scummvm/common/stream.cpp

525 lines
13 KiB
C++

/* 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.
*
*/
#include "common/ptr.h"
#include "common/stream.h"
#include "common/memstream.h"
#include "common/substream.h"
#include "common/str.h"
namespace Common {
void WriteStream::writeString(const String &str) {
write(str.c_str(), str.size());
}
SeekableReadStream *ReadStream::readStream(uint32 dataSize) {
void *buf = malloc(dataSize);
dataSize = read(buf, dataSize);
assert(dataSize > 0);
return new MemoryReadStream((byte *)buf, dataSize, DisposeAfterUse::YES);
}
Common::String ReadStream::readPascalString(bool transformCR) {
Common::String s;
char *buf;
int len;
int i;
len = readByte();
buf = (char *)malloc(len + 1);
for (i = 0; i < len; i++) {
buf[i] = readByte();
if (transformCR && buf[i] == 0x0d)
buf[i] = '\n';
}
buf[i] = 0;
s = buf;
free(buf);
return s;
}
uint32 MemoryReadStream::read(void *dataPtr, uint32 dataSize) {
// Read at most as many bytes as are still available...
if (dataSize > _size - _pos) {
dataSize = _size - _pos;
_eos = true;
}
memcpy(dataPtr, _ptr, dataSize);
_ptr += dataSize;
_pos += dataSize;
return dataSize;
}
bool MemoryReadStream::seek(int32 offs, int whence) {
// Pre-Condition
assert(_pos <= _size);
switch (whence) {
case SEEK_END:
// SEEK_END works just like SEEK_SET, only 'reversed',
// i.e. from the end.
offs = _size + offs;
// Fall through
case SEEK_SET:
_ptr = _ptrOrig + offs;
_pos = offs;
break;
case SEEK_CUR:
_ptr += offs;
_pos += offs;
break;
}
// Post-Condition
assert(_pos <= _size);
// Reset end-of-stream flag on a successful seek
_eos = false;
return true; // FIXME: STREAM REWRITE
}
#pragma mark -
enum {
LF = 0x0A,
CR = 0x0D
};
char *SeekableReadStream::readLine(char *buf, size_t bufSize) {
assert(buf != nullptr && bufSize > 1);
char *p = buf;
size_t len = 0;
char c = 0;
// If end-of-file occurs before any characters are read, return NULL
// and the buffer contents remain unchanged.
if (eos() || err()) {
return nullptr;
}
// Loop as long as there is still free space in the buffer,
// and the line has not ended
while (len + 1 < bufSize && c != LF) {
c = readByte();
if (eos()) {
// If end-of-file occurs before any characters are read, return
// NULL and the buffer contents remain unchanged.
if (len == 0)
return nullptr;
break;
}
// If an error occurs, return NULL and the buffer contents
// are indeterminate.
if (err())
return nullptr;
// Check for CR or CR/LF
// * DOS and Windows use CRLF line breaks
// * Unix and OS X use LF line breaks
// * Macintosh before OS X used CR line breaks
if (c == CR) {
// Look at the next char -- is it LF? If not, seek back
c = readByte();
if (err()) {
return nullptr; // error: the buffer contents are indeterminate
}
if (eos()) {
// The CR was the last character in the file.
