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/*
This file is part of jellything (https://codeberg.org/metamuffin/jellything)
which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
Copyright (C) 2023 metamuffin <metamuffin.org>
*/
use crate::{matroska::MatroskaTag, size::EbmlSize, Master};
use anyhow::{bail, Result};
use std::io::Write;
pub struct EbmlWriter {
inner: Box<dyn Write>,
position: usize,
}
impl EbmlWriter {
pub fn new<T: Write + 'static>(inner: T, position: usize) -> Self {
Self {
inner: Box::new(inner),
position,
}
}
pub fn write(&mut self, data: &[u8]) -> Result<()> {
self.inner.write_all(data)?;
self.position += data.len();
Ok(())
}
pub fn write_padding(&mut self, position: usize) -> Result<()> {
let mut size = position - self.position;
match size {
0 => return Ok(()),
1 => bail!("this is sadly not possible"),
_ => (),
}
size -= 1; // subtract tag size
size -= 4; // subtract vint size
// match size {
// _ if size < (1 << 7) => size -= 1,
// _ if size < (1 << 14) => size -= 2,
// _ if size < (1 << 21) => size -= 3,
// _ if size < (1 << 28) => size -= 4,
// _ if size < (1 << 35) => size -= 5,
// _ => bail!("padding to large"),
// }
self.write(&[0xec])?;
self.write_vint_len(size.try_into().unwrap(), 4)?;
self.write(&vec![0; size])?;
Ok(())
}
pub fn write_tag(&mut self, tag: &MatroskaTag) -> Result<()> {
let mut buf = vec![];
tag.write_full(&mut buf)?;
self.write(&buf)?;
Ok(())
}
pub fn write_vint(&mut self, i: u64) -> Result<()> {
if i > (1 << 56) - 1 {
bail!("vint does not fit");
}
let mut len = 1;
while len <= 8 {
if i < (1 << ((7 * len) - 1)) {
break;
}
len += 1;
}
self.write_vint_len(i, len)
}
pub fn write_vint_len(&mut self, i: u64, len: usize) -> Result<()> {
let mut bytes = i.to_be_bytes();
let trunc = &mut bytes[(8 - len)..];
trunc[0] |= 1 << (8 - len);
self.write(&trunc)
}
}
impl MatroskaTag {
pub fn write_full(&self, w: &mut Vec<u8>) -> Result<()> {
let mut buf = vec![];
buf.extend(self.id().to_be_bytes().iter().skip_while(|&v| *v == 0u8));
// note: it is relevant here, to pass the buffer with the id, such that closing tags, can clear it
self.write(&mut buf)?;
w.extend_from_slice(&buf);
Ok(())
}
}
pub trait WriteValue {
fn write_to(&self, w: &mut Vec<u8>) -> Result<()>;
}
impl WriteValue for i64 {
fn write_to(&self, w: &mut Vec<u8>) -> Result<()> {
Ok(match 64 - self.leading_zeros() {
x if x <= 8 => {
w.push(0x81);
w.extend_from_slice(&(*self as i8).to_be_bytes());
}
x if x <= 16 => {
w.push(0x82);
w.extend_from_slice(&(*self as i16).to_be_bytes());
}
x if x <= 32 => {
w.push(0x84);
w.extend_from_slice(&(*self as i32).to_be_bytes());
}
_ => {
w.push(0x88);
w.extend_from_slice(&self.to_be_bytes());
}
})
}
}
impl WriteValue for u64 {
fn write_to(&self, w: &mut Vec<u8>) -> Result<()> {
Ok(match 64 - self.leading_zeros() {
x if x <= 8 => {
w.push(0x81);
w.extend_from_slice(&(*self as u8).to_be_bytes());
}
x if x <= 16 => {
w.push(0x82);
w.extend_from_slice(&(*self as u16).to_be_bytes());
}
x if x <= 32 => {
w.push(0x84);
w.extend_from_slice(&(*self as u32).to_be_bytes());
}
_ => {
w.push(0x88);
w.extend_from_slice(&self.to_be_bytes());
}
})
}
}
impl WriteValue for f64 {
fn write_to(&self, w: &mut Vec<u8>) -> Result<(), anyhow::Error> {
w.push(0x88);
w.extend_from_slice(&self.to_be_bytes());
Ok(())
}
}
impl WriteValue for Vec<u8> {
fn write_to(&self, w: &mut Vec<u8>) -> Result<(), anyhow::Error> {
write_vint(w, self.len() as u64)?;
w.extend_from_slice(&self);
Ok(())
}
}
impl WriteValue for String {
fn write_to(&self, w: &mut Vec<u8>) -> Result<(), anyhow::Error> {
let sl = self.as_bytes();
write_vint(w, sl.len() as u64)?;
w.extend_from_slice(sl);
Ok(())
}
}
impl WriteValue for EbmlSize {
fn write_to(&self, w: &mut Vec<u8>) -> Result<()> {
match self {
EbmlSize::Exact(s) => write_vint(w, *s as u64)?,
EbmlSize::Unknown => w.extend_from_slice(&(u64::MAX >> 7).to_be_bytes()),
}
Ok(())
}
}
impl WriteValue for Master {
fn write_to(&self, w: &mut Vec<u8>) -> Result<()> {
match self {
Master::Start => EbmlSize::Unknown.write_to(w),
Master::End => Ok(w.clear()),
Master::Collected(c) => {
let mut ib = vec![];
for c in c {
c.write_full(&mut ib)?;
}
EbmlSize::Exact(ib.len()).write_to(w)?;
w.extend_from_slice(&ib);
Ok(())
}
}
}
}
pub fn write_vint(w: &mut Vec<u8>, i: u64) -> Result<()> {
if i > (1 << 56) - 1 {
bail!("vint does not fit");
}
let len = (64 - i.leading_zeros() as usize) / 7 + 1;
let mut bytes = i.to_be_bytes();
let trunc = &mut bytes[(8 - len)..];
trunc[0] |= 1 << (8 - len);
w.extend_from_slice(&trunc);
Ok(())
}
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