[Octave-bug-tracker] [bug #60016] libqhull was deprecated in favor of libqhull_r

[Stefan Brüns]

Follow-up Comment #20, bug #60016 (project octave):

[comment #18 comment #18:]
> It's not clear that we need to initialize the variable "context" of type
qhT.  The Qhull website has an example of using the re-entrant library.  The
code is at http://www.qhull.org/src/qhull/unix_r.c.
> 
> Quoting from that code,
> 
> 
> int main(int argc, char *argv[]) {
>   int curlong, totlong; /* used !qh_NOmem */
>   int exitcode, numpoints, dim;
>   coordT *points;
>   boolT ismalloc;
>   qhT qh_qh;
>   qhT *qh= &qh_qh;
> 
>   QHULL_LIB_CHECK /* Check for compatible library */
> 

You omit the relevant part of code later, which *does* initialize qh_qh.

> Our equivalent code is
> 
> 
> +      qhT context = { 0 };
> +      qhT *qh = &context;
> 
> 
> I'd just drop the initialization "{ 0 }".

Nope. Definitely breaks qhull when you are unlucky and some fields are not
0-initialized.

Run the following through valgrind:

#include <string>
#include <iostream>

#include <libqhull_r/libqhull_r.h>
#include <libqhull_r/geom_r.h>

int main(int argc, char* argv[])
{
    qhT context; // not initialized = { 0 };
    qhT* qh = &context;

    int numpoints = 4;
    coordT points[] = {0,0,0, 1,0,0, 0,1,0, 0,0,1};
    int dim = 3;
    bool ismalloc = false;

    std::string cmd = "qhull s FA";

    FILE* outfile = fopen("/dev/stdout", "w+");
    FILE* errfile = fopen("/dev/stderr", "w+");

    qh_new_qhull (qh, dim, numpoints, points,
                  ismalloc, &cmd[0], outfile, errfile);

    qh_getarea(qh, qh->facet_list);
    std::cout << qh->totvol << std::endl;
    std::cout << qh->totarea << std::endl;

    qh_freeqhull (qh, !qh_ALL);
}


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