[Rd] system()/system2() using short paths of commands on Windows?

[Tomas Kalibera]

On 10/31/23 10:05, Duncan Murdoch wrote:
> On 31/10/2023 4:32 a.m., Tomas Kalibera wrote:
>>
>> On 10/30/23 19:07, Yihui Xie wrote:
>>> Sure. I'm not sure if it's possible to make it easier to reproduce,
>>> but for now the example would require installing TinyTeX (via
>>> tinytex::install_tinytex(), which can be later uninstalled cleanly via
>>> tinytex::uninstall_tinytex() after you finish the investigation). Then
>>> run:
>>>
>>>    system2('fmtutil-sys', '--all')
>>>    # or tinytex:::fmtutil() if fmtutil-sys.exe is not on PATH
>>>
>>> and TeX Live would throw an error like this:
>>>
>>> ...\username\AppData\Roaming\TinyTeX\bin\windows\runscript.tlu:864: no
>>> appropriate script or program found: fmtuti~1
>>>
>>> The command "fmtutil-sys" is longer than 8 characters and hence
>>> shortened to "fmtutil~1". Yes, in principle, TeX Live should work with
>>> short path names, but it doesn't at the moment. I haven't figured out
>>> if it was a recent breakage in TeX Live or not (I've tried to contact
>>> TeX Live developers).
>>>
>>> BTW, shell('fmtutil-sys --all') works fine.
>>
>> I can reproduce the problem, also separately from R. It is not an R 
>> problem
>>
>> ./fmtutil-sys.exe --version
>> works
>>
>> ./fmtuti~1 --version
>> doesn't work
>>
>> The problem is in runscript.tlu, when it looks at "progname", it parses
>> it assuming it is the full name, looking for "-sys" suffix, which won't
>> be in the short name:
>>
>> progname, substcount = string.gsub(progname, '%-sys$', '')
>> local sysprog = (substcount > 0) -- true if there was a -sys suffix 
>> removed
>>
>> and it does further processing using the program name.
>>
>> This has to be fixed on the luatex end, it must be able to work with
>> short paths (e.g. expand it appropriately). You could probably work
>> around the installation before it gets fixed, e.g. by creating another
>> wrapper which would expand to long names, delete the short name, patch
>> the script, etc. After all, if it works via a shell, then probably the
>> shell is expanding to the long names and you have a work-around (I don't
>> know how reliable).
>>
>> Adding an option to R's system*() functions to use only long names
>> doesn't make sense.
>
> On the other hand, not modifying the executable name would make a lot 
> of sense, wouldn't it?  I'm pretty sure all supported versions of 
> Windows can handle long filenames.

There could be an option to pass the "module" name directly, which would 
end up as the first argument of CreateProcess, so avoid the search-path 
lookup and the complete path expansion. That would make sense, but I am 
not persuaded it is needed. I don't think the luatex wrapper bug is a 
strong enough case to complicate the code and API (which is already 
rather complicated) any further. It would not be "just" a new option, 
but also dissecting the module name from the command (when not using a 
shell).

While thinking about this and reading the related code I found a bug in 
handling paths with spaces when short paths are not available, fixed now.

Tomas

>
> Duncan Murdoch
>