104 lines
2.9 KiB
Rust
104 lines
2.9 KiB
Rust
use failure::*;
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use futures::*;
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use bytes::{Bytes, BytesMut};
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pub trait IndexFile: Send {
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fn index_count(&self) -> usize;
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fn index_digest(&self, pos: usize) -> Option<&[u8; 32]>;
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}
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/// Encode digest list from an `IndexFile` into a binary stream
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///
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/// The reader simply returns a birary stream of 32 byte digest values.
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pub struct DigestListEncoder {
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index: Box<dyn IndexFile>,
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pos: usize,
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count: usize,
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}
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impl DigestListEncoder {
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pub fn new(index: Box<dyn IndexFile>) -> Self {
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let count = index.index_count();
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Self { index, pos: 0, count }
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}
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}
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impl std::io::Read for DigestListEncoder {
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fn read(&mut self, buf: &mut [u8]) -> Result<usize, std::io::Error> {
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if buf.len() < 32 { panic!("read buffer too small"); }
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if self.pos < self.count {
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let mut written = 0;
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loop {
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let digest = self.index.index_digest(self.pos).unwrap();
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unsafe { std::ptr::copy_nonoverlapping(digest.as_ptr(), buf.as_mut_ptr().add(written), 32); }
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self.pos += 1;
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written += 32;
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if self.pos >= self.count { break; }
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if (written + 32) >= buf.len() { break; }
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}
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return Ok(written);
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} else {
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return Ok(0);
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}
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}
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}
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/// Decodes a Stream<Item=Bytes> into Stream<Item=<[u8;32]>
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///
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/// The reader simply returns a birary stream of 32 byte digest values.
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pub struct DigestListDecoder<S> {
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input: S,
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buffer: BytesMut,
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}
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impl <S> DigestListDecoder<S> {
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pub fn new(input: S) -> Self {
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Self { input, buffer: BytesMut::new() }
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}
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}
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impl <S> Stream for DigestListDecoder<S>
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where S: Stream<Item=Bytes>,
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S::Error: Into<Error>,
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{
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type Item = [u8; 32];
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type Error = Error;
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fn poll(&mut self) -> Result<Async<Option<Self::Item>>, Self::Error> {
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loop {
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if self.buffer.len() >= 32 {
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let left = self.buffer.split_to(32);
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let mut digest: [u8; 32] = unsafe { std::mem::uninitialized() };
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unsafe { std::ptr::copy_nonoverlapping(left.as_ptr(), digest.as_mut_ptr(), 32); }
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return Ok(Async::Ready(Some(digest)));
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}
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match self.input.poll() {
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Err(err) => {
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return Err(err.into());
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}
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Ok(Async::NotReady) => {
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return Ok(Async::NotReady);
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}
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Ok(Async::Ready(None)) => {
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let rest = self.buffer.len();
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if rest == 0 { return Ok(Async::Ready(None)); }
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return Err(format_err!("got small digest ({} != 32).", rest));
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}
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Ok(Async::Ready(Some(data))) => {
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self.buffer.extend_from_slice(&data);
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// continue
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}
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}
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}
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}
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}
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