FileSplitter.pas

unit FileSplitter;

interface

uses
	System.SysUtils, System.Classes, MRC_Helper, Winapi.Windows, PLUGIN_TYPES;

Const
	CRCSeed = $FFFFFFFF;
	CRC32tab: Array [0 .. 255] of DWord = ($00000000, $77073096, $EE0E612C, $990951BA, $076DC419, $706AF48F, $E963A535, $9E6495A3, $0EDB8832, $79DCB8A4, $E0D5E91E, $97D2D988, $09B64C2B, $7EB17CBD, $E7B82D07, $90BF1D91, $1DB71064, $6AB020F2, $F3B97148, $84BE41DE, $1ADAD47D, $6DDDE4EB, $F4D4B551, $83D385C7, $136C9856, $646BA8C0, $FD62F97A, $8A65C9EC, $14015C4F, $63066CD9, $FA0F3D63, $8D080DF5, $3B6E20C8, $4C69105E, $D56041E4, $A2677172, $3C03E4D1, $4B04D447, $D20D85FD, $A50AB56B, $35B5A8FA, $42B2986C, $DBBBC9D6, $ACBCF940, $32D86CE3, $45DF5C75, $DCD60DCF, $ABD13D59, $26D930AC, $51DE003A, $C8D75180, $BFD06116, $21B4F4B5, $56B3C423, $CFBA9599, $B8BDA50F, $2802B89E, $5F058808, $C60CD9B2, $B10BE924, $2F6F7C87, $58684C11, $C1611DAB, $B6662D3D, $76DC4190, $01DB7106, $98D220BC, $EFD5102A, $71B18589,
		$06B6B51F, $9FBFE4A5, $E8B8D433, $7807C9A2, $0F00F934, $9609A88E, $E10E9818, $7F6A0DBB, $086D3D2D, $91646C97, $E6635C01, $6B6B51F4, $1C6C6162, $856530D8, $F262004E, $6C0695ED, $1B01A57B, $8208F4C1, $F50FC457, $65B0D9C6, $12B7E950, $8BBEB8EA, $FCB9887C, $62DD1DDF, $15DA2D49, $8CD37CF3, $FBD44C65, $4DB26158, $3AB551CE, $A3BC0074, $D4BB30E2, $4ADFA541, $3DD895D7, $A4D1C46D, $D3D6F4FB, $4369E96A, $346ED9FC, $AD678846, $DA60B8D0, $44042D73, $33031DE5, $AA0A4C5F, $DD0D7CC9, $5005713C, $270241AA, $BE0B1010, $C90C2086, $5768B525, $206F85B3, $B966D409, $CE61E49F, $5EDEF90E, $29D9C998, $B0D09822, $C7D7A8B4, $59B33D17, $2EB40D81, $B7BD5C3B, $C0BA6CAD, $EDB88320, $9ABFB3B6, $03B6E20C, $74B1D29A, $EAD54739, $9DD277AF, $04DB2615, $73DC1683, $E3630B12, $94643B84, $0D6D6A3E, $7A6A5AA8, $E40ECF0B,
		$9309FF9D, $0A00AE27, $7D079EB1, $F00F9344, $8708A3D2, $1E01F268, $6906C2FE, $F762575D, $806567CB, $196C3671, $6E6B06E7, $FED41B76, $89D32BE0, $10DA7A5A, $67DD4ACC, $F9B9DF6F, $8EBEEFF9, $17B7BE43, $60B08ED5, $D6D6A3E8, $A1D1937E, $38D8C2C4, $4FDFF252, $D1BB67F1, $A6BC5767, $3FB506DD, $48B2364B, $D80D2BDA, $AF0A1B4C, $36034AF6, $41047A60, $DF60EFC3, $A867DF55, $316E8EEF, $4669BE79, $CB61B38C, $BC66831A, $256FD2A0, $5268E236, $CC0C7795, $BB0B4703, $220216B9, $5505262F, $C5BA3BBE, $B2BD0B28, $2BB45A92, $5CB36A04, $C2D7FFA7, $B5D0CF31, $2CD99E8B, $5BDEAE1D, $9B64C2B0, $EC63F226, $756AA39C, $026D930A, $9C0906A9, $EB0E363F, $72076785, $05005713, $95BF4A82, $E2B87A14, $7BB12BAE, $0CB61B38, $92D28E9B, $E5D5BE0D, $7CDCEFB7, $0BDBDF21, $86D3D2D4, $F1D4E242, $68DDB3F8, $1FDA836E, $81BE16CD,
		$F6B9265B, $6FB077E1, $18B74777, $88085AE6, $FF0F6A70, $66063BCA, $11010B5C, $8F659EFF, $F862AE69, $616BFFD3, $166CCF45, $A00AE278, $D70DD2EE, $4E048354, $3903B3C2, $A7672661, $D06016F7, $4969474D, $3E6E77DB, $AED16A4A, $D9D65ADC, $40DF0B66, $37D83BF0, $A9BCAE53, $DEBB9EC5, $47B2CF7F, $30B5FFE9, $BDBDF21C, $CABAC28A, $53B39330, $24B4A3A6, $BAD03605, $CDD70693, $54DE5729, $23D967BF, $B3667A2E, $C4614AB8, $5D681B02, $2A6F2B94, $B40BBE37, $C30C8EA1, $5A05DF1B, $2D02EF8D);

