Delphi - threads and FindFirst function

Question

Hi,

I'm encountering a big problem when i'm trying to make a recursive search function inside a thread (using delphi 7) bellow is the code:

TParcFicDir = class(TThread)
private
 several variables..
 protected
    procedure Execute; override;
  public
    constructor Create(CreateSuspended: Boolean);


constructor TParcFicDir.Create(CreateSuspended: Boolean);
begin
 inherited Create(CreateSuspended);
end;

procedure TParcFicDir.Execute;
begin
 try
  FindFiles(FStartDir,FMask);//'c:\' and '*.*'
 except on e:Exception do
 end;
end;

procedure TParcFicDir.FindFiles(StartDir, FileMask: string);
var
  wTmp              : string;
  f:TextFile;
  wTempSR:TSearchRec;

  function Search(StartDir, FileMask: string): string;
  var
    SR              : TSearchRec;
    IsFound         : Boolean;
    files           : integer;
    dirs            : integer;
    t               : string;
  begin
    try
      files := 0;
      dirs := 0;
      if StartDir[length(StartDir)] <> '\' then
        StartDir := StartDir + '\';
      try
        IsFound := (FindFirst(StartDir + '*.*', faAnyFile, SR) = 0);// here the thread gets interrupted
      except on e: Exception do
      end;
      while IsFound do
      begin
        if (SR.Name <> '.') and (SR.Name <> '..') then
          if ((SR.Attr and faDirectory) <> 0) then
          if FScanDirs then 
          begin
            inc(dirs);
            t := Search(StartDir + SR.Name, FileMask);
            try
              files := files + strtoint(copy((t), 0, pos('#', t) - 1));//old code, don't take on calcul;
              Delete(t, 1, pos('#', t));
              dirs := dirs + strtoint(t);
            except on e: Exception do
            end;
            begin
              t := StartDir + SR.Name;
              wTmp := t;
              wtmp := '';
              Inc(FDirNo);
              writeln(f,t);
              inc(filno);
            end;
          end
          else
          if ScanFiles then 
          begin
           inc(filno);
           inc(files);
          end;
        IsFound := FindNext(SR) = 0;
      end;
      Result := IntToStr(files) + '#' + IntToStr(dirs);
      sysutils.FindClose(SR);
    except on e: Exception do
    end;
  end;
begin
 filno := 0;
  try
    try
      if trim(FPathFileTmp)<>'' then
       AssignFile(f, FPathFileTmp+'Temp.bak')
      else
       AssignFile(f,ExtractFileDir(GetDllName)+'\Temp.bak');
      Rewrite(f);
      Search(StartDir, FileMask);
      if StartDir[length(StartDir)] = '\' then
        delete(StartDir, length(StartDir), 1);
      wTmp := StartDir;
      wTmp := '';
      if FindFirst(StartDir, faDirectory, wTempSR) = 0 then
      writeln(f);
      writeln(f);
      CloseFile(f);
    except on e: Exception do
    end;
  finally
  end;
end;

ok, probably the code is a little messed up, but i don't understand why the thread ends at 'findfirst' part....i googled it, no results.

any help will be appreciated!

Thanks in advance

Answer 1

In your posted code I see that you try catch and forget the exception. When you have broken code that contains something like that, the very first thing I do is remove the empty except block. Odds are that don't know what is going on because your throwing the information you need away.

You have two calls to FindFirst() in your code. The usage of the one where your trying to find a directory is suspect. I would change your code to something like this.

var
 SR : TSearchRec;

begin
  if FindFirst('C:\',faDirectory,SR) <> 0 then
     RaiseLastOSError;
end;

Then you will see the reason FindFirst() Failed.

Instead of using FindFirst() in the case where your looking for the directory I would use the DirectoryExists() call instead.