ProcessSingletonLinux: check if lock pid is part of the current Chrome instance.

If it is, it must be an orphaned lock file that just happens to have an unfortunate pid, since we haven't tried to create a lockfile ourselves yet.

Also, don't allow kill with pid 0, which would be another way to theoretically kill ourselves.

BUG=42568,43594
TEST=ui_tests, manual testing

Review URL: http://codereview.chromium.org/1981009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@46977 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 36 insertions, 6 deletions

diff --git a/chrome/browser/process_singleton_linux.cc b/chrome/browser/process_singleton_linux.cc
index 0a9a427..fdf4c2b 100644
--- a/chrome/browser/process_singleton_linux.cc
+++ b/chrome/browser/process_singleton_linux.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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.
 
@@ -280,8 +280,31 @@ void DisplayProfileInUseError(const std::string& lock_path,
 #endif
 }
 
+bool IsChromeProcess(pid_t pid) {
+  FilePath other_chrome_path(base::GetProcessExecutablePath(pid));
+  return (!other_chrome_path.empty() &&
+          other_chrome_path.BaseName() ==
+          FilePath::FromWStringHack(chrome::kBrowserProcessExecutableName));
+}
+
+// Return true if the given pid is one of our child processes.
+// Assumes that the current pid is the root of all pids of the current instance.
+bool IsSameChromeInstance(pid_t pid) {
+  pid_t cur_pid = base::GetCurrentProcId();
+  while (pid != cur_pid) {
+    pid = base::GetParentProcessId(pid);
+    if (pid < 0)
+      return false;
+    if (!IsChromeProcess(pid))
+      return false;
+  }
+  return true;
+}
+
 // Extract the process's pid from a symbol link path and if it is on
 // the same host, kill the process, unlink the lock file and return true.
+// If the process is part of the same chrome instance, unlink the lock file and
+// return true without killing it.
 // If the process is on a different host, return false.
 bool KillProcessByLockPath(const std::string& path) {
   std::string hostname;
@@ -294,7 +317,10 @@ bool KillProcessByLockPath(const std::string& path) {
   }
   UnlinkPath(path);
 
-  if (pid >= 0) {
+  if (IsSameChromeInstance(pid))
+    return true;
+
+  if (pid > 0) {
     // TODO(james.su@gmail.com): Is SIGKILL ok?
     int rv = kill(static_cast<base::ProcessHandle>(pid), SIGKILL);
     // ESRCH = No Such Process (can happen if the other process is already in
@@ -669,15 +695,19 @@ ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcessWithTimeout(
       return PROFILE_IN_USE;
     }
 
-    FilePath other_chrome_path(base::GetProcessExecutablePath(pid));
-    if (other_chrome_path.empty() ||
-        other_chrome_path.BaseName() !=
-        FilePath::FromWStringHack(chrome::kBrowserProcessExecutableName)) {
+    if (!IsChromeProcess(pid)) {
       // Orphaned lockfile (no process with pid, or non-chrome process.)
       UnlinkPath(lock_path_.value());
       return PROCESS_NONE;
     }
 
+    if (IsSameChromeInstance(pid)) {
+      // Orphaned lockfile (pid is part of same chrome instance we are, even
+      // though we haven't tried to create a lockfile yet).
+      UnlinkPath(lock_path_.value());
+      return PROCESS_NONE;
+    }
+
     if (retries == timeout_seconds) {
       // Retries failed.  Kill the unresponsive chrome process and continue.
       if (!KillProcessByLockPath(lock_path_.value()))