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engines/agi/disk_image.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/formats/disk_image.h"
+#include "common/memstream.h"
+#include "common/path.h"
+#include "common/textconsole.h"
+
+#include "agi/disk_image.h"
+
+namespace Agi {
+
+/**
+ * DiskImageStream is a stream wrapper around Common::DiskImage.
+ *
+ * This allows DiskImage to lazily decode tracks as a stream is used.
+ * This is important for detection, because the .woz format is noticeably
+ * expensive to decode all tracks at once, and detection has to read
+ * INITDIR to discover which track to read LOGDIR from.
+ */
+class DiskImageStream : virtual public Common::SeekableReadStream {
+public:
+	DiskImageStream(Common::DiskImage *diskImage) : _diskImage(diskImage), _stream(_diskImage->getDiskStream()) {}
+
+	~DiskImageStream() {
+		delete _diskImage;
+	}
+
+	uint32 read(void *dataPtr, uint32 dataSize) override {
+		return _diskImage->read(dataPtr, pos(), dataSize);
+	}
+
+	bool eos() const override { return _stream->eos(); }
+	void clearErr() override { _stream->clearErr(); }
+
+	int64 pos() const override{ return _stream->pos(); }
+	int64 size() const override { return _stream->size(); }
+
+	bool seek(int64 offs, int whence = SEEK_SET) override { return _stream->seek(offs, whence); }
+
+private:
+	Common::DiskImage *_diskImage;
+	Common::SeekableReadStream *_stream;
+};
+
+Common::SeekableReadStream *openPCDiskImage(const Common::Path &path, const Common::FSNode &node) {
+	Common::SeekableReadStream *stream = node.createReadStream();
+	if (stream == nullptr) {
+		warning("unable to open disk image: %s", path.baseName().c_str());
+		return nullptr;
+	}
+
+	// validate disk size
+	if (stream->size() != PC_DISK_SIZE) {
+		delete stream;
+		return nullptr;
+	}
+
+	return stream;
+}
+
+Common::SeekableReadStream *openA2DiskImage(const Common::Path &path, const Common::FSNode &node, bool loadAllTracks) {
+	Common::String name = path.baseName();
+
+	// Open the image with Common::DiskImage, unless the file extension is ".img".
+	// DiskImage expects ".img" to be a PC disk image, but it also gets used as
+	// an Apple II raw sector disk image, so just open it and and read it.
+	Common::SeekableReadStream *stream = nullptr;
+	if (name.hasSuffixIgnoreCase(".img")) {
+		stream = node.createReadStream();
+	} else {
+		if (loadAllTracks) {
+			// when loading all tracks, open with DiskImage and take the stream.
+			Common::DiskImage diskImage;
+			if (diskImage.open(node)) {
+				stream = diskImage.releaseStream();
+			}
+		} else {
+			// when loading tracks as they're used, create a DiskImage with lazy
+			// decoding and wrap it in a stream.
+			Common::DiskImage *diskImage = new Common::DiskImage();
+			diskImage->setLazyDecoding(true);
+			if (diskImage->open(node)) {
+				stream = new DiskImageStream(diskImage);
+			} else {
+				delete diskImage;
+			}
+		}
+	}
+
+	if (stream == nullptr) {
+		warning("unable to open disk image: %s", path.baseName().c_str());
+		return nullptr;
+	}
+
+	// validate disk size
+	if (stream->size() != A2_DISK_SIZE) {
+		delete stream;
+		return nullptr;
+	}
+
+	return stream;
+}
+
+} // End of namespace Agi