Pass OpenMode::Truncate on write on Android

Because unlike every other platform, this is not implied there. Instead
you start overwriting the file from the beginning, but potentially leave
garbage at the end of it if the new file is shorter than the old one.

Fixes #1252.

ChangeLog

@@ -87,6 +87,7 @@ Unreleased Version 2.2.2-pre
  * Feature: New dialog Selection > Expand/Shrink/Feather Selection that alters selections accordingly. Thanks MorrowShore for suggesting.
  * Feature: Zooming with keyboard shortcuts now zooms in on the cursor when it's pointing at the canvas. If you don't like this, there's new shortcuts that always zoom on the center, which you can bind in the preferences. Thanks Chryssabliss for suggesting.
  * Feature: Make header and footer buttons on docks stretch further if there's empty space, making them easier to hit. Thanks MorrowShore for suggesting.
+ * Fix: Properly truncate files when writing them on Android to avoid corruption from leftover junk at the end.
 
 2024-02-25 Version 2.2.2-beta.1
  * Server Feature: Allow adding a message when kicking someone through the admin API.

src/desktop/dialogs/sessionsettings.cpp

@@ -22,6 +22,7 @@
 #include <QStringListModel>
 #include <QTemporaryFile>
 #include <QTimer>
+#include <dpcommon/platform_qt.h>
 
 namespace dialogs {
 
@@ -538,7 +539,7 @@ void SessionSettingsDialog::permissionPresetSaving(const QString &presetFile)
 
 	// Save
 	QFile f(presetFile);
-	if(!f.open(QFile::WriteOnly)) {
+	if(!f.open(DP_QT_WRITE_FLAGS)) {
 		qWarning("%s: could not open file", qPrintable(presetFile));
 		return;
 	}

src/desktop/filewrangler.cpp

@@ -18,6 +18,7 @@
 #include <QTemporaryDir>
 #include <QTemporaryFile>
 #include <QThreadPool>
+#include <dpcommon/platform_qt.h>
 #if defined(Q_OS_ANDROID) || defined(__EMSCRIPTEN__)
 #	include "desktop/dialogs/filetypedialog.h"
 #endif
@@ -890,7 +891,7 @@ bool FileWrangler::saveBytesContent(
 		return true;
 	} else {
 		QFile file(path);
-		bool ok = file.open(QFile::WriteOnly) &&
+		bool ok = file.open(DP_QT_WRITE_FLAGS) &&
 				  file.write(bytes) == bytes.size() && file.flush();
 		if(!ok && outError) {
 			*outError = file.errorString();

src/drawdance/libcommon/CMakeLists.txt

@@ -78,6 +78,7 @@ if(FILE_IO_IMPL STREQUAL "QT")
         dpcommon/input_qt.h
         dpcommon/output_qt.cpp
         dpcommon/output_qt.h
+        dpcommon/platform_qt.h
     )
     target_link_libraries(dpcommon PUBLIC "Qt${QT_VERSION_MAJOR}::Core")
 

src/drawdance/libcommon/dpcommon/output_qt.cpp

@@ -2,7 +2,7 @@ extern "C" {
 #include "output_qt.h"
 #include "output.h"
 }
-
+#include "platform_qt.h"
 #include <QFile>
 #include <QSaveFile>
 #ifdef DP_QT_IO_KARCHIVE
@@ -138,7 +138,7 @@ extern "C" DP_Output *DP_qfile_output_new_from_path(const char *path,
                                                     DP_OutputQtNewFn new_fn)
 {
     QFile *file = new QFile{QString::fromUtf8(path)};
-    if (file->open(QIODevice::WriteOnly)) {
+    if (file->open(DP_QT_WRITE_FLAGS)) {
         return DP_qfile_output_new(file, true, new_fn);
     }
     else {
@@ -214,7 +214,7 @@ extern "C" DP_Output *DP_qsavefile_output_new_from_path(const char *path,
 {
     QSaveFile *sf = new QSaveFile{QString::fromUtf8(path)};
     sf->setDirectWriteFallback(true);
-    if (sf->open(QIODevice::WriteOnly)) {
+    if (sf->open(DP_QT_WRITE_FLAGS)) {
         return new_fn(qsavefile_output_init, sf, sizeof(DP_QFileOutputState));
     }
     else {
@@ -301,7 +301,7 @@ DP_karchive_gzip_output_new_from_path(const char *path, DP_OutputQtNewFn new_fn)
 {
     KCompressionDevice *dev = new KCompressionDevice{QString::fromUtf8(path),
                                                      KCompressionDevice::GZip};
-    if (dev->open(QIODevice::WriteOnly)) {
+    if (dev->open(DP_QT_WRITE_FLAGS)) {
         return new_fn(kcompressiondevice_output_init, dev,
                       sizeof(DP_KCompressionDeviceOutputState));
     }

