aux: cluster_num=%d, index1=%d,index2=%d\n",cluster_num,index1,index2);

    while(1) {

        mapping_t* mapping;