The Be Book - Classes And Methods

BVolume

Derived From:	None
Mix-in Classes:	None
Declared In:	`storage/Volume.h`
Library:	`libbe.so`
Allocation:	–

Class Overview

Constructor and Destructor

BVolume()

BVolume(); BVolume(dev_t device); BVolume(BVolume& volume);

Creates a new BVolume object and initializes it according to the argument. The status of the initialization is recorded by the InitCheck() function.

The default constructor does nothing and sets InitCheck() to B_NO_INIT.
The device constructor sets the BVolume to point to the volume represented by the argument. See the SetTo() function for status codes.
The copy constructor sets the object to point to the same device as does the argument.

~BVolume

~BVolume();

Destroys the BVolume object.

Member Functions

Capacity(), FreeBytes()

off_t Capacity() const;off_t FreeBytes() const;

Returns the volume's total storage capacity and the amount of storage that's currently unused. Both measurements are in bytes.

Device()

dev_t Device() const;

Returns the object's dev_t number.

GetIcon()

status_t GetIcon(BBitmap* icon,
                 icon_size which) const;

Returns the volume's icon in icon. which specifies the icon to retrieve, either B_MINI_ICON (16x16) or B_LARGE_ICON (32x32).

GetName()

status_t GetName(char* buffer) const;

Copies the name of the volume into buffer.

GetRootDirectory()

status_t GetRootDirectory(BDirectory* dir) const;

Initializes dir (which must be allocated) to refer to the volume's "root directory." The root directory stands at the "root" of the volume's file hierarchy. Note that this isn't necessarily the root of the entire file hierarchy.

InitCheck()

status_t InitCheck() const;

Returns the status of the last initialization (from either the constructor or SetTo()).

IsPersistent(), IsRemovable(), IsReadOnly(), IsShared()

bool IsPersistent() const;bool IsRemovable() const;bool IsReadOnly() const;bool IsShared() const;

These functions answer media-related questions about the volume:

IsPersistent(). Is the storage persistent (such as on a floppy or hard disk)?
IsRemovable(). Can the media be removed?
IsReadOnly(). Can it be read but not written to?
IsShared(). Is it accessed through the network (as opposed to being directly connected to this computer)?

KnowsAttr(), KnowsMime(), KnowsQuery()

bool KnowsAttr() const;bool KnowsMime() const;bool KnowsQuery() const;

These functions answer questions about the file system on the volume:

KnowsAttr(). Do its files accept attributes?
KnowsMime(). Does it use MIME to type files?
KnowsQuery(). Can it respond to queries?

SetTo(), Unset()

status_t SetTo(dev_t dev);void Unset();

SetTo() initializes the BVolume object to represent the volume (device) identified by the argument.

Unset() uninitializes the BVolume.

Operators

= (assignment)

BVolume& operator =(const BEntry& volume);

In the expression

BVolume a = b;

BVolume a is initialized to refer to the same volume as b. To gauge the success of the assignment, you should call InitCheck() immediately afterwards. Assigning a BVolume to itself is safe.

Assigning from an uninitialized BVolume is "successful": The assigned-to BVolume will also be uninitialized (B_NO_INIT).

== , != (comparison)

bool operator ==(const BVolume& volume) const;bool operator !=(const BVolume& volume) const;

Two BVolume objects are said to be equal if they refer to the same volume, or if they're both uninitialized.