src/drawdance/libcommon/dpcommon/platform_qt.h

@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+#ifndef DPCOMMON_PLATFORM_H
+#define DPCOMMON_PLATFORM_H
+#include <QIODevice>
+
+// On Android, files don't get truncated when writing without the truncate flag.
+static constexpr QIODevice::OpenMode DP_QT_WRITE_FLAGS =
+#ifdef Q_OS_ANDROID
+    QIODevice::WriteOnly | QIODevice::Truncate;
+#else
+    QIODevice::WriteOnly;
+#endif
+
+#endif

src/drawdance/libengine/dpengine/image_qt.cpp

@@ -29,6 +29,7 @@ extern "C" {
 #include <dpcommon/input.h>
 #include <dpcommon/output.h>
 }
+#include <dpcommon/platform_qt.h>
 #include <QIODevice>
 #include <QImage>
 
@@ -75,7 +76,7 @@ class DP_OutputDevice : public QIODevice {
   public:
     explicit DP_OutputDevice(DP_Output *output) : QIODevice{}, m_output{output}
     {
-        open(QIODevice::WriteOnly);
+        open(DP_QT_WRITE_FLAGS);
     }
 
   protected:

src/drawdance/libengine/dpengine/zip_archive_karchive.cpp

@@ -19,6 +19,7 @@ extern "C" {
 #include <dpcommon/common.h>
 #include <dpcommon/conversions.h>
 }
+#include <dpcommon/platform_qt.h>
 #include <KZip>
 
 
@@ -83,7 +84,7 @@ extern "C" void DP_zip_reader_file_free(DP_ZipReaderFile *zrf)
 extern "C" DP_ZipWriter *DP_zip_writer_new(const char *path)
 {
     KZip *kz = new KZip{path};
-    if (kz->open(QIODevice::WriteOnly)) {
+    if (kz->open(DP_QT_WRITE_FLAGS)) {
         return reinterpret_cast<DP_ZipWriter *>(kz);
     }
     else {

src/libclient/brushes/brushpresetmodel.cpp

@@ -7,7 +7,7 @@
 #include "libshared/util/paths.h"
 #include "libshared/util/qtcompat.h"
 #include "libclient/drawdance/ziparchive.h"
-
+#include <dpcommon/platform_qt.h>
 #include <QBuffer>
 #include <QDebug>
 #include <QDirIterator>
@@ -1263,7 +1263,7 @@ QByteArray BrushPresetModel::toPng(const QPixmap &pixmap)
 {
 	QByteArray bytes;
 	QBuffer buffer(&bytes);
-	buffer.open(QIODevice::WriteOnly);
+	buffer.open(DP_QT_WRITE_FLAGS);
 	pixmap.save(&buffer, "PNG");
 	buffer.close();
 	return bytes;

