This adds vendor-specific messaging capabilities to the
HAL driver to avoid the possibility of vendors clobbering
general-purpose methods. The framework translates these
additional messages as an offset into a custom message array.
Additionally, authenticate() now takes a group id to restrict
authentication to a subset of possible fingerprints.
Bug 16487912
Change-Id: I8a92a6c86b4729af03a5576b4a150b1c73fbc9cc
Inheritance of HAL object is performed by composing a child structure of a
single parent structure located at offset 0 followed by new data members
and function pointers in the child structure.
For example,
struct child {
struct parent common;
int a_data_member;
void (*a_method)(struct child *c, int v);
};
HAL code assumes this layout when accessing child structures given a pointer
to a parent structure such that users write code like the following...
void child_method(struct *parent, int v) {
struct child * c = (struct child*)parent;
// do stuff with c
}
Code above will break if a member is added before "common" in "struct child".
This change adds comments that describe the restriction on the location of
parent HAL objects within a derived HAL object. HAL objects that already
have comments that describe the required location of parent objects are not
modified.
Change-Id: Ibe4300275286ef275b2097534c84f1029d761d87
