QMimeType::suffixForFileName shouldn't lowercase the file suffix

It was returning a lowercased suffix because it was extracting it from
the pattern (*.txt) rather than from the filename ("README.TXT").

This broke expectations on the application side, since this method is
documented to return a suffix from the given filename.

Ref: https://bugs.kde.org/show_bug.cgi?id=402388

Change-Id: I7dae13db31280249d3f592fa9592c4067804e22d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

5 files changed, 33 insertions, 16 deletions

diff --git a/src/corelib/mimetypes/qmimedatabase.cpp b/src/corelib/mimetypes/qmimedatabase.cpp
index d65f1bdebd..974ca36a40 100644
--- a/src/corelib/mimetypes/qmimedatabase.cpp
+++ b/src/corelib/mimetypes/qmimedatabase.cpp
@@ -638,7 +638,8 @@ QList<QMimeType> QMimeDatabase::mimeTypesForFileName(const QString &fileName) co
 QString QMimeDatabase::suffixForFileName(const QString &fileName) const
 {
     QMutexLocker locker(&d->mutex);
-    return d->findByFileName(QFileInfo(fileName).fileName()).m_foundSuffix;
+    const int suffixLength = d->findByFileName(QFileInfo(fileName).fileName()).m_knownSuffixLength;
+    return fileName.right(suffixLength);
 }
 
 /*!
diff --git a/src/corelib/mimetypes/qmimeglobpattern.cpp b/src/corelib/mimetypes/qmimeglobpattern.cpp
index 6d2a1f5425..9971913f9d 100644
--- a/src/corelib/mimetypes/qmimeglobpattern.cpp
+++ b/src/corelib/mimetypes/qmimeglobpattern.cpp
@@ -56,7 +56,7 @@ QT_BEGIN_NAMESPACE
     Handles glob weights, and preferring longer matches over shorter matches.
 */
 
-void QMimeGlobMatchResult::addMatch(const QString &mimeType, int weight, const QString &pattern)
+void QMimeGlobMatchResult::addMatch(const QString &mimeType, int weight, const QString &pattern, int knownSuffixLength)
 {
     if (m_allMatchingMimeTypes.contains(mimeType))
         return;
@@ -84,8 +84,7 @@ void QMimeGlobMatchResult::addMatch(const QString &mimeType, int weight, const Q
     if (!m_matchingMimeTypes.contains(mimeType)) {
         m_matchingMimeTypes.append(mimeType);
         m_allMatchingMimeTypes.append(mimeType);
-        if (pattern.startsWith(QLatin1String("*.")))
-            m_foundSuffix = pattern.mid(2);
+        m_knownSuffixLength = knownSuffixLength;
     }
 }
 
@@ -152,6 +151,18 @@ bool QMimeGlobPattern::matchFileName(const QString &inputFilename) const
 #endif
 }
 
+static bool isSimplePattern(const QString &pattern)
+{
+   // starts with "*.", has no other '*'
+   return pattern.lastIndexOf(QLatin1Char('*')) == 0
+      && pattern.length() > 1
+      && pattern.at(1) == QLatin1Char('.') // (other dots are OK, like *.tar.bz2)
+      // and contains no other special character
+      && !pattern.contains(QLatin1Char('?'))
+      && !pattern.contains(QLatin1Char('['))
+      ;
+}
+
 static bool isFastPattern(const QString &pattern)
 {
    // starts with "*.", has no other '*' and no other '.'
@@ -205,8 +216,11 @@ void QMimeGlobPatternList::match(QMimeGlobMatchResult &result,
     const QMimeGlobPatternList::const_iterator endIt = this->constEnd();
     for (; it != endIt; ++it) {
         const QMimeGlobPattern &glob = *it;
-        if (glob.matchFileName(fileName))
-            result.addMatch(glob.mimeType(), glob.weight(), glob.pattern());
+        if (glob.matchFileName(fileName)) {
+            const QString pattern = glob.pattern();
+            const int suffixLen = isSimplePattern(pattern) ? pattern.length() - 2 : 0;
+            result.addMatch(glob.mimeType(), glob.weight(), pattern, suffixLen);
+        }
     }
 }
 
