Memory leaks in C code

[HuwCampbell]

Looking at the C code, a very common pattern is this:

doublecomplex * workv = (doublecomplex*)malloc(n*sizeof(doublecomplex));
CHECK(!workv,MEM);
do_stuff(&work, &res);
CHECK(res,res);
free(workv);
OK

where CHECK and OK are macros which call return. There's an issue here in that if the calls to CHECK fail, none of the memory allocated will be freed (until the program exits completely).

[HuwCampbell]

Fixing this is pretty mechanical. I've fixed up a few by creating a macro UNWIND, which sets a return variable and jumps to a label where we will call free.

    UNWIND(!work,MEM,done)
    do_stuff (&work, &res);
    UNWIND(res,res,cleanup)

cleanup:
    free(work);
done:
    return ret;

[HuwCampbell]

This is also effecting calls to solvers, so singular matrices under the linear solve family are leaking memory.

[idontgetoutmuch]

Fixed by https://github.com/haskell-numerics/hmatrix/pull/327