Linux: refactor zygote support

http://code.google.com/p/chromium/wiki/LinuxZygote

* Move Chrome specific bits out of base
* Move away from the idea of reserved file descriptors (which don't
  really work with zygotes)
* Load resources before forking renderers (means that we don't need
  communication between the zygote process and the renderers)
* Make sure that gdb works against the browser again
* Make sure that we have different ASLR between the renderers and the
  browser.

http://codereview.chromium.org/119335


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@18109 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 32 insertions, 20 deletions

diff --git a/chrome/app/breakpad_linux.cc b/chrome/app/breakpad_linux.cc
index 0ee0bed..ef3dfa2 100644
--- a/chrome/app/breakpad_linux.cc
+++ b/chrome/app/breakpad_linux.cc
@@ -14,13 +14,13 @@
 #include "base/file_version_info_linux.h"
 #include "base/path_service.h"
 #include "base/rand_util.h"
-#include "base/reserved_file_descriptors.h"
 #include "breakpad/linux/directory_reader.h"
 #include "breakpad/linux/exception_handler.h"
 #include "breakpad/linux/linux_libc_support.h"
 #include "breakpad/linux/linux_syscall_support.h"
 #include "breakpad/linux/memory.h"
 #include "chrome/common/chrome_switches.h"
+#include "chrome/common/chrome_descriptors.h"
 #include "chrome/installer/util/google_update_settings.h"
 
 static const char kUploadURL[] =
@@ -501,13 +501,11 @@ RendererCrashHandler(const void* crash_context, size_t crash_context_size,
 }
 
 void EnableRendererCrashDumping() {
-  // When the browser forks off our process, it installs the crash signal file
-  // descriptor in slot kMagicCrashSignalFd.
-
+  const int fd = Singleton<base::GlobalDescriptors>()->Get(kCrashDumpSignal);
   // We deliberately leak this object.
   google_breakpad::ExceptionHandler* handler =
       new google_breakpad::ExceptionHandler("" /* unused */, NULL, NULL,
-                                            (void*) kMagicCrashSignalFd, true);
+                                            (void*) fd, true);
   handler->set_crash_handler(RendererCrashHandler);
 }
 
diff --git a/chrome/app/chrome_dll_main.cc b/chrome/app/chrome_dll_main.cc
index b6ba22f..33e774c 100644
--- a/chrome/app/chrome_dll_main.cc
+++ b/chrome/app/chrome_dll_main.cc
@@ -34,6 +34,9 @@
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/debug_util.h"
+#if defined(OS_POSIX)
+#include "base/global_descriptors_posix.h"
+#endif
 #include "base/icu_util.h"
 #include "base/message_loop.h"
 #include "base/path_service.h"
@@ -45,9 +48,6 @@
 #if defined(OS_WIN)
 #include "base/win_util.h"
 #endif
-#if defined(OS_LINUX)
-#include "base/zygote_manager.h"
-#endif
 #if defined(OS_MACOSX)
 #include "chrome/app/breakpad_mac.h"
 #elif defined(OS_LINUX)
@@ -57,6 +57,7 @@
 #include "chrome/browser/renderer_host/render_process_host.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_counters.h"
+#include "chrome/common/chrome_descriptors.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/logging_chrome.h"
@@ -75,6 +76,7 @@ extern int RendererMain(const MainFunctionParams&);
 extern int PluginMain(const MainFunctionParams&);
 extern int WorkerMain(const MainFunctionParams&);
 extern int UtilityMain(const MainFunctionParams&);
+extern int ZygoteMain(const MainFunctionParams&);
 
 #if defined(OS_WIN)
 // TODO(erikkay): isn't this already defined somewhere?
@@ -292,21 +294,19 @@ int ChromeMain(int argc, const char** argv) {
   // its main event loop to get rid of the cruft.
   base::ScopedNSAutoreleasePool autorelease_pool;
 
+#if defined(OS_POSIX)
+  base::GlobalDescriptors* g_fds = Singleton<base::GlobalDescriptors>::get();
+  g_fds->Set(kPrimaryIPCChannel,
+             kPrimaryIPCChannel + base::GlobalDescriptors::kBaseDescriptor);
+#if defined(OS_LINUX)
+  g_fds->Set(kCrashDumpSignal,
+             kCrashDumpSignal + base::GlobalDescriptors::kBaseDescriptor);
+#endif
+#endif
+
   // Initialize the command line.
 #if defined(OS_WIN)
   CommandLine::Init(0, NULL);
-#elif defined(OS_LINUX)
-  base::ZygoteManager* zm = base::ZygoteManager::Get();
-  std::vector<std::string>* zargv = NULL;
-  if (zm)
-    zargv = zm->Start();
-  if (zargv) {
-    // Forked child.
-    CommandLine::Init(*zargv);
-  } else {
-    // Original process.
-    CommandLine::Init(argc, argv);
-  }
 #else
   CommandLine::Init(argc, argv);
 #endif
@@ -339,11 +339,13 @@ int ChromeMain(int argc, const char** argv) {
     CHECK(sigaction(SIGPIPE, &action, 0) == 0);
 #endif  // OS_POSIX
   } else {
+#if defined(OS_WIN)
     std::wstring channel_name =
       parsed_command_line.GetSwitchValue(switches::kProcessChannelID);
 
     browser_pid = StringToInt(WideToASCII(channel_name));
     DCHECK(browser_pid != 0);
+#endif
 
 #if defined(OS_POSIX)
     // When you hit Ctrl-C in a terminal running the browser
@@ -489,6 +491,13 @@ int ChromeMain(int argc, const char** argv) {
 #else
     NOTIMPLEMENTED();
 #endif
+  } else if (process_type == switches::kZygoteProcess) {
+#if defined(OS_LINUX)
+    if (ZygoteMain(main_params))
+      RendererMain(main_params);
+#else
+    NOTIMPLEMENTED();
+#endif
   } else if (process_type.empty()) {
 #if defined(OS_LINUX)
     // Glib type system initialization. Needed at least for gconf,
diff --git a/chrome/app/chrome_main_uitest.cc b/chrome/app/chrome_main_uitest.cc
index 5ce05c2..f229751 100644
--- a/chrome/app/chrome_main_uitest.cc
+++ b/chrome/app/chrome_main_uitest.cc
@@ -18,9 +18,14 @@ TEST_F(ChromeMainTest, AppLaunch) {
   if (UITest::in_process_renderer()) {
     EXPECT_EQ(1, UITest::GetBrowserProcessCount());
   } else {
+#if defined(OS_LINUX)
+    // On Linux we'll have three processes: browser, renderer and zygote.
+    EXPECT_EQ(3, UITest::GetBrowserProcessCount());
+#else
     // We should have two instances of the browser process alive -
     // one is the Browser and the other is the Renderer.
     EXPECT_EQ(2, UITest::GetBrowserProcessCount());
+#endif
   }
 }