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RMW implementation library wrapper/shim #266

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68a7c25
Let RMW_IMPLEMENTATION_WRAPPER override
emersonknapp Jun 18, 2024
31ec525
Load wrapper library alongside implementation library, to simplify th…
emersonknapp Jun 18, 2024
0f19343
Fix return code for rmw_init
emersonknapp Nov 22, 2024
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85 changes: 83 additions & 2 deletions rmw_implementation/src/functions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,29 @@ get_library()
return g_rmw_lib;
}

std::shared_ptr<rcpputils::SharedLibrary>
get_wrap_library()
{
static bool tried_load = false;
static std::shared_ptr<rcpputils::SharedLibrary> wrap_lib = nullptr;
if (!wrap_lib && !tried_load) {
tried_load = true;
std::string wrapper_var;
try {
wrapper_var = rcpputils::get_env_var("RMW_IMPLEMENTATION_WRAPPER");
} catch (const std::exception & e) {
RMW_SET_ERROR_MSG_WITH_FORMAT_STRING(
"failed to fetch RMW_IMPLEMENTATION_WRAPPER "
"from environment due to %s", e.what());
return nullptr;
}
if (!wrapper_var.empty()) {
wrap_lib = attempt_to_load_one_rmw(wrapper_var);
}
}
return wrap_lib;
}

void *
lookup_symbol(std::shared_ptr<rcpputils::SharedLibrary> lib, const std::string & symbol_name)
{
Expand Down Expand Up @@ -175,6 +198,25 @@ get_symbol(const char * symbol_name)
}
}

void * get_wrap_symbol(const char * symbol_name)
{
try {
auto lib = get_wrap_library();
if (!lib) {
return nullptr;
}
if (!lib->has_symbol(symbol_name)) {
return nullptr;
}
return lib->get_symbol(symbol_name);
} catch (const std::exception & e) {
RMW_SET_ERROR_MSG_WITH_FORMAT_STRING(
"failed to get wrapper symbol '%s' due to %s",
symbol_name, e.what());
return nullptr;
}
}

#ifdef __cplusplus
extern "C"
{
Expand Down Expand Up @@ -202,6 +244,27 @@ extern "C"
#define ARGS_6(t6, ...) t6 v6, EXPAND(ARGS_5(__VA_ARGS__))
#define ARGS_7(t7, ...) t7 v7, EXPAND(ARGS_6(__VA_ARGS__))

// Macros for "wrapped function" args, allow us to prepend one extra argument more than _NR value
// "tX" params are "type" for the type declaration of the argument
// "vX" params are "variable" for the variable name declaration
#define WARGS_0(t0, tvoid) t0 v0
#define WARGS_1(t1, t0) t1 v1, t0 v0
#define WARGS_2(t2, ...) t2 v2, EXPAND(WARGS_1(__VA_ARGS__))
#define WARGS_3(t3, ...) t3 v3, EXPAND(WARGS_2(__VA_ARGS__))
#define WARGS_4(t4, ...) t4 v4, EXPAND(WARGS_3(__VA_ARGS__))
#define WARGS_5(t5, ...) t5 v5, EXPAND(WARGS_4(__VA_ARGS__))
#define WARGS_6(t6, ...) t6 v6, EXPAND(WARGS_5(__VA_ARGS__))
#define WARGS_7(t7, ...) t7 v7, EXPAND(WARGS_6(__VA_ARGS__))

#define WARG_VALUES_0(impl, ...) impl
#define WARG_VALUES_1(impl, ...) impl, EXPAND(ARG_VALUES_1(__VA_ARGS__))
#define WARG_VALUES_2(impl, ...) impl, EXPAND(ARG_VALUES_2(__VA_ARGS__))
#define WARG_VALUES_3(impl, ...) impl, EXPAND(ARG_VALUES_3(__VA_ARGS__))
#define WARG_VALUES_4(impl, ...) impl, EXPAND(ARG_VALUES_4(__VA_ARGS__))
#define WARG_VALUES_5(impl, ...) impl, EXPAND(ARG_VALUES_5(__VA_ARGS__))
#define WARG_VALUES_6(impl, ...) impl, EXPAND(ARG_VALUES_6(__VA_ARGS__))
#define WARG_VALUES_7(impl, ...) impl, EXPAND(ARG_VALUES_7(__VA_ARGS__))

#define CALL_SYMBOL(symbol_name, ReturnType, error_value, ArgTypes, arg_values) \
if (!symbol_ ## symbol_name) { \
/* only necessary for functions called before rmw_init */ \
Expand All @@ -218,8 +281,14 @@ extern "C"
// cppcheck-suppress preprocessorErrorDirective
#define RMW_INTERFACE_FN(name, ReturnType, error_value, _NR, ...) \
void * symbol_ ## name = nullptr; \
void * symbol_wrap_ ## name = nullptr; \
ReturnType name(EXPAND(ARGS_ ## _NR(__VA_ARGS__))) \
{ \
if (symbol_wrap_ ## name) { \
typedef ReturnType (* WrapFunctionSignature)(EXPAND (WARGS_ ## _NR(void *, __VA_ARGS__))); \
auto wrap_func = reinterpret_cast<WrapFunctionSignature>(symbol_wrap_ ## name); \
return wrap_func(EXPAND(WARG_VALUES_ ## _NR(symbol_ ## name, __VA_ARGS__))); \
} \
CALL_SYMBOL( \
name, ReturnType, error_value, ARG_TYPES(__VA_ARGS__), \
EXPAND(ARG_VALUES_ ## _NR(__VA_ARGS__))); \
Expand Down Expand Up @@ -789,7 +858,9 @@ RMW_INTERFACE_FN(
const char *, rcutils_allocator_t *, rosidl_dynamic_typesupport_serialization_support_t *))


#define GET_SYMBOL(x) symbol_ ## x = get_symbol(#x);
#define GET_SYMBOL(x) \
symbol_ ## x = get_symbol(#x); \
symbol_wrap_ ## x = get_wrap_symbol(STRINGIFY(wrap_ ## x));

void prefetch_symbols(void)
{
Expand Down Expand Up @@ -891,6 +962,7 @@ void prefetch_symbols(void)
}

void * symbol_rmw_init = nullptr;
void * symbol_wrap_rmw_init = nullptr;

rmw_ret_t
rmw_init(const rmw_init_options_t * options, rmw_context_t * context)
Expand All @@ -902,10 +974,19 @@ rmw_init(const rmw_init_options_t * options, rmw_context_t * context)
if (!symbol_rmw_init) {
return RMW_RET_ERROR;
}
if (!symbol_wrap_rmw_init) {
symbol_wrap_rmw_init = get_wrap_symbol("wrap_rmw_init");
}
rmw_ret_t ret = RMW_RET_OK;
if (symbol_wrap_rmw_init) {
typedef rmw_ret_t (* WrapperInitSignature)(void *, const rmw_init_options_t *, rmw_context_t *);
auto wrap_init_func = reinterpret_cast<WrapperInitSignature>(symbol_wrap_rmw_init);
ret = wrap_init_func(get_library().get(), options, context);
}

typedef rmw_ret_t (* FunctionSignature)(const rmw_init_options_t *, rmw_context_t *);
FunctionSignature func = reinterpret_cast<FunctionSignature>(symbol_rmw_init);
return func(options, context);
return ret != RMW_RET_OK ? ret : func(options, context);
}

#ifdef __cplusplus
Expand Down