Skip to content

Fixes overflow in libstd/io/cursor.rs "seek" #39874

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Feb 21, 2017
Merged

Fixes overflow in libstd/io/cursor.rs "seek" #39874

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
ab57e7b
std::io::cursor Added test for seeking beyond i64.
amosonn Feb 16, 2017
a2d176e
std::io::cursor: Fixed Seek so test passes.
amosonn Feb 16, 2017
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
59 changes: 49 additions & 10 deletions src/libstd/io/cursor.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -200,18 +200,20 @@ impl<T> Cursor<T> {
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> io::Seek for Cursor<T> where T: AsRef<[u8]> {
fn seek(&mut self, style: SeekFrom) -> io::Result<u64> {
let pos = match style {
SeekFrom::Start(n) => { self.pos = n; return Ok(n) }
SeekFrom::End(n) => self.inner.as_ref().len() as i64 + n,
SeekFrom::Current(n) => self.pos as i64 + n,
let (base_pos, offset) = match style {
SeekFrom::Start(n) => { self.pos = n; return Ok(n); }
SeekFrom::End(n) => (self.inner.as_ref().len() as u64, n),
SeekFrom::Current(n) => (self.pos, n),
};

if pos < 0 {
Err(Error::new(ErrorKind::InvalidInput,
"invalid seek to a negative position"))
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as u64)
} else {
self.pos = pos as u64;
Ok(self.pos)
base_pos.checked_sub((offset.wrapping_neg()) as u64)
};
match new_pos {
Some(n) => {self.pos = n; Ok(self.pos)}
None => Err(Error::new(ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position"))
}
}
}
Expand Down Expand Up @@ -526,6 +528,43 @@ mod tests {
assert_eq!(r.write(&[3]).unwrap(), 0);
}

#[test]
fn seek_past_i64() {
let buf = [0xff];
let mut r = Cursor::new(&buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);

let mut r = Cursor::new(vec![10]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);

let mut buf = [0];
let mut r = Cursor::new(&mut buf[..]);
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);

let mut r = Cursor::new(vec![10].into_boxed_slice());
assert_eq!(r.seek(SeekFrom::Start(6)).unwrap(), 6);
assert_eq!(r.seek(SeekFrom::Current(0x7ffffffffffffff0)).unwrap(), 0x7ffffffffffffff6);
assert_eq!(r.seek(SeekFrom::Current(0x10)).unwrap(), 0x8000000000000006);
assert_eq!(r.seek(SeekFrom::Current(0)).unwrap(), 0x8000000000000006);
assert!(r.seek(SeekFrom::Current(0x7ffffffffffffffd)).is_err());
assert_eq!(r.seek(SeekFrom::Current(-0x8000000000000000)).unwrap(), 6);
}

#[test]
fn seek_before_0() {
let buf = [0xff];
Expand Down