Detect-It-Easy/db/rar

// Detect a RAR archive.
// Author: Jason Hood <jadoxa@yahoo.com.au>

includeScript("archive");
sName="RAR";

function detect_RAR(bFile,bShowOptions)
{
    var nOffset,nSize;
    if(bFile)
    {
        nOffset=0;
        nSize=File.getSize();
    }
    else
    {
        nOffset=File.getOverlayOffset();
        nSize=File.getOverlaySize();
    }
    if(nSize>=64)
    {
        if(File.compare("'Rar!'1A07",nOffset))
        {
            switch(File.readByte(nOffset+6))
            {
            case 0: sVersion="4"; break;
            case 1: sVersion="5"; break;
            }
            bDetected=1;
        }
        else if(File.compare("'RE~^'",nOffset))
        {
            sVersion="1.4";
            bDetected=1;
        }
        if(sVersion=="4")
        {
            var nOptions=File.readByte(nOffset+10);
            if(nOptions&8)
            {
                sOptions="solid";
            }
            if(nOptions&0x80)
            {
                sOptions=sOptions.append("encrypted");
            }
            else if(bShowOptions)
            {
                nOffset+=7+File.readWord(nOffset+12);
                while(File.readByte(nOffset+2)!=0x74)
                {
                    nOffset+=File.readWord(nOffset+5)+File.readDword(nOffset+7);
                }
                while(File.readByte(nOffset+2)==0x74)
                {
                    var nLen=File.readDword(nOffset+7);
                    Archive.add(File.readDword(nOffset+11),nLen,
                                (File.readByte(nOffset+3)&0xE0)==0xE0);
                    nOffset+=File.readWord(nOffset+5)+nLen;
                }
                sOptions=sOptions.append(Archive.contents());
            }
        }
    }
}