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Fix invalid slice access in String::retain

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This commit is contained in:
Giacomo Stevanato 2021-02-26 15:44:35 +01:00
parent d95d304861
commit c89e64363b
1 changed files with 23 additions and 16 deletions
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39
library/alloc/src/string.rs
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@ -1233,37 +1233,44 @@ impl String {
where
F: FnMut(char) -> bool,
{
let len = self.len();
let mut del_bytes = 0;
let mut idx = 0;
unsafe {
self.vec.set_len(0);
struct SetLenOnDrop<'a> {
s: &'a mut String,
idx: usize,
del_bytes: usize,
}
while idx < len {
let ch = unsafe { self.get_unchecked(idx..len).chars().next().unwrap() };
impl<'a> Drop for SetLenOnDrop<'a> {
fn drop(&mut self) {
let new_len = self.idx - self.del_bytes;
debug_assert!(new_len <= self.s.len());
unsafe { self.s.vec.set_len(new_len) };
}
}
let len = self.len();
let mut guard = SetLenOnDrop { s: self, idx: 0, del_bytes: 0 };
while guard.idx < len {
let ch = unsafe { guard.s.get_unchecked(guard.idx..len).chars().next().unwrap() };
let ch_len = ch.len_utf8();
if !f(ch) {
del_bytes += ch_len;
} else if del_bytes > 0 {
guard.del_bytes += ch_len;
} else if guard.del_bytes > 0 {
unsafe {
ptr::copy(
self.vec.as_ptr().add(idx),
self.vec.as_mut_ptr().add(idx - del_bytes),
guard.s.vec.as_ptr().add(guard.idx),
guard.s.vec.as_mut_ptr().add(guard.idx - guard.del_bytes),
ch_len,
);
}
}
// Point idx to the next char
idx += ch_len;
guard.idx += ch_len;
}
unsafe {
self.vec.set_len(len - del_bytes);
}
drop(guard);
}
/// Inserts a character into this `String` at a byte position.