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diff --git a/test/util/signal_util.h b/test/util/signal_util.h
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+// Copyright 2018 Google LLC
+//
+// 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.
+
+#ifndef GVISOR_TEST_UTIL_SIGNAL_UTIL_H_
+#define GVISOR_TEST_UTIL_SIGNAL_UTIL_H_
+
+#include <signal.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <ostream>
+
+#include "gmock/gmock.h"
+#include "test/util/cleanup.h"
+#include "test/util/posix_error.h"
+
+// Format a sigset_t as a comma separated list of numeric ranges.
+::std::ostream& operator<<(::std::ostream& os, const sigset_t& sigset);
+
+namespace gvisor {
+namespace testing {
+
+// The maximum signal number.
+static constexpr int kMaxSignal = 64;
+
+// Wrapper for the tgkill(2) syscall, which glibc does not provide.
+inline int tgkill(pid_t tgid, pid_t tid, int sig) {
+  return syscall(__NR_tgkill, tgid, tid, sig);
+}
+
+// Installs the passed sigaction and returns a cleanup function to restore the
+// previous handler when it goes out of scope.
+PosixErrorOr<Cleanup> ScopedSigaction(int sig, struct sigaction const& sa);
+
+// Updates the signal mask as per sigprocmask(2) and returns a cleanup function
+// to restore the previous signal mask when it goes out of scope.
+PosixErrorOr<Cleanup> ScopedSignalMask(int how, sigset_t const& set);
+
+// ScopedSignalMask variant that creates a mask of the single signal 'sig'.
+inline PosixErrorOr<Cleanup> ScopedSignalMask(int how, int sig) {
+  sigset_t set;
+  sigemptyset(&set);
+  sigaddset(&set, sig);
+  return ScopedSignalMask(how, set);
+}
+
+// Asserts equality of two sigset_t values.
+MATCHER_P(EqualsSigset, value, "equals " + ::testing::PrintToString(value)) {
+  for (int sig = 1; sig <= kMaxSignal; ++sig) {
+    if (sigismember(&arg, sig) != sigismember(&value, sig)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+#ifdef __x86_64__
+// Fault can be used to generate a synchronous SIGSEGV.
+//
+// This fault can be fixed up in a handler via fixup, below.
+inline void Fault() {
+  // Zero and dereference %ax.
+  asm("movabs $0, %%rax\r\n"
+      "mov 0(%%rax), %%rax\r\n"
+      :
+      :
+      : "ax");
+}
+
+// FixupFault fixes up a fault generated by fault, above.
+inline void FixupFault(ucontext* ctx) {
+  // Skip the bad instruction above.
+  //
+  // The encoding is 0x48 0xab 0x00.
+  ctx->uc_mcontext.gregs[REG_RIP] += 3;
+}
+#endif
+
+}  // namespace testing
+}  // namespace gvisor
+
+#endif  // GVISOR_TEST_UTIL_SIGNAL_UTIL_H_