f9/sdk/dart/package-fuchsia_vfs_vfs/PseudoFile-class.md

# PseudoFile class






    *[<Null safety>](https://dart.dev/null-safety)*



<p>A <a href="../package-fuchsia_vfs_vfs/PseudoFile-class.md">PseudoFile</a> is a file-like object whose content is generated and modified
dynamically on-the-fly by invoking handler functions rather than being
directly persisted as a sequence of bytes.</p>
<p>This class is designed to allow programs to publish read-only,
or read-write properties such as configuration options, debug flags,
and dumps of internal state which may change dynamically.</p>
<p>Although <a href="../package-fuchsia_vfs_vfs/PseudoFile-class.md">PseudoFile</a> usually contain text, they can also be used for binary
data.</p>
<p>Read callback, is called when the connection to the file is opened and
pre-populates a buffer that will be used to when serving this file content
over this particular connection.</p>
<p>Write callback, if any, is called when the connection is closed if the file
content was ever modified while the connection was open.
Modifications are: <code>fidl_fuchsia_io.File#write()</code> calls or opening a file
for writing with the <code>OpenFlags.truncate</code> flag set.</p>



**Inheritance**

- Object
- [Vnode](../package-fuchsia_vfs_vfs/Vnode-class.md)
- PseudoFile



**Implementers**

- [PseudoVmoFile](../package-fuchsia_vfs_vfs/PseudoVmoFile-class.md)
- [VmoFile](../package-fuchsia_vfs_vfs/VmoFile-class.md)





## Constructors

[PseudoFile.readOnly](../package-fuchsia_vfs_vfs/PseudoFile/PseudoFile.readOnly.md) ([ReadFn](../package-fuchsia_vfs_vfs/ReadFn.md)? _readFn)

Creates a new read-only <a href="../package-fuchsia_vfs_vfs/PseudoFile-class.md">PseudoFile</a> backed by the specified read handler.   

[PseudoFile.readOnlyStr](../package-fuchsia_vfs_vfs/PseudoFile/PseudoFile.readOnlyStr.md) ([ReadFnStr](../package-fuchsia_vfs_vfs/ReadFnStr.md) fn)

See <code>#readOnly()</code>.  Wraps the callback, allowing it to return a String instead of a Uint8List,
but otherwise behaves identical to <code>#readOnly()</code>.   

[PseudoFile.readWrite](../package-fuchsia_vfs_vfs/PseudoFile/PseudoFile.readWrite.md) (int _capacity, [ReadFn](../package-fuchsia_vfs_vfs/ReadFn.md)? _readFn, [WriteFn](../package-fuchsia_vfs_vfs/WriteFn.md)? _writeFn)

Creates new <a href="../package-fuchsia_vfs_vfs/PseudoFile-class.md">PseudoFile</a> backed by the specified read and write handlers.   

[PseudoFile.readWriteStr](../package-fuchsia_vfs_vfs/PseudoFile/PseudoFile.readWriteStr.md) (int _capacity, [ReadFnStr](../package-fuchsia_vfs_vfs/ReadFnStr.md) rfn, [WriteFnStr](../package-fuchsia_vfs_vfs/WriteFnStr.md) wfn)

See <code>#readWrite()</code>.  Wraps the read callback, allowing it to return a <code>String</code> instead of a
<code>Uint8List</code>.  Wraps the write callback, only allowing valid UTF-8 content to be written into
the file.  Written bytes are converted into a string instance, and the passed to the handler.
In every other aspect behaves just like <code>#readWrite()</code>.   


## Properties

##### [hashCode](../package-fuchsia_vfs_vfs/Vnode/hashCode.md) &#8594; int



The hash code for this object.  
_<span class="feature read-only">read-only</span><span class="feature inherited">inherited</span>_



##### [runtimeType](../package-fuchsia_vfs_vfs/Vnode/runtimeType.md) &#8594; Type



A representation of the runtime type of the object.  
_<span class="feature read-only">read-only</span><span class="feature inherited">inherited</span>_





## Methods

##### [close](../package-fuchsia_vfs_vfs/PseudoFile/close.md)() void



Close this node and all of its bindings and children.  
_<span class="feature override">override</span>_



##### [connect](../package-fuchsia_vfs_vfs/PseudoFile/connect.md)(dynamic flags, int mode, [InterfaceRequest](../package-fidl_fidl/InterfaceRequest-class.md) request, [dynamic parentFlags]) int



Connects to this instance of <a href="../package-fuchsia_vfs_vfs/PseudoFile-class.md">PseudoFile</a> and serves <code>fidl_fuchsia_io.File</code> over fidl.  
_<span class="feature override">override</span>_



##### [describe2](../package-fuchsia_vfs_vfs/PseudoFile/describe2.md)() dynamic



  




##### [describeDeprecated](../package-fuchsia_vfs_vfs/PseudoFile/describeDeprecated.md)() dynamic



  




##### [filterForNodeReference](../package-fuchsia_vfs_vfs/Vnode/filterForNodeReference.md)(dynamic flags) dynamic



Filter flags when <code>OpenFlags.nodeReference</code> is passed.
This will maintain compatibility with c++ layer.  
_<span class="feature inherited">inherited</span>_



##### [getBackingMemory](../package-fuchsia_vfs_vfs/PseudoFile/getBackingMemory.md)(dynamic flags) [Vmo](../zircon/Vmo-class.md)



  




##### [getConnectionInfo](../package-fuchsia_vfs_vfs/PseudoFile/getConnectionInfo.md)() dynamic



  




##### [inodeNumber](../package-fuchsia_vfs_vfs/PseudoFile/inodeNumber.md)() int



Inode number as defined in fuchsia.io.  
_<span class="feature override">override</span>_



##### [noSuchMethod](../package-fuchsia_vfs_vfs/Vnode/noSuchMethod.md)(Invocation invocation) dynamic



Invoked when a non-existent method or property is accessed.  
_<span class="feature inherited">inherited</span>_



##### [open](../package-fuchsia_vfs_vfs/Vnode/open.md)(dynamic flags, int mode, String path, [InterfaceRequest](../package-fidl_fidl/InterfaceRequest-class.md) request, [dynamic parentFlags]) void



This function is called from <code>fidl_fuchsia_io.Directory#open</code>.
This function parses path and opens correct node.  
_<span class="feature inherited">inherited</span>_



##### [sendErrorEvent](../package-fuchsia_vfs_vfs/Vnode/sendErrorEvent.md)(dynamic flags, int status, [InterfaceRequest](../package-fidl_fidl/InterfaceRequest-class.md) request) void



Create a error node to send onOpen event with failure status.  
_<span class="feature inherited">inherited</span>_



##### [toString](../package-fuchsia_vfs_vfs/Vnode/toString.md)() String



A string representation of this object.  
_<span class="feature inherited">inherited</span>_



##### [type](../package-fuchsia_vfs_vfs/PseudoFile/type.md)() dynamic



  
_<span class="feature override">override</span>_





## Operators

##### [operator ==](../package-fuchsia_vfs_vfs/Vnode/operator_equals.md)(Object other) bool



The equality operator.  
_<span class="feature inherited">inherited</span>_