[Plplot-devel] valgrind warning generated by this line, why?

[Alan W. I. <ir...@be...>]

I have just been checking Joao's recent change using valgrind.  The only
*PLplot* memory management problem that it finds now is

==9658== Use of uninitialised value of size 8
==9658==    at 0x4025DECC: plP_draw3d (plot3d.c:1451)
==9658==    by 0x4025DD7A: plnxtvhi_draw (plot3d.c:1400)
==9658==    by 0x4025D968: plnxtvhi (plot3d.c:1244)
==9822==    by 0x4025D7D9: plnxtv (plot3d.c:1174)
==9822==    by 0x4025C40E: plt3zz (plot3d.c:947)
==9822==    by 0x4025BAFC: c_plot3d (plot3d.c:729)
==9822==    by 0x40259611: c_plmesh (plot3d.c:100)
==9822==    by 0x8049046: main (x08c.c:176)

Line 1451 of plot3d.c is

if (c != NULL && c[--j] >= 0. && c[j] <= 1.)

Under gdb for some reason I cannot print out c or j for the plP_draw3d stack
frame, but if I use "up" to get to the plnxtvhi_draw stack frame j is 37 and
c has reasonable values in it up c[35].  However, c[36] is 0. strongly
suggesting that may be the uninitialized value that is causing the valgrind
warning.

Can you have a further look at this, Joao, to see why that c value is
uninitialized?

There continue to be large diffs between the postscript files produced by
./x08c -dev psc -o x08c.ps
../test/test_single_tcl.sh 08
../test/test_single_python.sh 08

Note the uninitialized value could be anything for the various front ends
and indeed could change depending on the history of the memory that is
malloced for c. Thus, my working hypothesis is this uninitialized value is
the source of the C, tcl, and python example 8 differences.

Alan

email: ir...@be...
phone: 250-727-2902	FAX: 250-721-7715
snail-mail:
Dr. Alan W. Irwin
Department of Physics and Astronomy,
University of Victoria, P.O. Box 3055,
Victoria, British Columbia, Canada, V8W 3P6
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