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fix(string/memcmp): use read_unaligned where alignment is not guaranteed

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Signed-off-by: Anhad Singh <andypython@protonmail.com>
This commit is contained in:
Anhad Singh
2026-01-02 00:52:40 +11:00
parent 75f6b9d64e
commit 5f256f91cd
1 changed files with 9 additions and 7 deletions
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src/header/string/mod.rs
+9 -7
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@@ -66,13 +66,15 @@ pub unsafe extern "C" fn memchr(
#[unsafe(no_mangle)]
pub unsafe extern "C" fn memcmp(s1: *const c_void, s2: *const c_void, n: usize) -> c_int {
let (div, rem) = (n / mem::size_of::<usize>(), n % mem::size_of::<usize>());
let mut a = s1 as *const usize;
let mut b = s2 as *const usize;
let mut a = s1.cast::<usize>();
let mut b = s2.cast::<usize>();
for _ in 0..div {
if *a != *b {
// SAFETY: `s1` and `s2` are `*const c_void`, which only guarantees byte
// alignment. Hence `a` and `b` may be unaligned.
if a.read_unaligned() != b.read_unaligned() {
for i in 0..mem::size_of::<usize>() {
let c = *(a as *const u8).add(i);
let d = *(b as *const u8).add(i);
let c = *(a.cast::<u8>()).add(i);
let d = *(b.cast::<u8>()).add(i);
if c != d {
return c as c_int - d as c_int;
}
@@ -83,8 +85,8 @@ pub unsafe extern "C" fn memcmp(s1: *const c_void, s2: *const c_void, n: usize)
b = b.offset(1);
}
let mut a = a as *const u8;
let mut b = b as *const u8;
let mut a = a.cast::<u8>();
let mut b = b.cast::<u8>();
for _ in 0..rem {
if *a != *b {
return *a as c_int - *b as c_int;