Merge branch 'explicit_bzero_in_strings' into 'master'

explicit_bzero implementation proposal

See merge request redox-os/relibc!337

src/header/strings/mod.rs

@@ -1,6 +1,7 @@
 //! strings implementation for Redox, following http://pubs.opengroup.org/onlinepubs/7908799/xsh/strings.h.html
 
 use core::ptr;
+use core::arch;
 
 use crate::{
     header::{ctype, string},
@@ -22,6 +23,14 @@ pub unsafe extern "C" fn bzero(dst: *mut c_void, n: size_t) {
     ptr::write_bytes(dst as *mut u8, 0, n);
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn explicit_bzero(s: *mut c_void, n: size_t) {
+    for i in 0..n {
+        *(s as *mut u8).add(i) = 0 as u8;
+    }
+    arch::asm!("");
+}
+
 #[no_mangle]
 pub extern "C" fn ffs(i: c_int) -> c_int {
     if i == 0 {

tests/strings.c

@@ -40,4 +40,8 @@ int main(void) {
     char* str = "hihih";
     assert(index(str, 'i') == str + 1);
     assert(rindex(str, 'i') == str + 3);
+
+    char buf[] = "password";
+    explicit_bzero(buf, sizeof(buf));
+    assert(buf[0] == 0);
 }