scummvm/common/stream.h

/* 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 *
 */

#ifndef COMMON_STREAM_H
#define COMMON_STREAM_H

#include "common/scummsys.h"

namespace Common {

class String;
class MemoryReadStream;

/**
 * Virtual base class for both ReadStream and WriteStream.
 */
class Stream {
public:
	virtual ~Stream() {}

	/**
	 * Returns true if an I/O failure occurred.
	 * This flag is never cleared automatically. In order to clear it,
	 * client code has to call clearErr() explicitly.
	 */
	virtual bool err() const { return false; }

	/**
	 * Reset the I/O error status as returned by err().
	 * For a ReadStream, also reset the end-of-stream status returned by eos().
	 */
	virtual void clearErr() {}
};

/**
 * Generic interface for a writable data stream.
 */
class WriteStream : virtual public Stream {
public:
	/**
	 * Write data into the stream. Subclasses must implement this
	 * method; all other write methods are implemented using it.
	 *
	 * @param dataPtr	pointer to the data to be written
	 * @param dataSize	number of bytes to be written
	 * @return the number of bytes which were actually written.
	 */
	virtual uint32 write(const void *dataPtr, uint32 dataSize) = 0;

	/**
	 * Commit any buffered data to the underlying channel or
	 * storage medium; unbuffered streams can use the default
	 * implementation.
	 *
	 * @return true on success, false in case of a failure
	 */
	virtual bool flush() { return true; }

	/**
	 * Finalize and close this stream. To be called right before this
	 * stream instance is deleted. The goal here is to enable calling
	 * code to detect and handle I/O errors which might occur when
	 * closing (and this flushing, if buffered) the stream.
	 *
	 * After this method has been called, no further writes may be
	 * performed on the stream. Calling err() is allowed.
	 *
	 * By default, this just flushes the stream.
	 */
	virtual void finalize() {
		flush();
	}


	// The remaining methods all have default implementations; subclasses
	// need not (and should not) overload them.

	void writeByte(byte value) {
		write(&value, 1);
	}

	void writeSByte(int8 value) {
		write(&value, 1);
	}

	void writeUint16LE(uint16 value) {
		writeByte((byte)(value & 0xff));
		writeByte((byte)(value >> 8));
	}

	void writeUint32LE(uint32 value) {
		writeUint16LE((uint16)(value & 0xffff));
		writeUint16LE((uint16)(value >> 16));
	}

	void writeUint16BE(uint16 value) {
		writeByte((byte)(value >> 8));
		writeByte((byte)(value & 0xff));
	}

	void writeUint32BE(uint32 value) {
		writeUint16BE((uint16)(value >> 16));
		writeUint16BE((uint16)(value & 0xffff));
	}

	void writeSint16LE(int16 value) {
		writeUint16LE((uint16)value);
	}

	void writeSint32LE(int32 value) {
		writeUint32LE((uint32)value);
	}

	void writeSint16BE(int16 value) {
		writeUint16BE((uint16)value);
	}

	void writeSint32BE(int32 value) {
		writeUint32BE((uint32)value);
	}

	/**
	 * Write the given string to the stream.
	 * This writes str.size() characters, but no terminating zero byte.
	 */
	void writeString(const String &str);
};


/**
 * Generic interface for a readable data stream.
 */
class ReadStream : virtual public Stream {
public:
	/**
	 * Returns true if a read failed because the stream has been reached.
	 * This flag is cleared by clearErr().
	 * For a SeekableReadStream, it is also cleared by a successful seek.
	 */
	virtual bool eos() const = 0;

	/**
	 * Read data from the stream. Subclasses must implement this
	 * method; all other read methods are implemented using it.
	 *
	 * @param dataPtr	pointer to a buffer into which the data is read
	 * @param dataSize	number of bytes to be read
	 * @return the number of bytes which were actually read.
	 */
	virtual uint32 read(void *dataPtr, uint32 dataSize) = 0;


	// The remaining methods all have default implementations; subclasses
	// in general should not overload them.

