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od: remove potential unsoundness and an allocation in PartialReader (#1730)

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Alex Lyon 2021-02-17 23:23:13 -08:00 • committed by GitHub
parent e2b58051e6
commit 39d62c6c1f
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1 changed files with 13 additions and 9 deletions
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22
src/uu/od/src/partialreader.rs
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@ -8,7 +8,7 @@ use crate::multifilereader::HasError;
/// When a large number of bytes must be skipped, it will be read into a
/// dynamically allocated buffer. The buffer will be limited to this size.
const MAX_SKIP_BUFFER: usize = 64 * 1024;
const MAX_SKIP_BUFFER: usize = 16 * 1024;
/// Wrapper for `std::io::Read` which can skip bytes at the beginning
/// of the input, and it can limit the returned bytes to a particular
@ -31,21 +31,25 @@ impl<R> PartialReader<R> {
impl<R: Read> Read for PartialReader<R> {
fn read(&mut self, out: &mut [u8]) -> io::Result<usize> {
if self.skip > 0 {
let buf_size = cmp::min(self.skip, MAX_SKIP_BUFFER);
let mut bytes: Vec<u8> = Vec::with_capacity(buf_size);
unsafe {
bytes.set_len(buf_size);
}
let mut bytes = [0; MAX_SKIP_BUFFER];
while self.skip > 0 {
let skip_count = cmp::min(self.skip, buf_size);
let skip_count = cmp::min(self.skip, MAX_SKIP_BUFFER);
match self.inner.read_exact(&mut bytes[..skip_count]) {
match self.inner.read(&mut bytes[..skip_count]) {
Ok(0) => {
// this is an error as we still have more to skip
return Err(io::Error::new(
io::ErrorKind::UnexpectedEof,
"tried to skip past end of input",
));
}
Ok(n) => self.skip -= n,
Err(e) => return Err(e),
Ok(()) => self.skip -= skip_count,
}
}
}
match self.limit {
None => self.inner.read(out),
Some(0) => Ok(0),