linux: use /proc/self/exe when exec'ing ourselves

chrome/common/child_process_host.cc

Index: chrome/common/child_process_host.cc
diff --git a/chrome/common/child_process_host.cc b/chrome/common/child_process_host.cc
index d4a9edae18f65a1618109023352df2ef1a1bf3b8..2e0f1f600c45da326389b7640fc34d7c8776069f 100644
--- a/chrome/common/child_process_host.cc
+++ b/chrome/common/child_process_host.cc
@@ -93,16 +93,20 @@ FilePath ChildProcessHost::GetChildPath() {
   if (!child_path.empty())
     return child_path;
 
-#if !defined(OS_MACOSX)
-  // On most platforms, the child executable is the same as the current
-  // executable.
-  PathService::Get(base::FILE_EXE, &child_path);
-#else
+#if defined(OS_LINUX)
+  // Use /proc/self/exe rather than our known binary path so updates
+  // can't swap out the binary from underneath us.
+  child_path = FilePath("/proc/self/exe");
+#elif defined(OS_MACOSX)
   // On the Mac, the child executable lives at a predefined location within
   // the app bundle's versioned directory.
   child_path = chrome::GetVersionedDirectory().
       Append(chrome::kHelperProcessExecutablePath);
-#endif  // OS_MACOSX
+#else
+  // On most platforms, the child executable is the same as the current
+  // executable.
+  PathService::Get(base::FILE_EXE, &child_path);
+#endif
 
   return child_path;
 }