input/InputStream: make IsEOF() and IsAvailable() const

src/archive/plugins/Bzip2ArchivePlugin.cxx

@@ -71,7 +71,7 @@ public:
 	~Bzip2InputStream();
 
 	/* virtual methods from InputStream */
-	bool IsEOF() noexcept override;
+	bool IsEOF() const noexcept override;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t size) override;
 
@@ -183,7 +183,7 @@ Bzip2InputStream::Read(std::unique_lock<Mutex> &, void *ptr, size_t length)
 }
 
 bool
-Bzip2InputStream::IsEOF() noexcept
+Bzip2InputStream::IsEOF() const noexcept
 {
 	return eof;
 }

src/archive/plugins/Iso9660ArchivePlugin.cxx

@@ -156,7 +156,7 @@ public:
 	}
 
 	/* virtual methods from InputStream */
-	bool IsEOF() noexcept override;
+	bool IsEOF() const noexcept override;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t size) override;
 };
@@ -210,7 +210,7 @@ Iso9660InputStream::Read(std::unique_lock<Mutex> &,
 }
 
 bool
-Iso9660InputStream::IsEOF() noexcept
+Iso9660InputStream::IsEOF() const noexcept
 {
 	return offset == size;
 }

src/archive/plugins/ZzipArchivePlugin.cxx

@@ -110,7 +110,7 @@ public:
 	}
 
 	/* virtual methods from InputStream */
-	bool IsEOF() noexcept override;
+	bool IsEOF() const noexcept override;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t size) override;
 	void Seek(std::unique_lock<Mutex> &lock, offset_type offset) override;
@@ -144,7 +144,7 @@ ZzipInputStream::Read(std::unique_lock<Mutex> &, void *ptr, size_t read_size)
 }
 
 bool
-ZzipInputStream::IsEOF() noexcept
+ZzipInputStream::IsEOF() const noexcept
 {
 	return offset_type(zzip_tell(file)) == size;
 }

src/input/AsyncInputStream.cxx

@@ -88,7 +88,7 @@ AsyncInputStream::Check()
 }
 
 bool
-AsyncInputStream::IsEOF() noexcept
+AsyncInputStream::IsEOF() const noexcept
 {
 	return (KnownSize() && offset >= size) ||
 		(!open && buffer.empty());
@@ -164,7 +164,7 @@ AsyncInputStream::ReadTag() noexcept
 }
 
 bool
-AsyncInputStream::IsAvailable() noexcept
+AsyncInputStream::IsAvailable() const noexcept
 {
 	return postponed_exception ||
 		IsEOF() ||

src/input/AsyncInputStream.hxx

@@ -82,11 +82,11 @@ public:
 
 	/* virtual methods from InputStream */
 	void Check() final;
-	bool IsEOF() noexcept final;
+	bool IsEOF() const noexcept final;
 	void Seek(std::unique_lock<Mutex> &lock,
 		  offset_type new_offset) final;
 	std::unique_ptr<Tag> ReadTag() noexcept final;
-	bool IsAvailable() noexcept final;
+	bool IsAvailable() const noexcept final;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t read_size) final;
 

src/input/BufferedInputStream.cxx

@@ -53,13 +53,13 @@ BufferedInputStream::Seek(std::unique_lock<Mutex> &,
 }
 
 bool
-BufferedInputStream::IsEOF() noexcept
+BufferedInputStream::IsEOF() const noexcept
 {
 	return InputStream::offset == BufferingInputStream::size();
 }
 
 bool
-BufferedInputStream::IsAvailable() noexcept
+BufferedInputStream::IsAvailable() const noexcept
 {
 	return BufferingInputStream::IsAvailable(offset);
 }

