ProxyFileDescriptorCallback

Kotlin |Java

abstract class ProxyFileDescriptorCallback

kotlin.Any
↳	android.os.ProxyFileDescriptorCallback

Callback that handles file system requests from ProxyFileDescriptor. All callback methods except for onRelease should throw android.system.ErrnoException with proper errno on errors. See errno(3) and android.system.OsConstants. Typical errnos are

android.system.OsConstants#EIO for general I/O issues
android.system.OsConstants#ENOENT when the file is not found
android.system.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.)
android.system.OsConstants#ENOSPC if you cannot handle a write operation to space/quota limitations.

Summary

Public constructors
`ProxyFileDescriptorCallback()`

Public methods
open Unit	`onFsync()` Ensures all the written data are stored in permanent storage device.
open Long	`onGetSize()` Returns size of bytes provided by the file descriptor.
open Int	`onRead(offset: Long, size: Int, data: ByteArray!)` Provides bytes read from file descriptor.
abstract Unit	`onRelease()` Invoked after the file is closed.
open Int	`onWrite(offset: Long, size: Int, data: ByteArray!)` Handles bytes written to file descriptor.

Public constructors

ProxyFileDescriptorCallback

ProxyFileDescriptorCallback()

Public methods

onFsync

Added in API level 26

open fun onFsync(): Unit

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.

Exceptions
`android.system.ErrnoException`	ErrnoException containing E constants in OsConstants.

onGetSize

Added in API level 26

open fun onGetSize(): Long

Returns size of bytes provided by the file descriptor.

Return
`Long`	Size of bytes.

Exceptions
`android.system.ErrnoException`	ErrnoException containing E constants in OsConstants.

onRead

Added in API level 26

open fun onRead(
    offset: Long, 
    size: Int, 
    data: ByteArray!
): Int

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`	ByteArray!: Byte array to store read bytes.

Return
`Int`	Size of bytes returned by the function.

Exceptions
`android.system.ErrnoException`	ErrnoException containing E constants in OsConstants.

onRelease

Added in API level 26

abstract fun onRelease(): Unit

Invoked after the file is closed.

onWrite

Added in API level 26

open fun onWrite(
    offset: Long, 
    size: Int, 
    data: ByteArray!
): Int

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`	ByteArray!: Byte array to be written to somewhere.

Return
`Int`	Size of bytes processed by the function.

Exceptions
`android.system.ErrnoException`	ErrnoException containing E constants in OsConstants.