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|
use std::io;
use std::cmp;
use super::*;
/// A `BufferedReaderLimitor` limits the amount of data that can be
/// read from a `BufferedReader`.
#[derive(Debug)]
pub struct BufferedReaderLimitor<T: BufferedReader> {
reader: T,
limit: u64,
}
impl<T: BufferedReader> BufferedReaderLimitor<T> {
pub fn new(reader: T, limit: u64) -> BufferedReaderLimitor<T> {
BufferedReaderLimitor {
reader: reader,
limit: limit,
}
}
}
impl<T: BufferedReader> io::Read for BufferedReaderLimitor<T> {
fn read(&mut self, buf: &mut [u8]) -> Result<usize, io::Error> {
let len = cmp::min(self.limit, buf.len() as u64) as usize;
return self.reader.read(&mut buf[0..len]);
}
}
impl<T: BufferedReader> BufferedReader for BufferedReaderLimitor<T> {
/// Return the buffer. Ensure that it contains at least `amount`
/// bytes.
fn data(&mut self, amount: usize) -> Result<&[u8], io::Error> {
let amount = cmp::min(amount as u64, self.limit) as usize;
let result = self.reader.data(amount);
match result {
Ok(ref buffer) =>
if buffer.len() as u64 > self.limit {
return Ok(&buffer[0..self.limit as usize]);
} else {
return Ok(buffer);
},
Err(err) => return Err(err),
}
}
fn consume(&mut self, amount: usize) -> &[u8] {
assert!(amount as u64 <= self.limit);
self.limit -= amount as u64;
let data = self.reader.consume(amount);
return &data[..cmp::min(self.limit + amount as u64, data.len() as u64) as usize];
}
fn data_consume(&mut self, amount: usize) -> Result<&[u8], io::Error> {
let amount = cmp::min(amount as u64, self.limit) as usize;
let result = self.reader.data_consume(amount);
if let Ok(ref buffer) = result {
self.limit -= amount as u64;
return Ok(&buffer[
..cmp::min(buffer.len() as u64, self.limit + amount as u64) as usize]);
}
return result;
}
fn data_consume_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
if amount as u64 > self.limit {
return Err(Error::new(ErrorKind::UnexpectedEof, "EOF"));
}
let result = self.reader.data_consume_hard(amount);
if let Ok(ref buffer) = result {
self.limit -= amount as u64;
return Ok(&buffer[
..cmp::min(buffer.len() as u64, self.limit + amount as u64) as usize]);
}
return result;
}
fn into_inner<'b>(self: Box<Self>) -> Option<Box<BufferedReader + 'b>>
where Self: 'b {
Some(Box::new(self.reader))
}
}
#[test]
fn buffered_reader_limitor_test() {
let data : &[u8] = b"01234567890123456789";
/* Add a single limitor. */
{
let mut bio : Box<BufferedReader>
= Box::new(BufferedReaderMemory::new(data));
bio = {
let mut bio2 = Box::new(BufferedReaderLimitor::new(bio, 5));
{
let result = bio2.data(5).unwrap();
assert_eq!(result.len(), 5);
assert_eq!(result, &b"01234"[..]);
}
bio2.consume(5);
{
let result = bio2.data(1).unwrap();
assert_eq!(result.len(), 0);
assert_eq!(result, &b""[..]);
}
bio2.into_inner().unwrap()
};
{
{
let result = bio.data(15).unwrap();
assert_eq!(result.len(), 15);
assert_eq!(result, &b"567890123456789"[..]);
}
bio.consume(15);
{
let result = bio.data(1).unwrap();
assert_eq!(result.len(), 0);
assert_eq!(result, &b""[..]);
}
}
}
/* Try with two limitors where the first one imposes the real
* limit. */
{
let mut bio : Box<BufferedReader>
= Box::new(BufferedReaderMemory::new(data));
bio = {
let bio2 : Box<BufferedReader>
= Box::new(BufferedReaderLimitor::new(bio, 5));
// We limit to 15 bytes, but bio2 will still limit us to 5
// bytes.
let mut bio3 : Box<BufferedReader>
= Box::new(BufferedReaderLimitor::new(bio2, 15));
{
let result = bio3.data(100).unwrap();
assert_eq!(result.len(), 5);
assert_eq!(result, &b"01234"[..]);
}
bio3.consume(5);
{
let result = bio3.data(1).unwrap();
assert_eq!(result.len(), 0);
assert_eq!(result, &b""[..]);
}
bio3.into_inner().unwrap().into_inner().unwrap()
};
{
{
let result = bio.data(15).unwrap();
assert_eq!(result.len(), 15);
assert_eq!(result, &b"567890123456789"[..]);
}
bio.consume(15);
{
let result = bio.data(1).unwrap();
assert_eq!(result.len(), 0);
assert_eq!(result, &b""[..]);
}
}
}
}
|
