Limit to lenient parsing of non-standard URLs only where needed

This allows us to put `parseURL` in more spots without furthering
technical debt.

src/libexpr/primops/fetchClosure.cc

@@ -185,7 +185,7 @@ static void prim_fetchClosure(EvalState & state, const PosIdx pos, Value ** args
             {.msg = HintFmt("attribute '%s' is missing in call to 'fetchClosure'", "fromStore"),
              .pos = state.positions[pos]});
 
-    auto parsedURL = parseURL(*fromStoreUrl);
+    auto parsedURL = parseURL(*fromStoreUrl, /*lenient=*/true);
 
     if (parsedURL.scheme != "http" && parsedURL.scheme != "https"
         && !(getEnv("_NIX_IN_TEST").has_value() && parsedURL.scheme == "file"))

src/libflake-tests/url-name.cc

@@ -13,8 +13,9 @@ TEST(getNameFromURL, getNameFromURL)
     ASSERT_EQ(getNameFromURL(parseURL("path:~/repos/nixpkgs#packages.x86_64-linux.Hello")), "Hello");
     ASSERT_EQ(getNameFromURL(parseURL("path:.#nonStandardAttr.mylaptop")), "mylaptop");
     ASSERT_EQ(getNameFromURL(parseURL("path:./repos/myflake#nonStandardAttr.mylaptop")), "mylaptop");
-    ASSERT_EQ(getNameFromURL(parseURL("path:./nixpkgs#packages.x86_64-linux.complex^bin,man")), "complex");
+    ASSERT_EQ(
-    ASSERT_EQ(getNameFromURL(parseURL("path:./myproj#packages.x86_64-linux.default^*")), "myproj");
+        getNameFromURL(parseURL("path:./nixpkgs#packages.x86_64-linux.complex^bin,man", /*lenient=*/true)), "complex");
+    ASSERT_EQ(getNameFromURL(parseURL("path:./myproj#packages.x86_64-linux.default^*", /*lenient=*/true)), "myproj");
     ASSERT_EQ(getNameFromURL(parseURL("path:./myproj#defaultPackage.x86_64-linux")), "myproj");
 
     ASSERT_EQ(getNameFromURL(parseURL("github:NixOS/nixpkgs#packages.x86_64-linux.hello")), "hello");
@@ -80,6 +81,6 @@ TEST(getNameFromURL, getNameFromURL)
     ASSERT_EQ(getNameFromURL(parseURL("path:.")), std::nullopt);
     ASSERT_EQ(getNameFromURL(parseURL("file:.#")), std::nullopt);
     ASSERT_EQ(getNameFromURL(parseURL("path:.#packages.x86_64-linux.default")), std::nullopt);
-    ASSERT_EQ(getNameFromURL(parseURL("path:.#packages.x86_64-linux.default^*")), std::nullopt);
+    ASSERT_EQ(getNameFromURL(parseURL("path:.#packages.x86_64-linux.default^*", /*lenient=*/true)), std::nullopt);
 }
 } // namespace nix

src/libflake/flakeref.cc

@@ -82,7 +82,7 @@ std::pair<FlakeRef, std::string> parsePathFlakeRefWithFragment(
     auto succeeds = std::regex_match(url, match, pathFlakeRegex);
     assert(succeeds);
     auto path = match[1].str();
-    auto query = decodeQuery(match[3].str());
+    auto query = decodeQuery(match[3].str(), /*lenient=*/true);
     auto fragment = percentDecode(match[5].str());
 
     if (baseDir) {
@@ -210,7 +210,7 @@ std::optional<std::pair<FlakeRef, std::string>> parseURLFlakeRef(
     bool isFlake)
 {
     try {
-        auto parsed = parseURL(url);
+        auto parsed = parseURL(url, /*lenient=*/true);
         if (baseDir && (parsed.scheme == "path" || parsed.scheme == "git+file") && !isAbsolute(parsed.path))
             parsed.path = absPath(parsed.path, *baseDir);
         return fromParsedURL(fetchSettings, std::move(parsed), isFlake);
@@ -289,7 +289,7 @@ FlakeRef FlakeRef::canonicalize() const
        filtering the `dir` query parameter from the URL. */
     if (auto url = fetchers::maybeGetStrAttr(flakeRef.input.attrs, "url")) {
         try {
-            auto parsed = parseURL(*url);
+            auto parsed = parseURL(*url, /*lenient=*/true);
             if (auto dir2 = get(parsed.query, "dir")) {
                 if (flakeRef.subdir != "" && flakeRef.subdir == *dir2)
                     parsed.query.erase("dir");

