check does not check that package examples remove tempdir()

I was looking at the CRAN package 'bfork-0.1.2', which exposes the Unix
fork() and waitpid() calls at the R code level, and noticed that the help
file example for bfork::fork removes R's temporary directory, the value of
tempdir().   I think it happens because the forked process shares the value
of tempdir() with the parent process and removes it when it exits.

This seems like a serious problem - should 'check' make sure that running
code in a package's examples, vignettes, etc. leaves tempdir() intact?

dir.exists(tempdir())

[1] TRUE

library(bfork)
example(fork)

fork>     ## create a function to be run as a separate process
fork>     fn <- function() {
fork+         Sys.sleep(4)
fork+         print("World!")
fork+     }

fork>     ## fork the process
fork>     pid <- fork(fn)

fork>     ## do work in the parent process
fork>     print("Hello")
[1] "Hello"

fork>     ## wait for the child process
fork>     waitpid(pid)
[1] "World!"
[1] 7063

dir.exists(tempdir())

[1] FALSE


Bill Dunlap
TIBCO Software
wdunlap tibco.com

        [[alternative HTML version deleted]]

wrote:

Related to this problem - from R-devel NEWS
(https://cran.r-project.org/doc/manuals/r-devel/NEWS.html):

* tempdir(check = TRUE) recreates the tmpdir() if it is no longer
valid (e.g. because some other process has cleaned up the ?/tmp?
directory).

Not sure if there's a plan to make check = TRUE the default though.

/Henrik

On Wed, Nov 8, 2017 at 4:43 PM, William Dunlap via R-devel
<r-devel at r-project.org> wrote:

I was looking at the CRAN package 'bfork-0.1.2', which exposes the Unix
fork() and waitpid() calls at the R code level, and noticed that the help
file example for bfork::fork removes R's temporary directory, the value

of

tempdir().   I think it happens because the forked process shares the

value

of tempdir() with the parent process and removes it when it exits.

This seems like a serious problem - should 'check' make sure that running
code in a package's examples, vignettes, etc. leaves tempdir() intact?

dir.exists(tempdir())

[1] TRUE

library(bfork)
example(fork)

fork>     ## create a function to be run as a separate process
fork>     fn <- function() {
fork+         Sys.sleep(4)
fork+         print("World!")
fork+     }

fork>     ## fork the process
fork>     pid <- fork(fn)

fork>     ## do work in the parent process
fork>     print("Hello")
[1] "Hello"

fork>     ## wait for the child process
fork>     waitpid(pid)
[1] "World!"
[1] 7063

dir.exists(tempdir())

[1] FALSE


Bill Dunlap
TIBCO Software
wdunlap tibco.com

        [[alternative HTML version deleted]]

tempdir(). I think it happens because the forked process shares the
value of tempdir() with the parent process and removes it when it
exits.

tempdir(). I think it happens because the forked process shares the
value of tempdir() with the parent process and removes it when it
exits.

This is very likely the case. Pretty much the entire library can be
summed up by bfork_fork, which is the following.

     SEXP res;
     pid_t pid;
     if((pid = fork()) == 0) {
         PROTECT(res = eval(lang1(fn), R_GlobalEnv));
         PROTECT(res = eval(lang2(install("q"), mkString("no")), R_GlobalEnv));
         UNPROTECT(2);
     }

     return ScalarInteger(pid);

I wrote this lib when I was still in school and can see several issues
with the implementation of `bfork_fork`. This issue happens because
we do not exit with _exit, but by essentially calling q("no").

Cheers,

Dan

I was looking at the CRAN package 'bfork-0.1.2', which exposes the Unix
fork() and waitpid() calls at the R code level, and noticed that the help
file example for bfork::fork removes R's temporary directory, the value of
tempdir().   I think it happens because the forked process shares the value
of tempdir() with the parent process and removes it when it exits.