fn read_pssh()

in mp4parse/src/lib.rs [4192:4234]
36 lines of code
4 McCabe index (conditional complexity)

fn read_pssh<T: Read>(src: &mut BMFFBox<T>) -> Result<ProtectionSystemSpecificHeaderBox> {
    let len = src.bytes_left();
    let mut box_content = read_buf(src, len)?;
    let (system_id, kid, data) = {
        let pssh = &mut Cursor::new(&box_content);

        let (version, _) = read_fullbox_extra(pssh)?;

        let system_id = read_buf(pssh, 16)?;

        let mut kid = TryVec::<ByteData>::new();
        if version > 0 {
            const KID_ELEMENT_SIZE: usize = 16;
            let count = be_u32(pssh)?.to_usize();
            kid.reserve(
                count
                    .checked_mul(KID_ELEMENT_SIZE)
                    .ok_or_else(|| Error::from(Status::PsshSizeOverflow))?,
            )?;
            for _ in 0..count {
                let item = read_buf(pssh, KID_ELEMENT_SIZE.to_u64())?;
                kid.push(item)?;
            }
        }

        let data_size = be_u32(pssh)?;
        let data = read_buf(pssh, data_size.into())?;

        (system_id, kid, data)
    };

    let mut pssh_box = TryVec::new();
    write_be_u32(&mut pssh_box, src.head.size.try_into()?)?;
    pssh_box.extend_from_slice(b"pssh")?;
    pssh_box.append(&mut box_content)?;

    Ok(ProtectionSystemSpecificHeaderBox {
        system_id,
        kid,
        data,
        box_content: pssh_box,
    })
}