	/**
	 * DEPRECATED
	 * Default implementation for backward compatibility
	 */
	virtual bool ioFailed() { return (eos() || err()); }

	/**
	 * Read an unsigned byte from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	byte readByte() {
		byte b = 0;
		read(&b, 1);
		return b;
	}

	/**
	 * Read a signed byte from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	int8 readSByte() {
		int8 b = 0;
		read(&b, 1);
		return b;
	}

	/**
	 * Read an unsigned 16-bit word stored in little endian (LSB first) order
	 * from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	uint16 readUint16LE() {
		uint16 a = readByte();
		uint16 b = readByte();
		return a | (b << 8);
	}

	/**
	 * Read an unsigned 32-bit word stored in little endian (LSB first) order
	 * from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	uint32 readUint32LE() {
		uint32 a = readUint16LE();
		uint32 b = readUint16LE();
		return (b << 16) | a;
	}

	/**
	 * Read an unsigned 16-bit word stored in big endian (MSB first) order
	 * from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	uint16 readUint16BE() {
		uint16 b = readByte();
		uint16 a = readByte();
		return a | (b << 8);
	}

	/**
	 * Read an unsigned 32-bit word stored in big endian (MSB first) order
	 * from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	uint32 readUint32BE() {
		uint32 b = readUint16BE();
		uint32 a = readUint16BE();
		return (b << 16) | a;
	}

	/**
	 * Read a signed 16-bit word stored in little endian (LSB first) order
	 * from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	int16 readSint16LE() {
		return (int16)readUint16LE();
	}

	/**
	 * Read a signed 32-bit word stored in little endian (LSB first) order
	 * from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	int32 readSint32LE() {
		return (int32)readUint32LE();
	}

	/**
	 * Read a signed 16-bit word stored in big endian (MSB first) order
	 * from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	int16 readSint16BE() {
		return (int16)readUint16BE();
	}

	/**
	 * Read a signed 32-bit word stored in big endian (MSB first) order
	 * from the stream and return it.
	 * Performs no error checking. The return value is undefined
	 * if a read error occurred (for which client code can check by
	 * calling err() and eos() ).
	 */
	int32 readSint32BE() {
		return (int32)readUint32BE();
	}

	/**
	 * Read the specified amount of data into a malloc'ed buffer
	 * which then is wrapped into a MemoryReadStream.
	 * The returned stream might contain less data than requested,
	 * if reading more failed, because of an I/O error or because
	 * the end of the stream was reached. Which can be determined by
	 * calling err() and eos().
	 */
	MemoryReadStream *readStream(uint32 dataSize);

};


/**
 * Interface for a seekable & readable data stream.
 *
 * @todo Get rid of SEEK_SET, SEEK_CUR, or SEEK_END, use our own constants
 */
class SeekableReadStream : virtual public ReadStream {
public:

	/**
	 * Obtains the current value of the stream position indicator of the
	 * stream.
	 *
	 * @return the current position indicator, or -1 if an error occurred.
	 */
	virtual int32 pos() const = 0;

	/**
	 * Obtains the total size of the stream, measured in bytes.
	 * If this value is unknown or can not be computed, -1 is returned.
	 *
	 * @return the size of the stream, or -1 if an error occurred
	 */
	virtual int32 size() const = 0;

	/**
	 * Sets the stream position indicator for the stream. The new position,
	 * measured in bytes, is obtained by adding offset bytes to the position
	 * specified by whence. If whence is set to SEEK_SET, SEEK_CUR, or
	 * SEEK_END, the offset is relative to the start of the file, the current
	 * position indicator, or end-of-file, respectively. A successful call
	 * to the seek() method clears the end-of-file indicator for the stream.
	 *
	 * @param offset	the relative offset in bytes
	 * @param whence	the seek reference: SEEK_SET, SEEK_CUR, or SEEK_END
	 * @return true on success, false in case of a failure
	 */
	virtual bool seek(int32 offset, int whence = SEEK_SET) = 0;

	/**
	 * TODO: Get rid of this??? Or keep it and document it
	 * @return true on success, false in case of a failure
	 */
	virtual bool skip(uint32 offset) { return seek(offset, SEEK_CUR); }

	/**
	 * Reads at most one less than the number of characters specified
	 * by bufSize from the and stores them in the string buf. Reading
	 * stops when the end of a line is reached (CR, CR/LF or LF), and
	 * at end-of-file or error. The newline, if any, is retained (CR
	 * and CR/LF are translated to LF = 0xA = '\n'). If any characters
	 * are read and there is no error, a `\0' character is appended
	 * to end the string.
	 *
	 * Upon successful completion, return a pointer to the string. If
	 * end-of-file occurs before any characters are read, returns NULL
	 * and the buffer contents remain unchanged.  If an error occurs,
	 * returns NULL and the buffer contents are indeterminate.
	 * This method does not distinguish between end-of-file and error;
	 * callers must use err() or eos() to determine which occurred.
	 *
	 * @note This methods is closely modeled after the standard fgets()
	 *       function from stdio.h.
	 *
	 * @param buf	the buffer to store into
	 * @param bufSize	the size of the buffer
	 * @return a pointer to the read string, or NULL if an error occurred
	 */
	virtual char *readLine_NEW(char *s, size_t bufSize);


