fatfs_supp.c

该工程是从ecos嵌入式系统下移植过来的一个小型的fat16文件系统

{
    dentry->name[0] = 0xE5;
}

// -------------------------------------------------------------------------
// get_dentry_filename()
// Gets the filename from given dir entry. 
 
static void 
get_dentry_filename(fat_dir_entry_t *fde, char *name)
{
    int i = 0;
    char *cptr  = fde->name;
    char *cname = name;

    while (*cptr != ' ' && i < 8)
    {
        *cname++ = *cptr++; i++;
    }
    cptr = fde->ext;

    if (*cptr != ' ')
    {
        *cname++ = '.'; i = 0;
        while (*cptr != ' ' && i < 3)
        {
            *cname++ = *cptr++; i++;
        }
    }
    *cname = '\0';

    printf( "dos_name='%s' dos_ext='%s' filename='%s'",
                    fde->name, fde->ext, name);
}

// -------------------------------------------------------------------------
// set_dentry_filename()
// Sets the filename to given dir entry. 
 
static void 
set_dentry_filename(fat_dir_entry_t *fde, const char *name, int namelen)
{
    int i, nidx;
    const char *cname;
    char *cptr;

    // Special case check
    if (name[0] == '.')
    {
        if (name[1] == '\0')
        {
            strcpy(fde->name, ".       ");
            strcpy(fde->ext,  "   ");
            return;
        }
        else if (name[1] == '.' && name[2] == '\0')
        {
            strcpy(fde->name, "..      ");
            strcpy(fde->ext,  "   ");
            return;
        }
    }
    
    if (0 == namelen)
        namelen = 9999;
    
    nidx  = 0;
    cname = name;
    cptr  = fde->name;
    for (i = 0; i < 8; i++)
    {
        if (*cname != '.' && *cname != '\0' && nidx++ < namelen)
            *cptr++ = toupper(*cname++);
        else
            *cptr++ = ' ';
    }
    *cptr = '\0';
    
    while (*cname != '.' && *cname != '\0' && nidx++ < namelen)
        cname++;
   
    if (*cname == '.' && nidx++ < namelen) 
        cname++;
    
    cptr = fde->ext;
    for (i = 0; i < 3; i++)
    {
        if (*cname != '.' && *cname != '\0' && nidx++ < namelen)
            *cptr++ = toupper(*cname++);
        else
            *cptr++ = ' ';
    }
    *cptr = '\0';

    printf( "filename='%s' namelen=%d dos_name='%s' dos_ext='%s'", 
                    name, namelen, fde->name, fde->ext);
}

// -------------------------------------------------------------------------
// get_next_dentry()
// Gets next dir entry searching from given position to the end.
// Position is expected in DENTRY_SIZE units.
// If EEOF is returned there are no more extries in given dir.
 
static int
get_next_dentry(fatfs_disk_t    *disk,
                fatfs_node_t    *dir,
                cyg_uint32      *pos,
                fat_dir_entry_t *dentry)
{
    fatfs_data_pos_t dpos;
    cyg_uint32 off;
    int err = ENOERR;

    // Calculate dentry offset
    off = *pos * DENTRY_SIZE;
    
    printf( "pos=%d off=%d dir=%p cluster=%d",
                    off, *pos, dir, dir->cluster);

    // Root dir check
    if (0 == dir->cluster)
    {
        dpos.cluster      = 0;
        dpos.cluster_snum = 0;
        dpos.cluster_pos  = off;
    }
    else
    {
        err = get_data_position_from_off(disk, dir->cluster, 
            off, &dpos, &dir->tcache, false);
        if (err != ENOERR)
            return err;
    }

    while (true)
    {
        // Root dir check
        if (0 != dir->cluster) 
        {
            // Change cluster if needed
            if (!is_pos_inside_cluster(disk, dpos.cluster_pos))
                err = get_next_cluster(disk, &dpos, &dir->tcache, CO_NONE);
        }
        else
        {
            if (*pos >= disk->fat_root_dir_nents)
                err = EEOF;
        }

        if (err != ENOERR)
            break;

        err = read_dentry(disk, &dpos, dentry);
        if (err != ENOERR)
            return err;

        if (DENTRY_IS_ZERO(dentry))
        {
            // If we get a ZERO dir entry, we assume that
            // there are no more entries in current dir
            printf( "ZERO dentry"); 
            err = EEOF;
            break;
        }
        else if (!DENTRY_IS_DELETED(dentry))
        {
            // Dir entry found
            printf( "dentry_pos=%d cluster=%d pos=%d",
                            *pos, dpos.cluster, dpos.cluster_pos);
            break;
        }

