FileIOStream

`GFileIOStream` provides I/O streams that both read and write to the same file handle.

`GFileIOStream` implements [iface@Gio.Seekable], which allows the I/O stream to jump to arbitrary positions in the file and to truncate the file, provided the filesystem of the file supports these operations.

To find the position of a file I/O stream, use [method@Gio.Seekable.tell].

To find out if a file I/O stream supports seeking, use [method@Gio.Seekable.can_seek]. To position a file I/O stream, use [ method@Gio.Seekable.seek]. To find out if a file I/O stream supports truncating, use [method@Gio.Seekable.can_truncate]. To truncate a file I/O stream, use [method@Gio.Seekable.truncate].

The default implementation of all the `GFileIOStream` operations and the implementation of [iface@Gio.Seekable] just call into the same operations on the output stream.

Example: FileIOStream:

public static int main (string[] args) {
	try {
		// Create a file that can only be accessed by the current user:
		File file = File.new_for_path ("my-test.bin");
		FileIOStream ios = file.create_readwrite (FileCreateFlags.PRIVATE);

		//
		// Write data:
		//

		size_t bytes_written;
		FileOutputStream os = ios.output_stream as FileOutputStream;
		os.write_all ("My 1. line\n".data, out bytes_written);
		os.write_all ("My 2. line\n".data, out bytes_written);

		DataOutputStream dos = new DataOutputStream (os);
		dos.put_string ("My 3. line\n");
		dos.put_int16 (10);


		//
		// Set the file pointer to the beginning of the stream:
		//
		assert (ios.can_seek ());
		ios.seek (0, SeekType.SET);


		//
		// Read n bytes:
		//

		FileInputStream @is = ios.input_stream as FileInputStream;

		// Output: ``M``
		uint8 buffer[1];
		size_t size = @is.read (buffer);
		stdout.write (buffer, size);

		// Output: ``y 1. line``
		DataInputStream dis = new DataInputStream (@is);
		string str = dis.read_line ();
		print ("%s\n", str);

		// Output: ``My 2. line``
		str = dis.read_line ();
		print ("%s\n", str);

		// Output: ``My 3. line``
		str = dis.read_line ();
		print ("%s\n", str);

		// Output: ``10``
		int16 i = dis.read_int16 ();
		print ("%d\n", i);
	} catch (Error e) {
		print ("Error: %s\n", e.message);
	}

	return 0;
}

valac --pkg gio-2.0 GLib.FileIOStream.vala