QMimeDatabase: don't stat() something that isn't a local file

We must check that the path is an actual file on the filesystem before
using native APIs. This regression was introduced by commit
047d8f36de45ebb318726167f941b0dbc64754ba.

[ChangeLog][QtCore][QMimeDatabase] Fixed a regression from 6.4.0 that
made certain QMimeDatabase functions that inspected file contents to fail
on Unix systems, if the file was not a native file (e.g., a Qt resource).

Fixes: QTBUG-110707
Change-Id: I570832c9ac8b4e03bde8fffd173f7b4c6b164192
Reviewed-by: Igor Kushnir <igorkuo@gmail.com>
Reviewed-by: David Faure <david.faure@kdab.com>
(cherry picked from commit 40dd38813cba4bc8425e846f220e358ffb0d19ac)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/mimetypes/qmimedatabase.cpp

@@ -444,31 +444,32 @@ QMimeType QMimeDatabasePrivate::mimeTypeForData(QIODevice *device)
 }
 
 QMimeType QMimeDatabasePrivate::mimeTypeForFile(const QString &fileName,
-                                                [[maybe_unused]] const QFileInfo *fileInfo,
+                                                const QFileInfo &fileInfo,
                                                 QMimeDatabase::MatchMode mode)
 {
+    if (false) {
 #ifdef Q_OS_UNIX
-    // Cannot access statBuf.st_mode from the filesystem engine, so we have to stat again.
+    } else if (fileInfo.isNativePath()) {
-    // In addition we want to follow symlinks.
+        // If this is a local file, we'll want to do a stat() ourselves so we can
-    const QByteArray nativeFilePath = QFile::encodeName(fileName);
+        // detect additional inode types. In addition we want to follow symlinks.
-    QT_STATBUF statBuffer;
+        const QByteArray nativeFilePath = QFile::encodeName(fileName);
-    if (QT_STAT(nativeFilePath.constData(), &statBuffer) == 0) {
+        QT_STATBUF statBuffer;
-        if (S_ISDIR(statBuffer.st_mode))
+        if (QT_STAT(nativeFilePath.constData(), &statBuffer) == 0) {
-            return mimeTypeForName(directoryMimeType());
+            if (S_ISDIR(statBuffer.st_mode))
-        if (S_ISCHR(statBuffer.st_mode))
+                return mimeTypeForName(directoryMimeType());
-            return mimeTypeForName(QStringLiteral("inode/chardevice"));
+            if (S_ISCHR(statBuffer.st_mode))
-        if (S_ISBLK(statBuffer.st_mode))
+                return mimeTypeForName(QStringLiteral("inode/chardevice"));
-            return mimeTypeForName(QStringLiteral("inode/blockdevice"));
+            if (S_ISBLK(statBuffer.st_mode))
-        if (S_ISFIFO(statBuffer.st_mode))
+                return mimeTypeForName(QStringLiteral("inode/blockdevice"));
-            return mimeTypeForName(QStringLiteral("inode/fifo"));
+            if (S_ISFIFO(statBuffer.st_mode))
-        if (S_ISSOCK(statBuffer.st_mode))
+                return mimeTypeForName(QStringLiteral("inode/fifo"));
-            return mimeTypeForName(QStringLiteral("inode/socket"));
+            if (S_ISSOCK(statBuffer.st_mode))
-    }
+                return mimeTypeForName(QStringLiteral("inode/socket"));
-#else
+        }
-    const bool isDirectory = fileInfo ? fileInfo->isDir() : QFileInfo(fileName).isDir();
-    if (isDirectory)
-        return mimeTypeForName(directoryMimeType());
 #endif
+    } else if (fileInfo.isDir()) {
+        return mimeTypeForName(directoryMimeType());
+    }
 
     switch (mode) {
     case QMimeDatabase::MatchDefault:
@@ -615,7 +616,7 @@ QMimeType QMimeDatabase::mimeTypeForFile(const QFileInfo &fileInfo, MatchMode mo
 {
     QMutexLocker locker(&d->mutex);
 
-    return d->mimeTypeForFile(fileInfo.filePath(), &fileInfo, mode);
+    return d->mimeTypeForFile(fileInfo.filePath(), fileInfo, mode);
 }
 
 /*!
@@ -630,7 +631,8 @@ QMimeType QMimeDatabase::mimeTypeForFile(const QString &fileName, MatchMode mode
     if (mode == MatchExtension) {
         return d->mimeTypeForFileExtension(fileName);
     } else {
-        return d->mimeTypeForFile(fileName, nullptr, mode);
+        QFileInfo fileInfo(fileName);
+        return d->mimeTypeForFile(fileName, fileInfo, mode);
     }
 }
 

