R devel - Jan 2009 - Segfault when mistakenly calling [.data.frame (PR#13487)

Full_Name: Christian Brechbuehler
Version: 2.7.2, 2.8.1
OS: linux-gnu
Submission from: (NULL) (24.128.51.18)


Calling [.data.frame on an object that's not a data frame, specifically
1:10,
causes segmentation fault.

Context
======We can subscript with a number of different notations:

   > (1:10)[3]
   [1] 3
   > do.call(get("[",pos="package:base"),list(1:10,3))
   [1] 3
   >
do.call(get("[.numeric_version",pos="package:base"),list(1:10,3))
   [1] 3

Problem
======If we mistakenly believe the object is a data frame (as we did in a much
more
complicated real situation), this happens: 

   >
do.call(get("[.data.frame",pos="package:base"),list(1:10,3))
   Error in NextMethod("[") : 
     no calling generic was found: was a method called directly?

    *** caught segfault ***
   address (nil), cause 'unknown'

   Process R:2 segmentation fault (core dumped) at Thu Jan 29 09:26:29 2009

The Error message is appropriate.  But the segmentation fault is unexpected.


Versions
=======I reproduced the problem on R 2.7.2 and 2.8.1.  Details:
> version
               _                                          
platform       x86_64-unknown-linux-gnu                   
arch           x86_64                                     
os             linux-gnu                                  
system         x86_64, linux-gnu                          
status         Patched                                    
major          2                                          
minor          7.2                                        
year           2008                                       
month          09                                         
day            20                                         
svn rev        46776                                      
language       R                                          
version.string R version 2.7.2 Patched (2008-09-20 r46776)

=========================================================
> version
               _                                          
platform       x86_64-unknown-linux-gnu                   
arch           x86_64                                     
os             linux-gnu                                  
system         x86_64, linux-gnu                          
status         Patched                                    
major          2                                          
minor          8.1                                        
year           2009                                       
month          01                                         
day            26                                         
svn rev        47743                                      
language       R                                          
version.string R version 2.8.1 Patched (2009-01-26 r47743)

What did your actual application do?  This seems a very strange thing 
to do, and the segfault is in trying to construct the traceback.

Only by using do.call on the object (and not even by name) do I get 
this error.  E.g.
> `[.data.frame`(1:10, 3)
Error in NextMethod("[") : object not
specified
> do.call("[.data.frame", list(1:10, 3))
Error in NextMethod("[") : object not specified

are fine.

Obviously it would be nice to fix this, but I'd like to understand the 
actual circumstances: there is more to it than the subject line.

On Thu, 29 Jan 2009, brechbuehler at gmail.com wrote:
> Full_Name: Christian Brechbuehler
> Version: 2.7.2, 2.8.1
> OS: linux-gnu
> Submission from: (NULL) (24.128.51.18)
>
>
> Calling [.data.frame on an object that's not a data frame, specifically
1:10,
> causes segmentation fault.
>
> Context
> ======> We can subscript with a number of different notations:
>
>   > (1:10)[3]
>   [1] 3
>   >
do.call(get("[",pos="package:base"),list(1:10,3))
>   [1] 3
>   >
do.call(get("[.numeric_version",pos="package:base"),list(1:10,3))
>   [1] 3
>
> Problem
> ======> If we mistakenly believe the object is a data frame (as we did
in a much more
> complicated real situation), this happens:
>
>   >
do.call(get("[.data.frame",pos="package:base"),list(1:10,3))
>   Error in NextMethod("[") :
>     no calling generic was found: was a method called directly?
>
>    *** caught segfault ***
>   address (nil), cause 'unknown'
>
>   Process R:2 segmentation fault (core dumped) at Thu Jan 29 09:26:29 2009
>
> The Error message is appropriate.  But the segmentation fault is
unexpected.
>
>
> Versions
> =======> I reproduced the problem on R 2.7.2 and 2.8.1.  Details:
>
>> version
>               _
> platform       x86_64-unknown-linux-gnu
> arch           x86_64
> os             linux-gnu
> system         x86_64, linux-gnu
> status         Patched
> major          2
> minor          7.2
> year           2008
> month          09
> day            20
> svn rev        46776
> language       R
> version.string R version 2.7.2 Patched (2008-09-20 r46776)
>
> =========================================================>
>> version
>               _
> platform       x86_64-unknown-linux-gnu
> arch           x86_64
> os             linux-gnu
> system         x86_64, linux-gnu
> status         Patched
> major          2
> minor          8.1
> year           2009
> month          01
> day            26
> svn rev        47743
> language       R
> version.string R version 2.8.1 Patched (2009-01-26 r47743)
>
> ______________________________________________
> 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