What's the right way to use libfdt's fdt_setprop to set a property to have an empty value? At the moment in QEMU we tend to use fdt_setprop(fdt, nodeoffset, "propertyname", NULL, 0);
and git grep 'fdt_setprop.*NULL' produces examples of this usage in PPC and ARM fdt creation code. However the fdt_setprop() documentation doesn't document that a NULL value pointer is OK if the length is 0, and indeed the implementation unconditionally calls memcpy(prop->data, val, len), which is undefined behaviour, and warned about by clang sanitizers if you build libfdt with them: dtc/libfdt/fdt_rw.c:288:21: runtime error: null pointer passed as argument 2, which is declared to never be null So what's the best thing to do here? I can't offhand think of a non-ugly/non-confusing way to pass a valid pointer here... thanks -- PMM
