| 1 | /* |
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| 2 | This file is part of the KDE libraries |
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| 3 | SPDX-FileCopyrightText: 2008 Christian Ehrlicher <ch.ehrlicher@gmx.de> |
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| 4 | |
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| 5 | SPDX-License-Identifier: LGPL-2.0-or-later |
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| 6 | */ |
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| 7 | |
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| 8 | #ifndef KMEMFILE_H |
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| 9 | #define KMEMFILE_H |
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| 10 | |
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| 11 | #include <QIODevice> |
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| 12 | #include <kservice_export.h> |
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| 13 | #include <memory> |
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| 14 | |
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| 15 | #ifndef QT_NO_SHAREDMEMORY |
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| 16 | |
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| 17 | /** |
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| 18 | * @internal |
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| 19 | * Simple QIODevice for QSharedMemory to keep ksycoca cache in memory only once |
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| 20 | * The first call to open() loads the file into a shm segment. Every |
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| 21 | * subsequent call only attaches to this segment. When the file content changed, |
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| 22 | * you have to execute KMemFile::fileContentsChanged() to update the internal |
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| 23 | * structures. The next call to open() creates a new shm segment. The old one |
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| 24 | * is automatically destroyed when the last process closed KMemFile. |
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| 25 | */ |
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| 26 | |
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| 27 | class KMemFile : public QIODevice |
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| 28 | { |
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| 29 | Q_OBJECT |
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| 30 | public: |
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| 31 | /** |
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| 32 | * ctor |
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| 33 | * |
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| 34 | * @param filename the file to load into memory |
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| 35 | * @param parent our parent |
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| 36 | */ |
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| 37 | explicit KMemFile(const QString &filename, QObject *parent = nullptr); |
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| 38 | /** |
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| 39 | * dtor |
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| 40 | */ |
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| 41 | ~KMemFile() override; |
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| 42 | /** |
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| 43 | * closes the KMemFile |
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| 44 | * |
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| 45 | * @reimp |
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| 46 | */ |
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| 47 | void close() override; |
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| 48 | /** |
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| 49 | * As KMemFile is a random access device, it returns false |
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| 50 | * |
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| 51 | * @reimp |
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| 52 | */ |
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| 53 | bool isSequential() const override; |
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| 54 | /** |
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| 55 | * @reimp |
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| 56 | * @param mode only QIODevice::ReadOnly is accepted |
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| 57 | */ |
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| 58 | bool open(OpenMode mode) override; |
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| 59 | /** |
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| 60 | * Sets the current read/write position to pos |
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| 61 | * @reimp |
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| 62 | * @param pos the new read/write position |
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| 63 | */ |
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| 64 | bool seek(qint64 pos) override; |
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| 65 | /** |
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| 66 | * Returns the size of the file |
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| 67 | * @reimp |
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| 68 | */ |
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| 69 | qint64 size() const override; |
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| 70 | /** |
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| 71 | * This static function updates the internal information about the file |
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| 72 | * loaded into shared memory. The next time the file is opened, the file is |
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| 73 | * reread from the file system. |
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| 74 | */ |
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| 75 | static void fileContentsChanged(const QString &filename); |
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| 76 | |
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| 77 | protected: |
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| 78 | /** @reimp */ |
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| 79 | qint64 readData(char *data, qint64 maxSize) override; |
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| 80 | /** @reimp */ |
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| 81 | qint64 writeData(const char *data, qint64 maxSize) override; |
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| 82 | |
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| 83 | private: |
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| 84 | class Private; |
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| 85 | friend class Private; |
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| 86 | std::unique_ptr<Private> const d; |
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| 87 | }; |
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| 88 | |
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| 89 | #endif // QT_NO_SHAREDMEMORY |
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| 90 | |
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| 91 | #endif // KMEMFILE_H |
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| 92 | |
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