fix: Improve URL compatibility (#6807)

- Fix protocol regex.
- Truncate repeated leading slashes in file paths.
- Make drive letter support platform-independent.
- Drop the hostname if a drive letter is parsed.
- Fix drive letter normalization and basing.
- Allow basing over the host.
- Fix same-protocol basing.
- Remove Windows UNC path support.
- Reverts #6418. This is non-standard. Wouldn't be too much of a problem but it 
   makes other parts of the spec hard to realize.

3 files changed, 11 insertions, 20 deletions

diff --git a/std/path/from_file_url_test.ts b/std/path/from_file_url_test.ts
index 8bbc4e986..7a0432f68 100644
--- a/std/path/from_file_url_test.ts
+++ b/std/path/from_file_url_test.ts
@@ -7,14 +7,13 @@ Deno.test("[path] fromFileUrl", function () {
   assertEquals(posix.fromFileUrl("file:///home/foo"), "/home/foo");
   assertEquals(posix.fromFileUrl("https://example.com/foo"), "/foo");
   assertEquals(posix.fromFileUrl("file:///"), "/");
-  // FIXME(nayeemrmn): Remove the condition. UNC paths are supported here when
-  // run on Windows (matching the underlying URL class), but
-  // `posix.fromFileUrl()` should not support them under any circumstance.
-  if (Deno.build.os != "windows") {
-    assertEquals(posix.fromFileUrl("file:////"), "//");
-    assertEquals(posix.fromFileUrl("file:////server"), "//server");
-    assertEquals(posix.fromFileUrl("file:////server/file"), "//server/file");
-  }
+  // Drive letters are supported platform-independently to align with the WHATWG
+  // URL specification.
+  assertEquals(posix.fromFileUrl("file:///c:"), "c:/");
+  assertEquals(posix.fromFileUrl("file:///c:/"), "c:/");
+  assertEquals(posix.fromFileUrl("file:///C:/"), "C:/");
+  assertEquals(posix.fromFileUrl("file:///C:/Users/"), "C:/Users/");
+  assertEquals(posix.fromFileUrl("file:///C:foo/bar"), "/C:foo/bar");
 });
 
 Deno.test("[path] fromFileUrl (win32)", function () {
@@ -22,18 +21,9 @@ Deno.test("[path] fromFileUrl (win32)", function () {
   assertEquals(win32.fromFileUrl("file:///home/foo"), "\\home\\foo");
   assertEquals(win32.fromFileUrl("https://example.com/foo"), "\\foo");
   assertEquals(win32.fromFileUrl("file:///"), "\\");
-  // FIXME(nayeemrmn): Remove the condition. UNC paths are only supported here
-  // when run on Windows (matching the underlying URL class), but
-  // `win32.fromFileUrl()` should support them under every circumstance.
-  if (Deno.build.os == "windows") {
-    assertEquals(win32.fromFileUrl("file:////"), "\\");
-    assertEquals(win32.fromFileUrl("file:////server"), "\\");
-    assertEquals(win32.fromFileUrl("file:////server/file"), "\\file");
-  }
-  assertEquals(win32.fromFileUrl("file:///c"), "\\c");
   assertEquals(win32.fromFileUrl("file:///c:"), "c:\\");
   assertEquals(win32.fromFileUrl("file:///c:/"), "c:\\");
   assertEquals(win32.fromFileUrl("file:///C:/"), "C:\\");
   assertEquals(win32.fromFileUrl("file:///C:/Users/"), "C:\\Users\\");
-  assertEquals(win32.fromFileUrl("file:///C:cwd/another"), "\\C:cwd\\another");
+  assertEquals(win32.fromFileUrl("file:///C:foo/bar"), "\\C:foo\\bar");
 });
diff --git a/std/path/posix.ts b/std/path/posix.ts
index 03d07a84a..3c4262203 100644
--- a/std/path/posix.ts
+++ b/std/path/posix.ts
@@ -435,5 +435,6 @@ export function parse(path: string): ParsedPath {
  * are ignored.
  */
 export function fromFileUrl(url: string | URL): string {
-  return new URL(String(url)).pathname;
+  return (url instanceof URL ? url : new URL(url)).pathname
+    .replace(/^\/*([A-Za-z]:)(\/|$)/, "$1/");
 }
diff --git a/std/path/win32.ts b/std/path/win32.ts
index 66ed1ff14..cf0e69537 100644
--- a/std/path/win32.ts
+++ b/std/path/win32.ts
@@ -914,7 +914,7 @@ export function parse(path: string): ParsedPath {
  * are ignored.
  */
 export function fromFileUrl(url: string | URL): string {
-  return new URL(String(url)).pathname
+  return (url instanceof URL ? url : new URL(url)).pathname
     .replace(/^\/*([A-Za-z]:)(\/|$)/, "$1/")
     .replace(/\//g, "\\");
 }