type
	TFilePart = record
		filename: WideString;
		filesize: Int64;
	end;

	TSplittedFile = record
		filename: WideString;
		size: Int64;
		crc32: WideString; //String representation

		path: WideString; //Path to temp dir with splited files
		parts: array of TFilePart; //parts names
	end;

	TFileSplitter = class
	private
		Splitted: TSplittedFile;
		PartSize: Int64;
		totalPartsCount: Int64;
		ExternalProgressProc: TProgressHandler;

		function AddLeadingZeroes(const aNumber, Length: Integer): string;
		function crc32_update(inbuffer: pointer; buffersize, crc: DWord): DWord;
		function CRCend(crc: DWord): DWord;
	public
		constructor Create(filename: WideString; SplitSize: Int64; ExternalProgressProc: TProgressHandler = nil);
		destructor Destroy; override;
		function split(): Integer;
		function getSplittedPart(partNumber: Integer; var partStream: TFileStream): Integer; {Get nth part as tfilestream without splitting of all file}
		function getCRC32File(filename: WideString): WideString;
		function writeCRCFile: WideString;
		property SplitResult: TSplittedFile read Splitted;

	end;

implementation

{TFileSplitter}

function TFileSplitter.AddLeadingZeroes(const aNumber, Length: Integer): string;
begin
	result := System.SysUtils.Format('%.*d', [Length, aNumber]);
end;

function TFileSplitter.crc32_update(inbuffer: pointer; buffersize, crc: DWord): DWord;
type
	PDWord = ^DWord;
	PByte = ^Byte;
var
	currptr: pointer;
	i: Byte;
begin
	currptr := inbuffer;
	result := crc;
	while buffersize > 4 do
	begin
		result := result xor PDWord(currptr)^;
		inc(NativeInt(currptr), 4);
		result := (result shr 8) xor CRC32tab[Byte(result)];
		result := (result shr 8) xor CRC32tab[Byte(result)];
		result := (result shr 8) xor CRC32tab[Byte(result)];
		result := (result shr 8) xor CRC32tab[Byte(result)];
		dec(buffersize, 4);
	end;
	for i := 1 to buffersize do
	begin
		result := CRC32tab[Byte(result xor DWord(PByte(currptr)^))] xor (result shr 8);
		inc(NativeInt(currptr), 1);
	end;

end;

function TFileSplitter.CRCend(crc: DWord): DWord;
begin
	CRCend := (crc xor CRCSeed);
end;

constructor TFileSplitter.Create(filename: WideString; SplitSize: Int64; ExternalProgressProc: TProgressHandler = nil);
begin
	//TODO проверка на существование
	self.PartSize := SplitSize;
	self.Splitted.filename := filename;
	self.Splitted.size := SizeOfFile(filename);
	self.ExternalProgressProc := ExternalProgressProc;

	self.totalPartsCount := self.Splitted.size div self.PartSize;
	if (self.Splitted.size mod self.PartSize) <> 0 then
		inc(self.totalPartsCount);

	self.Splitted.path := IncludeTrailingBackslash(GetTmpDir + GetCurrentProcessId.ToString());
	if not DirectoryExists(self.Splitted.path) then
	begin
		if not CreateDir(self.Splitted.path) then
			Raise Exception.CreateFmt('Can''t create temp directory : ''%s''', [self.Splitted.path]);
	end;
	//self.Splitted.crc32 := self.getCRC32File(filename);
end;

destructor TFileSplitter.Destroy;
var
	SplittedPartIndex: Integer;
begin
	for SplittedPartIndex := 0 to Length(self.SplitResult.parts) - 1 do
	begin
		if FileExists(self.SplitResult.parts[SplittedPartIndex].filename) then
			DeleteFileW(PWideChar(self.SplitResult.parts[SplittedPartIndex].filename));
	end;
	if FileExists(self.Splitted.path + ChangeFileExt(ExtractFileName(self.Splitted.filename), '.crc')) then
		DeleteFileW(PWideChar(self.Splitted.path + ChangeFileExt(ExtractFileName(self.Splitted.filename), '.crc')));
	inherited;
end;

