From 8594f3cd5ad34838b2b7997af4909160e5887d73 Mon Sep 17 00:00:00 2001
From: Bryan Lai <bryanlais@gmail.com>
Date: Wed, 31 Jan 2024 19:41:17 +0800
Subject: [PATCH] libutil/url: fix git+file:./ parse error

Previously, the "file:./" prefix was not correctly recognized in
fixGitURL; instead, it was mistaken as a file path, which resulted in a
parsed url of the form "file://file:./".

This commit fixes the issue by properly detecting the "file:" prefix.
Note, however, that unlike "file://", the "file:./" URI is _not_
standardized, but has been widely used to referred to relative file
paths. In particular, the "git+file:./" did work for nix<=2.18, and was
broken since nix 2.19.0.

Finally, this commit fixes the issue completely for the 2.19 series, but
is still inadequate for the 2.20 series due to new behaviors from the
switch to libgit2. However, it does improve the correctness of parsing
even though it is not yet a complete solution.
---
 src/libutil/url.cc | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/libutil/url.cc b/src/libutil/url.cc
index c6561441d..f4178f87f 100644
--- a/src/libutil/url.cc
+++ b/src/libutil/url.cc
@@ -171,16 +171,16 @@ std::string fixGitURL(const std::string & url)
     std::regex scpRegex("([^/]*)@(.*):(.*)");
     if (!hasPrefix(url, "/") && std::regex_match(url, scpRegex))
         return std::regex_replace(url, scpRegex, "ssh://$1@$2/$3");
-    else {
-        if (url.find("://") == std::string::npos) {
-            return (ParsedURL {
-                .scheme = "file",
-                .authority = "",
-                .path = url
-            }).to_string();
-        } else
-            return url;
+    if (hasPrefix(url, "file:"))
+        return url;
+    if (url.find("://") == std::string::npos) {
+        return (ParsedURL {
+            .scheme = "file",
+            .authority = "",
+            .path = url
+        }).to_string();
     }
+    return url;
 }
 
 // https://www.rfc-editor.org/rfc/rfc3986#section-3.1