Daniel P. Berrangé <berra...@redhat.com> writes:
> On Thu, Dec 16, 2021 at 02:11:37PM +0000, Alex Bennée wrote: >> >> Philippe Mathieu-Daudé <phi...@redhat.com> writes: >> >> > When experimenting raising GLIB_VERSION_MIN_REQUIRED to 2.68 >> > (Fedora 34 provides GLib 2.68.1) we get: >> > >> > hw/virtio/virtio-crypto.c:245:24: error: 'g_memdup' is deprecated: Use >> > 'g_memdup2' instead [-Werror,-Wdeprecated-declarations] >> > ... >> > >> > g_memdup() has been updated by g_memdup2() to fix eventual security >> > issues (size argument is 32-bit and could be truncated / wrapping). >> > GLib recommends to copy their static inline version of g_memdup2(): >> > https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538 >> > >> > Our glib-compat.h provides a comment explaining how to deal with >> > these deprecated declarations (see commit e71e8cc0355 >> > "glib: enforce the minimum required version and warn about old APIs"). >> > >> > Following this comment suggestion, implement the g_memdup2_qemu() >> > wrapper to g_memdup2(), and use the safer equivalent inlined when >> > we are using pre-2.68 GLib. >> > >> > Reported-by: Eric Blake <ebl...@redhat.com> >> > Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com> >> > --- >> > include/glib-compat.h | 37 +++++++++++++++++++++++++++++++++++++ >> > 1 file changed, 37 insertions(+) >> > >> > diff --git a/include/glib-compat.h b/include/glib-compat.h >> > index 9e95c888f54..8d01a8c01fb 100644 >> > --- a/include/glib-compat.h >> > +++ b/include/glib-compat.h >> > @@ -68,6 +68,43 @@ >> > * without generating warnings. >> > */ >> > >> > +/* >> > + * g_memdup2_qemu: >> > + * @mem: (nullable): the memory to copy. >> > + * @byte_size: the number of bytes to copy. >> > + * >> > + * Allocates @byte_size bytes of memory, and copies @byte_size bytes into >> > it >> > + * from @mem. If @mem is %NULL it returns %NULL. >> > + * >> > + * This replaces g_memdup(), which was prone to integer overflows when >> > + * converting the argument from a #gsize to a #guint. >> > + * >> > + * This static inline version is a backport of the new public API from >> > + * GLib 2.68, kept internal to GLib for backport to older stable releases. >> > + * See https://gitlab.gnome.org/GNOME/glib/-/issues/2319. >> > + * >> > + * Returns: (nullable): a pointer to the newly-allocated copy of the >> > memory, >> > + * or %NULL if @mem is %NULL. >> > + */ >> > +static inline gpointer g_memdup2_qemu(gconstpointer mem, gsize byte_size) >> > +{ >> > +#if GLIB_CHECK_VERSION(2, 68, 0) >> > + return g_memdup2(mem, byte_size); >> > +#else >> > + gpointer new_mem; >> > + >> > + if (mem && byte_size != 0) { >> > + new_mem = g_malloc(byte_size); >> > + memcpy(new_mem, mem, byte_size); >> > + } else { >> > + new_mem = NULL; >> > + } >> > + >> > + return new_mem; >> > +#endif >> > +} >> > +#define g_memdup2(m, s) g_memdup2_qemu(m, s) >> > + >> >> As per our style wouldn't it make sense to just call it qemu_memdup(m, >> s)? > > Not in this case. We use suffix as we don't want people calling this > directly with the suffix. > > In the glibcompat.h header we're attempting to transparently/secretly > replace/wrap standard glib APIs. All the callers should remain using > the plain glib API name, never call the method with the suffix at > all. This lets us delete the wrapper later and not have to update > any callers. The suffix is basically just a hack of the impl we use > for transparent replacement. Right - at the risk of bike shedding names maybe we should choose a suffix the better reflects the purpose like _alt or _internal rather than overloading qemu? We already document _locked for example. > A method with a 'qemu_' prefix by constrast is something that callers > are explicitly expected to call directly. > > > Regards, > Daniel -- Alex Bennée
