fix strlcpy and strlcat

src/header/string/mod.rs

@@ -381,11 +381,11 @@ pub unsafe extern "C" fn strerror_r(errnum: c_int, buf: *mut c_char, buflen: siz
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/strlcat.html>.
 #[unsafe(no_mangle)]
-pub unsafe extern "C" fn strlcat(dst: *mut c_char, src: *const c_char, n: size_t) -> size_t {
-    let len = strlen(dst) as isize;
-    let d = dst.offset(len);
-
-    strlcpy(d, src, n)
+pub unsafe extern "C" fn strlcat(dst: *mut c_char, src: *const c_char, dstsize: size_t) -> size_t {
+    let dst_len = unsafe { strlen(dst) };
+    let d = unsafe { dst.offset(dst_len as isize) };
+    let src_len = unsafe { strlcpy(d, src, dstsize) };
+    src_len + if dst_len > dstsize { dstsize } else { dst_len }
 }
 
 #[unsafe(no_mangle)]
@@ -407,15 +407,25 @@ pub unsafe extern "C" fn strsep(str_: *mut *mut c_char, sep: *const c_char) -> *
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/strlcat.html>.
 #[unsafe(no_mangle)]
-pub unsafe extern "C" fn strlcpy(dst: *mut c_char, src: *const c_char, n: size_t) -> size_t {
+pub unsafe extern "C" fn strlcpy(dst: *mut c_char, src: *const c_char, dstsize: size_t) -> size_t {
     let mut i = 0;
 
-    while *src.add(i) != 0 && i < n {
-        *dst.add(i) = *src.add(i);
+    while unsafe { *src.add(i) } != 0 && i < dstsize {
+        unsafe {
+            *dst.add(i) = *src.add(i);
+        }
         i += 1;
     }
 
-    *dst.add(i) = 0;
+    if dstsize != 0 {
+        unsafe {
+            *dst.add(i) = 0;
+        }
+    }
+
+    while unsafe { *src.add(i) } != 0 {
+        i += 1;
+    }
 
     i as size_t
 }