        // Increment offset and position
        dpos.cluster_pos += DENTRY_SIZE;
        (*pos)++;
    }

    if (EEOF == err) printf( "end of dir");
            
    // EEOF could be returned if there are no more entries in this
    // dir - this should be cought by the calling function 
    return err;
}

// -------------------------------------------------------------------------
// get_free_dentry()
// Gets free dir entry slot searching from given position.
// If an deleated entry is found, its clusters are freed and the
// entry is reused. 
// The directory is extended if needed.

static int
get_free_dentry(fatfs_disk_t     *disk, 
                fatfs_data_pos_t *dpos,
                fatfs_tcache_t   *tcache)
{
    fat_dir_entry_t  dentry;
    fatfs_data_pos_t cdpos;
    int err = ENOERR;
    
    printf( "cluster=%d cluster_snum=%d cluster_pos=%d", 
                    dpos->cluster, dpos->cluster_snum, dpos->cluster_pos);
    cdpos = *dpos;

    while (true)
    {
        // Root dir check
        if (0 != cdpos.cluster) 
        {
            // Change cluster if needed
            if (!is_pos_inside_cluster(disk, cdpos.cluster_pos))
                err = get_next_cluster(disk, &cdpos, tcache, 
                                       CO_EXTEND | CO_ERASE_NEW);
        }
        else
        {
            if (cdpos.cluster_pos >= disk->fat_root_dir_size)
                err = ENOSPC;
        }

        if (err != ENOERR)
            return err;

        err = read_dentry(disk, &cdpos, &dentry);
        if (err != ENOERR)
            return err;

        if (DENTRY_IS_DELETED(&dentry))
        {
            printf( "deleted dentry at cluster=%d cluster_snum=%d "
                            "cluster_pos=%d", cdpos.cluster, cdpos.cluster_snum,
                            cdpos.cluster_pos);

            // Retrun found dentry position
            *dpos = cdpos;
            return ENOERR;
        }
        else if (DENTRY_IS_ZERO(&dentry))
        {
            printf( "zero dentry at cluster=%d cluster_snum=%d "
                            "cluster_pos=%d", cdpos.cluster, cdpos.cluster_snum,
                            cdpos.cluster_pos);

            // Retrun found dentry position
            *dpos = cdpos;
            return ENOERR;  
        }
       
        // Increment current position
        cdpos.cluster_pos += DENTRY_SIZE;
    }
}
 
// -------------------------------------------------------------------------
// dentry_to_node()
// Converts FAT dir entry to node. 
 
static void
dentry_to_node(fat_dir_entry_t *dentry, 
               fatfs_node_t    *node)
{
    get_dentry_filename(dentry, node->filename);

    if (DENTRY_IS_DIR(dentry))
        node->mode = __stat_mode_DIR;
    else
        node->mode = __stat_mode_REG;
    
    date_dos2unix(dentry->crt_time, dentry->crt_date, &node->ctime);
    date_dos2unix(0,                dentry->acc_date, &node->atime);
    date_dos2unix(dentry->wrt_time, dentry->wrt_date, &node->mtime);
    
    node->size       = dentry->size;
    node->priv_data  = dentry->nt_reserved;
    node->cluster    = dentry->cluster;
    node->dentry_pos = dentry->pos;
}

// -------------------------------------------------------------------------
// node_to_dentry()
// Converts node to FAT dir entry. 
 
static void
node_to_dentry(fatfs_node_t *node, fat_dir_entry_t *dentry)
{
    set_dentry_filename(dentry, node->filename, 0);

    if (node->mode == __stat_mode_DIR)
        dentry->attr = DENTRY_ATTR_DIR;
    else
        dentry->attr = DENTRY_ATTR_ARCHIVE;
        
    date_unix2dos(node->ctime, &dentry->crt_time, &dentry->crt_date);
    date_unix2dos(node->atime, NULL,              &dentry->acc_date);
    date_unix2dos(node->mtime, &dentry->wrt_time, &dentry->wrt_date);
    
    dentry->crt_sec_100 = 0; //FIXME
    dentry->size        = node->size;
    dentry->nt_reserved = node->priv_data;
    dentry->cluster     = node->cluster;
    dentry->cluster_HI  = 0;
    dentry->pos         = node->dentry_pos;
}