	/**
	 * Reads a full line and returns it as a Common::String. Reading
	 * stops when the end of a line is reached (CR, CR/LF or LF), and
	 * at end-of-file or error.
	 *
	 * Upon successful completion, return a string with the content
	 * of the line, *without* the end of a line marker. This method
	 * does not indicate whether an error occured. Callers must use
	 * err() or eos() to determine whether an exception occurred.
	 */
	virtual String readLine();
};

/**
 * SubReadStream provides access to a ReadStream restricted to the range
 * [currentPosition, currentPosition+end).
 * Manipulating the parent stream directly /will/ mess up a substream.
 * Likewise, manipulating two substreams of a parent stream will cause them to
 * step on each others toes.
 */
class SubReadStream : virtual public ReadStream {
protected:
	ReadStream *_parentStream;
	bool _disposeParentStream;
	uint32 _pos;
	uint32 _end;
	bool _eos;
public:
	SubReadStream(ReadStream *parentStream, uint32 end, bool disposeParentStream = false)
		: _parentStream(parentStream),
		  _disposeParentStream(disposeParentStream),
		  _pos(0),
		  _end(end),
		  _eos(false) {
		assert(parentStream);
	}
	~SubReadStream() {
		if (_disposeParentStream) delete _parentStream;
	}

	virtual bool eos() const { return _eos; }
	virtual bool err() const { return _parentStream->err(); }
	virtual void clearErr() { _eos = false; _parentStream->clearErr(); }
	virtual uint32 read(void *dataPtr, uint32 dataSize);
};

/*
 * SeekableSubReadStream provides access to a SeekableReadStream restricted to
 * the range [begin, end).
 * The same caveats apply to SeekableSubReadStream as do to SeekableReadStream.
 */
class SeekableSubReadStream : public SubReadStream, public SeekableReadStream {
protected:
	SeekableReadStream *_parentStream;
	uint32 _begin;
public:
	SeekableSubReadStream(SeekableReadStream *parentStream, uint32 begin, uint32 end, bool disposeParentStream = false);

	virtual int32 pos() const { return _pos - _begin; }
	virtual int32 size() const { return _end - _begin; }

	virtual bool seek(int32 offset, int whence = SEEK_SET);
};

/**
 * This is a wrapper around SeekableSubReadStream, but it adds non-endian
 * read methods whose endianness is set on the stream creation.
 */
class SeekableSubReadStreamEndian : public SeekableSubReadStream {
public:
	bool _bigEndian;

	SeekableSubReadStreamEndian(SeekableReadStream *parentStream, uint32 begin, uint32 end, bool bigEndian = false, bool disposeParentStream = false)
		: SeekableSubReadStream(parentStream, begin, end, disposeParentStream), _bigEndian(bigEndian) {
	}

	inline uint16 readUint16() {
		return (_bigEndian) ? readUint16BE() : readUint16LE();
	}

	inline uint32 readUint32() {
		return (_bigEndian) ? readUint32BE() : readUint32LE();
	}

	inline int16 readSint16() {
		return (int16)readUint16();
	}

	inline int32 readSint32() {
		return (int32)readUint32();
	}
};

/**
 * Wrapper class which adds buffering to any given ReadStream.
 * Users can specify how big the buffer should be, and whether the
 * wrapped stream should be disposed when the wrapper is disposed.
 */
class BufferedReadStream : virtual public ReadStream {
protected:
	ReadStream *_parentStream;
	bool _disposeParentStream;
	byte *_buf;
	uint32 _pos;
	uint32 _bufSize;
	uint32 _realBufSize;

public:
	BufferedReadStream(ReadStream *parentStream, uint32 bufSize, bool disposeParentStream = false);
	~BufferedReadStream();

	virtual bool eos() const { return (_pos == _bufSize) && _parentStream->eos(); }
	virtual bool err() const { return _parentStream->err(); }
	virtual void clearErr() { _parentStream->clearErr(); }

	virtual uint32 read(void *dataPtr, uint32 dataSize);
};

/**
 * Wrapper class which adds buffering to any given SeekableReadStream.
 * @see BufferedReadStream
 */
class BufferedSeekableReadStream : public BufferedReadStream, public SeekableReadStream {
protected:
	SeekableReadStream *_parentStream;
public:
	BufferedSeekableReadStream(SeekableReadStream *parentStream, uint32 bufSize, bool disposeParentStream = false);

	virtual int32 pos() const { return _parentStream->pos() - (_bufSize - _pos); }
	virtual int32 size() const { return _parentStream->size(); }

	virtual bool seek(int32 offset, int whence = SEEK_SET);
};



