Hi, I'm writing a wrapper library for libalpm for use in a GUI frontend. Anyway, while doing this I noticed that various calls to alpm_trans_prepare return a list of items that need to be free'd.

For example, in pacman/remove.c, line 86 (current git), a PM_ERR_UNSATISFIED_DEPS gives a list of pmdepmissing_t which is free'd using FREELIST. However, in libalpm/remove.c, line 181, this same list is free'd using alpm_list_free_inner with _alpm_depmiss_free followed by alpm_list_free. This appears to be the correct way of doing it, and since pacman doesn't then we are left with a dangling references to the members of each pmdepmissing_t in the list.

I suggest that firstly _alpm_depmiss_free should be exported from alpm so that pacman can use it, and secondly that pacman should be changed to make use of it in this case. Additionally, there are other cases where similar leaks occur. The ones I have been able to identify are in pacman/upgrade.c and pacman/sync.c where PM_ERR_UNSATISFIED_DEPS, PM_ERR_CONFLICTING_DEPS and PM_ERR_FILE_CONFLICTS are handled.

Admittedly, this is a fairly minor issue in pacman itself, as once an error occurs it is likely that the pacman process will end, but for frontends, such as mine, that run in the background it could be much worse. I hope this is not too difficult to fix, and I may be able to write a patch myself if the developers agree with my proposed course of action.