diff options
| -rw-r--r-- | src/bytes_mut.rs | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/src/bytes_mut.rs b/src/bytes_mut.rs index 0248df8..0ea0272 100644 --- a/src/bytes_mut.rs +++ b/src/bytes_mut.rs @@ -468,18 +468,26 @@ impl BytesMut { /// assert_eq!(&buf[..], &[0x1, 0x1, 0x3, 0x3]); /// ``` pub fn resize(&mut self, new_len: usize, value: u8) { - let len = self.len(); - if new_len > len { - let additional = new_len - len; - self.reserve(additional); - unsafe { - let dst = self.chunk_mut().as_mut_ptr(); - ptr::write_bytes(dst, value, additional); - self.set_len(new_len); - } + let additional = if let Some(additional) = new_len.checked_sub(self.len()) { + additional } else { self.truncate(new_len); + return; + }; + + if additional == 0 { + return; } + + self.reserve(additional); + let dst = self.spare_capacity_mut().as_mut_ptr(); + // SAFETY: `spare_capacity_mut` returns a valid, properly aligned pointer and we've + // reserved enough space to write `additional` bytes. + unsafe { ptr::write_bytes(dst, value, additional) }; + + // SAFETY: There are at least `new_len` initialized bytes in the buffer so no + // uninitialized bytes are being exposed. + unsafe { self.set_len(new_len) }; } /// Sets the length of the buffer. |