//==========================================================================
// FAT data functions 

// -------------------------------------------------------------------------
// read_data()
// Reads data from given position. 
 
static int
read_data(fatfs_disk_t     *disk,
          void             *data,
          cyg_uint32       *len,
          fatfs_data_pos_t *dpos,
          fatfs_tcache_t   *tcache)
{
    unsigned char *buf;
    cyg_uint32 apos;
    cyg_uint32 size;
    int err;

    // Initialize variables and get the absolute starting pos on disk
    buf   = (unsigned char *)data;
    size  = *len;
    apos  = get_data_disk_apos(disk, dpos->cluster, dpos->cluster_pos);
    err   = ENOERR;
  
    printf( "len=%d cluster=%d cluster_pos=%d "
                    "cluster_snum=%d apos=%d", *len, dpos->cluster, 
                    dpos->cluster_pos, dpos->cluster_snum, apos);

    while (size > 0)
    {
        cyg_uint32 csize;

        // Check if we are still inside current cluster
        if (!is_pos_inside_cluster(disk, dpos->cluster_pos))
        {
            // Get next cluster of file and adjust absolute disk position 
            err = get_next_cluster(disk, dpos, tcache, CO_NONE);
            if (err != ENOERR)
                goto out;
            apos = get_data_disk_apos(disk, dpos->cluster, dpos->cluster_pos);
        }
        
        // Adjust the data chunk size to be read to the cluster boundary
        if (size > (disk->cluster_size - dpos->cluster_pos))
            csize = disk->cluster_size - dpos->cluster_pos;
        else
            csize = size;

        printf( "-- len=%d cluster=%d cluster_pos=%d "
                        "cluster_snum=%d apos=%d", csize, dpos->cluster,
                        dpos->cluster_pos, dpos->cluster_snum, apos);

        // Read data chunk 
        err = ReadBlock((void*)buf, &csize, 0, apos);

        if (err != ENOERR)
            goto out;

        // Adjust running variables
        buf               += csize;
        dpos->cluster_pos += csize;
        apos              += csize;
        size              -= csize;    
    }
    
out:
    *len -= size;

    printf( "total len=%d", *len);

    return err;
}

// -------------------------------------------------------------------------
// write_data()
// Writes data to given position. 
 
static int
write_data(fatfs_disk_t     *disk,
           void             *data,
           cyg_uint32       *len,
           fatfs_data_pos_t *dpos,
           fatfs_tcache_t   *tcache)
{
    unsigned char *buf;
    cyg_uint32 apos;
    cyg_uint32 size;
    int err;

    // Initialize variables and get the absolute starting pos on disk
    buf   = (unsigned char *)data;
    size  = *len;
    apos  = get_data_disk_apos(disk, dpos->cluster, dpos->cluster_pos);
    err   = ENOERR;
  
    printf( "len=%d cluster=%d cluster_pos=%d "
                    "cluster_snum=%d apos=%d", *len, dpos->cluster, 
                    dpos->cluster_pos, dpos->cluster_snum, apos);

    while (size > 0)
    {
        cyg_uint32 csize;

        // Check if we are still inside current cluster
        if (!is_pos_inside_cluster(disk, dpos->cluster_pos))
        {
            // Get next cluster of file and adjust absolute disk position,
            // if at the last cluster try to extend the cluster chain 
            err = get_next_cluster(disk, dpos, tcache, CO_EXTEND);
            if (err != ENOERR)
                goto out;
            apos = get_data_disk_apos(disk, dpos->cluster, dpos->cluster_pos);
        }
        
        // Adjust the data chunk size to be read to the cluster boundary
        if (size > (disk->cluster_size - dpos->cluster_pos))
            csize = disk->cluster_size - dpos->cluster_pos;
        else
            csize = size;
 
        printf( "-- len=%d cluster=%d cluster_pos=%d "
                        "cluster_snum=%d apos=%d", csize, dpos->cluster,
                        dpos->cluster_pos, dpos->cluster_snum, apos);

        // Write data chunk 
        err = WriteBlock( (void*)buf, &csize, 0, apos);

        if (err != ENOERR)
            goto out;

        // Adjust running variables
        buf               += csize;
        dpos->cluster_pos += csize;
        apos              += csize;
        size              -= csize;    
    }
    
out: