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0
forked from 0ad/0ad
0ad/source/ps/FileIo.h
bb 157c6af18e Make the space in 0 A.D. non-breaking throughout the codebase.
Avoid cases of filenames
Update years in terms and other legal(ish) documents
Don't update years in license headers, since change is not meaningful

Will add linter rule in seperate commit

Happy recompiling everyone!

Original Patch By: Nescio
Comment By: Gallaecio
Differential Revision: D2620
This was SVN commit r27786.
2023-07-27 20:54:46 +00:00

150 lines
4.1 KiB
C++

/* Copyright (C) 2021 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. 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.
*
* 0 A.D. 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 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* endian-safe binary file IO helpers.
*/
// the file format has passing similarity to IFF. note however that
// "chunks" aren't identified by FOURCCs; only the file header is
// so marked.
// all > 8-bit integers are stored in little-endian format
// (hence the _le suffix). however, the caller is responsible for
// swapping their raw data before passing it to PackRaw. a convenience
// routine is provided for the common case of storing size_t.
#ifndef INCLUDED_FILEPACKER
#define INCLUDED_FILEPACKER
#include "lib/file/vfs/vfs_path.h"
#include "ps/CStrForward.h"
#include "ps/Errors.h"
#include "ps/Filesystem.h" // WriteBuffer
ERROR_GROUP(File);
ERROR_TYPE(File, OpenFailed);
ERROR_TYPE(File, WriteFailed);
ERROR_TYPE(File, InvalidType);
ERROR_TYPE(File, InvalidVersion);
ERROR_TYPE(File, ReadFailed);
ERROR_TYPE(File, UnexpectedEOF);
/**
* helper class for writing binary files. this is basically a
* resizable buffer that allows adding raw data and strings;
* upon calling Write(), everything is written out to disk.
**/
class CFilePacker
{
public:
/**
* adds version and signature (i.e. the header) to the buffer.
* this means Write() can write the entire buffer to file in one go,
* which is simpler and more efficient than writing in pieces.
**/
CFilePacker(u32 version, const char magic[4]);
~CFilePacker();
/**
* write out to file all packed data added so far.
* it's safe to call this multiple times, but typically would
* only be done once.
**/
void Write(const VfsPath& filename);
/**
* pack given number of bytes onto the end of the data stream
**/
void PackRaw(const void* rawData, size_t rawDataSize);
/**
* convenience: convert a number (almost always a size type) to
* little-endian u32 and pack that.
**/
void PackSize(size_t value);
/**
* pack a string onto the end of the data stream
* (encoded as a 32-bit length followed by the characters)
**/
void PackString(const CStr8& str);
private:
/**
* the output data stream built during pack operations.
* contains the header, so we can write this out in one go.
**/
WriteBuffer m_writeBuffer;
};
/**
* helper class for reading binary files
**/
class CFileUnpacker
{
public:
CFileUnpacker();
~CFileUnpacker();
/**
* open and read in given file, check magic bits against those given;
* throw variety of exceptions if open failed / version incorrect, etc.
**/
void Read(const VfsPath& filename, const char magic[4]);
/**
* @return version number that was stored in the file's header.
**/
u32 GetVersion() const
{
return m_version;
}
/**
* unpack given number of bytes from the input into the given array.
* throws PSERROR_File_UnexpectedEOF if the end of the data stream is
* reached before the given number of bytes have been read.
**/
void UnpackRaw(void* rawData, size_t rawDataSize);
/**
* use UnpackRaw to retrieve 32-bits; returns their value as size_t
* after converting from little endian to native byte order.
**/
size_t UnpackSize();
/**
* unpack a string from the raw data stream.
* @param result is assigned a newly constructed CStr8 holding the
* string read from the input stream.
**/
void UnpackString(CStr8& result);
private:
// the data read from file and used during unpack operations
std::shared_ptr<u8> m_buf;
size_t m_bufSize;
size_t m_unpackPos; /// current unpack position in stream
u32 m_version; /// version that was stored in the file header
};
#endif