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Auto merge of #23849 - bcoopers:master, r=pnkfelix 

Right now, if the user requests to increase the vector size via reserve() or push_back() and the request brings the attempted memory above usize::MAX, we panic.

With this change there is only a panic if the minimum requested memory that could meet the requirement is above usize::MAX- otherwise it simply requests its largest capacity possible, usize::MAX.
This commit is contained in:
bors 2015-04-13 00:34:21 +00:00
parent c3947061d6 ac617b6288
commit 47def3ef27
1 changed files with 18 additions and 6 deletions
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24
src/libcollections/vec.rs
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@ -65,10 +65,14 @@ use core::ops;
use core::ptr;
use core::ptr::Unique;
use core::slice;
use core::isize;
use core::usize;
use borrow::{Cow, IntoCow};
// FIXME- fix places which assume the max vector allowed has memory usize::MAX.
static MAX_MEMORY_SIZE: usize = isize::MAX as usize;
/// A growable list type, written `Vec<T>` but pronounced 'vector.'
///
/// # Examples
@ -307,10 +311,15 @@ impl<T> Vec<T> {
#[stable(feature = "rust1", since = "1.0.0")]
pub fn reserve(&mut self, additional: usize) {
if self.cap - self.len < additional {
let err_msg = "Vec::reserve: `usize` overflow";
let new_cap = self.len.checked_add(additional).expect(err_msg)
.checked_next_power_of_two().expect(err_msg);
self.grow_capacity(new_cap);
const ERR_MSG: &'static str = "Vec::reserve: `isize` overflow";
let new_min_cap = self.len.checked_add(additional).expect(ERR_MSG);
if new_min_cap > MAX_MEMORY_SIZE { panic!(ERR_MSG) }
self.grow_capacity(match new_min_cap.checked_next_power_of_two() {
Some(x) if x > MAX_MEMORY_SIZE => MAX_MEMORY_SIZE,
None => MAX_MEMORY_SIZE,
Some(x) => x,
});
}
}
@ -647,8 +656,11 @@ impl<T> Vec<T> {
#[inline(never)]
fn resize<T>(vec: &mut Vec<T>) {
let old_size = vec.cap * mem::size_of::<T>();
let size = max(old_size, 2 * mem::size_of::<T>()) * 2;
if old_size > size { panic!("capacity overflow") }
if old_size >= MAX_MEMORY_SIZE { panic!("capacity overflow") }
let mut size = max(old_size, 2 * mem::size_of::<T>()) * 2;
if old_size > size || size > MAX_MEMORY_SIZE {
size = MAX_MEMORY_SIZE;
}
unsafe {
let ptr = alloc_or_realloc(*vec.ptr, old_size, size);
if ptr.is_null() { ::alloc::oom() }