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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 Error;
use Result;
use ::BodyLength;
use super::{writer, write_byte, Serialize};
// Compute the log2 of an integer. (This is simply the most
// significant bit.) Note: log2(0) = -Inf, but this function returns
// log2(0) as 0 (which is the closest number that we can represent).
fn log2(x: u32) -> usize {
if x == 0 {
0
} else {
31 - x.leading_zeros() as usize
}
}
#[test]
fn log2_test() {
for i in 0..32 {
// eprintln!("log2(1 << {} = {}) = {}", i, 1u32 << i, log2(1u32 << i));
assert_eq!(log2(1u32 << i), i);
if i > 0 {
assert_eq!(log2((1u32 << i) - 1), i - 1);
assert_eq!(log2((1u32 << i) + 1), i);
}
}
}
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: u32,
}
const PARTIAL_BODY_FILTER_MAX_CHUNK_SIZE : u32 = 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> {
let buffer_threshold = PARTIAL_BODY_FILTER_BUFFER_THRESHOLD;
let max_chunk_size = PARTIAL_BODY_FILTER_MAX_CHUNK_SIZE;
writer::Stack::from(Box::new(PartialBodyFilter {
inner: Some(inner.into()),
cookie: cookie,
buffer: Vec::with_capacity(buffer_threshold as usize),
buffer_threshold: buffer_threshold,
max_chunk_size: max_chunk_size,
}))
}
// 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, 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>() {
Ok(err) => err,
Err(e) => {
match e.downcast::<Error>()
.expect("Unexpected error encoding full length")
{
Error::InvalidArgument(s) =>
panic!("Error encoding full length: {}", s),
_ =>
panic!("Unexpected error encoding \
full length"),
}
}
}
})?;
// Write the body.
inner.write_all(&self.buffer[..])?;
self.buffer.clear();
inner.write_all(other)?;
} else {
// Write a partial body length header.
let chunk_size_log2 =
log2(cmp::min(self.max_chunk_size,
self.buffer_threshold as u32));
let chunk_size = (1 as usize) << chunk_size_log2;
let size_byte = 224 + chunk_size_log2;
assert!(size_byte < 255);
let size_byte = size_byte as u8;
// The first pass we process self.buffer, the second pass
// we process other.
for i in 0..2 {
let mut rest = Vec::new();
for chunk in self.buffer.chunks(chunk_size) {
if chunk.len() < chunk_size {
// We don't have enough for a whole chunk.
rest = chunk.to_vec();
break;
}
// Write out the chunk.
write_byte(&mut inner, size_byte)?;
inner.write_all(chunk)?;
}
// In between, we have to see if we have a whole
// chunk.
if i == 0 && rest.len() + other.len() >= chunk_size {
write_byte(&mut inner, size_byte)?;
inner.write_all(&rest[..])?;
let amount = chunk_size - rest.len();
inner.write_all(&other[..amount])?;
rest = other[amount..].to_vec();
}
self.buffer = rest;
}
}
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.capacity() - self.buffer.len() {
self.write_out(buf, false)?;
} else {
self.buffer.append(buf.to_vec().as_mut());
}
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 fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("PartialBodyFilter")
.field("inner", &self.inner)
.finish()
}
}
impl<'a, C: 'a>
|