Fix FileStorage to not close files after they are opened

This is particularly an issue with KTX file reading/writing where we do
both concurrently.

libraries/gpu/src/gpu/Texture_ktx.cpp

@@ -210,7 +210,6 @@ std::shared_ptr<storage::FileStorage> KtxStorage::maybeOpenFile() const {
 }
 
 PixelsPointer KtxStorage::getMipFace(uint16 level, uint8 face) const {
-    storage::StoragePointer result;
     auto faceOffset = _ktxDescriptor->getMipFaceTexelsOffset(level, face);
     auto faceSize = _ktxDescriptor->getMipFaceTexelsSize(level, face);
     if (faceSize != 0 && faceOffset != 0) {
@@ -226,7 +225,7 @@ PixelsPointer KtxStorage::getMipFace(uint16 level, uint8 face) const {
             qWarning() << "Failed to get a valid file out of maybeOpenFile " << QString::fromStdString(_filename);
         }
     }
-    return result;
+    return nullptr;
 }
 
 Size KtxStorage::getMipFaceSize(uint16 level, uint8 face) const {
@@ -260,8 +259,13 @@ void KtxStorage::assignMipData(uint16 level, const storage::StoragePointer& stor
     }
 
     auto file = maybeOpenFile();
+    if (!file) {
+        qWarning() << "Failed to open file to assign mip data " << QString::fromStdString(_filename);
+        return;
+    }
 
-    auto imageData = file->mutableData();
+    auto fileData = file->mutableData();
+    auto imageData = fileData;
     imageData += ktx::KTX_HEADER_SIZE + _ktxDescriptor->header.bytesOfKeyValueData + _ktxDescriptor->images[level]._imageOffset;
     imageData += ktx::IMAGE_SIZE_WIDTH;
 
@@ -276,7 +280,7 @@ void KtxStorage::assignMipData(uint16 level, const storage::StoragePointer& stor
         memcpy(imageData, storage->data(), storage->size());
         _minMipLevelAvailable = level;
         if (_offsetToMinMipKV > 0) {
-            auto minMipKeyData = file->mutableData() + ktx::KTX_HEADER_SIZE + _offsetToMinMipKV;
+            auto minMipKeyData = fileData + ktx::KTX_HEADER_SIZE + _offsetToMinMipKV;
             memcpy(minMipKeyData, (void*)&_minMipLevelAvailable, 1);
         }
     }

libraries/shared/src/shared/Storage.cpp

@@ -70,7 +70,15 @@ StoragePointer FileStorage::create(const QString& filename, size_t size, const u
 }
 
 FileStorage::FileStorage(const QString& filename) : _file(filename) {
-    if (_file.open(QFile::ReadOnly)) {
+    bool opened = _file.open(QFile::ReadWrite);
+    if (opened) {
+        _hasWriteAccess = true;
+    } else {
+        _hasWriteAccess = false;
+        opened = _file.open(QFile::ReadOnly);
+    }
+
+    if (opened) {
         _mapped = _file.map(0, _file.size());
         if (_mapped) {
             _valid = true;
@@ -91,35 +99,4 @@ FileStorage::~FileStorage() {
     if (_file.isOpen()) {
         _file.close();
     }
-}
-
-void FileStorage::ensureWriteAccess() {
-    if (_hasWriteAccess) {
-        return;
-    }
-
-    if (_mapped) {
-        if (!_file.unmap(_mapped)) {
-            throw std::runtime_error("Unable to unmap file");
-        }
-    }
-    if (_file.isOpen()) {
-        _file.close();
-    }
-    _valid = false;
-    _mapped = nullptr;
-
-    if (_file.open(QFile::ReadWrite)) {
-        _mapped = _file.map(0, _file.size());
-        if (_mapped) {
-            _valid = true;
-            _hasWriteAccess = true;
-        } else {
-            qCWarning(storagelogging) << "Failed to map file " << _file.fileName();
-            throw std::runtime_error("Failed to map file");
-        }
-    } else {
-        qCWarning(storagelogging) << "Failed to open file " << _file.fileName();
-        throw std::runtime_error("Failed to open file");
-    }
 }

libraries/shared/src/shared/Storage.h

@@ -60,11 +60,10 @@ namespace storage {
         FileStorage& operator=(const FileStorage& other) = delete;
 
         const uint8_t* data() const override { return _mapped; }
-        uint8_t* mutableData() override { ensureWriteAccess(); return _mapped; }
+        uint8_t* mutableData() override { return _hasWriteAccess ? _mapped : nullptr; }
         size_t size() const override { return _file.size(); }
         operator bool() const override { return _valid; }
     private:
-        void ensureWriteAccess();
 
         bool _valid { false };
         bool _hasWriteAccess { false };