From 0676843875b783e8157fc062b2bb322948b4f29a Mon Sep 17 00:00:00 2001 From: Jamie Liu Date: Wed, 9 Jan 2019 14:26:52 -0800 Subject: Make CooperativeSaveEnabled() async-signal-safe(r). The static local variable `enabled` in CooperativeSaveEnabled() is not initialized until the first call to CooperativeSaveEnabled(), per the C++14 standard, section 6.7 ("Declaration statement"), paragraph 4. This initialization is thread-safe as of C++11, but it is *not* required to be async-signal-safe. Use a namespace-scope variable instead, since this is guaranteed to be zero-initialized before main() by section 3.6.2 ("Initialization of non-local variables"). getenv() is technically not async-signal-safe either, hence the hedging in the change summary line. However, glibc's implementation of getenv() appears to be async-signal-safe in the absence of calls to setenv(). PiperOrigin-RevId: 228588617 Change-Id: I669f555d1c91352d55c606970bb237ec888fa7ca --- test/util/save_util.cc | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) (limited to 'test') diff --git a/test/util/save_util.cc b/test/util/save_util.cc index 71f4078a7..5540e2146 100644 --- a/test/util/save_util.cc +++ b/test/util/save_util.cc @@ -27,9 +27,23 @@ namespace gvisor { namespace testing { namespace { +enum class CooperativeSaveMode { + kUnknown = 0, // cooperative_save_mode is statically-initialized to 0 + kAvailable, + kNotAvailable, +}; + +std::atomic cooperative_save_mode; + bool CooperativeSaveEnabled() { - static bool enabled = getenv(GVISOR_COOPERATIVE_SAVE_TEST) != nullptr; - return enabled; + auto mode = cooperative_save_mode.load(); + if (mode == CooperativeSaveMode::kUnknown) { + mode = (getenv(GVISOR_COOPERATIVE_SAVE_TEST) != nullptr) + ? CooperativeSaveMode::kAvailable + : CooperativeSaveMode::kNotAvailable; + cooperative_save_mode.store(mode); + } + return mode == CooperativeSaveMode::kAvailable; } std::atomic save_disable; -- cgit v1.2.3