/**
 * Simple memory based 'stream', which implements the ReadStream interface for
 * a plain memory block.
 */
class MemoryReadStream : public SeekableReadStream {
private:
	const byte * const _ptrOrig;
	const byte *_ptr;
	const uint32 _size;
	uint32 _pos;
	byte _encbyte;
	bool _disposeMemory;
	bool _eos;

public:

	/**
	 * This constructor takes a pointer to a memory buffer and a length, and
	 * wraps it. If disposeMemory is true, the MemoryReadStream takes ownership
	 * of the buffer and hence free's it when destructed.
	 */
	MemoryReadStream(const byte *dataPtr, uint32 dataSize, bool disposeMemory = false) :
		_ptrOrig(dataPtr),
		_ptr(dataPtr),
		_size(dataSize),
		_pos(0),
		_encbyte(0),
		_disposeMemory(disposeMemory),
		_eos(false) {}

	~MemoryReadStream() {
		if (_disposeMemory)
			free(const_cast<byte *>(_ptrOrig));
	}

	void setEnc(byte value) { _encbyte = value; }

	uint32 read(void *dataPtr, uint32 dataSize);

	bool eos() const { return _eos; }
	void clearErr() { _eos = false; }

	int32 pos() const { return _pos; }
	int32 size() const { return _size; }

	bool seek(int32 offs, int whence = SEEK_SET);
};


/**
 * This is a wrapper around MemoryReadStream, but it adds non-endian
 * read methods whose endianness is set on the stream creation.
 */
class MemoryReadStreamEndian : public Common::MemoryReadStream {
private:
public:
	bool _bigEndian;
	MemoryReadStreamEndian(const byte *buf, uint32 len, bool bigEndian = false) : MemoryReadStream(buf, len), _bigEndian(bigEndian) {}

	inline uint16 readUint16() {
		return (_bigEndian) ? readUint16BE() : readUint16LE();
	}

	inline uint32 readUint32() {
		return (_bigEndian) ? readUint32BE() : readUint32LE();
	}

	inline int16 readSint16() {
		return (int16)readUint16();
	}

	inline int32 readSint32() {
		return (int32)readUint32();
	}
};

/**
 * Simple memory based 'stream', which implements the WriteStream interface for
 * a plain memory block.
 */
class MemoryWriteStream : public WriteStream {
private:
	byte *_ptr;
	const uint32 _bufSize;
	uint32 _pos;
public:
	MemoryWriteStream(byte *buf, uint32 len) : _ptr(buf), _bufSize(len), _pos(0) {}

	uint32 write(const void *dataPtr, uint32 dataSize) {
		// Write at most as many bytes as are still available...
		if (dataSize > _bufSize - _pos)
			dataSize = _bufSize - _pos;
		memcpy(_ptr, dataPtr, dataSize);
		_ptr += dataSize;
		_pos += dataSize;
		return dataSize;
	}

	uint32 pos() const { return _pos; }
	uint32 size() const { return _bufSize; }
};

/**
 * A sort of hybrid between MemoryWriteStream and Array classes. A stream
 * that grows as it's written to.
 */
class MemoryWriteStreamDynamic : public Common::WriteStream {
private:
	uint32 _capacity;
	uint32 _size;
	byte *_ptr;
	byte *_data;
	uint32 _pos;
	bool _disposeMemory;

	void ensureCapacity(uint32 new_len) {
		if (new_len <= _capacity)
			return;

		byte *old_data = _data;

		_capacity = new_len + 32;
		_data = new byte[_capacity];
		_ptr = _data + _pos;

		if (old_data) {
			// Copy old data
			memcpy(_data, old_data, _size);
			delete[] old_data;
		}

		_size = new_len;
	}
public:
	MemoryWriteStreamDynamic(bool disposeMemory = false) : _capacity(0), _size(0), _ptr(0), _data(0), _pos(0), _disposeMemory(disposeMemory) {}

	~MemoryWriteStreamDynamic() {
		if (_disposeMemory)
			delete[] _data;
	}

	uint32 write(const void *dataPtr, uint32 dataSize) {
		ensureCapacity(_pos + dataSize);
		memcpy(_ptr, dataPtr, dataSize);
		_ptr += dataSize;
		_pos += dataSize;
		if (_pos > _size)
			_size = _pos;
		return dataSize;
	}

	uint32 pos() const { return _pos; }
	uint32 size() const { return _size; }

	byte *getData() { return _data; }
};

}	// End of namespace Common

#endif