Build ForkWithFlags and part of NamespaceSandbox under nonsfi newlib.

sandbox/linux/services/namespace_sandbox.cc

Index: sandbox/linux/services/namespace_sandbox.cc
diff --git a/sandbox/linux/services/namespace_sandbox.cc b/sandbox/linux/services/namespace_sandbox.cc
index 23796446f3044e88a6ddcb5d6e38fb41156e8456..3d10e47cf88f2d584cf311a58ffb9476ef61142e 100644
--- a/sandbox/linux/services/namespace_sandbox.cc
+++ b/sandbox/linux/services/namespace_sandbox.cc
@@ -24,6 +24,7 @@
 #include "base/process/process.h"
 #include "sandbox/linux/services/credentials.h"
 #include "sandbox/linux/services/namespace_utils.h"
+#include "sandbox/linux/system_headers/linux_signal.h"
 
 namespace sandbox {
 
@@ -65,6 +66,7 @@ void SetEnvironForNamespaceType(base::EnvironmentMap* environ,
   // An empty string causes the env var to be unset in the child process.
   (*environ)[env_var] = value ? "1" : "";
 }
+#endif  // !defined(OS_NACL_NONSFI)
 
 // Linux supports up to 64 signals. This should be updated if that ever changes.
 int g_signal_exit_codes[64];
@@ -79,7 +81,6 @@ void TerminationSignalHandler(int sig) {
 
   _exit(NamespaceSandbox::kDefaultExitCode);
 }
-#endif  // !defined(OS_NACL_NONSFI)
 
 }  // namespace
 
@@ -129,11 +130,12 @@ base::Process NamespaceSandbox::LaunchProcess(
 
   return base::LaunchProcess(argv, launch_options);
 }
+#endif  // !defined(OS_NACL_NONSFI)
 
 // static
 pid_t NamespaceSandbox::ForkInNewPidNamespace(bool drop_capabilities_in_child) {
   const pid_t pid =
-      base::ForkWithFlags(CLONE_NEWPID | SIGCHLD, nullptr, nullptr);
+      base::ForkWithFlags(CLONE_NEWPID | LINUX_SIGCHLD, nullptr, nullptr);
   if (pid < 0) {
     return pid;
   }
@@ -168,10 +170,13 @@ bool NamespaceSandbox::InstallTerminationSignalHandler(
   struct sigaction old_action;
   PCHECK(sigaction(sig, nullptr, &old_action) == 0);

[hidehiko, 2015/06/16 05:41:53]

Youl'll need to call sys_sigaction instead. Ditto for below.

[rickyz (no longer on Chrome), 2015/06/16 20:57:07]

Oops, done - do you know whether we need our own definition of struct sigaction
as well then? I remember you saying something about sigset_t having a different
size before.

I wonder how much work it'd be to make our unit tests compile under newlib
nonsfi NaCl. Seems like there's a decent risk of bugs in these things slipping
through :-

 
+#if !defined(OS_NACL_NONSFI)
   if (old_action.sa_flags & SA_SIGINFO &&
       old_action.sa_sigaction != nullptr) {
     return false;
-  } else if (old_action.sa_handler != SIG_DFL) {
+  } else

[hidehiko, 2015/06/16 05:41:53]

nit: you don't need "else"

[rickyz (no longer on Chrome), 2015/06/16 20:57:06]

Done.

+#endif
+  if (old_action.sa_handler != SIG_DFL) {

[hidehiko, 2015/06/16 05:41:53]

SIG_DFL needs to be LINUX_SIG_DFL.

[rickyz (no longer on Chrome), 2015/06/16 20:57:06]

Done.

     return false;
   }
 
@@ -188,7 +193,6 @@ bool NamespaceSandbox::InstallTerminationSignalHandler(
   PCHECK(sigaction(sig, &action, nullptr) == 0);
   return true;
 }
-#endif  // !defined(OS_NACL_NONSFI)
 
 // static
 bool NamespaceSandbox::InNewUserNamespace() {