// Reset the eos() flag since we successfully finished a line
clearErr();
} else if (c != LF) {
seek(-1, SEEK_CUR);
}
// Treat CR & CR/LF as plain LF
c = LF;
}
*p++ = c;
len++;
}
// We always terminate the buffer if no error occurred
*p = 0;
return buf;
}
String SeekableReadStream::readLine() {
// Read a line
String line;
while (line.lastChar() != '\n') {
char buf[256];
if (!readLine(buf, 256))
break;
line += buf;
}
if (line.lastChar() == '\n')
line.deleteLastChar();
return line;
}
uint32 SubReadStream::read(void *dataPtr, uint32 dataSize) {
if (dataSize > _end - _pos) {
dataSize = _end - _pos;
_eos = true;
}
dataSize = _parentStream->read(dataPtr, dataSize);
_pos += dataSize;
return dataSize;
}
SeekableSubReadStream::SeekableSubReadStream(SeekableReadStream *parentStream, uint32 begin, uint32 end, DisposeAfterUse::Flag disposeParentStream)
: SubReadStream(parentStream, end, disposeParentStream),
_parentStream(parentStream),
_begin(begin) {
assert(_begin <= _end);
_pos = _begin;
_parentStream->seek(_pos);
_eos = false;
}
bool SeekableSubReadStream::seek(int32 offset, int whence) {
assert(_pos >= _begin);
assert(_pos <= _end);
switch (whence) {
case SEEK_END:
offset = size() + offset;
// fallthrough
case SEEK_SET:
_pos = _begin + offset;
break;
case SEEK_CUR:
_pos += offset;
}
assert(_pos >= _begin);
assert(_pos <= _end);
bool ret = _parentStream->seek(_pos);
if (ret) _eos = false; // reset eos on successful seek
return ret;
}
uint32 SafeSeekableSubReadStream::read(void *dataPtr, uint32 dataSize) {
// Make sure the parent stream is at the right position
seek(0, SEEK_CUR);
return SeekableSubReadStream::read(dataPtr, dataSize);
}
void SeekableReadStream::hexdump(int len, int bytesPerLine, int startOffset) {
uint pos_ = pos();
uint size_ = size();
uint toRead = MIN<uint>(len + startOffset, size_ - pos_);
byte *data = (byte *)calloc(toRead, 1);
read(data, toRead);
Common::hexdump(data, toRead, bytesPerLine, startOffset);
free(data);
seek(pos_);
}
#pragma mark -
namespace {
/**
* 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:
DisposablePtr<ReadStream> _parentStream;
byte *_buf;
uint32 _pos;
bool _eos; // end of stream
uint32 _bufSize;
uint32 _realBufSize;
public:
BufferedReadStream(ReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream);
virtual ~BufferedReadStream();
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);
};
BufferedReadStream::BufferedReadStream(ReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream)
: _parentStream(parentStream, disposeParentStream),
_pos(0),
_eos(false),
_bufSize(0),
_realBufSize(bufSize) {
assert(parentStream);
_buf = new byte[bufSize];
assert(_buf);
}
BufferedReadStream::~BufferedReadStream() {
delete[] _buf;
}
uint32 BufferedReadStream::read(void *dataPtr, uint32 dataSize) {
uint32 alreadyRead = 0;
const uint32 bufBytesLeft = _bufSize - _pos;
// Check whether the data left in the buffer suffices....
if (dataSize > bufBytesLeft) {
// Nope, we need to read more data
// First, flush the buffer, if it is non-empty
if (0 < bufBytesLeft) {
memcpy(dataPtr, _buf + _pos, bufBytesLeft);
_pos = _bufSize;
alreadyRead += bufBytesLeft;
dataPtr = (byte *)dataPtr + bufBytesLeft;
dataSize -= bufBytesLeft;
}
// At this point the buffer is empty. Now if the read request
// exceeds the buffer size, just satisfy it directly.
if (dataSize > _realBufSize) {
uint32 n = _parentStream->read(dataPtr, dataSize);
if (_parentStream->eos())
_eos = true;
return alreadyRead + n;
}
// Refill the buffer.
// If we didn't read as many bytes as requested, the reason
// is EOF or an error. In that case we truncate the buffer
// size, as well as the number of bytes we are going to
// return to the caller.
_bufSize = _parentStream->read(_buf, _realBufSize);
_pos = 0;
if (_bufSize < dataSize) {
// we didn't get enough data from parent
if (_parentStream->eos())
_eos = true;
dataSize = _bufSize;
}
}
if (dataSize) {
// Satisfy the request from the buffer
memcpy(dataPtr, _buf + _pos, dataSize);
_pos += dataSize;
}
return alreadyRead + dataSize;
}
} // End of anonymous namespace
ReadStream *wrapBufferedReadStream(ReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream) {
if (parentStream)
return new BufferedReadStream(parentStream, bufSize, disposeParentStream);
return nullptr;
}
#pragma mark -
namespace {
/**
* 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, DisposeAfterUse::Flag disposeParentStream = DisposeAfterUse::NO);
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);
};
BufferedSeekableReadStream::BufferedSeekableReadStream(SeekableReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream)
: BufferedReadStream(parentStream, bufSize, disposeParentStream),
_parentStream(parentStream) {
}
bool BufferedSeekableReadStream::seek(int32 offset, int whence) {
// If it is a "local" seek, we may get away with "seeking" around
// in the buffer only.