src/libclient/document.cpp

@@ -25,6 +25,7 @@
 #include <QThreadPool>
 #include <QTimer>
 #include <QtEndian>
+#include <dpcommon/platform_qt.h>
 #include <parson.h>
 #ifndef HAVE_CLIPBOARD_EMULATION
 #	include <QClipboard>
@@ -1197,7 +1198,7 @@ void Document::downloadSelection(const QString &fileName)
 	QFileInfo fileInfo(fileName);
 	QByteArray bytes;
 	QBuffer buffer(&bytes);
-	buffer.open(QIODevice::WriteOnly);
+	buffer.open(DP_QT_WRITE_FLAGS);
 	bool ok = selectionToImage().save(
 		&buffer, qUtf8Printable(fileInfo.completeSuffix()));
 	buffer.close();

src/libclient/net/login.cpp

@@ -23,6 +23,7 @@
 #include <QStringList>
 #include <QUrlQuery>
 #include <QUuid>
+#include <dpcommon/platform_qt.h>
 #include <utility>
 #ifdef __EMSCRIPTEN__
 #	include "libclient/wasmsupport.h"
@@ -1033,7 +1034,7 @@ void saveCert(const QFileInfo &file, const QSslCertificate &cert)
 
 	QFile certOut(filename);
 
-	if(certOut.open(QFile::WriteOnly))
+	if(certOut.open(DP_QT_WRITE_FLAGS))
 		certOut.write(cert.toPem());
 	else
 		qCWarning(lcDpLogin) << "Couldn't open" << filename << "for writing!";

src/libclient/utils/avatarlistmodel.cpp

@@ -4,7 +4,7 @@
 #include "libclient/utils/identicon.h"
 #include "libclient/utils/wasmpersistence.h"
 #include "libshared/util/paths.h"
-
+#include <dpcommon/platform_qt.h>
 #include <QDir>
 #include <QBuffer>
 #include <QCryptographicHash>
@@ -169,7 +169,7 @@ void AvatarListModel::commit()
 
 			const QString filename = QString::fromUtf8(hash.result().toHex() + ".png");
 			QFile f { dir.filePath(filename) };
-			if(!f.open(QFile::WriteOnly)) {
+			if(!f.open(DP_QT_WRITE_FLAGS)) {
 				qWarning("Couldn't open %s", qUtf8Printable(filename));
 				continue;
 			}

src/libclient/utils/certificatestoremodel.cpp

@@ -3,7 +3,7 @@
 #include "libclient/utils/certificatestoremodel.h"
 #include "libclient/utils/wasmpersistence.h"
 #include "libshared/util/paths.h"
-
+#include <dpcommon/platform_qt.h>
 #include <QDir>
 #include <QFile>
 #include <QIcon>
@@ -198,7 +198,7 @@ bool CertificateStoreModel::submit()
 
 			if (cert.pending == Pending::Copy) {
 				auto file = QFile(to);
-				if (!file.open(QFile::WriteOnly)) {
+				if (!file.open(DP_QT_WRITE_FLAGS)) {
 					m_lastError = tr("Could not open '%1' for writing: %2.")
 						.arg(file.fileName())
 						.arg(file.errorString());

src/libclient/utils/listservermodel.cpp

@@ -4,7 +4,7 @@
 #include "libclient/utils/listservermodel.h"
 #include "libclient/utils/wasmpersistence.h"
 #include "libshared/util/paths.h"
-
+#include <dpcommon/platform_qt.h>
 #include <QImage>
 #include <QBuffer>
 #include <QCryptographicHash>
@@ -152,7 +152,7 @@ QIcon ListServerModel::setFavicon(const QString &url, const QImage &icon)
 	// Serialize icon in PNG format
 	QByteArray data;
 	QBuffer buffer(&data);
-	buffer.open(QIODevice::WriteOnly);
+	buffer.open(DP_QT_WRITE_FLAGS);
 	scaledIcon.save(&buffer, "PNG");
 
