From: fv@tcenl.nospam.com   
      
   In the obscure news:1128668078.984102.77090@o13g2000cwo.googlegroups.com,   
    Someone calling himself Wim   
    suspiciously hiding as  uttered:   
   > A TP program crashes sometimes because the file it tries to   
   > rewrite/rename is locked by a virusscanner. I would like to include   
   > some code to check for a locked file and wait some time to see if the   
   > file lock has been removed.   
   >   
   > Typically a function like the following will be invoked just before   
   > doing a (major) file operation:   
   >   
   > function WaiFF( const FileName: string ): Boolean ;   
   > {*   
   >  * Function Wait_File_Free returns a true value if file FileName is   
   > not   
   >  * locked. If the file is locked, it will wait for some time. WaiFF   
   > will   
   >  * return a false value if the file is still locked.   
   >  *}   
   > const   
   >   MaxTries= 3 ;  { Maximum number of tries minus one }   
   > var   
   >   WaitTime: Integer ;  { Time lapse }   
   >   i : Integer ;  { Loop control variable }   
   > begin   
   >   WaiFF:= True ;  { Expected function result }   
   >   
   >   if ufFileLocked( FileName ) then   
   >    begin   
   >     WaitTime:= 1 ;  { Waiting time in seconds }   
   >     for i:=0 to MaxTries do   
   >      begin   
   >       ufTimedWait( WaitTime ) ;   
   >       WaitTime:= WaitTime * 2 ;  { Increase wait time for next pass }   
   >       if not ufFileLocked( FileName ) then  Exit ;   
   >      end ;  { of for}   
   >    end   
   >   else  { if file not locked then }   
   >     Exit ;   
   >   
   >   WriteLn( LogFile, 'Error - File ', FileName, ' is locked' ) ;   
   >   WaiFF:= False ;   
   > end ;   
   >   
   > Searching the web i did not find any code snippets for implementing   
   > the functions ufFileLocked and ufTimedWait. For the latter function,   
   > the function Wait in TPL is probably not a good choice ,as it is only   
   > a CPU-time-consuming loop. The process which locked the file (in my   
   > case a virusscanner), should get the CPU to finish it's job.   
   >   
   > Can someone give me pointers on how to write those two uf* functions?   
   >   
      
   Why so difficult?   
      
   The standard way of preventing an IO crash in TP is by switching off   
   input/output checking   
   code    {$I-}   
   In order to check the result call the IOResult function.   
   Look for both of these in the TP help file. {shift F1}   
   e.g.   
      
    var F: text;   
    begin   
     Assign(F, 'c:\autoexec.bat');   
     {$I-}                 {turn off IO error checking, }   
     Reset(F);   
       if IOResult <> 0 then   
            Writeln('File opening error');   
       else   
       begin   
            while not eof(f) do   
              ........   {start reading}   
           close(F);   
       end;   
     {$I+}      {turn IO checking back on}   
    end.   
      
      
      
      
   --   
   Femme Verbeek   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)