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Commit 44e0aff1 authored by Eric Niebler's avatar Eric Niebler Committed by Facebook Github Bot
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make msan happy with exception_wrapper 

Summary:
When reading a `std::exception_ptr` out of a moved-from `folly::exception_wrapper`, we end up reading a `std::exception_ptr` field of a deleted `ExceptionPtr` object. This was causing MSAN much consternation.

The fix is to test for emptiness in `to_exception_ptr` and return a default-constructed `std::exception_ptr`.

This commit also adds extra test cases, since `to_exception_ptr` does something slightly different depending on whether the `exception_wrapper` object is `const` or not.

Reviewed By: yfeldblum

Differential Revision: D19403528

fbshipit-source-id: fde74a5c4b2ddb2025703432c1ac5a19d26b9426
parent 9450078d
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Showing with 23 additions and 5 deletions
folly/ExceptionWrapper-inl.h
View file @ 44e0aff1
......@@ -425,10 +425,12 @@ inline Ex const* exception_wrapper::get_exception() const noexcept {
return object;
}
inline std::exception_ptr const&
exception_wrapper::to_exception_ptr() noexcept {
// Computing an exception_ptr is expensive so cache the result.
return (*this = vptr_->get_exception_ptr_(this)).eptr_.ptr_;
inline std::exception_ptr exception_wrapper::to_exception_ptr() noexcept {
if (*this) {
// Computing an exception_ptr is expensive so cache the result.
return (*this = vptr_->get_exception_ptr_(this)).eptr_.ptr_;
}
return {};
}
inline std::exception_ptr exception_wrapper::to_exception_ptr() const noexcept {
return vptr_->get_exception_ptr_(this).eptr_.ptr_;
......
folly/ExceptionWrapper.h
View file @ 44e0aff1
......@@ -498,7 +498,7 @@ class exception_wrapper final {
//! \note The non-const overload of this function mutates `*this` to cache the
//! computed `std::exception_ptr`; that is, this function may cause
//! `has_exception_ptr()` to change from `false` to `true`.
std::exception_ptr const& to_exception_ptr() noexcept;
std::exception_ptr to_exception_ptr() noexcept;
//! \overload
std::exception_ptr to_exception_ptr() const noexcept;
......
folly/test/ExceptionWrapperTest.cpp
View file @ 44e0aff1
......@@ -109,6 +109,8 @@ TEST(ExceptionWrapper, members) {
EXPECT_FALSE(bool(ew));
EXPECT_EQ(ew.what(), "");
EXPECT_EQ(ew.class_name(), "");
EXPECT_EQ(nullptr, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(nullptr, ew.to_exception_ptr());
ew = make_exception_wrapper<std::runtime_error>("payload");
EXPECT_TRUE(bool(ew));
EXPECT_EQ(ew.what(), kRuntimeErrorClassName + ": payload");
......@@ -236,6 +238,7 @@ TEST(ExceptionWrapper, from_exception_ptr_exn) {
auto ep = std::make_exception_ptr(std::runtime_error("foo"));
auto ew = exception_wrapper::from_exception_ptr(ep);
EXPECT_TRUE(bool(ew));
EXPECT_EQ(ep, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(ep, ew.to_exception_ptr());
EXPECT_TRUE(ew.is_compatible_with<std::runtime_error>());
}
......@@ -244,6 +247,7 @@ TEST(ExceptionWrapper, from_exception_ptr_any) {
auto ep = std::make_exception_ptr<int>(12);
auto ew = exception_wrapper::from_exception_ptr(ep);
EXPECT_TRUE(bool(ew));
EXPECT_EQ(ep, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(ep, ew.to_exception_ptr());
EXPECT_TRUE(ew.is_compatible_with<int>());
}
......@@ -256,6 +260,8 @@ TEST(ExceptionWrapper, with_exception_ptr_empty) {
EXPECT_EQ(nullptr, ew.get_exception<std::exception>());
EXPECT_EQ(nullptr, ew.get_exception<int>());
EXPECT_FALSE(ew.has_exception_ptr());
EXPECT_EQ(nullptr, folly::as_const(ew).to_exception_ptr());
EXPECT_FALSE(ew.has_exception_ptr());
EXPECT_EQ(nullptr, ew.to_exception_ptr());
