R devel - Sep 2006 - Memory problems with a custom R package

Hi everyone,

I have been attempting to build a very simple R package interfacing with  
some very simple C++ code.  Everything I try though results in the  
function working but on return it produces a memory error.  Here is the  
output:

***********OUTPUT***************************
> library(MyPackage)
> hello();
  *** caught segfault ***
address 0x3, cause 'memory not mapped'

**********END OUTPUT*************************

I have read that some time this occurs because it cannot find the function  
in the shared library but I have tested this theory with a simple text  
message and this is displayed but again the memory error occurs.

The C++ code has been reduced to the simplest possible:

*** helloworld.h

extern "C" void helloworld(void);

*** helloworld.cpp

#include <iostream>
#include "helloworld.h"

void helloworld(void) {
//	This was my test line that was displayed as described above.
//      std::cout << "My first R Package Test." <<
std::endl;
}

I also wrote an R wrapper called hello as follows:

*** helloworld.R

hello <- function()
{
  .Call("helloworld", PACKAGE="MyPackage");
}

The namespaces file (NAMESPACE) is as follows:

useDynLib(MyPackage)
export(hello)

I have compared mine against other package sources available that do the  
same thing and cannot find the key difference.

Thank you for your help in advance,

Tom

On Tue, 12 Sep 2006, Tom McCallum wrote:
> Hi everyone,
> 
> I have been attempting to build a very simple R package interfacing with  
> some very simple C++ code.  Everything I try though results in the  
> function working but on return it produces a memory error.  Here is the  
> output:
> 
> ***********OUTPUT***************************
> 
> > library(MyPackage)
> > hello();
> 
>   *** caught segfault ***
> address 0x3, cause 'memory not mapped'
> 
> **********END OUTPUT*************************
> 
> I have read that some time this occurs because it cannot find the function
> in the shared library but I have tested this theory with a simple text  
Where did you read that?  It is not true: you get an R error message in 
that case.
> message and this is displayed but again the memory error occurs.
> 
> The C++ code has been reduced to the simplest possible:
> 
> *** helloworld.h
> 
> extern "C" void helloworld(void);
> 
> *** helloworld.cpp
> 
> #include <iostream>
> #include "helloworld.h"
> 
> void helloworld(void) {
> //	This was my test line that was displayed as described above.
> //      std::cout << "My first R Package Test." <<
std::endl;
> }
> 
But that is the problem: .Call requires a SEXP return value from the entry 
point it calls.

> I also wrote an R wrapper called hello as follows:
> 
> *** helloworld.R
> 
> hello <- function()
> {
>   .Call("helloworld", PACKAGE="MyPackage");
> }
> 
> The namespaces file (NAMESPACE) is as follows:
> 
> useDynLib(MyPackage)
> export(hello)
> 
> I have compared mine against other package sources available that do the  
> same thing and cannot find the key difference.
> 
> Thank you for your help in advance,
> 
> Tom
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
> 
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

compiler/platform?

I did this:
R CMD SHLIB helloworld.cpp

Then this in R:
 >  dyn.load("helloworld.so")
 > .Call("helloworld")

and it doesn't segfault. (x86_64 linux with 32-bit R).


Tom McCallum wrote:
> Hi everyone,
> 
> I have been attempting to build a very simple R package interfacing with  
> some very simple C++ code.  Everything I try though results in the  
> function working but on return it produces a memory error.  Here is the  
> output:
> 
> ***********OUTPUT***************************
> 
>> library(MyPackage)
>> hello();
> 
>   *** caught segfault ***
> address 0x3, cause 'memory not mapped'
> 
> **********END OUTPUT*************************
> 
> I have read that some time this occurs because it cannot find the function
> in the shared library but I have tested this theory with a simple text  
> message and this is displayed but again the memory error occurs.
> 
> The C++ code has been reduced to the simplest possible:
> 
> *** helloworld.h
> 
> extern "C" void helloworld(void);
> 
> *** helloworld.cpp
> 
> #include <iostream>
> #include "helloworld.h"
> 
> void helloworld(void) {
> //	This was my test line that was displayed as described above.
> //      std::cout << "My first R Package Test." <<
std::endl;
> }
> 
> I also wrote an R wrapper called hello as follows:
> 
> *** helloworld.R
> 
> hello <- function()
> {
>   .Call("helloworld", PACKAGE="MyPackage");
> }
> 
> The namespaces file (NAMESPACE) is as follows:
> 
> useDynLib(MyPackage)
> export(hello)
> 
> I have compared mine against other package sources available that do the  
> same thing and cannot find the key difference.
> 
> Thank you for your help in advance,
> 
> Tom
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel