Prototype implementation of zygotes.

Limitations that need addressing still:
- Doesn't forcibly terminate children that should have exited but haven't

Enable with env var ENABLE_ZYGOTE_MANAGER=1.

BUG=11841
TEST=
start the browser, then make chrome and all .pak files unreadable; or alternately, start an installed browser, and uninstall the browser while it's running.  Then create a new tab and browse to two new sites. 

Here's an example script to hide and unhide the .pak files (note: do not move the directory they're in, that doesn't work):

#!/bin/sh
chmod_all() {
   chmod $1 sconsbuild/Debug/chrome
   for path in . locales obj/chrome/app/intermediate/repack obj/global_intermediate/* themes
   do
     chmod $1 sconsbuild/Debug/$path/*.pak
   done
}
case $1 in
hide) chmod_all 000 ;;
show) chmod_all 755 ;;
esac


Review URL: http://codereview.chromium.org/115773

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17840 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 40 insertions, 9 deletions

diff --git a/chrome/app/breakpad_linux.cc b/chrome/app/breakpad_linux.cc
index 0712241..0ee0bed 100644
--- a/chrome/app/breakpad_linux.cc
+++ b/chrome/app/breakpad_linux.cc
@@ -14,6 +14,7 @@
 #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"
@@ -501,8 +502,7 @@ 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 this slot:
-  static const int kMagicCrashSignalFd = 4;
+  // descriptor in slot kMagicCrashSignalFd.
 
   // We deliberately leak this object.
   google_breakpad::ExceptionHandler* handler =
diff --git a/chrome/app/chrome_dll_main.cc b/chrome/app/chrome_dll_main.cc
index 006d923..b6ba22f 100644
--- a/chrome/app/chrome_dll_main.cc
+++ b/chrome/app/chrome_dll_main.cc
@@ -45,6 +45,9 @@
 #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)
@@ -292,6 +295,18 @@ int ChromeMain(int argc, const char** argv) {
   // 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
diff --git a/chrome/browser/renderer_host/browser_render_process_host.cc b/chrome/browser/renderer_host/browser_render_process_host.cc
index 771b4d6..9be8769 100644
--- a/chrome/browser/renderer_host/browser_render_process_host.cc
+++ b/chrome/browser/renderer_host/browser_render_process_host.cc
@@ -22,6 +22,7 @@
 #include "base/path_service.h"
 #include "base/process_util.h"
 #include "base/rand_util.h"
+#include "base/reserved_file_descriptors.h"
 #include "base/scoped_ptr.h"
 #include "base/shared_memory.h"
 #include "base/singleton.h"
@@ -345,10 +346,12 @@ bool BrowserRenderProcessHost::Init() {
     const int crash_signal_fd =
         Singleton<RenderCrashHandlerHostLinux>()->GetDeathSignalSocket();
     if (crash_signal_fd >= 0)
-      fds_to_map.push_back(std::make_pair(crash_signal_fd, 4));
-#endif
+      fds_to_map.push_back(std::make_pair(crash_signal_fd, kMagicCrashSignalFd));
+    base::ForkApp(cmd_line.argv(), fds_to_map, &process);
+#else
     base::LaunchApp(cmd_line.argv(), fds_to_map, false, &process);
 #endif
+#endif
     if (!process) {
       channel_.reset();
       return false;
diff --git a/chrome/common/ipc_channel_posix.cc b/chrome/common/ipc_channel_posix.cc
index b7a9666..52cad9d 100644
--- a/chrome/common/ipc_channel_posix.cc
+++ b/chrome/common/ipc_channel_posix.cc
@@ -20,6 +20,7 @@
 #include "base/lock.h"
 #include "base/logging.h"
 #include "base/process_util.h"
+#include "base/reserved_file_descriptors.h"
 #include "base/scoped_ptr.h"
 #include "base/string_util.h"
 #include "base/singleton.h"
@@ -114,10 +115,6 @@ class PipeMap {
   ChannelToFDMap map_;
 };
 
-// This is the file descriptor number that a client process expects to find its
-// IPC socket.
-static const int kClientChannelFd = 3;
-
 // Used to map a channel name to the equivalent FD # in the client process.
 int ChannelNameToClientFD(const std::string& channel_id) {
   // See the large block comment above PipeMap for the reasoning here.
@@ -127,6 +124,9 @@ int ChannelNameToClientFD(const std::string& channel_id) {
 
   // If we don't find an entry, we assume that the correct value has been
   // inserted in the magic slot.
+  // kClientChannelFd is the file descriptor number that a client process
+  // expects to find its IPC socket; see reserved_file_descriptors.h.
+
   return kClientChannelFd;
 }
 
diff --git a/chrome/common/process_watcher_posix.cc b/chrome/common/process_watcher_posix.cc
index f1ae4f4..497b80b 100644
--- a/chrome/common/process_watcher_posix.cc
+++ b/chrome/common/process_watcher_posix.cc
@@ -11,6 +11,7 @@
 
 #include "base/eintr_wrapper.h"
 #include "base/platform_thread.h"
+#include "base/zygote_manager.h"
 
 // Return true if the given child is dead. This will also reap the process.
 // Doesn't block.
@@ -69,8 +70,20 @@ class BackgroundReaper : public PlatformThread::Delegate {
 // static
 void ProcessWatcher::EnsureProcessTerminated(base::ProcessHandle process) {
   // If the child is already dead, then there's nothing to do
-  if (IsChildDead(process))
+  const int result = HANDLE_EINTR(waitpid(process, NULL, WNOHANG));
+  if (result > 0)
     return;
+  if (result == -1) {
+#if defined(OS_LINUX)
+    // If it wasn't our child, maybe it was the zygote manager's child
+    base::ZygoteManager* zm = base::ZygoteManager::Get();
+    if (zm) {
+      zm->EnsureProcessTerminated(process);
+      return;
+    }
+#endif  // defined(OS_LINUX)
+    NOTREACHED();
+  }
 
   BackgroundReaper* reaper = new BackgroundReaper(process);
   PlatformThread::CreateNonJoinable(0, reaper);