function TFileSplitter.getCRC32File(filename: WideString): WideString;
var
	inFile: file;
	CRCValue: DWord;
	inbuffer: array [1 .. 32768] of Byte;
	ReadBytes: Integer;
begin //todo: change to TFileStream (just for code sameness
	AssignFile(inFile, filename);
	FileMode := fmOpenRead or fmShareDenyWrite;
	Reset(inFile, 1);
	CRCValue := CRCSeed;
	blockread(inFile, inbuffer, Sizeof(inbuffer), ReadBytes);
	repeat
		CRCValue := crc32_update(@inbuffer, ReadBytes, CRCValue);
		blockread(inFile, inbuffer, Sizeof(inbuffer), ReadBytes);
	until ReadBytes = 0;
	CloseFile(inFile);
	CRCValue := CRCend(CRCValue);
	exit(IntToHex(CRCValue, 8));
end;

function TFileSplitter.getSplittedPart(partNumber: Integer; var partStream: TFileStream): Integer;
var
	PartSize: Int64;
	FStream: TFileStream;
begin
	try
		FStream := TFileStream.Create(self.Splitted.filename, fmOpenRead or fmShareDenyWrite);
	except
		exit(FS_FILE_READERROR);
	end;
	if partNumber >= self.totalPartsCount then
		exit(FS_FILE_NOTSUPPORTED);

	FStream.Position := self.PartSize * partNumber;

	if partNumber = self.totalPartsCount - 1 then //last part of file
	begin
		PartSize := self.Splitted.size - (self.PartSize * partNumber);
	end
	else
		PartSize := self.PartSize;
	partStream.CopyFrom(FStream, PartSize);
	result := FS_FILE_OK;
end;

function TFileSplitter.split: Integer;
var
	partsCount: Integer;
	FStream, WStream: TFileStream;
	PartName: WideString;
	PartSize: Int64;
	Percent: Integer;
begin

	try
		FStream := TFileStream.Create(self.Splitted.filename, fmOpenRead or fmShareDenyWrite);
	except
		exit(FS_FILE_READERROR);
	end;
	FStream.Position := 0;

	SetLength(self.Splitted.parts, self.totalPartsCount);
	for partsCount := 0 to self.totalPartsCount - 1 do
	begin
		PartName := self.Splitted.path + ExtractFileName(ChangeFileExt(self.Splitted.filename, '.' + self.AddLeadingZeroes(partsCount + 1, 3)));
		if Assigned(self.ExternalProgressProc) then
		begin
			Percent := 100 * partsCount div self.totalPartsCount;
			if ExternalProgressProc(PWideChar('Splitting ' + self.Splitted.filename), PWideChar((partsCount + 1).ToString + ' of ' + self.totalPartsCount.ToString), Percent) = 1 then
			begin //отменили разбивку
				FStream.Destroy;
				exit(FS_FILE_USERABORT);
			end;
		end;

		try
			WStream := TFileStream.Create(PartName, fmCreate);
		except
			exit(FS_FILE_WRITEERROR);
		end;
		FStream.Position := self.PartSize * partsCount;
		if partsCount = self.totalPartsCount - 1 then //last part of file
		begin
			PartSize := self.Splitted.size - (self.PartSize * partsCount);
		end
		else
			PartSize := self.PartSize;
		try
			WStream.CopyFrom(FStream, PartSize);
		except
			FStream.Destroy;
			Raise Exception.CreateFmt('Can''t write to temp file : ''%s''', [WStream.filename]);
			exit(FS_FILE_WRITEERROR);
		end;
		WStream.Destroy;
		self.Splitted.parts[partsCount].filename := PartName;
		self.Splitted.parts[partsCount].filesize := PartSize;
	end;
	FStream.Destroy;
	result := FS_FILE_OK;
end;

function TFileSplitter.writeCRCFile: WideString;
var
	content: TStringList;
begin
	content := TStringList.Create;
	content.Text := 'filename=' + ExtractFileName(self.Splitted.filename) + sLineBreak + 'size=' + self.SplitResult.size.ToString + sLineBreak + 'crc32=' + self.getCRC32File(self.Splitted.filename);
	result := self.Splitted.path + ChangeFileExt(ExtractFileName(self.Splitted.filename), '.crc');
	content.SaveToFile(result);
	content.Destroy;
end;

end.