diff options
Diffstat (limited to 'src/third_party/abseil-cpp-master/abseil-cpp/absl/debugging/internal/address_is_readable.cc')
| -rw-r--r-- | src/third_party/abseil-cpp-master/abseil-cpp/absl/debugging/internal/address_is_readable.cc | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/src/third_party/abseil-cpp-master/abseil-cpp/absl/debugging/internal/address_is_readable.cc b/src/third_party/abseil-cpp-master/abseil-cpp/absl/debugging/internal/address_is_readable.cc index 7455aa0b416..329c285f3b5 100644 --- a/src/third_party/abseil-cpp-master/abseil-cpp/absl/debugging/internal/address_is_readable.cc +++ b/src/third_party/abseil-cpp-master/abseil-cpp/absl/debugging/internal/address_is_readable.cc @@ -4,7 +4,7 @@ // 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 +// https://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, @@ -20,12 +20,14 @@ #if !defined(__linux__) || defined(__ANDROID__) namespace absl { +ABSL_NAMESPACE_BEGIN namespace debugging_internal { // On platforms other than Linux, just return true. bool AddressIsReadable(const void* /* addr */) { return true; } } // namespace debugging_internal +ABSL_NAMESPACE_END } // namespace absl #else @@ -33,13 +35,16 @@ bool AddressIsReadable(const void* /* addr */) { return true; } #include <fcntl.h> #include <sys/syscall.h> #include <unistd.h> + #include <atomic> #include <cerrno> #include <cstdint> +#include "absl/base/internal/errno_saver.h" #include "absl/base/internal/raw_logging.h" namespace absl { +ABSL_NAMESPACE_BEGIN namespace debugging_internal { // Pack a pid and two file descriptors into a 64-bit word, @@ -63,8 +68,9 @@ static void Unpack(uint64_t x, int *pid, int *read_fd, int *write_fd) { // unimplemented. // This is a namespace-scoped variable for correct zero-initialization. static std::atomic<uint64_t> pid_and_fds; // initially 0, an invalid pid. + bool AddressIsReadable(const void *addr) { - int save_errno = errno; + absl::base_internal::ErrnoSaver errno_saver; // We test whether a byte is readable by using write(). Normally, this would // be done via a cached file descriptor to /dev/null, but linux fails to // check whether the byte is readable when the destination is /dev/null, so @@ -81,7 +87,7 @@ bool AddressIsReadable(const void *addr) { int pid; int read_fd; int write_fd; - uint64_t local_pid_and_fds = pid_and_fds.load(std::memory_order_relaxed); + uint64_t local_pid_and_fds = pid_and_fds.load(std::memory_order_acquire); Unpack(local_pid_and_fds, &pid, &read_fd, &write_fd); while (current_pid != pid) { int p[2]; @@ -93,13 +99,13 @@ bool AddressIsReadable(const void *addr) { fcntl(p[1], F_SETFD, FD_CLOEXEC); uint64_t new_pid_and_fds = Pack(current_pid, p[0], p[1]); if (pid_and_fds.compare_exchange_strong( - local_pid_and_fds, new_pid_and_fds, std::memory_order_relaxed, + local_pid_and_fds, new_pid_and_fds, std::memory_order_release, std::memory_order_relaxed)) { local_pid_and_fds = new_pid_and_fds; // fds exposed to other threads } else { // fds not exposed to other threads; we can close them. close(p[0]); close(p[1]); - local_pid_and_fds = pid_and_fds.load(std::memory_order_relaxed); + local_pid_and_fds = pid_and_fds.load(std::memory_order_acquire); } Unpack(local_pid_and_fds, &pid, &read_fd, &write_fd); } @@ -119,15 +125,15 @@ bool AddressIsReadable(const void *addr) { // If pid_and_fds contains the problematic file descriptors we just used, // this call will forget them, and the loop will try again. pid_and_fds.compare_exchange_strong(local_pid_and_fds, 0, - std::memory_order_relaxed, + std::memory_order_release, std::memory_order_relaxed); } } while (errno == EBADF); - errno = save_errno; return bytes_written == 1; } } // namespace debugging_internal +ABSL_NAMESPACE_END } // namespace absl #endif |