Chris Lalancette <clalance@xxxxxxxxxx> wrote: > For 0.4.3, danpb's new memory management scheme went into libvirt. This is > fine, except that is subtly alters the semantics of malloc(), calloc(), and > realloc(). In particular, if you say: > > foo = malloc(0); > > glibc will happily return a non-NULL pointer to you. However, with the new > memory management stuff, if you say: > > foo = VIR_ALLOC(0); > > you will actually get a NULL pointer back. Personally, I think this is a > dangerous deviation from malloc() semantics that everyone is used to, and is > indeed causing problems with the remote driver. The short of it is that the > remote driver allocates memory on behalf of the remote side using VIR_ALLOC_N, > and this call is returning NULL so that the NULL checks elsewhere in the code > fire and return failure. > > The attached patch fixes this situation by removing the 0 checks from the memory > allocation paths, and just lets them fall through to the normal malloc(), > calloc(), or realloc() routines, restoring old semantics. Wow. That's a nasty one, violating such assumptions. Good catch. In case anyone reading along wonders about the portability of libvirt's assumption that those functions return non-NULL for N=0, it's fine because gnulib wrappers protect us from libc functions with the undesirable semantics. ACK. -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list