nodejs调用delphi编写的dll

公司的业务需要，nodejs要读取文件版本号。

同事要求我用delphi编写dll，以供nodejs调用，结果通过json返回。

delphi代码如下：

 function GetFileInfo(APath: PAnsiChar): PAnsiChar;
 var
   sPath: string;
   FInfoSize, Temp, Len: Cardinal;
   InfoBuf: Pointer;
   TranslationLength: Cardinal;
   TranslationTable: Pointer;
   LanguageID, CodePage, LookupString: String;
   Value: PChar;
   vJ: ISuperObject;
 begin
   sPath := Utf8ToAnsi(strPas(APath));
   FInfoSize := GetFileVersionInfoSize(PChar(sPath), Temp);
   vJ := SO;
   if FInfoSize >  then
   begin
     InfoBuf := AllocMem(FInfoSize);
     try  // try
       GetFileVersionInfo(PChar(sPath), , FInfoSize, InfoBuf);

       if VerQueryValue( InfoBuf, '\VarFileInfo\Translation', TranslationTable, TranslationLength ) then
       begin
         CodePage := Format( '%.4x', [ HiWord( PLongInt( TranslationTable )^ ) ] );
         LanguageID := Format( '%.4x', [ LoWord( PLongInt( TranslationTable )^ ) ] );
       end;
       LookupString := 'StringFileInfo\' + LanguageID + CodePage + '\';

       if VerQueryValue( InfoBuf, PChar( LookupString + 'CompanyName' ), Pointer( Value ), Len ) then
         vJ.S['CompanyName'] := Value;
       if VerQueryValue( InfoBuf, PChar( LookupString + 'FileDescription' ), Pointer( Value ), Len ) then
         vJ.S['FileDescription'] := Value;
       if VerQueryValue( InfoBuf, PChar( LookupString + 'FileVersion' ), Pointer( Value ), Len ) then
         vJ.S['FileVersion'] := Value;
       if VerQueryValue( InfoBuf, PChar( LookupString + 'InternalName' ), Pointer( Value ), Len ) then
         vJ.S['InternalName'] := Value;
       if VerQueryValue( InfoBuf, PChar( LookupString + 'LegalCopyright' ), Pointer( Value ), Len ) then
         vJ.S['LegalCopyright'] := Value;
       if VerQueryValue( InfoBuf, PChar( LookupString + 'LegalTrademarks' ), Pointer( Value ), Len ) then
         vJ.S['LegalTrademarks'] := Value;
       if VerQueryValue( InfoBuf, PChar( LookupString + 'OriginalFilename' ), Pointer( Value ), Len ) then
         vJ.S['OriginalFilename'] := Value;
       if VerQueryValue( InfoBuf, PChar( LookupString + 'ProductName' ), Pointer( Value ), Len ) then
         vJ.S['ProductName'] := Value;
       if VerQueryValue( InfoBuf, PChar( LookupString + 'ProductVersion' ), Pointer( Value ), Len ) then
         vJ.S['ProductVersion'] := Value;
       if VerQueryValue( InfoBuf, PChar( LookupString + 'Comments' ), Pointer( Value ), Len ) then
         vJ.S['Comments'] := Value;
     finally  // wrap up finally
       FreeMem(InfoBuf, FInfoSize);
     end;  // end try finally
   end;
   Result := PAnsiChar(AnsiString(vJ.AsJSon));
 end;

PS：

1. 用到的字符串可能较长，注意调用ShareMem

2. 所有的string类型都需要定义成PAnsiChar

3. 此处nodejs使用的编码是utf8，需要转码

4. 返回值，需先通过AnsiString转换，再转换PAnsiChar，不然只能读取到第一个字符

nodejs测试代码如下：

 var ffi = require('ffi');

 try {
     var demo = ffi.Library('./fileInfo', {
         'GetFileInfo': [ 'string', ['string'] ],
     });

     console.log(demo);
     const info = demo.GetFileInfo('C:\\Program Files (x86)\\Tencent\\WeChat\\WeChat.exe');
     console.log(JSON.parse(info));
     console.log('End Test');
 } catch(err) {
     console.log(err);
 }

测试结果如下：