From c89ac2540fb207830d78d55326aed48c2e14d0a0 Mon Sep 17 00:00:00 2001
From: Yagiz Nizipli <yagiz@cloudflare.com>
Date: Tue, 3 Dec 2024 15:11:36 -0500
Subject: [PATCH] fix panic on empty host and hostname entries

---
 src/ffi.rs | 12 ++++++++++++
 src/lib.rs |  8 ++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/ffi.rs b/src/ffi.rs
index a7bab7d..a61bfad 100644
--- a/src/ffi.rs
+++ b/src/ffi.rs
@@ -22,6 +22,12 @@ pub struct ada_string {
 impl ada_string {
     #[must_use]
     pub const fn as_str(&self) -> &'static str {
+        // We need to handle length 0 since data will be `nullptr`
+        // Not handling will result in a panic due to core::slice::from_raw_parts
+        // implementation
+        if self.length == 0 {
+            return "";
+        }
         unsafe {
             let slice = core::slice::from_raw_parts(self.data.cast(), self.length);
             core::str::from_utf8_unchecked(slice)
@@ -37,6 +43,12 @@ pub struct ada_owned_string {
 
 impl AsRef<str> for ada_owned_string {
     fn as_ref(&self) -> &str {
+        // We need to handle length 0 since data will be `nullptr`
+        // Not handling will result in a panic due to core::slice::from_raw_parts
+        // implementation
+        if self.length == 0 {
+            return "";
+        }
         unsafe {
             let slice = core::slice::from_raw_parts(self.data.cast(), self.length);
             core::str::from_utf8_unchecked(slice)
diff --git a/src/lib.rs b/src/lib.rs
index d944c5f..04bf111 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1079,4 +1079,12 @@ mod test {
         assert_eq!(first.href(), "https://lemire.me/");
         assert_eq!(second.href(), "https://yagiz.co/");
     }
+
+    #[test]
+    fn should_handle_empty_host() {
+        // Ref: https://github.com/ada-url/rust/issues/74
+        let url = Url::parse("file:///C:/Users/User/Documents/example.pdf", None).unwrap();
+        assert_eq!(url.host(), "");
+        assert_eq!(url.hostname(), "");
+    }
 }