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Why exception from os.path.exists()?


On Mon, 04 Jun 2018 22:13:47 +0200, Peter J. Holzer wrote:

> On 2018-06-04 13:23:59 +0000, Steven D'Aprano wrote:
[...]

>> I don't know whether or not the Linux OS is capable of accessing files
>> with embedded NULs in the file name. But Mac OS is capable of doing so,
>> so it should be possible. Wikipedia says:
>> 
>> "HFS Plus mandates support for an escape sequence to allow arbitrary
>> Unicode. Users of older software might see the escape sequences instead
>> of the desired characters."
> 
> I don't know about MacOS. In Linux there is no way to pass a filename
> with an embedded '\0' (or a '/' which is not path separator) between the
> kernel and user space. So if a filesystem contained such a filename, the
> kernel would have to map it (via an escape sequence or some other
> mechanism) to a different file name. Which of course means that - from
> the perspective of any user space process - the filename doesn't contain
> a '\0' or '/'.

That's an invalid analogy. According to that analogy, Python strings 
don't contain ASCII NULs, because you have to use an escape mechanism to 
insert them:

    string = "Is this \0 not a NULL?"


But we know that Python strings are not NUL-terminated and can contain 
NUL. It's just another character.


-- 
Steven D'Aprano
"Ever since I learned about confirmation bias, I've been seeing
it everywhere." -- Jon Ronson