From 107da49f8163113ef04c0c724f3e00c9f7e414f8 Mon Sep 17 00:00:00 2001
From: Karl Seguin <k@openmymind.io>
Date: Sat, 21 Mar 2026 18:37:06 +0800
Subject: [PATCH] new URL('about:blank');

Add correct handling for new URL('about:blank');

When a frame is navigated to about:blank (which happens often, since it happens
as soon as a dynamic iframe is created), we make sure to give window._location
a unique value. This prevents 2 frames from referencing the same
window._location object.

Fixes a WPT crash in: 0/html/browsers/browsing-the-web/navigating-across-documents/initial-empty-document/iframe-nosrc.html
---
 src/browser/Page.zig       |  6 ++++++
 src/browser/URL.zig        | 16 ++++++++++++----
 src/browser/tests/url.html | 16 ++++++++++++++++
 src/browser/webapi/URL.zig |  9 ++++++++-
 4 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/src/browser/Page.zig b/src/browser/Page.zig
index eef70bbc..18292aa6 100644
--- a/src/browser/Page.zig
+++ b/src/browser/Page.zig
@@ -441,6 +441,12 @@ pub fn navigate(self: *Page, request_url: [:0]const u8, opts: NavigateOpts) !voi
     if (is_about_blank or is_blob) {
         self.url = if (is_about_blank) "about:blank" else try self.arena.dupeZ(u8, request_url);
 
+        // even though this might be the same _data_ as `default_location`, we
+        // have to do this to make sure window.location is at a unique _address_.
+        // If we don't do this, mulitple window._location will have the same
+        // address and thus be mapped to the same v8::Object in the identity map.
+        self.window._location = try Location.init(self.url, self);
+
         if (is_blob) {
             // strip out blob:
             self.origin = try URL.getOrigin(self.arena, request_url[5.. :0]);
diff --git a/src/browser/URL.zig b/src/browser/URL.zig
index 1c26a981..935d1791 100644
--- a/src/browser/URL.zig
+++ b/src/browser/URL.zig
@@ -323,14 +323,22 @@ pub fn getPassword(raw: [:0]const u8) []const u8 {
 }
 
 pub fn getPathname(raw: [:0]const u8) []const u8 {
-    const protocol_end = std.mem.indexOf(u8, raw, "://") orelse 0;
-    const path_start = std.mem.indexOfScalarPos(u8, raw, if (protocol_end > 0) protocol_end + 3 else 0, '/') orelse raw.len;
+    const protocol_end = std.mem.indexOf(u8, raw, "://");
+
+    // Handle scheme:path URLs like about:blank (no "://")
+    if (protocol_end == null) {
+        const colon_pos = std.mem.indexOfScalar(u8, raw, ':') orelse return "";
+        const path = raw[colon_pos + 1 ..];
+        const query_or_hash = std.mem.indexOfAny(u8, path, "?#") orelse path.len;
+        return path[0..query_or_hash];
+    }
+
+    const path_start = std.mem.indexOfScalarPos(u8, raw, protocol_end.? + 3, '/') orelse raw.len;
 
     const query_or_hash_start = std.mem.indexOfAnyPos(u8, raw, path_start, "?#") orelse raw.len;
 
     if (path_start >= query_or_hash_start) {
-        if (std.mem.indexOf(u8, raw, "://") != null) return "/";
-        return "";
+        return "/";
     }
 
     return raw[path_start..query_or_hash_start];
diff --git a/src/browser/tests/url.html b/src/browser/tests/url.html
index f8074422..c1bfa09b 100644
--- a/src/browser/tests/url.html
+++ b/src/browser/tests/url.html
@@ -798,3 +798,19 @@
   testing.expectEqual(true, url2.startsWith('blob:'));
 }
 </script>
+
+<script id="about:blank">
+  {
+    const url = new URL('about:blank');
+    testing.expectEqual('about:blank', url.href);
+    testing.expectEqual('null', url.origin);
+    testing.expectEqual('about:', url.protocol);
+    testing.expectEqual('blank', url.pathname);
+    testing.expectEqual('', url.username);
+    testing.expectEqual('', url.password);
+    testing.expectEqual('', url.host);
+    testing.expectEqual('', url.hostname);
+    testing.expectEqual('', url.port);
+    testing.expectEqual('', url.search);
+  }
+</script>
diff --git a/src/browser/webapi/URL.zig b/src/browser/webapi/URL.zig
index e9263319..cb8e5d11 100644
--- a/src/browser/webapi/URL.zig
+++ b/src/browser/webapi/URL.zig
@@ -37,6 +37,14 @@ pub const resolve = @import("../URL.zig").resolve;
 pub const eqlDocument = @import("../URL.zig").eqlDocument;
 
 pub fn init(url: [:0]const u8, base_: ?[:0]const u8, page: *Page) !*URL {
+    const arena = page.arena;
+
+    if (std.mem.eql(u8, url, "about:blank")) {
+        return page._factory.create(URL{
+            ._raw = "about:blank",
+            ._arena = arena,
+        });
+    }
     const url_is_absolute = @import("../URL.zig").isCompleteHTTPUrl(url);
 
     const base = if (base_) |b| blk: {
@@ -53,7 +61,6 @@ pub fn init(url: [:0]const u8, base_: ?[:0]const u8, page: *Page) !*URL {
         return error.TypeError;
     } else page.url;
 
-    const arena = page.arena;
     const raw = try resolve(arena, base, url, .{ .always_dupe = true });
 
     return page._factory.create(URL{