Re: Synchronous file IO in Lua? Shell escaping?

[Marvin Scholz <epirat07@...>]

On 20 Sep 2022, at 9:47, Tomas Mudrunka wrote:

> Turns out that this is roughly equivalent to calling fsync() on fd:
>
> os.execute("sync "..filename);
>
> So i went with that. But the argument is not properly escaped, which is fine in my case, since filename is hardcoded.
>
> On the other hand it would be better if there was some way to pass individual arguments in array without using shell to parse the commandline.
> Eg.: something like this:
>
> os.execute({"sync", "filename"});
>
> lua can detect that table was passed rather than string. and bypass the shell in that case.
> That would prevent need to have shell-specific (platform-specific) escaping in lua...
>


Unfortunately on Windows that is not so trivial to do:

https://learn.microsoft.com/de-de/archive/blogs/twistylittlepassagesallalike/everyone-quotes-command-line-arguments-the-wrong-way

>
>
>
> Dne 2022-09-20 08:40, bil til napsal:
>> The nasty thing here seems to be, that this is different for any
>> operating system.
>>
>> Usually it would be nice to implement such functionality into flush I
>> think, but if you have to write different code for any operating
>> system, then this gets a bit much for Lua?
>>
>> (fsync e. g. will not be available in MS-Win, in fact I am not sure at
>> all how you can accomplish this in MS Win software).
>>
>> (but you could also say, that it would be job of your Linux compiler
>> to organize such things, so that flush really works "sure" and not
>> possibly only "virtual").
>>
>> Am Mo., 19. Sept. 2022 um 18:40 Uhr schrieb Tomas Mudrunka <mudrunka@spoje.net>:
>>>
>>> Note that fflush() flushes only the user-space buffers provided
>>>         by the C library.  To ensure that the data is physically stored
>>>         on disk the kernel buffers must be flushed too, for example, with
>>>         sync(2) or fsync(2).
>
> -- 
> S pozdravem
> Best regards
>      Tomáš Mudruňka - SPOJE.NET s.r.o.