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|
//! Encodes a byte stream using OpenPGP's partial body encoding.
use std;
use std::fmt;
use std::io;
use std::cmp;
use crate::Error;
use crate::Result;
use crate::packet::header::BodyLength;
use super::{
stream::writer,
write_byte,
Marshal,
};
pub struct PartialBodyFilter<'a, C: 'a> {
// The underlying writer.
//
// Because this writer implements `Drop`, we cannot move the inner
// writer out of this writer. We therefore wrap it with `Option`
// so that we can `take()` it.
inner: Option<writer::BoxStack<'a, C>>,
// The cookie.
cookie: C,
// The buffer.
buffer: Vec<u8>,
// The amount to buffer before flushing.
buffer_threshold: usize,
// The maximum size of a partial body chunk. The standard allows
// for chunks up to 1 GB in size.
max_chunk_size: usize,
// The number of bytes written to this filter.
position: u64,
}
const PARTIAL_BODY_FILTER_MAX_CHUNK_SIZE : usize = 1 << 30;
// The amount to buffer before flushing. If this is small, we get
// lots of small partial body packets, which is annoying.
const PARTIAL_BODY_FILTER_BUFFER_THRESHOLD : usize = 4 * 1024 * 1024;
impl<'a, C: 'a> PartialBodyFilter<'a, C> {
/// Returns a new partial body encoder.
pub fn new(inner: writer::Stack<'a, C>, cookie: C)
-> writer::Stack<'a, C> {
Self::with_limits(inner, cookie,
PARTIAL_BODY_FILTER_BUFFER_THRESHOLD,
PARTIAL_BODY_FILTER_MAX_CHUNK_SIZE)
.expect("safe limits")
}
/// Returns a new partial body encoder with the given limits.
pub fn with_limits(inner: writer::Stack<'a, C>, cookie: C,
buffer_threshold: usize,
max_chunk_size: usize)
-> Result<writer::Stack<'a, C>> {
if buffer_threshold.count_ones() != 1 {
return Err(Error::InvalidArgument(
"buffer_threshold is not a power of two".into()).into());
}
if max_chunk_size.count_ones() != 1 {
return Err(Error::InvalidArgument(
"max_chunk_size is not a power of two".into()).into());
}
if max_chunk_size > PARTIAL_BODY_FILTER_MAX_CHUNK_SIZE {
return Err(Error::InvalidArgument(
"max_chunk_size exceeds limit".into()).into());
}
Ok(writer::Stack::from(Box::new(PartialBodyFilter {
inner: Some(inner.into()),
cookie,
buffer: Vec::with_capacity(buffer_threshold),
buffer_threshold,
max_chunk_size,
position: 0,
})))
}
// Writes out any full chunks between `self.buffer` and `other`.
// Any extra data is buffered.
//
// If `done` is set, then flushes any data, and writes the end of
// the partial body encoding.
fn write_out(&mut self, mut other: &[u8], done: bool)
-> io::Result<()> {
if self.inner.is_none() {
return Ok(());
}
let mut inner = self.inner.as_mut().unwrap();
if done {
// We're done. The last header MUST be a non-partial body
// header. We have to write it even if it is 0 bytes
// long.
// Write the header.
let l = self.buffer.len() + other.len();
if l > std::u32::MAX as usize {
unimplemented!();
}
BodyLength::Full(l as u32).serialize(inner).map_err(
|e| match e.downcast::<io::Error>() {
// An io::Error. Pass as-is.
Ok(err) => err,
// A failure. Wrap it.
Err(e) => io::Error::new(io::ErrorKind::Other, e),
})?;
// Write the body.
inner.write_all(&self.buffer[..])?;
crate::vec_truncate(&mut self.buffer, 0);
inner.write_all(other)?;
} else {
while self.buffer.len() + other.len() > self.buffer_threshold {
// Write a partial body length header.
let chunk_size_log2 =
super::log2(cmp::min(self.max_chunk_size,
self.buffer.len() + other.len())
as u32);
let chunk_size = (1usize) << chunk_size_log2;
let size = BodyLength::Partial(chunk_size as u32);
let mut size_byte = [0u8];
size.serialize(&mut io::Cursor::new(&mut size_byte[..]))
.expect("size should be representable");
let size_byte = size_byte[0];
// Write out the chunk...
write_byte(&mut inner, size_byte)?;
// ... from our buffer first...
let l = cmp::min(self.buffer.len(), chunk_size);
inner.write_all(&self.buffer[..l])?;
crate::vec_drain_prefix(&mut self.buffer, l);
// ... then from other.
if chunk_size > l {
inner.write_all(&other[..chunk_size - l])?;
other = &other[chunk_size - l..];
}
}
self.buffer.extend_from_slice(other);
assert!(self.buffer.len() <= self.buffer_threshold);
}
Ok(())
}
}
impl<'a, C: 'a> io::Write for PartialBodyFilter<'a, C> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
// If we can write out a chunk, avoid an extra copy.
if buf.len() >= self.buffer_threshold - self.buffer.len() {
self.write_out(buf, false)?;
} else {
self.buffer.append(buf.to_vec().as_mut());
}
self.position += buf.len() as u64;
Ok(buf.len())
}
// XXX: The API says that `flush` is supposed to flush any
// internal buffers to disk. We don't do that.
fn flush(&mut self) -> io::Result<()> {
self.write_out(&b""[..], false)
}
}
impl<'a, C: 'a> Drop for PartialBodyFilter<'a, C> {
// Make sure the internal buffer is flushed.
fn drop(&mut self) {
let _ = self.write_out(&b""[..], true);
}
}
impl<'a, C: 'a> fmt::Debug for PartialBodyFilter<'a, C> {
fn
|