{
* UFolderBackup.pas
*
* Class that can back up all the files in a folder into a single file. All
* files to be backed up must be text files.
*
* $Rev$
* $Date$
*
* ***** BEGIN LICENSE BLOCK *****
*
* Version: MPL 1.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
* the specific language governing rights and limitations under the License.
*
* The Original Code is UFolderBackup.pas
*
* The Initial Developer of the Original Code is Peter Johnson
* (http://www.delphidabbler.com/).
*
* Portions created by the Initial Developer are Copyright (C) 2009 Peter
* Johnson. All Rights Reserved.
*
* Contributor(s)
* NONE
*
* ***** END LICENSE BLOCK *****
}
unit UFolderBackup;
interface
type
{
TFolderBackup:
Class that can back up and restore all the files in a folder to or from a
single file. All files to be backed up must be text files.
}
TFolderBackup = class(TObject)
strict private
var
fSrcFolder: string; // Folder to be backed up or restored
fBakFile: string; // Full path to backup file
fFileID: SmallInt; // Identifies the type of file
const
cWatermark = SmallInt($FFFF); // File watermark (v2 and later)
function SourceFileSpec(const FileName: string): string;
{Full path to a file in backed up folder.
@param FileName [in] Base name of file.
@return Full file spec of FileName in source folder.
}
public
constructor Create(const SrcFolder, BakFile: string;
const FileID: SmallInt);
{Class constructor. Creates backup object for specified folder and backup
file.
@param SrcFolder [in] Folder to be backed up / restored. Must contain
only text files. Sub folders are ignored.
@param BakFile [in] Name of backup file.
@param FileID [in] File type identifier.
}
procedure Backup;
{Backs up source folder into single backup file. Backup file is marked
with the file ID passed to constructor.
}
procedure Restore;
{Restores folder from backup file.
@except ECodeSnip raised if any checksum errors are found or, for v3 and
later format files, if file type id is incorrect.
}
end;
implementation
uses
// Delphi
SysUtils, Classes,
// Project
UCheckSum, UDataStreamIO, UDOSDateTime, UExceptions, UUtils;
{
Backup file format
------------------
File comprises ASCII text characters. Numbers are encoded in hex format. Only
text files can be backed up. There are three supported file formats. All three
formats can be read while only v3 files are written.
Version 1 Format
----------------
FileCount: SmallInt - number of files encoded in backup file
followed by FileCount file records of:
Name: SizedString; - name of file without path information
FileDate: LongInt; - file's modification date (DOS file stamp as
LongInt).
MD5: String[32]; - MD5 checksum of original file on server
(MD5 of Content should match this value)
Content: SizedString; - file contents
Version 2 Format
----------------
$FFFF - Indicator of post-v1 file type
$0002 - Indicator for v2 file type
FileCount: SmallInt - number of files encoded in backup file
followed by FileCount file records of:
Name: SizedString; - name of file without path information
FileDate: LongInt; - file's modification date (DOS file stamp as
LongInt).
MD5: String[32]; - MD5 checksum of original file on server
(MD5 of Content should match this value)
Content: SizedLongString; - file contents
Version 3 Format
----------------
$FFFF - Indicator of post-v1 file type
$0003 - Indicator for v3 file type
FileID: SmallInt - indicator for file type (user defined)
FileCount: SmallInt - number of files encoded in backup file
followed by FileCount file records of:
Name: SizedString; - name of file without path information
FileDate: LongInt; - file's modification date (DOS file stamp as
LongInt).
MD5: String[32]; - MD5 checksum of original file on server
(MD5 of Content should match this value)
Content: SizedLongString; - file contents
Data types
----------
SmallInt - 16 bit integer encoded as 4 hex digits
LongInt - 32 bit integer encoded as 8 hex digits
SizedString - SmallInt specifying string length followed by specified
number of characters
SizedLongString - LongInt specifying string length followed by specified
number of characters
String[32] - 32 character fixed length string
}
{ TFolderBackup }
procedure TFolderBackup.Backup;
{Backs up source folder into single backup file. Backup file is marked with
the file ID passed to constructor.
