Added support for greylisting of system calls.

sandbox/linux/seccomp-bpf/die.cc

Index: sandbox/linux/seccomp-bpf/die.cc
diff --git a/sandbox/linux/seccomp-bpf/die.cc b/sandbox/linux/seccomp-bpf/die.cc
index b141424f58de33a93cdd4bbfc6d6681b6f7c549e..95cc91a2b69567cf2a23c01f18054db46c0efc7c 100644
--- a/sandbox/linux/seccomp-bpf/die.cc
+++ b/sandbox/linux/seccomp-bpf/die.cc
@@ -5,6 +5,7 @@
 #include <string>
 
 #include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
+#include "sandbox/linux/seccomp-bpf/syscall.h"
 
 
 namespace playground2 {
@@ -15,7 +16,7 @@ void Die::ExitGroup() {
   // 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(__NR_exit_group, 1);
+  Syscall(__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
@@ -23,7 +24,7 @@ void Die::ExitGroup() {
   // succeeded in doing so. Nonetheless, triggering a fatal signal could help
   // us terminate.
   signal(SIGSEGV, SIG_DFL);
-  syscall(__NR_prctl, PR_SET_DUMPABLE, (void *)0, (void *)0, (void *)0);
+  Syscall(__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
@@ -32,7 +33,7 @@ void Die::ExitGroup() {
   // 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 (;;) {
-    syscall(__NR_exit_group, 1);
+    Syscall(__NR_exit_group, 1);
   }
 }
 
@@ -49,6 +50,16 @@ void Die::SandboxDie(const char *msg, const char *file, int line) {
   ExitGroup();
 }
 
+void Die::SandboxInfo(const char *msg, const char *file, int line) {
+  if (!suppress_info_) {
+  #if defined(SECCOMP_BPF_STANDALONE)
+    Die::LogToStderr(msg, file, line);
+  #else
+    logging::LogMessage(file, line, logging::LOG_INFO).stream() << msg;
+  #endif
+  }
+}
+
 void Die::LogToStderr(const char *msg, const char *file, int line) {
   if (msg) {
     char buf[40];
@@ -57,10 +68,11 @@ void Die::LogToStderr(const char *msg, const char *file, int line) {
 
     // No need to loop. Short write()s are unlikely and if they happen we
     // probably prefer them over a loop that blocks.
-    if (HANDLE_EINTR(write(2, s.c_str(), s.length()))) { }
+    if (HANDLE_EINTR(Syscall(__NR_write, 2, s.c_str(), s.length()))) { }
   }
 }
 
-bool Die::simple_exit_ = false;
+bool Die::simple_exit_   = false;
+bool Die::suppress_info_ = false;
 
 }  // namespace