1 files changed, 63 insertions, 0 deletions
diff --git a/vendor/os_str_bytes/src/windows/wtf8/string.rs b/vendor/os_str_bytes/src/windows/wtf8/string.rs
new file mode 100644
index 000000000..10b8fafb6
--- /dev/null
+++ b/vendor/os_str_bytes/src/windows/wtf8/string.rs
@@ -0,0 +1,63 @@
+use crate::util::is_continuation;
+
+use super::encode_wide;
+
+const SURROGATE_LENGTH: usize = 3;
+
+pub(crate) fn ends_with(string: &[u8], mut suffix: &[u8]) -> bool {
+    let index = match string.len().checked_sub(suffix.len()) {
+        Some(index) => index,
+        None => return false,
+    };
+    if let Some(&byte) = string.get(index) {
+        if is_continuation(byte) {
+            let index = index.checked_sub(1).expect("invalid string");
+            let mut wide_surrogate = match suffix.get(..SURROGATE_LENGTH) {
+                Some(surrogate) => encode_wide(surrogate),
+                None => return false,
+            };
+            let surrogate_wchar = wide_surrogate
+                .next()
+                .expect("failed decoding non-empty suffix");
+
+            if wide_surrogate.next().is_some()
+                || encode_wide(&string[index..])
+                    .take_while(Result::is_ok)
+                    .nth(1)
+                    != Some(surrogate_wchar)
+            {
+                return false;
+            }
+            suffix = &suffix[SURROGATE_LENGTH..];
+        }
+    }
+    string.ends_with(suffix)
+}
+
+pub(crate) fn starts_with(string: &[u8], mut prefix: &[u8]) -> bool {
+    if let Some(&byte) = string.get(prefix.len()) {
+        if is_continuation(byte) {
+            let index = match prefix.len().checked_sub(SURROGATE_LENGTH) {
+                Some(index) => index,
+                None => return false,
+            };
+            let (substring, surrogate) = prefix.split_at(index);
+            let mut wide_surrogate = encode_wide(surrogate);
+            let surrogate_wchar = wide_surrogate
+                .next()
+                .expect("failed decoding non-empty prefix");
+
+            if surrogate_wchar.is_err()
+                || wide_surrogate.next().is_some()
+                || encode_wide(&string[index..])
+                    .next()
+                    .expect("failed decoding non-empty substring")
+                    != surrogate_wchar
+            {
+                return false;
+            }
+            prefix = substring;
+        }
+    }
+    string.starts_with(prefix)
+}