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|
use std::io;
/// A reader that also throws an error when a seek
/// to a non existing position is executed (not normally the behavior).
///
/// Note that this is not the default behavior of seek
/// but it is needed for testing purposes.
pub struct TestReader {
data: Vec<u8>,
cur_offset: usize
}
impl TestReader {
/// Creates a reader with the given data
pub fn new(data: &[u8]) -> TestReader {
TestReader{
data: {
let mut v = Vec::with_capacity(data.len());
v.extend_from_slice(data);
v
},
cur_offset: 0
}
}
/// Current offset from the start.
pub fn cur_offset(&self) -> usize {
self.cur_offset
}
}
impl io::Read for TestReader {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
if buf.len() > self.data.len() - self.cur_offset {
Err(io::Error::new(io::ErrorKind::UnexpectedEof, "failed to fill whole buffer"))
} else {
buf.clone_from_slice(
&self.data[
self.cur_offset..(self.cur_offset + buf.len())
]
);
self.cur_offset += buf.len();
Ok(buf.len())
}
}
}
impl io::Seek for TestReader{
fn seek(&mut self, pos: io::SeekFrom) -> io::Result<u64> {
use io::SeekFrom::*;
let new_offset = match pos {
Start(start_offset) => start_offset as i64,
End(end_offset) => (self.data.len() as i64) + end_offset,
Current(offset) => (self.cur_offset as i64) + offset,
};
if new_offset < 0 {
Err(
io::Error::new(
io::ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position",
)
)
} else if new_offset > (self.data.len() as i64) {
// Note this is not default behavior but is usefull for
// testing. Normally a seek over the end is allowed.
Err(
io::Error::new(
io::ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position",
)
)
} else {
self.cur_offset = new_offset as usize;
Ok(self.cur_offset as u64)
}
}
}
#[test]
fn read() {
use io::Read;
{
let mut reader = TestReader::new(&[1,2,3,4]);
{
let mut tar: [u8;4] = [0;4];
assert_eq!(4, reader.read(&mut tar).unwrap());
assert_eq!(&tar[..], &[1,2,3,4]);
}
{
let mut tar: [u8;1] = [0];
assert_eq!(
io::ErrorKind::UnexpectedEof,
reader.read(&mut tar).unwrap_err().kind()
);
}
}
}
#[test]
fn seek() {
use io::Seek;
use io::SeekFrom::*;
// ok seeks
{
let mut reader = TestReader::new(&[1,2,3,4]);
assert_eq!(2, reader.seek(Start(2)).unwrap());
assert_eq!(reader.cur_offset(), 2);
assert_eq!(3, reader.seek(Current(1)).unwrap());
assert_eq!(3, reader.cur_offset());
assert_eq!(1, reader.seek(End(-3)).unwrap());
assert_eq!(1, reader.cur_offset());
}
// bad seeks
{
let mut reader = TestReader::new(&[1,2,3,4]);
assert_eq!(
io::ErrorKind::InvalidInput,
reader.seek(Start(5)).unwrap_err().kind()
);
}
{
let mut reader = TestReader::new(&[1,2,3,4]);
reader.seek(Start(2)).unwrap();
assert_eq!(
io::ErrorKind::InvalidInput,
reader.seek(Current(3)).unwrap_err().kind()
);
assert_eq!(
io::ErrorKind::InvalidInput,
reader.seek(Current(-3)).unwrap_err().kind()
);
}
{
let mut reader = TestReader::new(&[1,2,3,4]);
assert_eq!(
io::ErrorKind::InvalidInput,
reader.seek(End(-5)).unwrap_err().kind()
);
assert_eq!(
io::ErrorKind::InvalidInput,
reader.seek(End(1)).unwrap_err().kind()
);
}
}
|
