block-vvfat.c

qemu虚拟机代码

    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);
}

static char is_free(const direntry_t* direntry)
{
    /* return direntry->name[0]==0 ; */
    return direntry->attributes == 0 || direntry->name[0]==0xe5;
}

static char is_volume_label(const direntry_t* direntry)
{
    return direntry->attributes == 0x28;
}

static char is_long_name(const direntry_t* direntry)
{
    return direntry->attributes == 0xf;
}

static char is_short_name(const direntry_t* direntry)
{
    return !is_volume_label(direntry) && !is_long_name(direntry)
	&& !is_free(direntry);
}

static char is_directory(const direntry_t* direntry)
{
    return direntry->attributes & 0x10 && direntry->name[0] != 0xe5;
}

static inline char is_dot(const direntry_t* direntry)
{
    return is_short_name(direntry) && direntry->name[0] == '.';
}

static char is_file(const direntry_t* direntry)
{
    return is_short_name(direntry) && !is_directory(direntry);
}

static inline uint32_t begin_of_direntry(const direntry_t* direntry)
{
    return le16_to_cpu(direntry->begin)|(le16_to_cpu(direntry->begin_hi)<<16);
}

static inline uint32_t filesize_of_direntry(const direntry_t* direntry)
{
    return le32_to_cpu(direntry->size);
}

static void set_begin_of_direntry(direntry_t* direntry, uint32_t begin)
{
    direntry->begin = cpu_to_le16(begin & 0xffff);
    direntry->begin_hi = cpu_to_le16((begin >> 16) & 0xffff);
}

/* fat functions */

static inline uint8_t fat_chksum(const 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==32) {
	uint32_t* entry=array_get(&(s->fat),cluster);
	*entry=cpu_to_le32(value);
    } else if(s->fat_type==16) {
	uint16_t* entry=array_get(&(s->fat),cluster);
	*entry=cpu_to_le16(value&0xffff);
    } else {
	int offset = (cluster*3/2);
	unsigned char* p = array_get(&(s->fat), offset);
        switch (cluster&1) {
	case 0:
		p[0] = value&0xff;
		p[1] = (p[1]&0xf0) | ((value>>8)&0xf);
		break;
	case 1:
		p[0] = (p[0]&0xf) | ((value&0xf)<<4);
		p[1] = (value>>4);
		break;
	}
    }
}

static inline uint32_t fat_get(BDRVVVFATState* s,unsigned int cluster)
{
    if(s->fat_type==32) {
	uint32_t* entry=array_get(&(s->fat),cluster);
	return le32_to_cpu(*entry);
    } else if(s->fat_type==16) {
	uint16_t* entry=array_get(&(s->fat),cluster);
	return le16_to_cpu(*entry);
    } else {
	const uint8_t* x=s->fat.pointer+cluster*3/2;
	return ((x[0]|(x[1]<<8))>>(cluster&1?4:0))&0x0fff;
    }
}

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)
{
    if (s->fat_type == 12) {
	array_init(&(s->fat),1);
	array_ensure_allocated(&(s->fat),
		s->sectors_per_fat * 0x200 * 3 / 2 - 1);
    } else {
	array_init(&(s->fat),(s->fat_type==32?4:2));
	array_ensure_allocated(&(s->fat),
		s->sectors_per_fat * 0x200 / s->fat.item_size - 1);
    }
    memset(s->fat.pointer,0,s->fat.size);
    
    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=0x0fffffff; break;
	default: s->max_fat_value=0; /* error... */
    }

}

/* TODO: in create_short_filename, 0xe5->0x05 is not yet handled! */
/* TODO: in parse_short_filename, 0x05->0xe5 is not yet handled! */
static inline direntry_t* create_short_and_long_name(BDRVVVFATState* s,
	unsigned int directory_start, const char* filename, int is_dot)
{
    int i,j,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;
    }
    
    entry_long=create_long_filename(s,filename);
  
    i = strlen(filename); 
    for(j = i - 1; j>0  && filename[j]!='.';j--);
    if (j > 0)
	i = (j > 8 ? 8 : j);
    else if (i > 8)
	i = 8;

    entry=array_get_next(&(s->directory));
    memset(entry->name,0x20,11);
    strncpy(entry->name,filename,i);
    
    if(j > 0)
	for (i = 0; i < 3 && filename[j+1+i]; i++)
	    entry->extension[i] = filename[j+1+i];

    /* upcase & remove unwanted characters */
    for(i=10;i>=0;i--) {
	if(i==10 || i==7) for(;i>0 && 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(!is_long_name(entry1) && !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 && is_long_name(entry_long)) {
	    entry_long->reserved[1]=chksum;
	    entry_long++;
	}
    }

    return entry;
}

/*
 * Read a directory. (the index of the corresponding mapping must be passed).
 */
static int read_directory(BDRVVVFATState* s, int mapping_index)
{
    mapping_t* mapping = array_get(&(s->mapping), mapping_index);
    direntry_t* direntry;
    const char* dirname = mapping->path;
    int first_cluster = mapping->begin;
    int parent_index = mapping->info.dir.parent_mapping_index;
    mapping_t* parent_mapping = (mapping_t*)
	(parent_index >= 0 ? array_get(&(s->mapping), parent_index) : 0);
    int first_cluster_of_parent = parent_mapping ? parent_mapping->begin : -1;