EXPECT_FALSE(ew.has_exception_ptr());
EXPECT_EQ("", ew.class_name());
......@@ -274,6 +280,8 @@ TEST(ExceptionWrapper, with_shared_ptr_test) {
EXPECT_STREQ("foo", ew.get_exception<std::exception>()->what());
EXPECT_EQ(nullptr, ew.get_exception<int>());
EXPECT_FALSE(ew.has_exception_ptr());
EXPECT_NE(nullptr, folly::as_const(ew).to_exception_ptr());
EXPECT_FALSE(ew.has_exception_ptr());
EXPECT_NE(nullptr, ew.to_exception_ptr());
EXPECT_TRUE(ew.has_exception_ptr());
EXPECT_EQ(kRuntimeErrorClassName, ew.class_name());
......@@ -289,6 +297,7 @@ TEST(ExceptionWrapper, with_shared_ptr_test) {
EXPECT_EQ(nullptr, ew.get_exception());
EXPECT_EQ(nullptr, ew.get_exception<std::exception>());
EXPECT_EQ(nullptr, ew.get_exception<int>());
EXPECT_EQ(nullptr, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(nullptr, ew.to_exception_ptr());
EXPECT_EQ("", ew.class_name());
EXPECT_EQ("", ew.what());
......@@ -322,6 +331,7 @@ TEST(ExceptionWrapper, with_exception_ptr_exn_test) {
EXPECT_EQ(nullptr, ew.get_exception());
EXPECT_EQ(nullptr, ew.get_exception<std::exception>());
EXPECT_EQ(nullptr, ew.get_exception<int>());
EXPECT_EQ(nullptr, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(nullptr, ew.to_exception_ptr());
EXPECT_EQ("", ew.class_name());
EXPECT_EQ("", ew.what());
......@@ -339,6 +349,7 @@ TEST(ExceptionWrapper, with_exception_ptr_any_test) {
EXPECT_NE(nullptr, ew.get_exception<int>());
EXPECT_EQ(12, *ew.get_exception<int>());
EXPECT_TRUE(ew.has_exception_ptr());
EXPECT_EQ(ep, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(ep, ew.to_exception_ptr());
EXPECT_TRUE(ew.has_exception_ptr());
EXPECT_EQ(demangle(typeid(int)), ew.class_name());
......@@ -353,6 +364,7 @@ TEST(ExceptionWrapper, with_exception_ptr_any_test) {
EXPECT_EQ(nullptr, ew.get_exception());
EXPECT_EQ(nullptr, ew.get_exception<std::exception>());
EXPECT_EQ(nullptr, ew.get_exception<int>());
EXPECT_EQ(nullptr, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(nullptr, ew.to_exception_ptr());
EXPECT_FALSE(ew.has_exception_ptr());
EXPECT_EQ("", ew.class_name());
......@@ -372,6 +384,7 @@ TEST(ExceptionWrapper, with_non_std_exception_test) {
EXPECT_TRUE(ew.has_exception_ptr());
EXPECT_EQ(demangle(typeid(int)), ew.class_name());
EXPECT_EQ(demangle(typeid(int)), ew.what());
EXPECT_NE(nullptr, folly::as_const(ew).to_exception_ptr());
EXPECT_NE(nullptr, ew.to_exception_ptr());
EXPECT_TRUE(ew.has_exception_ptr());
EXPECT_EQ(demangle(typeid(int)), ew.class_name());
......@@ -386,6 +399,7 @@ TEST(ExceptionWrapper, with_non_std_exception_test) {
EXPECT_EQ(nullptr, ew.get_exception());
EXPECT_EQ(nullptr, ew.get_exception<std::exception>());
EXPECT_EQ(nullptr, ew.get_exception<int>());
EXPECT_EQ(nullptr, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(nullptr, ew.to_exception_ptr());
EXPECT_FALSE(ew.has_exception_ptr());
EXPECT_EQ("", ew.class_name());
......@@ -403,6 +417,7 @@ TEST(ExceptionWrapper, with_exception_ptr_any_nil_test) {
EXPECT_EQ(nullptr, ew.get_exception<std::exception>());
EXPECT_NE(nullptr, ew.get_exception<int>());
EXPECT_EQ(12, *ew.get_exception<int>());
EXPECT_EQ(ep, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(ep, ew.to_exception_ptr());
EXPECT_EQ("<unknown exception>", ew.class_name()); // because concrete type is
// erased
......@@ -417,6 +432,7 @@ TEST(ExceptionWrapper, with_exception_ptr_any_nil_test) {
EXPECT_EQ(nullptr, ew.get_exception());
EXPECT_EQ(nullptr, ew.get_exception<std::exception>());
EXPECT_EQ(nullptr, ew.get_exception<int>());
EXPECT_EQ(nullptr, folly::as_const(ew).to_exception_ptr());
EXPECT_EQ(nullptr, ew.to_exception_ptr());
EXPECT_EQ("", ew.class_name());
EXPECT_EQ("", ew.what());
......
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