File open or File close - my Question - your Answer ?

[paule32]

Hello,
I have the given Code.
The Problem I have is, that I get a "File access" problem - file in use.
How can I clode file handles ?

Code: Pascal  [Select][+][-]

1. procedure foo;
2. begin
3. ...
4.   if not FileExists(filename) then
5.   begin
6.     ShowMessage('Error: file: "' + filename + '" could not be found.');
7.     exit;
8.   end;
9.  
10.   Assign(SourceFile, filename);
11.   {$I-}
12.   Reset(SourceFile);
13.   {$I+}
14.  
15.   if IOResult <> 0 then
16.   begin
17.     ShowMessage(tr('Error: file: "') + filename + tr('" could not be open.'));
18.     Close(SourceFile);
19.     exit;
20.   end;
21.  
22.   Close(SourceFile);
23.   SendMessage('voodoo programming');
24. end;
25.  

[jamie]

By default, the RESET opens the file for Reading and Writing on untyped files.

You could try setting the

Code: Pascal  [Select][+][-]

1. FILEMODE :=0;
2.  

That would put it in read only mode.

jamie

[paule32]

Thanks for reply.

But I get a "File is open" error message.
The second MessageBox will not be displayed.

Code: Pascal  [Select][+][-]

1. procedure yymain(filename: String);
2. begin
3.   if not FileExists(filename) then
4.   begin
5.     ShowMessage(tr('Error: file: "') + filename + tr('" could not be found.'));
6.     yyclear;
7.     exit;
8.   end;
9.  
10.   filemode := 0;
11.   Assign(yyinput, filename);
12.   Reset(yyinput);
13.  
14.   Close(SourceFile);
15.   ShowMessage('Parsing abgeschlossen.');
16.   exit;

[Thaddy]

 Close(SourceFile);??
Must be
 Close(yyinput);

Filemode must indeed be 0
And before reset until after close the code must be in  {$I-} state otherwise IOResult makes no sense.

[d2010]

By default, the RESET opens the file for Reading and Writing on untyped files.

You could try setting the

Code: Pascal  [Select][+][-]

1. FILEMODE :=0;
2.  

That would put it in read only mode.
jamie

Please help me?,
C:Q1= You put FILEMODE:=00 before or After that "Assign?"
C:Q2= Why filesize (ftex7) is broken or crash?
         (I fix-it with Str_toFilesize ...)

Code: [Select]

  assign (ftex7,argv0);
  filemode :=000;
  {$I-}
  reset(ftex7, 1 );
  {$I+}
  IF ioresult <> 0 THEN exit...
  if (zprec.size<1) then zprec.size := filesize (ftex7);
  if (zprec.size<1) then  zprec.size:=Str_toFilesize(argv0);
End;
My Code work very good,

[Thaddy]

After assign and before reset/rewrite.
(Assign can not generate an IOResult)

[paule32]

I create the file with:
SynEdit.Lines.SaveToFile('tmp.tmp');

So, file exists

Code: Pascal  [Select][+][-]

1. procedure yymain(filename: String);
2. var
3.   fn: String;
4. begin
5.   if not FileExists(filename) then
6.   begin
7.     ShowMessage(tr('Error: file: "') + filename + tr('" could not be found.'));
8.     yyclear;
9.     exit;
10.   end;
11.  
12.   fn := StringReplace(ExtractFilePath(Paramstr(0)) + filename,
13.   '/', '\', [rfReplaceAll]);
14.  
15.   {$I-}
16.   Close(yyinput);
17.   Assign(yyinput, fn);
18.   filemode := 0;
19.   Reset(yyinput);
20.   {$I+}
21.  
22.   if IOResult <> 0 then
23.   begin
24.     ShowMessage('Error: file: "' + fn + '" could not be open.');
25.     yyclear;
26.     exit;
27.   end;
28.  
29.   yyWrap  := @newYYwrap;
30.   yyclear;
31.     ShowMessage('Parsing abgeschlossen.');
32.   yyParse;
33.  
34.   Close(yyinput);
35.   ShowMessage('Parsing abgeschlossen.');
36. end;

bring me Error - see screen shot.

[TRon]

bring me Error - see screen shot.

That is an imaginative error invented by yourself. Show the real error. And for that matter, all the relevant declarations.

