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[R] Run destructors of local C++ objects on SWIG_fail

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Arrange that destructors of local C++ objects in the wrapper function
get run on SWIG_fail (which calls Rf_error() which calls longjmp()).

We achieve this by putting almost everything in the function in its
own block, and end that right before Rf_error() at which point those
destructors will get called.
This commit is contained in:
Olly Betts 2022-10-14 13:18:56 +13:00 • committed by Olly Betts
commit 5f96d15943
3 changed files with 25 additions and 1 deletions
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5
CHANGES.current
View file

@ -7,6 +7,11 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
Version 4.1.0 (in progress)
===========================
2022-10-14: olly
[R] Arrange that destructors of local C++ objects in the wrapper
function get run on SWIG_fail (which calls Rf_error() which calls
longjmp()).
2022-10-14: olly
[Lua] Arrange that destructors of local C++ objects in the wrapper
function get run on SWIG_fail (which calls lua_error() which calls

13
Examples/test-suite/r/exception_memory_leak_runme.R
View file

@ -14,7 +14,7 @@ unittest(Foo_get_count(), 2);
invisible(trigger_internal_swig_exception("no problem", a));
unittest(Foo_get_count(), 2);
unittest(Foo_get_freearg_count(), 1);
# SWIG exception introduced
# SWIG exception introduced (return new object case).
result <- tryCatch({
trigger_internal_swig_exception("null", b);
}, warning = function(w) {
@ -26,3 +26,14 @@ result <- tryCatch({
})
unittest(Foo_get_count(), 2);
unittest(Foo_get_freearg_count(), 2);
# SWIG exception introduced (return by value case).
result <- tryCatch({
trigger_internal_swig_exception("null");
}, warning = function(w) {
# print(" Hum... We received a warning, but this should be an error");
unittest(1,0);
}, error = function(e) {
# print(" Gotcha!");
unittest(1,1);
})
unittest(Foo_get_count(), 2);

8
Source/Modules/r.cxx
View file

@ -1970,6 +1970,13 @@ int R::functionWrapper(Node *n) {
}
Printv(f->def, ")\n{\n", NIL);
// SWIG_fail in R leads to a call to Rf_error() which calls longjmp()
// which means the destructors of any live function-local C++ objects won't
// get run. To avoid this happening, we wrap almost everything in the
// function in a block, and end that right before Rf_error() at which
// point those destructors will get called.
if (CPlusPlus) Append(f->def, "{\n");
Printv(sfun->def, ")\n{\n", NIL);
@ -2123,6 +2130,7 @@ int R::functionWrapper(Node *n) {
if (need_cleanup) {
Printv(f->code, cleanup, NIL);
}
if (CPlusPlus) Append(f->code, "}\n");
Printv(f->code, " Rf_error(\"%s %s\", SWIG_ErrorType(SWIG_lasterror_code), SWIG_lasterror_msg);\n", NIL);
Printv(f->code, " return R_NilValue;\n", NIL);
Delete(cleanup);