[fpc-pascal] FreePascal Windows - Force files to write to disk

James Richters james at productionautomation.net
Fri Feb 24 19:52:37 CET 2017

Thanks for the advice everyone.   It is very much appreciated.   I have been
working on a combination of ideas here.  Currently I am doing an MD5sum of a
string created from all my variables concatenated together and writing that
as the second to the last line of the file, I also am writing some fixed
text at the beginning and end of the file as suggested so I can check for
variables being overwritten in memory, great idea!   I am then reading the
file back to verify it has written properly, making a backup, checking that,
and also using ioresults as below. I will probably rename the file as well,
and exclude it from virus checkers.  When I read the file I can verify the
MD5sum and if that test fails, I'll just automatically try the backup, If
that also fails the MD5sum I'll notify the user.  

Thanks again for all the help

-----Original Message-----
From: fpc-pascal-bounces at lists.freepascal.org
[mailto:fpc-pascal-bounces at lists.freepascal.org] On Behalf Of Klaus Hartnegg
Sent: Thursday, February 23, 2017 6:33 AM
To: fpc-pascal at lists.freepascal.org
Subject: Re: [fpc-pascal] FreePascal Windows - Force files to write to disk

Am 21.02.2017 um 22:12 schrieb James Richters:
>  Assign(BitFile,'BitSave.pax');
>  ReWrite(BitFile);
    if ioresult <> 0 then
       writeln ('error opening pax file');
>  WriteLn(BitFile,XADJ:1:8);
>  WriteLn(BitFile,YADJ:1:8);
>  WriteLn(BitFile,ZADJ:1:8);
>  WriteLn(BitFile,WADJ:1:8);
>  WriteLn(BitFile,AADJ:1:8);
>  WriteLn(BitFile,TADJ:1:8);
>  WriteLn(BitFile,VADJ:1:8);
>  WriteLn(BitFile,UADJ:1:8);
>  WriteLn(BitFile,CurrentTool);
>  WriteLn(Bitfile,P_Value[4]);
    writeln (bitfile, 'EOF');
    if ioresult <> 0 then
       writeln ('error writing pax file');
>  Close(BitFile);
    if ioresult <> 0 then
       writeln ('error closing pax file');

This writes something at the end of the file that does not come from a
variable. Next time the error happens, you can check if that is present. 
Then your variables were overwritten in memory. Also it checks for errors.
And I would disable antivirus or at least tell it to not scan this file.
fpc-pascal maillist  -  fpc-pascal at lists.freepascal.org

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