From 03753ba5a21fe0e4bfc34e9691d4b13f24c90af4 Mon Sep 17 00:00:00 2001
From: Steven Fackler <sfackler@gmail.com>
Date: Sat, 21 Feb 2015 11:15:58 -0800
Subject: [PATCH] Fix io::Take behavior with limit 0
We can't call into the inner reader for a 0-byte read because that may
end up blocking or returning an error.
---
src/libstd/io/mod.rs | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index c38d52161c9..5e810926ee4 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -669,6 +669,11 @@ impl<T> Take<T> {
impl<T: Read> Read for Take<T> {
fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
+ // Don't call into inner reader at all at EOF because it may still block
+ if self.limit == 0 {
+ return Ok(0);
+ }
+
let max = cmp::min(buf.len() as u64, self.limit) as usize;
let n = try!(self.inner.read(&mut buf[..max]));
self.limit -= n as u64;
@@ -846,6 +851,7 @@ impl<B: BufRead> Iterator for Lines<B> {
mod tests {
use prelude::v1::*;
use io::prelude::*;
+ use io;
use super::Cursor;
#[test]
@@ -943,4 +949,18 @@ mod tests {
let mut v = String::new();
assert!(c.read_to_string(&mut v).is_err());
}
+
+ #[test]
+ fn take_eof() {
+ struct R;
+
+ impl Read for R {
+ fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+ Err(io::Error::new(io::ErrorKind::Other, "", None))
+ }
+ }
+
+ let mut buf = [0; 1];
+ assert_eq!(Ok(0), R.take(0).read(&mut buf));
+ }
}