[erlang-bugs] Bug in file I/O under Windows.

[Dmitriy Kargapolov]

In your Windows environment do you have any antivirus online monitoring s/w?
Thanks.

John Hughes wrote:
> This bug manifests as follows:
> 
>  
> 
> Suppose FileName is the name of an existing file to which we have access.
> 
>  
> 
>                              file:delete(FileName)              
>                              returns ok
> 
>                              
> file:write_file(FileName,Bin)                             returns 
> {error,eacces}
> 
>  
> 
> This ought not to happen, because we do have access to the file. The 
> documentation says eacces means “Missing permission for writing the file 
> or searching one of the parent directories”, but neither of these is the 
> case—and indeed, if we repeat the same test, then it will almost always 
> succeed as it should.
> 
>  
> 
> Unfortunately, this bug is rare and very hard to reproduce, so I can’t 
> include instructions for doing so. I found the problem by running random 
> sequences of file:write_file and file:delete commands, operating on a 
> small set of filenames. I tried to get repeatable tests by running each 
> test in a newly created directory, on a newly spawned Erlang node, and 
> after a timer:sleep—but even so, I found that a sequence which failed 
> once could very well go on to succeed the next 100 times I tried it. 
>  However, I have been able to collect about 40 examples of the bug using 
> QuickCheck. All of them take the form above; they range in length from 4 
> commands to over 2,000. There are sometimes operations on other files 
> between the delete and the write_file that fails, but never further 
> operations on FileName itself.
> 
>  
> 
> I’ve observed this behaviour under R11B and R12B, under both Windows XP 
> and Vista. It doesn’t appear to happen at all under Linux.
> 
>  
> 
> John Hughes
> 
> 
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