ParcelFileDescriptor

MODE_APPEND

public static final int MODE_APPEND

For use with open(File, int): append to end of file while writing.

Constant Value: 33554432 (0x02000000)

MODE_CREATE

public static final int MODE_CREATE

For use with open(File, int): create the file if it doesn't already exist.

Constant Value: 134217728 (0x08000000)

MODE_READ_ONLY

public static final int MODE_READ_ONLY

For use with open(File, int): open the file with read-only access.

Constant Value: 268435456 (0x10000000)

MODE_READ_WRITE

public static final int MODE_READ_WRITE

For use with open(File, int): open the file with read and write access.

Constant Value: 805306368 (0x30000000)

MODE_TRUNCATE

public static final int MODE_TRUNCATE

For use with open(File, int): erase contents of file when opening.

Constant Value: 67108864 (0x04000000)

MODE_WORLD_READABLE

public static final int MODE_WORLD_READABLE

This constant was deprecated in API level 19.
Creating world-readable files is very dangerous, and likely to cause security holes in applications. It is strongly discouraged; instead, applications should use more formal mechanism for interactions such as ContentProvider, BroadcastReceiver, and Service. There are no guarantees that this access mode will remain on a file, such as when it goes through a backup and restore.

For use with open(File, int): if MODE_CREATE has been supplied and this file doesn't already exist, then create the file with permissions such that any application can read it.

Constant Value: 1 (0x00000001)

MODE_WORLD_WRITEABLE

public static final int MODE_WORLD_WRITEABLE

This constant was deprecated in API level 19.
Creating world-writable files is very dangerous, and likely to cause security holes in applications. It is strongly discouraged; instead, applications should use more formal mechanism for interactions such as ContentProvider, BroadcastReceiver, and Service. There are no guarantees that this access mode will remain on a file, such as when it goes through a backup and restore.

For use with open(File, int): if MODE_CREATE has been supplied and this file doesn't already exist, then create the file with permissions such that any application can write it.

Constant Value: 2 (0x00000002)

MODE_WRITE_ONLY

public static final int MODE_WRITE_ONLY

For use with open(File, int): open the file with write-only access.

Constant Value: 536870912 (0x20000000)

CREATOR

public static final Creator<ParcelFileDescriptor> CREATOR

ParcelFileDescriptor

public ParcelFileDescriptor (ParcelFileDescriptor wrapped)

Create a new ParcelFileDescriptor wrapped around another descriptor. By default all method calls are delegated to the wrapped descriptor.

adoptFd

public static ParcelFileDescriptor adoptFd (int fd)

Take ownership of a raw native fd in to a new ParcelFileDescriptor. The returned ParcelFileDescriptor now owns the given fd, and will be responsible for closing it.

WARNING: You must not close the fd yourself after this call, and ownership of the file descriptor must have been released prior to the call to this function.

canDetectErrors

public boolean canDetectErrors ()

Indicates if this ParcelFileDescriptor can communicate and detect remote errors/crashes.

checkError

public void checkError ()

Detect and throw if the other end of a pipe or socket pair encountered an error or crashed. This allows a reader to distinguish between a valid EOF and an error/crash.

If this ParcelFileDescriptor is unable to detect remote errors, it will return silently.

close

public void close ()

Close the ParcelFileDescriptor. This implementation closes the underlying OS resources allocated to represent this stream.

closeWithError

public void closeWithError (String msg)

Close the ParcelFileDescriptor, informing any peer that an error occurred while processing. If the creator of this descriptor is not observing errors, it will close normally.

createPipe

public static ParcelFileDescriptor[] createPipe ()

Create two ParcelFileDescriptors structured as a data pipe. The first ParcelFileDescriptor in the returned array is the read side; the second is the write side.

createReliablePipe

public static ParcelFileDescriptor[] createReliablePipe ()

Create two ParcelFileDescriptors structured as a data pipe. The first ParcelFileDescriptor in the returned array is the read side; the second is the write side.

The write end has the ability to deliver an error message through closeWithError(java.lang.String) which can be handled by the read end calling checkError(), usually after detecting an EOF. This can also be used to detect remote crashes.

createReliableSocketPair

public static ParcelFileDescriptor[] createReliableSocketPair ()

Create two ParcelFileDescriptors structured as a pair of sockets connected to each other. The two sockets are indistinguishable.

Both ends have the ability to deliver an error message through closeWithError(java.lang.String) which can be detected by the other end calling checkError(), usually after detecting an EOF. This can also be used to detect remote crashes.

createSocketPair

public static ParcelFileDescriptor[] createSocketPair ()

Create two ParcelFileDescriptors structured as a pair of sockets connected to each other. The two sockets are indistinguishable.

describeContents

public int describeContents ()

Describe the kinds of special objects contained in this Parcelable instance's marshaled representation. For example, if the object will include a file descriptor in the output of writeToParcel(android.os.Parcel, int), the return value of this method must include the CONTENTS_FILE_DESCRIPTOR bit.

detachFd

public int detachFd ()

Return the native fd int for this ParcelFileDescriptor and detach it from the object here. You are now responsible for closing the fd in native code.

