Hi
Protecting against empty rasters seems like a good idea(!)
Thanks for the report.
Could you please try sending me your suggested patch directly?
(it did not make it through via r-devel)
Paul
On 09/16/13 22:24, QRD wrote:
Hi,
A colleague recently came across an R crash, which I can boil down to
the following, running under Rgui on Windows 7:
library(ggplot2)
ggplot(data.frame(x=1, y=1, z=4.7), aes(x, y, z=z)) + stat_summary2d()
This reliably causes a segmentation fault. sessionInfo() below.
What's happening is that (for reasons which I'll discuss with the
ggplot2 developers) the 'colorbar' guide is being built with a zero-size
source raster.
In L_raster() (grid.c), this raster is not a "nativeRaster", so we do
image = (unsigned int*) R_alloc(n, sizeof(unsigned int));
with n = 0, and R_alloc() gives us a NULL pointer.
The display of this raster requests interpolation, so we end up in
R_GE_rasterInterpolate(), where 'sraster' is NULL, and chaos ensues as
it tries to read source pixels.
It seems to me that it doesn't make sense to display an empty raster, so
I inserted a check in L_raster(). A proof-of-concept patch is attached.
With this patch, R gives an error message instead of a segfault.
Does this seem a sensible change? If so, could something like it be
incorporated?
Thanks,
Ben.
- - - - 8< - - - -
sessionInfo()
R version 3.0.1 (2013-05-16)
Platform: x86_64-w64-mingw32/x64 (64-bit)
locale:
[1] LC_COLLATE=English_Ireland.1252 LC_CTYPE=English_Ireland.1252
[3] LC_MONETARY=English_Ireland.1252 LC_NUMERIC=C
[5] LC_TIME=English_Ireland.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] ggplot2_0.9.3.1
loaded via a namespace (and not attached):
[1] colorspace_1.2-2 compiler_3.0.1 dichromat_2.0-0 digest_0.6.3
[5] grid_3.0.1 gtable_0.1.2 labeling_0.2 MASS_7.3-26
[9] munsell_0.4 plyr_1.8 proto_0.3-10
RColorBrewer_1.0-5
[13] reshape2_1.2.2 scales_0.2.3 stringr_0.6.2 tools_3.0.1
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Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
p...@stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/
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