fixed a memory leak.

[Kray-G]

I found this code has a memory leak.
This is a simple fix for that.
Please check it.

A memory will be allocated every time whenever calling soliter_next and it will be never freed.
This means a memory will be leaked each iteration,
so amount of leaks are increased in proportion to the number of iterations.

[github-actions]

Hi there, thank you for your contribution!

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed automatically if no further activity occurs.

If you would like this pull request to remain open please:

1. Rebase and verify the changes still work
2. Leave a comment with the current status

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Thanks!

[github-actions]

Hi there, thank you for your contribution!

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed automatically if no further activity occurs.

If you would like this pull request to remain open please:

1. Rebase and verify the changes still work
2. Leave a comment with the current status

NOTE: If this pull request was closed prematurely, please leave a comment.

Thanks!

[Kray-G]

I think this is a bug. It would be really recommended to fix it.

[dholth]

I'm looking at the picosat source code, which uses a static signed char * sol; and allocates it the first time this function is called.

static void
blocksol (PicoSAT * picosat)
{
  int max_idx = picosat_variables (picosat), i;

  if (!sol)
    {
      sol = malloc (max_idx + 1);
      memset (sol, 0, max_idx + 1);
    }

  for (i = 1; i <= max_idx; i++)
    sol[i] = (picosat_deref (picosat, i) > 0) ? 1 : -1;

  for (i = 1; i <= max_idx; i++)
    picosat_add (picosat, (sol[i] < 0) ? i : -i);

  picosat_add (picosat, 0);
}

I think @Kray-G is probably correct. When we update *mem the caller doesn't see it, because it passed the memory address by value. I guess C warnings do not point out this problem for us? Will need to take the time to recompile it and see how it goes.

[dholth]

Thank you very much for your submission. Can you take a look at the shorter fix at https://github.com/conda/pycosat/pull/54/files to see if it would solve the same problem, with a bit less pointer indirection?

[jezdez]

Superseded by #54