You should not detach when the original creator of the descriptor is expecting a reliable signal through close() or closeWithError(java.lang.String).

dup

public static ParcelFileDescriptor dup (FileDescriptor orig)

Create a new ParcelFileDescriptor that is a dup of an existing FileDescriptor. This obeys standard POSIX semantics, where the new file descriptor shared state such as file position with the original file descriptor.

dup

public ParcelFileDescriptor dup ()

Create a new ParcelFileDescriptor that is a dup of the existing FileDescriptor. This obeys standard POSIX semantics, where the new file descriptor shared state such as file position with the original file descriptor.

fromDatagramSocket

public static ParcelFileDescriptor fromDatagramSocket (DatagramSocket datagramSocket)

Create a new ParcelFileDescriptor from the specified DatagramSocket. The new ParcelFileDescriptor holds a dup of the original FileDescriptor in the DatagramSocket, so you must still close the DatagramSocket as well as the new ParcelFileDescriptor.

WARNING: Prior to API level 29, this function would not actually dup the DatagramSocket's FileDescriptor, and would take a reference to the its internal FileDescriptor instead. If the DatagramSocket gets garbage collected before the ParcelFileDescriptor, this may lead to the ParcelFileDescriptor being unexpectedly closed. To avoid this, the following pattern can be used:

ParcelFileDescriptor pfd = ParcelFileDescriptor.fromDatagramSocket(socket).dup();
 

fromFd

public static ParcelFileDescriptor fromFd (int fd)

Create a new ParcelFileDescriptor from a raw native fd. The new ParcelFileDescriptor holds a dup of the original fd passed in here, so you must still close that fd as well as the new ParcelFileDescriptor.

fromSocket

public static ParcelFileDescriptor fromSocket (Socket socket)

Create a new ParcelFileDescriptor from the specified Socket. The new ParcelFileDescriptor holds a dup of the original FileDescriptor in the Socket, so you must still close the Socket as well as the new ParcelFileDescriptor.

WARNING: Prior to API level 29, this function would not actually dup the Socket's FileDescriptor, and would take a reference to the its internal FileDescriptor instead. If the Socket gets garbage collected before the ParcelFileDescriptor, this may lead to the ParcelFileDescriptor being unexpectedly closed. To avoid this, the following pattern can be used:

ParcelFileDescriptor pfd = ParcelFileDescriptor.fromSocket(socket).dup();
 

getFd

public int getFd ()

Return the native fd int for this ParcelFileDescriptor. The ParcelFileDescriptor still owns the fd, and it still must be closed through this API.

WARNING: Do not call close on the return value of this function or pass it to a function that assumes ownership of the fd.

getFileDescriptor

public FileDescriptor getFileDescriptor ()

Retrieve the actual FileDescriptor associated with this object.

getStatSize

public long getStatSize ()

Return the total size of the file representing this fd, as determined by stat(). Returns -1 if the fd is not a file.

open

public static ParcelFileDescriptor open (File file, 
                int mode)

Create a new ParcelFileDescriptor accessing a given file.

This method should only be used for files that you have direct access to; if you'd like to work with files hosted outside your app, use an API like ContentResolver.openFile(Uri, String, CancellationSignal).

open

public static ParcelFileDescriptor open (File file, 
                int mode, 
                Handler handler, 
                ParcelFileDescriptor.OnCloseListener listener)

Create a new ParcelFileDescriptor accessing a given file.

This method should only be used for files that you have direct access to; if you'd like to work with files hosted outside your app, use an API like ContentResolver.openFile(Uri, String, CancellationSignal).

parseMode

public static int parseMode (String mode)

Converts a string representing a file mode, such as "rw", into a bitmask suitable for use with open(File, int).

The argument must define at least one of the following base access modes:

• "r" indicates the file should be opened in read-only mode, equivalent to OsConstants.O_RDONLY.
• "w" indicates the file should be opened in write-only mode, equivalent to OsConstants.O_WRONLY.
• "rw" indicates the file should be opened in read-write mode, equivalent to OsConstants.O_RDWR.

• "a" indicates the file should be opened in append mode, equivalent to OsConstants.O_APPEND. Before each write, the file offset is positioned at the end of the file.
• "t" indicates the file should be opened in truncate mode, equivalent to OsConstants.O_TRUNC. If the file already exists and is a regular file and is opened for writing, it will be truncated to length 0.

toString

public String toString ()

Returns a string representation of the object.

wrap

public static ParcelFileDescriptor wrap (ParcelFileDescriptor pfd, 
                Handler handler, 
                ParcelFileDescriptor.OnCloseListener listener)

Create a new ParcelFileDescriptor wrapping an already-opened file.

writeToParcel

public void writeToParcel (Parcel out, 
                int flags)

Flatten this object in to a Parcel. If Parcelable.PARCELABLE_WRITE_RETURN_VALUE is set in flags, the file descriptor will be closed after a copy is written to the Parcel.

finalize

protected void finalize ()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.

The general contract of finalize is that it is invoked if and when the Java virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.

The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.

The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.

After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.

The finalize method is never invoked more than once by a Java virtual machine for any given object.

Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.