src/input/BufferedInputStream.hxx

@@ -55,10 +55,10 @@ public:
 	   have been copied already in our constructor */
 	//void Update() noexcept;
 	void Seek(std::unique_lock<Mutex> &lock, offset_type offset) override;
-	bool IsEOF() noexcept override;
+	bool IsEOF() const noexcept override;
 	/* we don't support tags */
 	// std::unique_ptr<Tag> ReadTag() override;
-	bool IsAvailable() noexcept override;
+	bool IsAvailable() const noexcept override;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t size) override;
 

src/input/BufferingInputStream.cxx

@@ -56,7 +56,7 @@ BufferingInputStream::Check()
 }
 
 bool
-BufferingInputStream::IsAvailable(size_t offset) noexcept
+BufferingInputStream::IsAvailable(size_t offset) const noexcept
 {
 	if (offset >= size() || error)
 		return true;

src/input/BufferingInputStream.hxx

@@ -57,7 +57,9 @@ class BufferingInputStream : InputStreamHandler {
 
 	bool stop = false;
 
-	size_t want_offset = INVALID_OFFSET;
+	/* must be mutable because IsAvailable() acts as a hint to
+	   modify this attribute */
+	mutable size_t want_offset = INVALID_OFFSET;
 
 	std::exception_ptr error, seek_error;
 
@@ -100,7 +102,7 @@ public:
 	 * Check whether data is available in the buffer at the given
 	 * offset..
 	 */
-	bool IsAvailable(size_t offset) noexcept;
+	bool IsAvailable(size_t offset) const noexcept;
 
 	/**
 	 * Copy data from the buffer into the given pointer.

src/input/FailingInputStream.hxx

@@ -49,7 +49,7 @@ public:
 		std::rethrow_exception(error);
 	}
 
-	bool IsEOF() noexcept override {
+	bool IsEOF() const noexcept override {
 		return false;
 	}
 

src/input/InputStream.cxx

@@ -105,7 +105,7 @@ InputStream::LockReadTag() noexcept
 }
 
 bool
-InputStream::IsAvailable() noexcept
+InputStream::IsAvailable() const noexcept
 {
 	return true;
 }
@@ -153,7 +153,7 @@ InputStream::LockReadFull(void *ptr, size_t _size)
 }
 
 bool
-InputStream::LockIsEOF() noexcept
+InputStream::LockIsEOF() const noexcept
 {
 	const std::lock_guard<Mutex> protect(mutex);
 	return IsEOF();

src/input/InputStream.hxx

@@ -310,14 +310,14 @@ public:
 	 * The caller must lock the mutex.
 	 */
 	gcc_pure
-	virtual bool IsEOF() noexcept = 0;
+	virtual bool IsEOF() const noexcept = 0;
 
 	/**
 	 * Wrapper for IsEOF() which locks and unlocks the mutex; the
 	 * caller must not be holding it already.
 	 */
 	gcc_pure
-	bool LockIsEOF() noexcept;
+	bool LockIsEOF() const noexcept;
 
 	/**
 	 * Reads the tag from the stream.
@@ -343,7 +343,7 @@ public:
 	 * The caller must lock the mutex.
 	 */
 	gcc_pure
-	virtual bool IsAvailable() noexcept;
+	virtual bool IsAvailable() const noexcept;
 
 	/**
 	 * Reads data from the stream into the caller-supplied buffer.

src/input/ProxyInputStream.cxx

@@ -99,7 +99,7 @@ ProxyInputStream::Seek(std::unique_lock<Mutex> &lock,
 }
 
 bool
-ProxyInputStream::IsEOF() noexcept
+ProxyInputStream::IsEOF() const noexcept
 {
 	return input && input->IsEOF();
 }
@@ -114,7 +114,7 @@ ProxyInputStream::ReadTag() noexcept
 }
 
 bool
-ProxyInputStream::IsAvailable() noexcept
+ProxyInputStream::IsAvailable() const noexcept
 {
 	return input && input->IsAvailable();
 }

