/* We use the garbage collector's feature to "pin" an Object at a
* particular memory location to allow C code to write directly into the
* contets of a Ruby String (actually, a CharArray, which provides the
* storage for String). Since any method on String that mutates self may
* cause a new CharArray to be created, we always check whether the
* String is pinned and update the RString structure unconditionally.
*/
void ensure_pinned(NativeMethodEnvironment* env, String* string, RString* rstring) {
CharArray* ca = string->data();
size_t byte_size = ca->size();
if(!ca->pinned_p()) {
ca = CharArray::create_pinned(env->state(), byte_size);
memcpy(ca->raw_bytes(), string->byte_address(), byte_size);
string->data(env->state(), ca);
}
char* ptr = reinterpret_cast<char*>(ca->raw_bytes());
ptr[byte_size-1] = 0;
rstring->dmwmb = rstring->ptr = ptr;
rstring->len = string->size();
rstring->aux.capa = byte_size;
rstring->aux.shared = Qfalse;
}
