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public
abstract
class
ProxyFileDescriptorCallback
extends Object
java.lang.Object | |
↳ | android.os.ProxyFileDescriptorCallback |
Callback that handles file system requests from ProxyFileDescriptor.
All callback methods except for onRelease should throw ErrnoException
with proper errno on errors. See
errno(3) and
OsConstants
.
Typical errnos are
OsConstants.EIO
for general I/O issues
OsConstants.ENOENT
when the file is not found
OsConstants.EBADF
if the file doesn't allow read/write operations
based on how it was opened. (For example, trying to write a file that was opened read-only.)
OsConstants.ENOSPC
if you cannot handle a write operation to
space/quota limitations.
Public constructors | |
---|---|
ProxyFileDescriptorCallback()
|
Public methods | |
---|---|
void
|
onFsync()
Ensures all the written data are stored in permanent storage device. |
long
|
onGetSize()
Returns size of bytes provided by the file descriptor. |
int
|
onRead(long offset, int size, byte[] data)
Provides bytes read from file descriptor. |
abstract
void
|
onRelease()
Invoked after the file is closed. |
int
|
onWrite(long offset, int size, byte[] data)
Handles bytes written to file descriptor. |
Inherited methods | |
---|---|
public ProxyFileDescriptorCallback ()
public void onFsync ()
Ensures all the written data are stored in permanent storage device. For example, if it has data stored in on memory cache, it needs to flush data to storage device.
Throws | |
---|---|
ErrnoException |
ErrnoException containing E constants in OsConstants. |
public long onGetSize ()
Returns size of bytes provided by the file descriptor.
Returns | |
---|---|
long |
Size of bytes. |
Throws | |
---|---|
ErrnoException |
ErrnoException containing E constants in OsConstants. |
public int onRead (long offset, int size, byte[] data)
Provides bytes read from file descriptor. It needs to return exact requested size of bytes unless it reaches file end.
Parameters | |
---|---|
offset |
long : Offset in bytes from the file head specifying where to read bytes. If a seek
operation is conducted on the file descriptor, then a read operation is requested, the
offset refrects the proper position of requested bytes. |
size |
int : Size for read bytes. |
data |
byte : Byte array to store read bytes. |
Returns | |
---|---|
int |
Size of bytes returned by the function. |
Throws | |
---|---|
ErrnoException |
ErrnoException containing E constants in OsConstants. |
public abstract void onRelease ()
Invoked after the file is closed.
public int onWrite (long offset, int size, byte[] data)
Handles bytes written to file descriptor.
Parameters | |
---|---|
offset |
long : Offset in bytes from the file head specifying where to write bytes. If a seek
operation is conducted on the file descriptor, then a write operation is requested, the
offset refrects the proper position of requested bytes. |
size |
int : Size for write bytes. |
data |
byte : Byte array to be written to somewhere. |
Returns | |
---|---|
int |
Size of bytes processed by the function. |
Throws | |
---|---|
ErrnoException |
ErrnoException containing E constants in OsConstants. |