romfs.c

eCos操作系统源码

    return ENOERR;
}

//==========================================================================
// Directory operations


// -------------------------------------------------------------------------
// find_direntry()
// Find a directory entry for the name and return a pointer to the first
// entry fragment.

static romfs_dirent *find_direntry( romfs_disk *disk, romfs_node *dir, const char *name, int namelen )
{
    off_t pos = 0;
    int err;

    // Loop over all the entries until a match is found or we run out
    // of data.
    while( pos < dir->size )
    {
        romfs_dirent *d;
        cyg_uint8 *buf;
        size_t size;
        
	err = findbuffer_node( disk, dir, pos, &buf, &size );
	if( err != ENOERR || size == 0)
	    return NULL;

	d = (romfs_dirent *)buf;

	// Is this the directory entry we're looking for?
	if ( match( d->name, name, namelen ) )
	    return d;

	// Otherwise move on to next entry in chain
        pos = d->next;
    }

    return NULL;
}

//==========================================================================
// Directory search

// -------------------------------------------------------------------------
// init_dirsearch()
// Initialize a dirsearch object to start a search

static void init_dirsearch( romfs_dirsearch *ds,
                            romfs_disk *disk,
			    romfs_node *dir,
                            const char *name)
{
    ds->disk     = disk;
    ds->dir      = dir;
    ds->path     = name;
    ds->node     = dir;
    ds->name     = name;
    ds->namelen  = 0;
    ds->last	 = false;
}

// -------------------------------------------------------------------------
// find_entry()
// Search a single directory for the next name in a path and update the
// dirsearch object appropriately.

static int find_entry( romfs_dirsearch *ds )
{
    romfs_node *dir = ds->dir;
    const char *name = ds->path;
    const char *n = name;
    int namelen = 0;
    romfs_dirent *d;
    
    // check that we really have a directory
    if( !S_ISDIR(dir->mode) )
        return ENOTDIR;

    // Isolate the next element of the path name. 
    while( *n != '\0' && *n != '/' )
        n++, namelen++;

    // Check if this is the last path element.
    while( *n == '/') n++;
    if( *n == '\0' ) 
        ds->last = true;

    // update name in dirsearch object
    ds->name = name;
    ds->namelen = namelen;
    
    // Here we have the name and its length set up.
    // Search the directory for a matching entry

    d = find_direntry( ds->disk, dir, name, namelen );

    if( d == NULL )
        return ENOENT;

    // pass back the node we have found
    ds->node = &ds->disk->node[d->node];

    return ENOERR;

}

// -------------------------------------------------------------------------
// romfs_find()
// Main interface to directory search code. This is used in all file
// level operations to locate the object named by the pathname.

static int romfs_find( romfs_dirsearch *d )
{
    int err;

    // Short circuit empty paths
    if( *(d->path) == '\0' )
        return ENOERR;

    // iterate down directory tree until we find the object
    // we want.
    for(;;)
    {
        err = find_entry( d );

        if( err != ENOERR )
            return err;

        if( d->last )
            return ENOERR;

        // Update dirsearch object to search next directory.
        d->dir = d->node;
        d->path += d->namelen;
        while( *(d->path) == '/' ) d->path++; // skip dirname separators
    }
}

//==========================================================================
// Pathconf support
// This function provides support for pathconf() and fpathconf().

static int romfs_pathconf( romfs_node *node, struct cyg_pathconf_info *info )
{
    int err = ENOERR;
    
    switch( info->name )
    {
    case _PC_LINK_MAX:
        info->value = LINK_MAX;
        break;
        
    case _PC_MAX_CANON:
        info->value = -1;       // not supported
        err = EINVAL;
        break;
        
    case _PC_MAX_INPUT:
        info->value = -1;       // not supported
        err = EINVAL;        
        break;
        
    case _PC_NAME_MAX:
        info->value = NAME_MAX;
        break;
        
    case _PC_PATH_MAX:
        info->value = PATH_MAX;
        break;        

    case _PC_PIPE_BUF:
        info->value = -1;       // not supported
        err = EINVAL;        
        break;        

        
    case _PC_ASYNC_IO:
        info->value = -1;       // not supported
        err = EINVAL;        
        break;
        
    case _PC_CHOWN_RESTRICTED:
        info->value = -1;       // not supported
        err = EINVAL;
        break;
        
    case _PC_NO_TRUNC:
        info->value = 0;
        break;
        
    case _PC_PRIO_IO:
        info->value = 0;
        break;
        
    case _PC_SYNC_IO:
        info->value = 0;
        break;
        
    case _PC_VDISABLE:
        info->value = -1;       // not supported
        err = EINVAL;        
        break;
        
    default:
        err = EINVAL;
        break;
    }

    return err;
}

//==========================================================================
// Filesystem operations

