From 97de53ee8cce3dc6347b08668f0de45e1000f01c Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Wed, 16 Sep 2020 20:48:38 -0700
Subject: [PATCH] QUrl::fromLocalFile: accept invalid hostnames

QUrl hostnames must be compliant with STD3, but we must somehow accept
file paths that begin with double slash but aren't valid hostnames.
Because the file URI spec requires us to start with "file://" anyway, we
can represent those with four slashes. Note that on Unix "//X/y" is a
valid but local file path. If given to QUrl::fromLocalFile(), if the
path at the root does parse as a hostname, we will still try to
normalize (the above becomes "file://x/y").

[ChangeLog][QtCore][QUrl] Changed QUrl::fromLocalFile() to accept
Windows UNC paths whose hostname component is not a valid Internet
hostname. This makes QUrl able to accept extended-length paths (\\?\),
device namespace (\\.\),  WSL (\\wsl$), etc.

Pick-to: 5.15
Fixes: QTBUG-86277
Change-Id: I3eb349b832c14610895efffd1635759348214a3b
Reviewed-by: David Faure <david.faure@kdab.com>
---
 src/corelib/io/qurl.cpp                 | 14 +++++++++++---
 tests/auto/corelib/io/qurl/tst_qurl.cpp | 15 +++++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/src/corelib/io/qurl.cpp b/src/corelib/io/qurl.cpp
index f0a853c965e..2b5839923a4 100644
--- a/src/corelib/io/qurl.cpp
+++ b/src/corelib/io/qurl.cpp
@@ -3342,12 +3342,20 @@ QUrl QUrl::fromLocalFile(const QString &localFile)
             hostSpec.truncate(hostSpec.size() - 4);
             scheme = webDavScheme();
         }
-        url.setHost(hostSpec.toString());
 
-        if (indexOfPath > 2)
+        // hosts can't be IPv6 addresses without [], so we can use QUrlPrivate::setHost
+        url.detach();
+        if (!url.d->setHost(hostSpec.toString(), 0, hostSpec.size(), StrictMode)) {
+            if (url.d->error->code != QUrlPrivate::InvalidRegNameError)
+                return url;
+
+            // Path hostname is not a valid URL host, so set it entirely in the path
+            // (by leaving deslashified unchanged)
+        } else if (indexOfPath > 2) {
             deslashified = deslashified.right(deslashified.length() - indexOfPath);
-        else
+        } else {
             deslashified.clear();
+        }
     }
 
     url.setScheme(scheme);
diff --git a/tests/auto/corelib/io/qurl/tst_qurl.cpp b/tests/auto/corelib/io/qurl/tst_qurl.cpp
index 896674e67c9..45a311230f5 100644
--- a/tests/auto/corelib/io/qurl/tst_qurl.cpp
+++ b/tests/auto/corelib/io/qurl/tst_qurl.cpp
@@ -1275,6 +1275,9 @@ void tst_QUrl::toLocalFile_data()
     QTest::newRow("windows-unc-path") << QString::fromLatin1("file://somehost/somedir/somefile") << QString::fromLatin1("//somehost/somedir/somefile");
     QTest::newRow("windows-unc-root") << QString::fromLatin1("file://somehost/") << QString::fromLatin1("//somehost/");
     QTest::newRow("windows-unc-nopath") << QString::fromLatin1("file://somehost") << QString::fromLatin1("//somehost");
+    QTest::newRow("windows-extlen-path") << QString::fromLatin1("file:////%3F/somedir/somefile") << QString::fromLatin1("//?/somedir/somefile");
+    QTest::newRow("windows-wsl-path") << QString::fromLatin1("file:////wsl$/somedir/somefile") << QString::fromLatin1("//wsl$/somedir/somefile");
+    QTest::newRow("windows-device-path") << QString::fromLatin1("file:////./somedir/somefile") << QString::fromLatin1("//./somedir/somefile");
 
     // and some that result in empty (i.e., not local)
     QTest::newRow("noscheme-absolute") << QString::fromLatin1("/a.txt") << QString();
@@ -1327,6 +1330,18 @@ void tst_QUrl::fromLocalFile_data()
                 << QString("file://somehost") + suffix
                 << QString(suffix);
 #endif
+        QTest::addRow("windows-extlen-%s", pathDescription)
+                << QString("//?") + suffix
+                << QString("file:////%3F") + suffix
+                << QString("//?") + suffix;
+        QTest::addRow("windows-wsl-%s", pathDescription)
+                << QString("//wsl$") + suffix
+                << QString("file:////wsl$") + suffix
+                << QString("//wsl$") + suffix;
+        QTest::addRow("windows-device--%s", pathDescription)
+                << QString("//.") + suffix
+                << QString("file:////.") + suffix
+                << QString("//.") + suffix;
     }
 
     QTest::newRow("windows-webdav")