_eos = false; // seeking always cancels EOS
int relOffset = 0;
switch (whence) {
case SEEK_SET:
relOffset = offset - pos();
break;
case SEEK_CUR:
relOffset = offset;
break;
case SEEK_END:
relOffset = (size() + offset) - pos();
break;
default:
break;
}
if ((int)_pos + relOffset >= 0 && _pos + relOffset <= _bufSize) {
_pos += relOffset;
// Note: we do not need to reset parent's eos flag here. It is
// sufficient that it is reset when actually seeking in the parent.
} else {
// Seek was not local enough, so we reset the buffer and
// just seek normally in the parent stream.
if (whence == SEEK_CUR)
offset -= (_bufSize - _pos);
// We invalidate the buffer here. This assures that successive seeks
// do not have the chance to incorrectly think they seeked back into
// the buffer.
// Note: This does not take full advantage of the buffer. But it is
// a simple way to prevent nasty errors. It would be possible to take
// full advantage of the buffer by saving its actual start position.
// This seems not worth the effort for this seemingly uncommon use.
_pos = _bufSize = 0;
_parentStream->seek(offset, whence);
}
return true;
}
} // End of anonymous namespace
SeekableReadStream *wrapBufferedSeekableReadStream(SeekableReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream) {
if (parentStream)
return new BufferedSeekableReadStream(parentStream, bufSize, disposeParentStream);
return nullptr;
}
#pragma mark -
namespace {
/**
* Wrapper class which adds buffering to any WriteStream.
*/
class BufferedWriteStream : public WriteStream {
protected:
WriteStream *_parentStream;
byte *_buf;
uint32 _pos;
const uint32 _bufSize;
/**
* Write out the data in the buffer.
*
* @note This method is identical to flush() (which actually is
* implemented by calling this method), except that it is not
* virtual, hence there is less overhead calling it.
*/
bool flushBuffer() {
const uint32 bytesToWrite = _pos;
if (bytesToWrite) {
_pos = 0;
if (_parentStream->write(_buf, bytesToWrite) != bytesToWrite)
return false;
}
return true;
}
public:
BufferedWriteStream(WriteStream *parentStream, uint32 bufSize)
: _parentStream(parentStream),
_pos(0),
_bufSize(bufSize) {
assert(parentStream);
_buf = new byte[bufSize];
assert(_buf);
}
virtual ~BufferedWriteStream() {
const bool flushResult = flushBuffer();
assert(flushResult);
delete _parentStream;
delete[] _buf;
}
virtual uint32 write(const void *dataPtr, uint32 dataSize) {
// check if we have enough space for writing to the buffer
if (_bufSize - _pos >= dataSize) {
memcpy(_buf + _pos, dataPtr, dataSize);
_pos += dataSize;
} else if (_bufSize >= dataSize) { // check if we can flush the buffer and load the data
const bool flushResult = flushBuffer();
assert(flushResult);
memcpy(_buf, dataPtr, dataSize);
_pos += dataSize;
} else { // too big for our buffer
const bool flushResult = flushBuffer();
assert(flushResult);
return _parentStream->write(dataPtr, dataSize);
}
return dataSize;
}
virtual bool flush() { return flushBuffer(); }
virtual int32 pos() const { return _pos; }
};
} // End of anonymous namespace
WriteStream *wrapBufferedWriteStream(WriteStream *parentStream, uint32 bufSize) {
if (parentStream)
return new BufferedWriteStream(parentStream, bufSize);
return nullptr;
}
} // End of namespace Common