// -------------------------------------------------------------------------
// romfs_mount()
// Process a mount request. This mainly finds root for the
// filesystem.

static int romfs_mount    ( cyg_fstab_entry *fste, cyg_mtab_entry *mte )
{
    romfs_disk *disk=NULL;
    
    if ( !mte->data ) {
	// If the image address was not in the MTE data word,
	if ( mte->devname && mte->devname[0] ) {
	    // And there's something in the 'hardware device' field,
	    // then read the address from there.
	    sscanf( mte->devname, "%p", (char**)&disk );
	}
    } else {
        disk = (romfs_disk *)mte->data;
    }

    if ( !disk ) {
	// If still no address, try the FSTAB entry data word
	disk = (romfs_disk *)fste->data;
    }

    if ( !disk ) {
	// If still no address, give up...
	return ENOENT;
    }


    
    // Check the ROMFS magic number to ensure that there's really an fs.
    if ( disk->magic == ROMFS_CIGAM ) {
	// The disk image has the wrong byte sex!!!
	return EIO;
    } else if ( disk->magic != ROMFS_MAGIC || disk->nodecount == 0 ) {
	// No image found
	return ENOENT;
    }

    mte->root = (cyg_dir)&disk->node[0];
    
    mte->data = (CYG_ADDRWORD)disk;
    return ENOERR;
}

// -------------------------------------------------------------------------
// romfs_umount()
// Unmount the filesystem. This will currently always succeed.

static int romfs_umount   ( cyg_mtab_entry *mte )
{
    // Clear root pointer
    mte->root = CYG_DIR_NULL;
    
    // That's all folks.
        
    return ENOERR;
}

// -------------------------------------------------------------------------
// romfs_open()
// Open a file for reading

static int romfs_open     ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,
                             int mode,  cyg_file *file )
{

    romfs_dirsearch ds;
    romfs_node *node = NULL;
    int err;

    init_dirsearch( &ds, (romfs_disk *)mte->data, (romfs_node *)dir, name );
    
    err = romfs_find( &ds );

    if( err == ENOENT )
    {
	return ENOENT;
    }
    else if( err == ENOERR )
    {
        // The node exists. If the O_CREAT and O_EXCL bits are set, we
        // must fail the open.
        
        if( (mode & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL) )
            err = EEXIST;
        else node = ds.node;
    }
    
    if( err == ENOERR && (mode & O_TRUNC ) )
    {
        // If the O_TRUNC bit is set we must fail the open

        err = EPERM;
    }

    if( err != ENOERR ) return err;

    // Check that we actually have a file here
    if( S_ISDIR(node->mode) ) return EISDIR;

    // Initialize the file object
    
    file->f_flag        |= mode & CYG_FILE_MODE_MASK;
    file->f_type        = CYG_FILE_TYPE_FILE;
    file->f_ops         = &romfs_fileops;
    file->f_offset      = 0;
    file->f_data        = (CYG_ADDRWORD)node;
    file->f_xops        = 0;

    return ENOERR;
}

// -------------------------------------------------------------------------
// romfs_opendir()
// Open a directory for reading.

static int romfs_opendir  ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,
                             cyg_file *file )
{
    romfs_dirsearch ds;
    int err;

    init_dirsearch( &ds, (romfs_disk *)mte->data, (romfs_node *)dir, name );
    
    err = romfs_find( &ds );

    if( err != ENOERR ) return err;

    // check it is really a directory.
    if( !S_ISDIR(ds.node->mode) ) return ENOTDIR;

    // Initialize the file object, setting the f_ops field to a
    // special set of file ops.
    
    file->f_type        = CYG_FILE_TYPE_FILE;
    file->f_ops         = &romfs_dirops;
    file->f_offset      = 0;
    file->f_data        = (CYG_ADDRWORD)ds.node;
    file->f_xops        = 0;
        
    return ENOERR;

}

// -------------------------------------------------------------------------
// romfs_chdir()
// Change directory support.