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UTF-8 validation: Add missing if conditional for short input

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We need to guard that `len` is large enough for the fast skip loop.
This commit is contained in:
Ulrik Sverdrup 2016-01-12 23:04:46 +01:00
parent 11e3de39d9
commit cadcd70775
1 changed files with 15 additions and 12 deletions
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11
src/libcore/str/mod.rs
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@ -1158,12 +1158,14 @@ fn run_utf8_validation(v: &[u8]) -> Result<(), Utf8Error> {
offset += 1;
} else {
// Ascii case, try to skip forward quickly.
// When the pointer is aligned, read 2 words of data per iteration
// until we find a word containing a non-ascii byte.
const BYTES_PER_ITERATION: usize = 2 * usize::BYTES;
let ptr = v.as_ptr();
let align = (ptr as usize + offset) & (usize::BYTES - 1);
if align == 0 {
// When the pointer is aligned, read 2 words of data per iteration
// until we find a word containing a non-ascii byte.
while offset <= len - 2 * usize::BYTES {
if len >= BYTES_PER_ITERATION {
while offset <= len - BYTES_PER_ITERATION {
unsafe {
let u = *(ptr.offset(offset as isize) as *const usize);
let v = *(ptr.offset((offset + usize::BYTES) as isize) as *const usize);
@ -1175,7 +1177,8 @@ fn run_utf8_validation(v: &[u8]) -> Result<(), Utf8Error> {
break;
}
}
offset += usize::BYTES * 2;
offset += BYTES_PER_ITERATION;
}
}
// step from the point where the wordwise loop stopped
while offset < len && v[offset] < 128 {