}
var
Writer: TDataStreamWriter; // object used to write data to stream
Files: TStringList; // list of files in database directory
FileName: string; // references each file in database
Content: string; // content of each database file
DOSDateTime: IDOSDateTime; // date stamp of each database file
begin
Files := nil;
// Create output stream to backup file
Writer := TDataStreamWriter.Create(
TFileStream.Create(fBakFile, fmCreate), True
);
try
// Get list of files in database
Files := TStringList.Create;
ListFiles(fSrcFolder, '*.*', Files, False);
// Write file header, including number of files
Writer.WriteSmallInt(cWatermark); // file marker
Writer.WriteSmallInt($0003); // file version
Writer.WriteSmallInt(fFileID); // file ID
Writer.WriteSmallInt(Files.Count); // number of files
// Write details of each file
for FileName in Files do
begin
Writer.WriteSizedString(FileName);
DOSDateTime := TDOSDateTimeFactory.CreateFromFile(
SourceFileSpec(FileName)
);
Writer.WriteLongInt(DOSDateTime.DateStamp);
Content := FileToString(SourceFileSpec(FileName));
Writer.WriteString(TCheckSum.Calculate(Content), 32);
Writer.WriteSizedLongString(Content);
end;
finally
FreeAndNil(Files);
FreeAndNil(Writer);
end;
end;
constructor TFolderBackup.Create(const SrcFolder, BakFile: string;
const FileID: SmallInt);
{Class constructor. Creates backup object for specified folder and backup
file.
@param SrcFolder [in] Folder to be backed up / restored. Must contain only
text files. Sub folders are ignored.
@param BakFile [in] Name of backup file.
@param FileID [in] File type identifier.
}
begin
inherited Create;
fSrcFolder := ExcludeTrailingPathDelimiter(SrcFolder);
fBakFile := BakFile;
fFileID := FileID;
end;
procedure TFolderBackup.Restore;
{Restores folder from backup file.
@except ECodeSnip raised if any checksum errors are found or, for v3 and
later format files, if file type id is incorrect.
}
var
Reader: TDataStreamReader; // object used to read data from file
FileCount: Integer; // number of files to restore
Idx: Integer; // loops through all files in backup
FileName: string; // name of file to restore
MD5: string; // checksum of file to restore
Content: string; // content of file to restore
DOSDateTime: IDOSDateTime; // date stamp of file to restore
HeaderWord: SmallInt; // first word value in file
Version: SmallInt; // file version
resourcestring
// Error message
sBadFileContent = 'Invalid content for file "%s"';
sBadFileID = 'Invalid file ID for file "%s"';
begin
// Make sure restore folder exists
EnsureFolders(fSrcFolder);
// Create reader to access data in backup file
Reader := TDataStreamReader.Create(
TFileStream.Create(fBakFile, fmOpenRead or fmShareDenyNone), True
);
try
// Get number of files stored in backup file and process each one
// Read 1st word of file. If it is $FFFF we have v2 or later file, otherwise
// it's v1
HeaderWord := Reader.ReadSmallInt;
if HeaderWord = cWatermark then
begin
// v2 or later: read version then file count
Version := Reader.ReadSmallInt;
if Version >= 3 then
begin
// version 3 of later: read file id
if Reader.ReadSmallInt <> fFileID then
raise ECodeSnip.CreateFmt(sBadFileID, [FileName]);
end;
FileCount := Reader.ReadSmallInt;
end
else
begin
// v1: file count was first word of file
Version := 1;
FileCount := HeaderWord;
end;
for Idx := 1 to FileCount do
begin
// Get file details: name, date stamp, checksum and content
FileName := SourceFileSpec(Reader.ReadSizedString);
DOSDateTime := TDOSDateTimeFactory.CreateFromDOSTimeStamp(
Reader.ReadLongInt
);
MD5 := Reader.ReadString(32);
if Version = 1 then
Content := Reader.ReadSizedString
else
Content := Reader.ReadSizedLongString;
if not TCheckSum.Compare(Content, MD5) then
raise ECodeSnip.CreateFmt(sBadFileContent, [FileName]);
// Write file and set date stamp
StringToFile(Content, FileName);
DOSDateTime.ApplyToFile(FileName);
end;
finally
FreeAndNil(Reader);
end;
end;
function TFolderBackup.SourceFileSpec(const FileName: string): string;
{Full path to a file in backed up folder.
@param FileName [in] Base name of file.
@return Full file spec of FileName in source folder.
}
begin
Result := IncludeTrailingPathDelimiter(fSrcFolder) + FileName;
end;
end.
