fpi-print: Add function to check if two prints match

While for raw prints this is just an equality check, for NBIS prints
they match if at least one of the minutiae match

libfprint/fpi-print.c

@@ -363,3 +363,68 @@ fpi_print_fill_from_user_id (FpPrint *print, const char *user_id)
 
   return FALSE;
 }
+
+/**
+ * fpi_print_match:
+ * @self: First #FpPrint
+ * @other: Second #FpPrint
+ *
+ * Tests whether the prints are matching.
+ * This is like fp_print_equal() for %FPI_PRINT_RAW prints,
+ * while for %FPI_PRINT_NBIS prints ensures that at least one
+ * sub-print minutiae matches.
+ *
+ * Returns: %TRUE if the prints are matching
+ */
+gboolean
+fpi_print_match (FpPrint *self, FpPrint *other)
+{
+  g_return_val_if_fail (FP_IS_PRINT (self), FALSE);
+  g_return_val_if_fail (FP_IS_PRINT (other), FALSE);
+  g_return_val_if_fail (self->type != FPI_PRINT_UNDEFINED, FALSE);
+  g_return_val_if_fail (other->type != FPI_PRINT_UNDEFINED, FALSE);
+
+  if (self == other)
+    return TRUE;
+
+  switch (self->type)
+    {
+    case FPI_PRINT_RAW:
+      return fp_print_equal (self, other);
+
+    case FPI_PRINT_NBIS:
+      {
+        if (other->type != FPI_PRINT_NBIS)
+          return FALSE;
+
+        if (g_strcmp0 (self->driver, other->driver) != 0)
+          return FALSE;
+
+        if (g_strcmp0 (self->device_id, other->device_id) != 0)
+          return FALSE;
+
+        if (self->prints->len == 0 || other->prints->len == 0)
+          return self->prints->len == other->prints->len;
+
+        for (guint i = 0; i < self->prints->len; i++)
+          {
+            struct xyt_struct *a = g_ptr_array_index (self->prints, i);
+
+            for (guint j = 0; j < other->prints->len; j++)
+              {
+                struct xyt_struct *b = g_ptr_array_index (other->prints, j);
+
+                if (memcmp (a, b, sizeof (struct xyt_struct)) == 0)
+                  return TRUE;
+              }
+          }
+
+        return FALSE;
+      }
+
+    case FPI_PRINT_UNDEFINED:
+      g_assert_not_reached ();
+    }
+
+  g_return_val_if_reached (FALSE);
+}

libfprint/fpi-print.h

@@ -35,6 +35,10 @@ void     fpi_print_add_print (FpPrint *print,
 
 void     fpi_print_set_type (FpPrint     *print,
                              FpiPrintType type);
+
+gboolean fpi_print_match (FpPrint *self,
+                          FpPrint *other);
+
 void     fpi_print_set_device_stored (FpPrint *print,
                                       gboolean device_stored);