src/libstore/store-reference.cc

@@ -45,7 +45,7 @@ StoreReference StoreReference::parse(const std::string & uri, const StoreReferen
 {
     auto params = extraParams;
     try {
-        auto parsedUri = parseURL(uri);
+        auto parsedUri = parseURL(uri, /*lenient=*/true);
         params.insert(parsedUri.query.begin(), parsedUri.query.end());
 
         auto baseURI = parsedUri.authority.value_or(ParsedURL::Authority{}).to_string() + parsedUri.path;
@@ -107,7 +107,7 @@ std::pair<std::string, StoreReference::Params> splitUriAndParams(const std::stri
     StoreReference::Params params;
     auto q = uri.find('?');
     if (q != std::string::npos) {
-        params = decodeQuery(uri.substr(q + 1));
+        params = decodeQuery(uri.substr(q + 1), /*lenient=*/true);
         uri = uri_.substr(0, q);
     }
     return {uri, params};

src/libutil-tests/url.cc

@@ -221,15 +221,20 @@ TEST(parseURL, parsedUrlsWithUnescapedChars)
      * 2. Unescaped spaces and quotes in query.
      */
     auto s = "http://www.example.org/file.tar.gz?query \"= 123\"#shevron^quote\"space ";
-    auto url = parseURL(s);
 
-    ASSERT_EQ(url.fragment, "shevron^quote\"space ");
+    /* Without leniency for back compat, this should throw. */
+    EXPECT_THROW(parseURL(s), Error);
+
+    /* With leniency for back compat, this should parse. */
+    auto url = parseURL(s, /*lenient=*/true);
+
+    EXPECT_EQ(url.fragment, "shevron^quote\"space ");
 
     auto query = StringMap{
         {"query \"", " 123\""},
     };
 
-    ASSERT_EQ(url.query, query);
+    EXPECT_EQ(url.query, query);
 }
 
 TEST(parseURL, parseFTPUrl)

src/libutil/include/nix/util/url.hh

@@ -96,14 +96,18 @@ MakeError(BadURL, Error);
 std::string percentDecode(std::string_view in);
 std::string percentEncode(std::string_view s, std::string_view keep = "");
 
-StringMap decodeQuery(const std::string & query);
+/**
+ * @param lenient @see parseURL
+ */
+StringMap decodeQuery(std::string_view query, bool lenient = false);
 
 std::string encodeQuery(const StringMap & query);
 
 /**
- * Parse a Nix URL into a ParsedURL.
+ * Parse a URL into a ParsedURL.
  *
- * Nix URI is mostly compliant with RFC3986, but with some deviations:
+ * @parm lenient Also allow some long-supported Nix URIs that are not quite compliant with RFC3986.
+ * Here are the deviations:
  * - Fragments can contain unescaped (not URL encoded) '^', '"' or space literals.
  * - Queries may contain unescaped '"' or spaces.
  *
@@ -111,7 +115,7 @@ std::string encodeQuery(const StringMap & query);
  *
  * @throws BadURL
  */
-ParsedURL parseURL(std::string_view url);
+ParsedURL parseURL(std::string_view url, bool lenient = false);
 
 /**
  * Although that’s not really standardized anywhere, an number of tools

src/libutil/url.cc

@@ -108,41 +108,48 @@ static std::string percentEncodeCharSet(std::string_view s, auto charSet)
     return res;
 }
 
-ParsedURL parseURL(std::string_view url)
+ParsedURL parseURL(std::string_view url, bool lenient)
 try {
     /* Account for several non-standard properties of nix urls (for back-compat):
      *  - Allow unescaped spaces ' ' and '"' characters in queries.
      *  - Allow '"', ' ' and '^' characters in the fragment component.
      * We could write our own grammar for this, but fixing it up here seems
      * more concise, since the deviation is rather minor.
+     *
+     * If `!lenient` don't bother initializing, because we can just
+     * parse `url` directly`.
      */
-    std::string fixedEncodedUrl = [&]() {
+    std::string fixedEncodedUrl;
-        std::string fixed;
-        std::string_view view = url;
 