    DIR* dir=opendir(dirname);
    struct dirent* entry;
    int i;

    assert(mapping->mode & MODE_DIRECTORY);

    if(!dir) {
	mapping->end = mapping->begin;
	return -1;
    }
   
    i = mapping->info.dir.first_dir_index =
	    first_cluster == 0 ? 0 : s->directory.next;

    /* actually read the directory, and allocate the mappings */ 
    while((entry=readdir(dir))) {
	unsigned int length=strlen(dirname)+2+strlen(entry->d_name);
        char* buffer;
	direntry_t* direntry;
        struct stat st;
	int is_dot=!strcmp(entry->d_name,".");
	int is_dotdot=!strcmp(entry->d_name,"..");

	if(first_cluster == 0 && (is_dotdot || is_dot))
	    continue;
	
	buffer=(char*)malloc(length);
	assert(buffer);
	snprintf(buffer,length,"%s/%s",dirname,entry->d_name);

	if(stat(buffer,&st)<0) {
	    free(buffer);
            continue;
	}

	/* create directory entry for this file */
	direntry=create_short_and_long_name(s, i, 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)
	    set_begin_of_direntry(direntry, first_cluster_of_parent);
	else if(is_dot)
	    set_begin_of_direntry(direntry, first_cluster);
	else
	    direntry->begin=0; /* do that later */
        if (st.st_size > 0x7fffffff) {
	    fprintf(stderr, "File %s is larger than 2GB\n", buffer);
	    free(buffer);
	    return -2;
        }
	direntry->size=cpu_to_le32(S_ISDIR(st.st_mode)?0:st.st_size);

	/* create mapping for this file */
	if(!is_dot && !is_dotdot && (S_ISDIR(st.st_mode) || st.st_size)) {
	    s->current_mapping=(mapping_t*)array_get_next(&(s->mapping));
	    s->current_mapping->begin=0;
	    s->current_mapping->end=st.st_size;
	    /*
	     * we get the direntry of the most recent direntry, which
	     * contains the short name and all the relevant information.
	     */
	    s->current_mapping->dir_index=s->directory.next-1;
	    s->current_mapping->first_mapping_index = -1;
	    if (S_ISDIR(st.st_mode)) {
		s->current_mapping->mode = MODE_DIRECTORY;
		s->current_mapping->info.dir.parent_mapping_index =
		    mapping_index;
	    } else {
		s->current_mapping->mode = MODE_UNDEFINED;
		s->current_mapping->info.file.offset = 0;
	    }
	    s->current_mapping->path=buffer;
	    s->current_mapping->read_only =
		(st.st_mode & (S_IWUSR | S_IWGRP | S_IWOTH)) == 0;
	}
    }
    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));
    }

/* TODO: if there are more entries, bootsector has to be adjusted! */
#define ROOT_ENTRIES (0x02 * 0x10 * s->sectors_per_cluster)
    if (mapping_index == 0 && s->directory.next < ROOT_ENTRIES) {
	/* root directory */
	int cur = s->directory.next;
	array_ensure_allocated(&(s->directory), ROOT_ENTRIES - 1);
	memset(array_get(&(s->directory), cur), 0,
		(ROOT_ENTRIES - cur) * sizeof(direntry_t));
    }
	
     /* reget the mapping, since s->mapping was possibly realloc()ed */
    mapping = (mapping_t*)array_get(&(s->mapping), mapping_index);
    first_cluster += (s->directory.next - mapping->info.dir.first_dir_index)
	* 0x20 / s->cluster_size;
    mapping->end = first_cluster;

    direntry = (direntry_t*)array_get(&(s->directory), mapping->dir_index);
    set_begin_of_direntry(direntry, mapping->begin);
   
    return 0;
}

static inline uint32_t sector2cluster(BDRVVVFATState* s,off_t sector_num)
{
    return (sector_num-s->faked_sectors)/s->sectors_per_cluster;
}

static inline off_t cluster2sector(BDRVVVFATState* s, uint32_t cluster_num)
{
    return s->faked_sectors + s->sectors_per_cluster * cluster_num;
}

static inline uint32_t sector_offset_in_cluster(BDRVVVFATState* s,off_t sector_num)
{
    return (sector_num-s->first_sectors_number-2*s->sectors_per_fat)%s->sectors_per_cluster;
}

#ifdef DBG
static direntry_t* get_direntry_for_mapping(BDRVVVFATState* s,mapping_t* mapping)
{
    if(mapping->mode==MODE_UNDEFINED)
	return 0;
    return (direntry_t*)(s->directory.pointer+sizeof(direntry_t)*mapping->dir_index);
}
#endif

static int init_directories(BDRVVVFATState* s,