src/input/ProxyInputStream.hxx

@@ -62,9 +62,9 @@ public:
 	void Update() noexcept override;
 	void Seek(std::unique_lock<Mutex> &lock,
 		  offset_type new_offset) override;
-	bool IsEOF() noexcept override;
+	bool IsEOF() const noexcept override;
 	std::unique_ptr<Tag> ReadTag() noexcept override;
-	bool IsAvailable() noexcept override;
+	bool IsAvailable() const noexcept override;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t read_size) override;
 

src/input/RewindInputStream.cxx

@@ -56,7 +56,7 @@ public:
 			ProxyInputStream::Update();
 	}
 
-	bool IsEOF() noexcept override {
+	bool IsEOF() const noexcept override {
 		return !ReadingFromBuffer() && ProxyInputStream::IsEOF();
 	}
 

src/input/ThreadInputStream.cxx

@@ -122,7 +122,7 @@ ThreadInputStream::Check()
 }
 
 bool
-ThreadInputStream::IsAvailable() noexcept
+ThreadInputStream::IsAvailable() const noexcept
 {
 	assert(!thread.IsInside());
 
@@ -160,7 +160,7 @@ ThreadInputStream::Read(std::unique_lock<Mutex> &lock,
 }
 
 bool
-ThreadInputStream::IsEOF() noexcept
+ThreadInputStream::IsEOF() const noexcept
 {
 	assert(!thread.IsInside());
 

src/input/ThreadInputStream.hxx

@@ -91,9 +91,9 @@ public:
 	void Start();
 
 	/* virtual methods from InputStream */
-	void Check() override final;
-	bool IsEOF() noexcept final;
-	bool IsAvailable() noexcept final;
+	void Check() final;
+	bool IsEOF() const noexcept final;
+	bool IsAvailable() const noexcept final;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t size) override final;
 

src/input/plugins/CdioParanoiaInputPlugin.cxx

@@ -90,7 +90,7 @@ class CdioParanoiaInputStream final : public InputStream {
 	}
 
 	/* virtual methods from InputStream */
-	bool IsEOF() noexcept override;
+	bool IsEOF() const noexcept override;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t size) override;
 	void Seek(std::unique_lock<Mutex> &lock, offset_type offset) override;
@@ -344,7 +344,7 @@ CdioParanoiaInputStream::Read(std::unique_lock<Mutex> &,
 }
 
 bool
-CdioParanoiaInputStream::IsEOF() noexcept
+CdioParanoiaInputStream::IsEOF() const noexcept
 {
 	return lsn_from + lsn_relofs > lsn_to;
 }

src/input/plugins/FfmpegInputPlugin.cxx

@@ -48,7 +48,7 @@ public:
 	}
 
 	/* virtual methods from InputStream */
-	bool IsEOF() noexcept override;
+	bool IsEOF() const noexcept override;
 	size_t Read(std::unique_lock<Mutex> &lock,
 		    void *ptr, size_t size) override;
 	void Seek(std::unique_lock<Mutex> &lock,
@@ -96,7 +96,7 @@ FfmpegInputStream::Read(std::unique_lock<Mutex> &,
 }
 
 bool
-FfmpegInputStream::IsEOF() noexcept
+FfmpegInputStream::IsEOF() const noexcept
 {
 	return io.IsEOF();
 }

src/input/plugins/FileInputPlugin.cxx

@@ -44,7 +44,7 @@ public:
 
 	/* virtual methods from InputStream */
 
-	bool IsEOF() noexcept override {
+	bool IsEOF() const noexcept override {
 		return GetOffset() >= GetSize();
 	}
 

src/input/plugins/SmbclientInputPlugin.cxx

@@ -52,7 +52,7 @@ public:
 
 	/* virtual methods from InputStream */
 
-	bool IsEOF() noexcept override {
+	bool IsEOF() const noexcept override {
 		return offset >= size;
 	}
 

test/TestRewindInputStream.cxx

@@ -24,7 +24,7 @@ public:
 	}
 
 	/* virtual methods from InputStream */
-	bool IsEOF() noexcept override {
+	bool IsEOF() const noexcept override {
 		return remaining == 0;
 	}