Incorrect result of function FileAge, when date 12-30-1899

[7bit]

I found that if the file modification date in the system is 12/30/1899 (TDateTime value = 0), the FileAge returns an incorrect result. Here is the code that demonstrates the problem:

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, LResources, Forms, Controls, Graphics, Dialogs, StdCtrls,
9.   BaseUnix, DateUtils;
10.  
11. type
12.  
13.   { TForm1 }
14.  
15.   TForm1 = class(TForm)
16.     Button1: TButton;
17.     procedure Button1Click(Sender: TObject);
18.   private
19.  
20.   public
21.  
22.   end;
23.  
24. var
25.   Form1: TForm1;
26.  
27. implementation
28.  
29. { TForm1 }
30.  
31. procedure TForm1.Button1Click(Sender: TObject);
32. var
33.   FlNm: String;
34.   Utime: UtimBuf;
35.   St: stat;
36. begin
37.   FlNm := GetTempDir + 'temp.tmp';
38.   with TFileStream.Create(FlNm, fmCreate) do
39.   begin
40.     Free;
41.   end;
42.  
43.   //UTime.modtime := DateTimeToUnix(StrToDateTime('30-12-1901'));
44.   UTime.modtime := DateTimeToUnix(0);
45.   UTime.actime := UTime.modtime;
46.   FpUtime(FlNm, @Utime);
47.  
48.   // invalid time
49.   ShowMessage(FormatDateTime('dd-mm-yyyy', UnixToDateTime(FileAge(FlNm))));
50.  
51.   // valid time
52.   FpStat(FlNm, St);
53.   ShowMessage(FormatDateTime('dd-mm-yyyy', UnixToDateTime(St.st_mtime)));
54. end;
55.  
56. initialization
57.   {$I unit1.lrs}
58.  
59. end.
60.                                                
61.  

Lazarus/FPC version: Lazarus 4.0RC2 (rev lazarus_4_0RC2-104-gb0513d9031) FPC 3.2.2 x86_64-linux-gtk2

[MarkMLl]

What happens if that's a simple non-GUI program? What date does the OS show for the file? Is it different depending on what utility you use? What filesystem are you using? Does the date survive an fsck?

I'm troubled by the fact that unix- in general- has no support for files older than its own epoch, so trying to force things might lead to inconsistent results.

MarkMLl

[7bit]

Here is a simple program:

Code: Pascal  [Select][+][-]

1. program project1;
2.  
3. uses
4.   SysUtils, Classes, BaseUnix, DateUtils;
5.  
6. var
7.   FlNm: String;
8.   Utime: UtimBuf;
9.   St: stat;
10. begin
11.   FlNm := GetTempDir + 'temp.tmp';
12.   with TFileStream.Create(FlNm, fmCreate) do
13.   begin
14.     Free;
15.   end;
16.  
17.   UTime.modtime := DateTimeToUnix(0);
18.   UTime.actime := UTime.modtime;
19.   FpUtime(FlNm, @Utime);
20.  
21.   // invalid time
22.   WriteLn(FormatDateTime('dd-mm-yyyy', UnixToDateTime(FileAge(FlNm))));
23.  
24.   // valid time
25.   FpStat(FlNm, St);
26.   WriteLn(FormatDateTime('dd-mm-yyyy', UnixToDateTime(St.st_mtime)));
27. end.  
28.  

The result is the same.

File system is Ext4.

Ouput of command ls -l:

Code: Bash  [Select][+][-]

1. #ls -l
2. -rw-r--r-- 1 user user  0 дек 30  1899 temp.tmp
3.  

Result fsck i not check.

Incorrect result of function FileAge, because it does not fit into the LongInt type. The Int64 type is required for the result.

[MarkMLl]

Incorrect result of function FileAge, because it does not fit into the LongInt type. The Int64 type is required for the result.

Well deduced, in that case raise a bug report.

MarkMLl

[Remy Lebeau]

What about using the FileAge() overload that outputs a TDateTime  instead of an integer?