QResource: deprecate isCompressed()

Current codebases assume isCompressed() implies ZlibCompression, since
there was no compressionAlgorithm() getter. In order to force codebases
to change, deprecate isCompressed() and force handling of the algorithm.

The replacement API is being introduced in 5.14, which is why the
warning is being emitted in 5.15 only.

Change-Id: Ief874765cd7b43798de3fffd15a9f5d978951ea5
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

4 files changed, 41 insertions, 23 deletions

diff --git a/src/corelib/io/qresource.cpp b/src/corelib/io/qresource.cpp
index fcc5b69179..747f153f48 100644
--- a/src/corelib/io/qresource.cpp
+++ b/src/corelib/io/qresource.cpp
@@ -1,7 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2018 The Qt Company Ltd.
-** Copyright (C) 2018 Intel Corporation.
+** Copyright (C) 2019 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -279,14 +279,14 @@ static inline QStringList *resourceSearchPaths()
     This enum is used by compressionAlgorithm() to indicate which algorithm the
     RCC tool used to compress the payload.
 
-    \value NoCompression    Contents are not compressed (isCompressed() is false).
+    \value NoCompression    Contents are not compressed
     \value ZlibCompression  Contents are compressed using \l{zlib}{https://zlib.net} and can
                             be decompressed using the qUncompress() function.
     \value ZstdCompression  Contents are compressed using \l{zstd}{https://zstd.net}. To
                             decompress, use the \c{ZSTD_decompress} function from the zstd
                             library.
 
-    \sa compressionAlgorithm(), isCompressed()
+    \sa compressionAlgorithm()
 */
 
 class QResourcePrivate {
@@ -551,13 +551,20 @@ bool QResource::isValid() const
     \sa isDir()
 */
 
-
+#if QT_DEPRECATED_SINCE(5, 13)
 /*!
+    \obsolete
+
     Returns \c true if the resource represents a file and the data backing it
     is in a compressed format, false otherwise. If the data is compressed,
     check compressionAlgorithm() to verify what algorithm to use to decompress
     the data.
 
+    \note This function is deprecated and can be replaced with
+    \code
+      compressionAlgorithm() != NoCompression
+    \endcode
+
     \sa data(), compressionAlgorithm(), isFile()
 */
 
@@ -565,6 +572,7 @@ bool QResource::isCompressed() const
 {
     return compressionAlgorithm() != NoCompression;
 }
+#endif
 
 /*!
     \since 5.13
@@ -582,7 +590,7 @@ bool QResource::isCompressed() const
 
     See \l{http://facebook.github.io/zstd/zstd_manual.html}{Zstandard manual}.
 
-    \sa isCompressed(), data(), isFile()
+    \sa data(), isFile()
 */
 QResource::Compression QResource::compressionAlgorithm() const
 {
@@ -606,11 +614,11 @@ qint64 QResource::size() const
 
 /*!
     Returns direct access to a read only segment of data that this resource
-    represents. If the resource is compressed the data returns is
-    compressed and qUncompress() must be used to access the data. If the
-    resource is a directory \nullptr is returned.
+    represents. If the resource is compressed the data returned is compressed
+    and the appropriate library functions must be used to access the data. If
+    the resource is a directory \nullptr is returned.
 
-    \sa size(), isCompressed(), isFile()
+    \sa size(), compressionAlgorithm(), isFile()
 */
 
 const uchar *QResource::data() const
@@ -1366,9 +1374,15 @@ bool QResourceFileEngine::open(QIODevice::OpenMode flags)
         qWarning("QResourceFileEngine::open: Missing file name");
         return false;
     }
-    if(flags & QIODevice::WriteOnly)
+    if (flags & QIODevice::WriteOnly)
         return false;
-    d->uncompress();
+    if (d->resource.compressionAlgorithm() != QResource::NoCompression) {
+        d->uncompress();
+        if (d->uncompressed.isNull()) {
+            d->errorString = QSystemError::stdString(EIO);
+            return false;
+        }
+    }
     if (!d->resource.isValid()) {
         d->errorString = QSystemError::stdString(ENOENT);
         return false;
@@ -1395,7 +1409,7 @@ qint64 QResourceFileEngine::read(char *data, qint64 len)
         len = size()-d->offset;
     if(len <= 0)
         return 0;
-    if(d->resource.isCompressed())
+    if (!d->uncompressed.isNull())
         memcpy(data, d->uncompressed.constData()+d->offset, len);
     else
         memcpy(data, d->resource.data()+d->offset, len);
@@ -1431,9 +1445,9 @@ bool QResourceFileEngine::link(const QString &)
 qint64 QResourceFileEngine::size() const
 {
     Q_D(const QResourceFileEngine);
-    if(!d->resource.isValid())
+    if (!d->resource.isValid())
         return 0;
-    if (d->resource.isCompressed()) {
+    if (d->resource.compressionAlgorithm() != QResource::NoCompression) {
         d->uncompress();
         return d->uncompressed.size();
     }
@@ -1596,7 +1610,7 @@ uchar *QResourceFileEnginePrivate::map(qint64 offset, qint64 size, QFile::Memory
     Q_UNUSED(flags);
 