 	// Generate file name
@@ -174,7 +174,7 @@ QIcon ListServerModel::setFavicon(const QString &url, const QImage &icon)
 		if(!saved) {
 			saved = true;
 			QFile f(utils::paths::writablePath("favicons/", s.iconName));
-			if(!f.open(QIODevice::WriteOnly)) {
+			if(!f.open(DP_QT_WRITE_FLAGS)) {
 				qWarning() << "Unable to open" << f.fileName() << f.errorString();
 			} else {
 				f.write(data);

src/libserver/filedhistory.cpp

@@ -16,6 +16,7 @@ extern "C" {
 #include <QSet>
 #include <QTimerEvent>
 #include <QVarLengthArray>
+#include <dpcommon/platform_qt.h>
 
 namespace server {
 
@@ -127,7 +128,7 @@ bool FiledHistory::create()
 		return false;
 	}
 
-	if(!m_journal->open(QFile::WriteOnly)) {
+	if(!m_journal->open(DP_QT_WRITE_FLAGS)) {
 		qWarning() << m_journal->fileName() << m_journal->errorString();
 		return false;
 	}

src/libserver/tests/filename.cpp

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #include "libserver/util/filename.h"
-
+#include <dpcommon/platform_qt.h>
 #include <QtTest/QtTest>
 #include <QTemporaryDir>
 #include <QDir>
@@ -38,7 +38,7 @@ private slots:
 	bool touch(const QString &path)
 	{
 		QFile f { path };
-		if(!f.open(QIODevice::WriteOnly))
+		if(!f.open(DP_QT_WRITE_FLAGS))
 			return false;
 		f.close();
 		return true;

src/libshared/tests/filename.cpp

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #include "libshared/util/filename.h"
-
+#include <dpcommon/platform_qt.h>
 #include <QtTest/QtTest>
 #include <QTemporaryDir>
 #include <QDir>
@@ -38,7 +38,7 @@ private slots:
 	bool touch(const QString &path)
 	{
 		QFile f { path };
-		if(!f.open(QIODevice::WriteOnly))
+		if(!f.open(DP_QT_WRITE_FLAGS))
 			return false;
 		f.close();
 		return true;

src/libshared/util/networkaccess.cpp

@@ -2,7 +2,7 @@
 
 #include "libshared/util/networkaccess.h"
 #include "libshared/util/qtcompat.h"
-
+#include <dpcommon/platform_qt.h>
 #include <QNetworkReply>
 #include <QMutexLocker>
 #include <QHash>
@@ -127,7 +127,7 @@ void FileDownload::onReadyRead()
 	Q_ASSERT(m_file);
 
 	if(!m_file->isOpen()) {
-		if(!m_file->open(m_file->inherits("QSaveFile") ? QIODevice::WriteOnly : QIODevice::ReadWrite)) {
+		if(!m_file->open(m_file->inherits("QSaveFile") ? DP_QT_WRITE_FLAGS : QIODevice::ReadWrite)) {
 			m_errorMessage = m_file->errorString();
 			m_reply->abort();
 			return;

src/thinsrv/tests/templates.cpp

@@ -9,6 +9,7 @@
 #include <QFile>
 #include <QTemporaryDir>
 #include <QtTest/QtTest>
+#include <dpcommon/platform_qt.h>
 
 using namespace server;
 
@@ -75,7 +76,7 @@ private slots:
 	bool touch(const QString &path)
 	{
 		QFile f{path};
-		if(!f.open(QIODevice::WriteOnly))
+		if(!f.open(DP_QT_WRITE_FLAGS))
 			return false;
 		f.close();
 		return true;

src/tools/drawpile-timelapse/main.cpp

@@ -4,6 +4,7 @@
 #include <QSaveFile>
 #include <QStandardPaths>
 #include <QString>
+#include <dpcommon/platform_qt.h>
 
 extern "C" int drawpile_timelapse_main(const char *default_logo_path);
 
@@ -29,7 +30,7 @@ static QString writeDefaultLogo()
 		QByteArray bytes = in.readAll();
 		in.close();
 
-		if(!out.open(QIODevice::WriteOnly)) {
+		if(!out.open(DP_QT_WRITE_FLAGS)) {
 			qWarning(
 				"Error opening '%s': %s", qUtf8Printable(out.fileName()),
 				qUtf8Printable(out.errorString()));