[Thaddy]

Try this code. It is at least all in the right order:

Code: Pascal  [Select][+][-]

1. procedure yymain(filename: String);
2. var
3.   Err:integer;
4.   ErrorMsg:String;
5. begin
6.   Assign(yyinput, filename);
7.   {$push}{$I-}
8.   filemode := 0;
9.   Reset(yyinput);
10.   Close(yyinput);
11.   { store IOResult, because IOResult resets after it is read }
12.   Err :=IOResult;
13.  {$pop}
14.   Case Err of
15.   0  : ErrorMsg := 'Success';
16.   2  : ErrorMsg := 'File not found';
17.   3  : ErrorMsg := 'Path not found';
18.   4  : ErrorMsg := 'Too many open files';
19.   5  : ErrorMsg := 'File access denied';
20.   6  : ErrorMsg := 'Invalid file handle';
21.   12 : ErrorMsg := 'Invalid file access code';
22.   102: ErrorMsg := 'File not assigned';
23.   103: ErrorMsg := 'File not open';
24.   104: ErrorMsg := 'File not open for input';
25.   105: ErrorMsg := 'File not open for output';
26.   else
27.     { Error codes in appendix D of the users guide }
28.     ErrorMsg := Format('Error %d occurred',[Err]);
29.   end;
30.   ShowMessage(ErrorMsg);
31. end;

[paule32]

Thank you for the reply and the code snippet.
It worked.

When I call the yymain procedure first time I get Success.
When I call the yymain procedure second time I get "File not open"

[Thaddy]

When I call the yymain procedure second time I get "File not open"

I can not reproduce that with my code.
Not on Windows nor on Linux.

But you should be able to debug that now.

[paule32]

for informative notices:

on a third party component, I have found a buffer overflow which destroy some frames.
firstly, I had thinking that the on board controls produce my problem - but I was far away from this.

Because a counter produce a loop that was manifested that a bunch of token was not in the range,
and I had switch off range checking.

So, all went in the right pov.
Thanks to all for helping hand's.

[TRon]

Code: Pascal  [Select][+][-]

1. FUNCTION FileExists ( CONST fname : string ) : boolean;
2. {simple fileexist function}
3. VAR ftex : file;
4.   imjpmig : integer;
5. BEGIN
6.     imjpmig := filemode;
7.    assignfile(ftex,fname);
8.     filemode:=00;
9.     {$i-}
10.     Reset (ftex, 1 );
11.     filemode :=imjpmig;
12.     FileExists:=ioresult = 0;
13.     Closefile(ftex ); IF ioresult <> 0 THEN;
14.     {$i+}
15. END;
16.  

IOResult = o doesn't mean the file exists.

IOResult can only be read once.

origin:

When the flag is read, it is reset to zero. If IOresult is zero, the operation completed successfully.

[paule32]

Hello sunshines,

I have create a utils.pas unit in which I am layout some helper functions:
Feel free to use it.

Code: Pascal  [Select][+][-]

1. procedure CheckError(Err: Integer);
2. var
3.   ErrorMsg: String;
4. begin
5.   case Err of
6.     0  : ErrorMsg := tr('Success');
7.     2  : ErrorMsg := tr('File not found');
8.     3  : ErrorMsg := tr('Path not found');
9.     4  : ErrorMsg := tr('Too many open files');
10.     5  : ErrorMsg := tr('File access denied');
11.     6  : ErrorMsg := tr('Invalid file handle');
12.     12 : ErrorMsg := tr('Invalid file access code');
13.     102: ErrorMsg := tr('File not assigned');
14.     103: ErrorMsg := tr('File not open');
15.     104: ErrorMsg := tr('File not open for input');
16.     105: ErrorMsg := tr('File not open for output');
17.   else
18.     ErrorMsg := Format(tr('Error %d occurred'), [Err]);
19.   end;
20.   if Err <> 0 then
21.   raise Exception.Create(ErrorMsg);
22. end;
23.  
24. procedure OpenFileToWrite(var
25.   FileHandle: TextFile;
26.   AFileName: String;
27.   AContent: String);
28. begin
29.   {$push}{$I-}
30.   AssignFile(FileHandle, AFileName);
31.   Rewrite(FileHandle);
32.   CheckError(IOResult);
33.  
34.   WriteLn(FileHandle, AContent);
35.   CloseFile(FileHandle);
36.   {$pop}
37. end;
38.  
39. procedure OpenFileToRead(var
40.   FileHandle: TextFile;
41.   AFileName: String; var
42.   AContent: String);
43. var
44.   ALine: String;
45. begin
46.   System.Assign(FileHandle, AFileName);
47.   {$push}{$I-}
48.   filemode := 0;
49.   Reset(FileHandle);
50.   CheckError(IOResult);
51.   {$pop}
52.  
53.   AContent := '';
54.   while not Eof(FileHandle) do
55.   begin
56.     ReadLn(FileHandle, ALine);
57.     AContent := AContent + ALine + sLineBreak;
58.   end;
59. end;

and in use:

Code: Pascal  [Select][+][-]

1. procedure TForm1.sbLoadFromFile1Click(Sender: TObject);
2. var
3.   TempFile: TextFile;
4.   TempSrc: String;
5.   TempName: String;
6. begin
7.   TempName := 'mytemp_' + IntToStr(Random(100000)) + '.tmp';
8.   TempSrc  := CommentLexer(synEditHeaderContent.Lines.Text).Text;
9.  
10.   OpenFileToWrite(TempFile, TempName, TempSrc);
11.   OpenFileToRead (TempFile, TempName, TempSrc);
12.  
13.   CloseFile(TempFile);
14. end;