     qint64 max = resource.size();
-    if (resource.isCompressed()) {
+    if (resource.compressionAlgorithm() != QResource::NoCompression) {
         uncompress();
         max = uncompressed.size();
     }
@@ -1609,7 +1623,7 @@ uchar *QResourceFileEnginePrivate::map(qint64 offset, qint64 size, QFile::Memory
     }
 
     const uchar *address = resource.data();
-    if (resource.isCompressed())
+    if (resource.compressionAlgorithm() != QResource::NoCompression)
         address = reinterpret_cast<const uchar *>(uncompressed.constData());
 
     return const_cast<uchar *>(address) + offset;
diff --git a/src/corelib/io/qresource.h b/src/corelib/io/qresource.h
index 5e798de436..5ee8d5d266 100644
--- a/src/corelib/io/qresource.h
+++ b/src/corelib/io/qresource.h
@@ -72,7 +72,6 @@ public:
 
     bool isValid() const;
 
-    bool isCompressed() const;
     Compression compressionAlgorithm() const;
     qint64 size() const;
     const uchar *data() const;
@@ -84,6 +83,10 @@ public:
     QT_DEPRECATED_X("Use QDir::searchPaths() instead")
     static QStringList searchPaths();
 #endif
+#if QT_DEPRECATED_SINCE(5, 15)
+    QT_DEPRECATED_VERSION_X_5_15("Use QResource::compressionAlgorithm() instead")
+    bool isCompressed() const;
+#endif
 
     static bool registerResource(const QString &rccFilename, const QString &resourceRoot=QString());
     static bool unregisterResource(const QString &rccFilename, const QString &resourceRoot=QString());
diff --git a/src/corelib/kernel/qtranslator.cpp b/src/corelib/kernel/qtranslator.cpp
index 637ef84d21..ddb96ecad6 100644
--- a/src/corelib/kernel/qtranslator.cpp
+++ b/src/corelib/kernel/qtranslator.cpp
@@ -528,7 +528,8 @@ bool QTranslatorPrivate::do_load(const QString &realname, const QString &directo
         // memory, so no need to use QFile to copy it again.
         Q_ASSERT(!d->resource);
         d->resource = new QResource(realname);
-        if (resource->isValid() && !resource->isCompressed() && resource->size() >= MagicLength
+        if (resource->isValid() && resource->compressionAlgorithm() == QResource::NoCompression
+                && resource->size() >= MagicLength
                 && !memcmp(resource->data(), magic, MagicLength)) {
             d->unmapLength = resource->size();
             d->unmapPointer = reinterpret_cast<char *>(const_cast<uchar *>(resource->data()));
diff --git a/tests/auto/corelib/io/qresourceengine/tst_qresourceengine.cpp b/tests/auto/corelib/io/qresourceengine/tst_qresourceengine.cpp
index df1dbebbf2..44c8c4b681 100644
--- a/tests/auto/corelib/io/qresourceengine/tst_qresourceengine.cpp
+++ b/tests/auto/corelib/io/qresourceengine/tst_qresourceengine.cpp
@@ -1,7 +1,7 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
-** Copyright (C) 2018 Intel Corporation.
+** Copyright (C) 2018 The Qt Company Ltd.
+** Copyright (C) 2019 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the test suite of the Qt Toolkit.
@@ -563,15 +563,15 @@ void tst_QResourceEngine::setLocale()
     // default constructed QResource gets the default locale
     QResource resource;
     resource.setFileName("aliasdir/aliasdir.txt");
-    QVERIFY(!resource.isCompressed());
+    QCOMPARE(resource.compressionAlgorithm(), QResource::NoCompression);
 
     // change the default locale and make sure it doesn't affect the resource
     QLocale::setDefault(QLocale("de_CH"));
-    QVERIFY(!resource.isCompressed());
+    QCOMPARE(resource.compressionAlgorithm(), QResource::NoCompression);
 
     // then explicitly set the locale on qresource
     resource.setLocale(QLocale("de_CH"));
-    QVERIFY(resource.isCompressed());
+    QVERIFY(resource.compressionAlgorithm() != QResource::NoCompression);
 
     // the reset the default locale back
     QLocale::setDefault(QLocale::system());