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

Jonas Maebe jonas at freepascal.org
Tue Mar 21 19:23:49 CET 2017

On 21/03/17 15:39, James Richters wrote:
> If I then power off the test computer (not doing a correct windows shutdown,
> this simulates an unattended power failure) when it boots back up, my file
> has the correct date and time and the correct length, hovever the contents
> of the file is a string of $00 with no other characters, no carriage returns
> and no linefeeds, however the number of $00s is EXACTLY how many bytes the
> file should have been.  It's like the file was allocated but data not
> actually written to disk yet... but I thought Close (file) was supposed to
> do that.

No, it does not do that. It flushes everything from the internal program 
buffers to the operating system, but the operating system will perform 
write-back caching. This is not specific to FPC programs, it does this 
almost all writes to a regular hard drive or SSD (Windows does not do it 
for USB sticks, afaik). Not doing so would slow down you system 


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