/* * Copyright (c) Facebook, Inc. and its affiliates. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include #include #include #include #include #include #ifndef _WIN32 #define _GNU_SOURCE 1 #include #endif namespace folly { namespace chrono { static int64_t clock_gettime_ns_fallback(clockid_t clock) { struct timespec ts; int r = clock_gettime(clock, &ts); if (UNLIKELY(r != 0)) { // Mimic what __clock_gettime_ns does (even though this can be a legit // value). return -1; } std::chrono::nanoseconds result = std::chrono::seconds(ts.tv_sec) + std::chrono::nanoseconds(ts.tv_nsec); return result.count(); } // Initialize with default behavior, which we might override on Linux hosts // with VDSO support. int (*clock_gettime)(clockid_t, timespec* ts) = &::clock_gettime; int64_t (*clock_gettime_ns)(clockid_t) = &clock_gettime_ns_fallback; // In MSAN mode use glibc's versions as they are intercepted by the MSAN // runtime which properly tracks memory initialization. #if defined(FOLLY_HAVE_LINUX_VDSO) && !defined(FOLLY_SANITIZE_MEMORY) namespace { struct VdsoInitializer { VdsoInitializer() { m_handle = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD); if (!m_handle) { return; } void* p = dlsym(m_handle, "__vdso_clock_gettime"); if (p) { folly::chrono::clock_gettime = (int (*)(clockid_t, timespec*))p; } p = dlsym(m_handle, "__vdso_clock_gettime_ns"); if (p) { folly::chrono::clock_gettime_ns = (int64_t(*)(clockid_t))p; } } ~VdsoInitializer() { if (m_handle) { clock_gettime = &::clock_gettime; clock_gettime_ns = &clock_gettime_ns_fallback; dlclose(m_handle); } } private: void* m_handle; }; const VdsoInitializer vdso_initializer; } // namespace #endif } // namespace chrono } // namespace folly