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 1/2] 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 c38d52161c96..5e810926ee4f 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));
+    }
 }

From b46e3eec7aec546d8c4e212cc4e27ec870071e74 Mon Sep 17 00:00:00 2001
From: Steven Fackler <sfackler@gmail.com>
Date: Sat, 21 Feb 2015 14:59:29 -0800
Subject: [PATCH 2/2] Implement BufRead for Take

---
 src/libstd/io/mod.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 5e810926ee4f..d0d97c44ce55 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -681,6 +681,21 @@ impl<T: Read> Read for Take<T> {
     }
 }
 
+impl<T: BufRead> BufRead for Take<T> {
+    fn fill_buf(&mut self) -> Result<&[u8]> {
+        let buf = try!(self.inner.fill_buf());
+        let cap = cmp::min(buf.len() as u64, self.limit) as usize;
+        Ok(&buf[..cap])
+    }
+
+    fn consume(&mut self, amt: usize) {
+        // Don't let callers reset the limit by passing an overlarge value
+        let amt = cmp::min(amt as u64, self.limit) as usize;
+        self.limit -= amt as u64;
+        self.inner.consume(amt);
+    }
+}
+
 /// An adaptor which will emit all read data to a specified writer as well.
 ///
 /// For more information see `ReadExt::tee`