[R] file.access returning -1 for a file on remote Windows drive.

Sam Albers ton|ght@then|ght @end|ng |rom gm@||@com
Sat Feb 29 00:35:09 CET 2020


Great question Will. If it were my code I would definitely do this.
However the problem is manifesting itself for my work with Dirk's
great digest package here:

https://github.com/eddelbuettel/digest/blob/947b77e82b97024a874a808a4644be21fc329275/R/digest.R#L170-L173

So because file.access is saying the permissions aren't right, I get
an error message from digest and can't create a hash. Knowing full
well that this is some weird Windows thing but also knowing I am stuck
in that environment, I wanted to figure where I was seeing a
difference between those two functions before I went asked Dirk if
he'd be interested in a change to that particular bit of code.


On Fri, Feb 28, 2020 at 3:28 PM William Dunlap <wdunlap using tibco.com> wrote:
>
> If file.access() says the file is unreadable but file() says it can be opened, why don't you
> just open the file and read it?  You can use tryCatch to deal with problems opening or
> reading the file.
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
>
> On Fri, Feb 28, 2020 at 2:54 PM Sam Albers <tonightsthenight using gmail.com> wrote:
>>
>> Thanks Jeff. I am probably not explaining myself very well but my
>> question under what circumstances would
>>
>> summary(file(remote_file, "rb"))$`can read`
>>
>> be different from:
>>
>> file.access(remote_file, 4)
>>
>> If my permissions were different across remote and local should that
>> not be reflected in both of these functions?
>>
>> On Fri, Feb 28, 2020 at 2:37 PM Jeff Newmiller <jdnewmil using dcn.davis.ca.us> wrote:
>> >
>> > Dunno. They agree for me. Maybe look closer at all permissions via Windows File Manager?
>> >
>> > On February 28, 2020 2:06:34 PM PST, Sam Albers <tonightsthenight using gmail.com> wrote:
>> > >Some additional follow-up:
>> > >
>> > >> summary(file(remote_file, "rb"))$`can read`
>> > >[1] "yes"
>> > >
>> > >> summary(file(local_file, "rb"))$`can read`
>> > >[1] "yes"
>> > >
>> > >compared to:
>> > >
>> > >> file.access(local_file, 4)
>> > >local.R
>> > >         0
>> > >
>> > >> file.access(remote_file, 4)
>> > >remote.R
>> > >            -1
>> > >
>> > >Can anyone think why file.access and file would be contradicting each
>> > >other?
>> > >
>> > >Sam
>> > >
>> > >On Fri, Feb 28, 2020 at 10:47 AM Sam Albers
>> > ><tonightsthenight using gmail.com> wrote:
>> > >>
>> > >> Hi there,
>> > >>
>> > >> Looking for some help in diagnosing or developing a work around to a
>> > >> problem I am having on a Windows machine. I am running R 3.6.2.
>> > >>
>> > >> I have two identical files, one stored locally and the other stored
>> > >on
>> > >> a network drive.
>> > >>
>> > >> For access:
>> > >>
>> > >> > file.access(local_file, 4)
>> > >> local.R
>> > >>          0
>> > >>
>> > >> > file.access(remote_file, 4)
>> > >> remote.R
>> > >>             -1
>> > >>
>> > >> Also for file.info
>> > >>
>> > >> > file.info(local_file)$mode:
>> > >> [1] "666"
>> > >>
>> > >> > file.info(remote_file)$mode:
>> > >> [1] "666"
>> > >>
>> > >> Ok so I am access issues. Maybe they are ephemeral and I can change
>> > >> the permissions:
>> > >>
>> > >> > Sys.chmod('remote.R', mode = '666')
>> > >> > file.access(remote_file, 4)
>> > >> remote.R
>> > >>             -1
>> > >>
>> > >> Nope. I am thoroughly stumped and maybe can't make it any further
>> > >> because of Windows.
>> > >>
>> > >> Downstream I am trying to use digest::digest to create a hash but
>> > >> digest thinks we don't have permission because file.access is
>> > >failing.
>> > >> Any thoughts on how I can get file.access to return 0 for the
>> > >remote.R
>> > >> file? Any ideas?
>> > >>
>> > >> Thanks in advance,
>> > >>
>> > >> Sam
>> > >
>> > >______________________________________________
>> > >R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> > >https://stat.ethz.ch/mailman/listinfo/r-help
>> > >PLEASE do read the posting guide
>> > >http://www.R-project.org/posting-guide.html
>> > >and provide commented, minimal, self-contained, reproducible code.
>> >
>> > --
>> > Sent from my phone. Please excuse my brevity.
>>
>> ______________________________________________
>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.



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