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std::io::cursor: Fixed Seek so test passes.

This commit is contained in:
Amos Onn 2017-02-16 02:21:08 +01:00
parent ab57e7b868
commit a2d176e8f4
1 changed files with 12 additions and 10 deletions
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22
src/libstd/io/cursor.rs
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@ -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"))
}
}
}