@@ -226,7 +240,7 @@ void QMimeAllGlobPatterns::matchingGlobs(const QString &fileName, QMimeGlobMatch
         const QStringList matchingMimeTypes = m_fastPatterns.value(simpleExtension);
         const QString simplePattern = QLatin1String("*.") + simpleExtension;
         for (const QString &mime : matchingMimeTypes)
-            result.addMatch(mime, 50, simplePattern);
+            result.addMatch(mime, 50, simplePattern, simpleExtension.size());
         // Can't return yet; *.tar.bz2 has to win over *.bz2, so we need the low-weight mimetypes anyway,
         // at least those with weight 50.
     }
diff --git a/src/corelib/mimetypes/qmimeglobpattern_p.h b/src/corelib/mimetypes/qmimeglobpattern_p.h
index cf27d6ab30..49f145e8db 100644
--- a/src/corelib/mimetypes/qmimeglobpattern_p.h
+++ b/src/corelib/mimetypes/qmimeglobpattern_p.h
@@ -62,17 +62,13 @@ QT_BEGIN_NAMESPACE
 
 struct QMimeGlobMatchResult
 {
-    QMimeGlobMatchResult()
-    : m_weight(0), m_matchingPatternLength(0)
-    {}
-
-    void addMatch(const QString &mimeType, int weight, const QString &pattern);
+    void addMatch(const QString &mimeType, int weight, const QString &pattern, int knownSuffixLength = 0);
 
     QStringList m_matchingMimeTypes; // only those with highest weight
     QStringList m_allMatchingMimeTypes;
-    int m_weight;
-    int m_matchingPatternLength;
-    QString m_foundSuffix;
+    int m_weight = 0;
+    int m_matchingPatternLength = 0;
+    int m_knownSuffixLength = 0;
 };
 
 class QMimeGlobPattern
diff --git a/src/corelib/mimetypes/qmimeprovider.cpp b/src/corelib/mimetypes/qmimeprovider.cpp
index 83574a40f0..e8e81e65ab 100644
--- a/src/corelib/mimetypes/qmimeprovider.cpp
+++ b/src/corelib/mimetypes/qmimeprovider.cpp
@@ -306,7 +306,7 @@ bool QMimeBinaryProvider::matchSuffixTree(QMimeGlobMatchResult &result, QMimeBin
                     const bool caseSensitive = flagsAndWeight & 0x100;
                     if (caseSensitiveCheck || !caseSensitive) {
                         result.addMatch(QLatin1String(mimeType), weight,
-                                        QLatin1Char('*') + fileName.midRef(charPos + 1));
+                                        QLatin1Char('*') + fileName.midRef(charPos + 1), fileName.size() - charPos - 2);
                         success = true;
                     }
                 }
diff --git a/tests/auto/corelib/mimetypes/qmimedatabase/tst_qmimedatabase.cpp b/tests/auto/corelib/mimetypes/qmimedatabase/tst_qmimedatabase.cpp
index 3c6da506e2..c214c75d52 100644
--- a/tests/auto/corelib/mimetypes/qmimedatabase/tst_qmimedatabase.cpp
+++ b/tests/auto/corelib/mimetypes/qmimedatabase/tst_qmimedatabase.cpp
@@ -667,6 +667,9 @@ void tst_QMimeDatabase::knownSuffix()
     QCOMPARE(db.suffixForFileName(QString::fromLatin1("foo.bz2")), QString::fromLatin1("bz2"));
     QCOMPARE(db.suffixForFileName(QString::fromLatin1("foo.bar.bz2")), QString::fromLatin1("bz2"));
     QCOMPARE(db.suffixForFileName(QString::fromLatin1("foo.tar.bz2")), QString::fromLatin1("tar.bz2"));
+    QCOMPARE(db.suffixForFileName(QString::fromLatin1("foo.TAR")), QString::fromLatin1("TAR")); // preserve case
+    QCOMPARE(db.suffixForFileName(QString::fromLatin1("foo.flatpakrepo")), QString::fromLatin1("flatpakrepo"));
+    QCOMPARE(db.suffixForFileName(QString::fromLatin1("foo.anim2")), QString()); // the glob is anim[0-9], no way to extract the extension without expensive regexp capturing
 }
 
 void tst_QMimeDatabase::symlinkToFifo() // QTBUG-48529
@@ -784,6 +787,9 @@ void tst_QMimeDatabase::findByFileName()
     // Test QFileInfo overload
     const QMimeType mimeForFileInfo = database.mimeTypeForFile(QFileInfo(filePath), QMimeDatabase::MatchExtension);
     QCOMPARE(mimeForFileInfo.name(), resultMimeTypeName);
+
+    const QString suffix = database.suffixForFileName(filePath);
+    QVERIFY2(filePath.endsWith(suffix), qPrintable(filePath + " does not end with " + suffix));
 }
 
 void tst_QMimeDatabase::findByData_data()