src/corelib/mimetypes/qmimedatabase_p.h

@@ -60,7 +60,7 @@ public:
     QMimeType mimeTypeForFileNameAndData(const QString &fileName, QIODevice *device);
     QMimeType mimeTypeForFileExtension(const QString &fileName);
     QMimeType mimeTypeForData(QIODevice *device);
-    QMimeType mimeTypeForFile(const QString &fileName, const QFileInfo *fileInfo, QMimeDatabase::MatchMode mode);
+    QMimeType mimeTypeForFile(const QString &fileName, const QFileInfo &fileInfo, QMimeDatabase::MatchMode mode);
     QMimeType findByData(const QByteArray &data, int *priorityPtr);
     QStringList mimeTypeForFileName(const QString &fileName);
     QMimeGlobMatchResult findByFileName(const QString &fileName);

tests/auto/corelib/mimetypes/qmimedatabase/qmimedatabase-cache/CMakeLists.txt

@@ -45,6 +45,14 @@ qt_internal_add_resource(tst_qmimedatabase-cache "testdata"
         ${testdata_resource_files}
 )
 
+qt_internal_add_resource(tst_qmimedatabase-cache "testfiles"
+    PREFIX
+        "/files"
+    FILES
+        "../test.txt"
+        "../test.qml"
+)
+
 # special case begin
 set(corelib_source_dir ../../../../../../src/corelib)
 include(${corelib_source_dir}/mimetypes/mimetypes_resources.cmake)

tests/auto/corelib/mimetypes/qmimedatabase/qmimedatabase-xml/CMakeLists.txt

@@ -45,6 +45,14 @@ qt_internal_add_resource(tst_qmimedatabase-xml "testdata"
         ${testdata_resource_files}
 )
 
+qt_internal_add_resource(tst_qmimedatabase-xml "testfiles"
+    PREFIX
+        "/files"
+    FILES
+        "../test.txt"
+        "../test.qml"
+)
+
 # special case begin
 set(corelib_source_dir ../../../../../../src/corelib)
 include(${corelib_source_dir}/mimetypes/mimetypes_resources.cmake)

tests/auto/corelib/mimetypes/qmimedatabase/test.txt

@@ -0,0 +1,6 @@
+// Copyright (C) 2012 David Faure <faure@kde.org>
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+import QtQuick 1.1
+Item {
+}

tests/auto/corelib/mimetypes/qmimedatabase/tst_qmimedatabase.cpp

@@ -25,6 +25,8 @@
 #include <QProcess>
 #endif
 
+using namespace Qt::StringLiterals;
+
 static const char *const additionalMimeFiles[] = {
     "yast2-metapackage-handler-mimetypes.xml",
     "qml-again.xml",
@@ -245,6 +247,7 @@ void tst_QMimeDatabase::mimeTypeForFileName_data()
     // fdo bug 15436, needs shared-mime-info >= 0.40 (and this tests the globs2-parsing code).
     QTest::newRow("glob that ends with *, also matches *.pdf. *.pdf has higher weight") << "README.pdf" << "application/pdf";
     QTest::newRow("directory") << "/" << "inode/directory";
+    QTest::newRow("resource-directory") << ":/files/" << "inode/directory";
     QTest::newRow("doesn't exist, no extension") << "IDontExist" << "application/octet-stream";
     QTest::newRow("doesn't exist but has known extension") << "IDontExist.txt" << "text/plain";
     QTest::newRow("empty") << "" << "application/octet-stream";
@@ -497,6 +500,42 @@ void tst_QMimeDatabase::mimeTypeForFileWithContent()
         QCOMPARE(mime.name(), QString::fromLatin1("application/smil+xml"));
     }
 
+    // Test what happens with Qt resources (file engines in general)
+    {
+        QFile rccFile(":/files/test.txt");
+
+        mime = db.mimeTypeForFile(rccFile.fileName());
+        QCOMPARE(mime.name(), "text/plain"_L1);
+
+        QVERIFY(rccFile.open(QIODevice::ReadOnly));
+        mime = db.mimeTypeForData(&rccFile);
+        QCOMPARE(mime.name(), "text/x-qml"_L1);
+        QVERIFY(rccFile.isOpen());
+
+        mime = db.mimeTypeForFile(rccFile.fileName(), QMimeDatabase::MatchContent);
+        QCOMPARE(mime.name(), "text/x-qml"_L1);
+    }
+
+    // Directories
+    {
+        mime = db.mimeTypeForFile("/");
+        QCOMPARE(mime.name(), "inode/directory"_L1);
+
+        QString dirName = QDir::tempPath();
+        if (!dirName.endsWith(u'/'))
+            dirName += u'/';
+        mime = db.mimeTypeForFile(dirName);
+        QCOMPARE(mime.name(), "inode/directory"_L1);
+
+        while (dirName.endsWith(u'/'))
+            dirName.chop(1);
+        mime = db.mimeTypeForFile(dirName);
+        QCOMPARE(mime.name(), "inode/directory"_L1);
+
+        mime = db.mimeTypeForFile(":/files");
+        QCOMPARE(mime.name(), "inode/directory"_L1);
+    }
+
     // Test what happens with an incorrect path
     mime = db.mimeTypeForFile(QString::fromLatin1("file:///etc/passwd" /* incorrect code, use a path instead */));
     QVERIFY(mime.isDefault());