/**
* Create new guarded memory.
*
* Wraps, starting at the given "base_ptr" with guards. Allows reuse of stack allocated helper.
*
* @param base_ptr allocation wishing to be wrapped, must be at least "GuardedMemory::get_total_size()" bytes.
* @param user_size the size of the user data to be wrapped.
* @param tag optional general purpose tag.
*
* @return user data pointer (inner pointer to supplied "base_ptr").
*/
void* wrap_with_guards(void* base_ptr, size_t user_size, const void* tag = NULL) {
assert(base_ptr != NULL, "Attempt to wrap NULL with memory guard");
_base_addr = (u_char*)base_ptr;
get_head_guard()->build();
get_head_guard()->set_user_size(user_size);
get_tail_guard()->build();
set_tag(tag);
set_user_bytes(uninitBlockPad);
assert(verify_guards(), "Expected valid memory guards");
return get_user_ptr();
}
void GuardedMemory::print_on(outputStream* st) const {
if (_base_addr == NULL) {
st->print_cr("GuardedMemory(" PTR_FORMAT ") not associated to any memory", p2i(this));
return;
}
st->print_cr("GuardedMemory(" PTR_FORMAT ") base_addr=" PTR_FORMAT
" tag=" PTR_FORMAT " user_size=" SIZE_FORMAT " user_data=" PTR_FORMAT,
p2i(this), p2i(_base_addr), p2i(get_tag()), get_user_size(), p2i(get_user_ptr()));
Guard* guard = get_head_guard();
st->print_cr(" Header guard @" PTR_FORMAT " is %s", p2i(guard), (guard->verify() ? "OK" : "BROKEN"));
guard = get_tail_guard();
st->print_cr(" Trailer guard @" PTR_FORMAT " is %s", p2i(guard), (guard->verify() ? "OK" : "BROKEN"));
u_char udata = *get_user_ptr();
switch (udata) {
case uninitBlockPad:
st->print_cr(" User data appears unused");
break;
case freeBlockPad:
st->print_cr(" User data appears to have been freed");
break;
default:
st->print_cr(" User data appears to be in use");
break;
}
}
/**
* Return the size of the user data.
*
* @return the size of the user data.
*/
size_t get_user_size() const {
assert(_base_addr, "Not wrapping any memory");
return get_head_guard()->get_user_size();
}
/**
* Return the general purpose tag.
*
* @return the general purpose tag, defaults to NULL.
*/
void* get_tag() const { return get_head_guard()->get_tag(); }
/**
* Set the general purpose tag.
*
* @param tag general purpose tag.
*/
void set_tag(const void* tag) { get_head_guard()->set_tag(tag); }
/**
* Verify head and tail guards.
*
* @return true if guards are intact, false would indicate a buffer overrun.
*/
bool verify_guards() const {
if (_base_addr != NULL) {
return (get_head_guard()->verify() && get_tail_guard()->verify());
}
return false;
}