[Rd] Segmentation fault, devPS.c, 0.99.0 (PR#413)

[Peter Dalgaard BSA]

Roger Bivand <rsb@reclus.nhh.no> writes:


> (gdb) p *fp
> Cannot access memory at address 0x20203665.
> (gdb) p fp
> $1 = (FILE *) 0x20203665
> (gdb) up
> #3  0x806d953 in PS_NewPage (dd=0x81df2d0) at devPS.c:1015
> 1015	    if(pd->pageno > 1) PostScriptEndPage(pd->psfp);
> (gdb) p pd->psfp
> $2 = (FILE *) 0x20203665
> (gdb) p pd->pageno
> $3 = 1920216697
> (gdb) up
> #4  0x8087c75 in Rf_GNewPlot (recording=1, ask=-2147483648) at
> graphics.c:1781
> 1781		    dd->dp.newPage(dd);
> 
> (including the function where the problem occurs). The (FILE *) looks
> healthy enough to me, so I'll accept that the problem is a machine
> idiosyncracy. 

I wouldn't think so! 0x20203665 looks suspiciously like a bit of a text
string. "e6  " to be precise (give or take byte ordering issues). And
the pointer is not pointing anywhere useful. I think something is
walking over  pd->psfp

Next step would be to find out where that happens. If you set a
breakpoint in PS_Open just after the R_fopen call, run to it and then
do a 

p &(pd->psfp)
watch *<address obtained from the above>
disp/x *<address obtained from the above>
run

and see if it stops with the memory location being overwritten


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
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