-        if (auto beforeQuery = splitPrefixTo(view, '?')) {
+    if (lenient) {
-            fixed += *beforeQuery;
+        fixedEncodedUrl = [&] {
-            fixed += '?';
+            std::string fixed;
-            auto fragmentStart = view.find('#');
+            std::string_view view = url;
-            auto queryView = view.substr(0, fragmentStart);
-            auto fixedQuery = percentEncodeCharSet(queryView, extraAllowedCharsInQuery);
-            fixed += fixedQuery;
-            view.remove_prefix(std::min(fragmentStart, view.size()));
-        }
 
-        if (auto beforeFragment = splitPrefixTo(view, '#')) {
+            if (auto beforeQuery = splitPrefixTo(view, '?')) {
-            fixed += *beforeFragment;
+                fixed += *beforeQuery;
-            fixed += '#';
+                fixed += '?';
-            auto fixedFragment = percentEncodeCharSet(view, extraAllowedCharsInFragment);
+                auto fragmentStart = view.find('#');
-            fixed += fixedFragment;
+                auto queryView = view.substr(0, fragmentStart);
+                auto fixedQuery = percentEncodeCharSet(queryView, extraAllowedCharsInQuery);
+                fixed += fixedQuery;
+                view.remove_prefix(std::min(fragmentStart, view.size()));
+            }
+
+            if (auto beforeFragment = splitPrefixTo(view, '#')) {
+                fixed += *beforeFragment;
+                fixed += '#';
+                auto fixedFragment = percentEncodeCharSet(view, extraAllowedCharsInFragment);
+                fixed += fixedFragment;
+                return fixed;
+            }
+
+            fixed += view;
             return fixed;
-        }
+        }();
+    }
 
-        fixed += view;
+    auto urlView = boost::urls::url_view(lenient ? fixedEncodedUrl : url);
-        return fixed;
-    }();
-
-    auto urlView = boost::urls::url_view(fixedEncodedUrl);
 
     if (!urlView.has_scheme())
         throw BadURL("'%s' doesn't have a scheme", url);
@@ -179,7 +186,7 @@ try {
         .scheme = scheme,
         .authority = authority,
         .path = path,
-        .query = decodeQuery(query),
+        .query = decodeQuery(query, lenient),
         .fragment = fragment,
     };
 } catch (boost::system::system_error & e) {
@@ -201,14 +208,17 @@ std::string percentEncode(std::string_view s, std::string_view keep)
         s, [keep](char c) { return boost::urls::unreserved_chars(c) || keep.find(c) != keep.npos; });
 }
 
-StringMap decodeQuery(std::string_view query)
+StringMap decodeQuery(std::string_view query, bool lenient)
 try {
-    /* For back-compat unescaped characters are allowed. */
+    /* When `lenient = true`, for back-compat unescaped characters are allowed. */
-    auto fixedEncodedQuery = percentEncodeCharSet(query, extraAllowedCharsInQuery);
+    std::string fixedEncodedQuery;
+    if (lenient) {
+        fixedEncodedQuery = percentEncodeCharSet(query, extraAllowedCharsInQuery);
+    }
 
     StringMap result;
 
-    auto encodedQuery = boost::urls::params_encoded_view(fixedEncodedQuery);
+    auto encodedQuery = boost::urls::params_encoded_view(lenient ? fixedEncodedQuery : query);
     for (auto && [key, value, value_specified] : encodedQuery) {
         if (!value_specified) {
             warn("dubious URI query '%s' is missing equal sign '%s', ignoring", std::string_view(key), "=");

src/nix/profile.cc

@@ -105,7 +105,8 @@ std::string getNameFromElement(const ProfileElement & element)
 {
     std::optional<std::string> result = std::nullopt;
     if (element.source) {
-        result = getNameFromURL(parseURL(element.source->to_string()));
+        // Seems to be for Flake URLs
+        result = getNameFromURL(parseURL(element.source->to_string(), /*lenient=*/true));
     }
     return result.value_or(element.identifier());
 }
@@ -160,11 +161,15 @@ struct ProfileManifest
                         e["outputs"].get<ExtendedOutputsSpec>()};
                 }
 
-                std::string name =
+                std::string name = [&] {
-                    elems.is_object() ? elem.key()
+                    if (elems.is_object())
-                    : element.source
+                        return elem.key();
-                        ? getNameFromURL(parseURL(element.source->to_string())).value_or(element.identifier())
+                    if (element.source) {
-                        : element.identifier();
+                        if (auto optName = getNameFromURL(parseURL(element.source->to_string(), /*lenient=*/true)))
+                            return *optName;
+                    }
+                    return element.identifier();
+                }();
 
                 addElement(name, std::move(element));
             }