4 files changed, 71 insertions, 9 deletions

diff --git a/chrome/nacl/nacl_fork_delegate_linux.cc b/chrome/nacl/nacl_fork_delegate_linux.cc
index 794cfda..e5ee01a 100644
--- a/chrome/nacl/nacl_fork_delegate_linux.cc
+++ b/chrome/nacl/nacl_fork_delegate_linux.cc
@@ -13,9 +13,11 @@
 #include "base/eintr_wrapper.h"
 #include "base/logging.h"
 #include "base/file_path.h"
+#include "base/path_service.h"
 #include "base/process_util.h"
 #include "content/common/unix_domain_socket_posix.h"
 #include "content/common/zygote_fork_delegate_linux.h"
+#include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/nacl_helper_linux.h"
 
@@ -40,18 +42,24 @@ void NaClForkDelegate::Init(const bool sandboxed,
   base::file_handle_mapping_vector fds_to_map;
   fds_to_map.push_back(std::make_pair(fds[1], kNaClZygoteDescriptor));
   fds_to_map.push_back(std::make_pair(sandboxdesc, kNaClSandboxDescriptor));
-  // TODO(bradchen): Before making this the default for release builds,
-  // replace command line switch with PathService::Get().
-  const std::string nacl_zygote_exe =
-      CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
-          switches::kNaClLinuxHelper);
+  // TODO(bradchen): To make this the default for release builds,
+  // remove command line switch.
   ready_ = false;
-  if (nacl_zygote_exe.length() != 0) {
+  const bool use_helper = CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kNaClLinuxHelper);
+  FilePath helper_exe;
+  if (use_helper && PathService::Get(chrome::FILE_NACL_HELPER, &helper_exe)) {
     CommandLine::StringVector argv = CommandLine::ForCurrentProcess()->argv();
-    argv[0] = nacl_zygote_exe;
+    argv[0] = helper_exe.value();
     base::LaunchOptions options;
     options.fds_to_remap = &fds_to_map;
     options.clone_flags = CLONE_FS | SIGCHLD;
+    // LD_BIND_NOW forces non-lazy binding in the dynamic linker, to
+    // prevent the linker from trying to look at the text of the nacl_helper
+    // program after it has been replaced by the nacl module.
+    base::environment_vector env;
+    env.push_back(std::make_pair("LD_BIND_NOW", "1"));
+    options.environ = &env;
     ready_ = base::LaunchProcess(argv, options, NULL);
     // parent and error cases are handled below
   }
diff --git a/chrome/nacl/nacl_helper_bootstrap_linux.c b/chrome/nacl/nacl_helper_bootstrap_linux.c
new file mode 100644
index 0000000..7a0ace7
--- /dev/null
+++ b/chrome/nacl/nacl_helper_bootstrap_linux.c
@@ -0,0 +1,24 @@
+/* Copyright (c) 2011 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.
+ *
+ * Bootstraping the nacl_helper. This executable reserves the bottom 1G
+ * of the address space, then invokes nacl_helper_init. Note that,
+ * as the text of this executable will eventually be overwritten by the
+ * native_client module, nacl_helper_init must not attempt to return.
+ */
+
+#include <stdlib.h>
+
+/* reserve 1GB of space */
+#define ONEGIG (1 << 30)
+char nacl_reserved_space[ONEGIG];
+
+void nacl_helper_init(int argc, char *argv[],
+                      const char *nacl_reserved_space);
+
+int main(int argc, char *argv[]) {
+  nacl_helper_init(argc, argv, nacl_reserved_space);
+  abort();
+  return 0;  // convince the tools I'm sane.
+}
diff --git a/chrome/nacl/nacl_helper_exports.txt b/chrome/nacl/nacl_helper_exports.txt
new file mode 100644
index 0000000..af930c1
--- /dev/null
+++ b/chrome/nacl/nacl_helper_exports.txt
@@ -0,0 +1,10 @@
+# gnu-ld version script for exporting desired symbols from nacl_helper
+#
+
+NACL_HELPER_1_0 {
+	global:
+		nacl_helper_init;
+		nacl_helper_get_1G_address;
+	local:
+		*;
+};
diff --git a/chrome/nacl/nacl_helper_linux.cc b/chrome/nacl/nacl_helper_linux.cc
index b943e2b..b53cf8d 100644
--- a/chrome/nacl/nacl_helper_linux.cc
+++ b/chrome/nacl/nacl_helper_linux.cc
@@ -116,14 +116,33 @@ void HandleForkRequest(const std::vector<int>& child_fds) {
 
 }  // namespace
 
-int main(int argc, char *argv[]) {
+static const void* g_nacl_reserved_space = NULL;
+extern "C" __attribute__((visibility("default")))
+const void* nacl_helper_get_1G_address() {
+  return g_nacl_reserved_space;
+}
+
+// nacl_helper_init does the real work of this module. It is invoked as
+// a static constructor and never returns, preventing main() from the
+// nacl_helper_bootstrap program from being called.
+//
+// NOTE This routine must not return.
+extern "C" __attribute__((visibility("default")))
+void nacl_helper_init(int argc, char *argv[],
+                      const char *nacl_reserved_space) {
   CommandLine::Init(argc, argv);
   base::AtExitManager exit_manager;
   base::RandUint64();  // acquire /dev/urandom fd before sandbox is raised
   std::vector<int> empty; // for SendMsg() calls
 
   g_suid_sandbox_active = (NULL != getenv("SBX_D"));
-
+  g_nacl_reserved_space = nacl_reserved_space;
+  if (!nacl_reserved_space) {
+    VLOG(1) << "nacl_reserved_space is NULL";
+  } else {
+    VLOG(1) << "nacl_reserved_space is at "
+            << (void *)nacl_reserved_space;
+  }
   // Send the zygote a message to let it know we are ready to help
   if (!UnixDomainSocket::SendMsg(kNaClZygoteDescriptor,
                                  kNaClHelperStartupAck,
@@ -163,4 +182,5 @@ int main(int argc, char *argv[]) {
       LOG(ERROR) << "*** send() to zygote failed";
     }
   }
+  CHECK(false);  // This routine must not return
 }