Example that this allows. Basically, when you write, you can read from a Reader!
pub enum Data {
/// On read: Save current stream_position() as `Offset`, seek `header.filesize`
/// This will be used to seek this this position if we want to extract *just* this file
Offset(u64),
/// On write: Write `Reader` to write buffer
Reader(Box<dyn ReadSeek>),
}
impl DekuReader<'_, u32> for Data {
fn from_reader_with_ctx<R: Read + Seek>(
reader: &mut Reader<R>,
filesize: u32,
) -> Result<Data, DekuError> {
let reader = reader.as_mut();
// Save the current offset, this is where the file exists for reading later
let current_pos = reader.stream_position().unwrap();
// Seek past that file
let position = filesize as i64 + pad_to_4(filesize as usize) as i64;
let _ = reader.seek(SeekFrom::Current(position));
Ok(Self::Offset(current_pos))
}
}
impl DekuWriterMut for Data {
fn to_writer_mut<W: Write + Seek>(
&mut self,
writer: &mut Writer<W>,
_: (),
) -> Result<(), DekuError> {
if let Self::Reader(reader) = self {
// read from reader
let mut data = vec![];
reader.read_to_end(&mut data).unwrap();
// write to deku
data.to_writer(writer, ())?;
// add padding
for _ in 0..pad_to_4(data.len()) {
0_u8.to_writer(writer, ())?;
}
} else {
panic!("ah");
}
Ok(())
}
}
#[derive(DekuWriteMut)]
pub struct Object {
// other fields
data: Data,
}
Add DekuWriterMut, to include parsers that mutate from &mut self during parsing.
github-actions[bot]
commented
1 month ago
Example that this allows. Basically, when you write, you can read from a
Reader!TODO