diff --git a/Cargo.toml b/Cargo.toml index c33eeff..b19b93e 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -1,6 +1,6 @@ [package] name = "smallvec" -version = "1.6.0" +version = "1.6.1" edition = "2018" authors = ["The Servo Project Developers"] license = "MIT/Apache-2.0" diff --git a/src/lib.rs b/src/lib.rs index 0241aef..5e9de82 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -1009,7 +1009,7 @@ impl SmallVec { /// Insert multiple elements at position `index`, shifting all following elements toward the /// back. pub fn insert_many>(&mut self, index: usize, iterable: I) { - let iter = iterable.into_iter(); + let mut iter = iterable.into_iter(); if index == self.len() { return self.extend(iter); } @@ -1017,13 +1017,16 @@ impl SmallVec { let (lower_size_bound, _) = iter.size_hint(); assert!(lower_size_bound <= core::isize::MAX as usize); // Ensure offset is indexable assert!(index + lower_size_bound >= index); // Protect against overflow - self.reserve(lower_size_bound); + + let mut num_added = 0; + let old_len = self.len(); + assert!(index <= old_len); unsafe { - let old_len = self.len(); - assert!(index <= old_len); + // Reserve space for `lower_size_bound` elements. + self.reserve(lower_size_bound); let start = self.as_mut_ptr(); - let mut ptr = start.add(index); + let ptr = start.add(index); // Move the trailing elements. ptr::copy(ptr, ptr.add(lower_size_bound), old_len - index); @@ -1036,42 +1039,39 @@ impl SmallVec { len: old_len + lower_size_bound, }; - let mut num_added = 0; - for element in iter { - let mut cur = ptr.add(num_added); - if num_added >= lower_size_bound { - // Iterator provided more elements than the hint. Move trailing items again. - self.reserve(1); - let start = self.as_mut_ptr(); - ptr = start.add(index); - cur = ptr.add(num_added); - ptr::copy(cur, cur.add(1), old_len - index); - - guard.start = start; - guard.len += 1; - guard.skip.end += 1; - } + while num_added < lower_size_bound { + let element = match iter.next() { + Some(x) => x, + None => break, + }; + let cur = ptr.add(num_added); ptr::write(cur, element); guard.skip.start += 1; num_added += 1; } - mem::forget(guard); if num_added < lower_size_bound { - // Iterator provided fewer elements than the hint + // Iterator provided fewer elements than the hint. Move the tail backward. ptr::copy( ptr.add(lower_size_bound), ptr.add(num_added), old_len - index, ); } - + // There are no more duplicate or uninitialized slots, so the guard is not needed. self.set_len(old_len + num_added); + mem::forget(guard); + } + + // Insert any remaining elements one-by-one. + for element in iter { + self.insert(index + num_added, element); + num_added += 1; } struct DropOnPanic { start: *mut T, - skip: Range, + skip: Range, // Space we copied-out-of, but haven't written-to yet. len: usize, } diff --git a/src/tests.rs b/src/tests.rs index 0452ae8..19f6da8 100644 --- a/src/tests.rs +++ b/src/tests.rs @@ -905,3 +905,16 @@ fn empty_macro() { fn zero_size_items() { SmallVec::<[(); 0]>::new().push(()); } + +#[test] +fn test_insert_many_overflow() { + let mut v: SmallVec<[u8; 1]> = SmallVec::new(); + v.push(123); + + // Prepare an iterator with small lower bound + let iter = (0u8..5).filter(|n| n % 2 == 0); + assert_eq!(iter.size_hint().0, 0); + + v.insert_many(0, iter); + assert_eq!(&*v, &[0, 2, 4, 123]); +}