Reland: Introduce sys_sigprocmask and sys_sigaction. (patchset #4 id:80001 of https://codereview.ch…

sandbox/linux/seccomp-bpf/die.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sandbox/linux/seccomp-bpf/die.h"
 
 #include <errno.h>
 #include <signal.h>
 #include <stdio.h>
 #include <sys/prctl.h>
 #include <sys/syscall.h>
 #include <unistd.h>
 
 #include <string>
 
 #include "base/logging.h"
 #include "base/posix/eintr_wrapper.h"
 #include "sandbox/linux/seccomp-bpf/syscall.h"
+#include "sandbox/linux/services/syscall_wrappers.h"
+#include "sandbox/linux/system_headers/linux_signal.h"
 
 namespace sandbox {
 
 void Die::ExitGroup() {
   // exit_group() should exit our program. After all, it is defined as a
   // function that doesn't return. But things can theoretically go wrong.
   // Especially, since we are dealing with system call filters. Continuing
   // execution would be very bad in most cases where ExitGroup() gets called.
   // So, we'll try a few other strategies too.
   Syscall::Call(__NR_exit_group, 1);
 
   // We have no idea what our run-time environment looks like. So, signal
   // handlers might or might not do the right thing. Try to reset settings
   // to a defined state; but we have not way to verify whether we actually
   // succeeded in doing so. Nonetheless, triggering a fatal signal could help
   // us terminate.
-  signal(SIGSEGV, SIG_DFL);
+  struct sigaction sa = {};
+  sa.sa_handler = LINUX_SIG_DFL;
+  sa.sa_flags = LINUX_SA_RESTART;
+  sys_sigaction(LINUX_SIGSEGV, &sa, nullptr);
   Syscall::Call(__NR_prctl, PR_SET_DUMPABLE, (void*)0, (void*)0, (void*)0);
   if (*(volatile char*)0) {
   }
 
   // If there is no way for us to ask for the program to exit, the next
   // best thing we can do is to loop indefinitely. Maybe, somebody will notice
   // and file a bug...
   // We in fact retry the system call inside of our loop so that it will
   // stand out when somebody tries to diagnose the problem by using "strace".
   for (;;) {
@@ skipping 33 matching lines @@
     // probably prefer them over a loop that blocks.
     ignore_result(
         HANDLE_EINTR(Syscall::Call(__NR_write, 2, s.c_str(), s.length())));
   }
 }
 
 bool Die::simple_exit_ = false;
 bool Die::suppress_info_ = false;
 
 }  // namespace sandbox