Amend PATH for nacl64 so loader can find x64 CRT

components/nacl/browser/nacl_process_host.cc

Index: components/nacl/browser/nacl_process_host.cc
diff --git a/components/nacl/browser/nacl_process_host.cc b/components/nacl/browser/nacl_process_host.cc
index a5a1341dcfb16c65a3bcc8baf41eccd24c8c6b65..31486fbfc2be38ebf86441949a1a480df81aeae2 100644
--- a/components/nacl/browser/nacl_process_host.cc
+++ b/components/nacl/browser/nacl_process_host.cc
@@ -512,6 +512,33 @@ bool NaClProcessHost::LaunchSelLdr() {
       SendErrorToRenderer("could not get path to nacl64.exe");
       return false;
     }
+
+#ifdef _DLL
+    // When using the DLL CRT on Windows, we need to amend the PATH to include
+    // the location of the x64 CRT DLLs. This is only the case when using a
+    // component=shared_library build (i.e. generally dev debug builds). The
+    // x86 CRT DLLs are in e.g. out\Debug for chrome.exe etc., so the x64 ones
+    // are put in out\Debug\x64 which we add to the PATH here so that loader
+    // can find them. See http://crbug.com/346034.
+    scoped_ptr<base::Environment> env(base::Environment::Create());
+    static const char kPath[] = "PATH";
+    std::string old_path;
+    base::FilePath module_path;
+    if (!PathService::Get(base::FILE_MODULE, &module_path)) {
+      SendErrorToRenderer("could not get path to current module");
+      return false;
+    }
+    std::string x64_crt_path =
+        base::WideToUTF8(module_path.DirName().Append(L"x64").value());
+    if (!env->GetVar(kPath, &old_path)) {
+      env->SetVar(kPath, x64_crt_path);
+    } else if (old_path.find(x64_crt_path) == std::string::npos) {

[Mark Seaborn, 2014/02/26 02:24:50]

This is a bit icky because it matches any substring.  It would be cleaner to
split on ";" and check whether the list contains the exact path.

Alternatively, you could append the path unconditionally but have a global
variable indicating whether this initialisation has already been done, so that
PATH doesn't grow over time.

[scottmg, 2014/02/26 04:27:59]

I admit I considered that when writing it and decided it was pretty unlikely,
but on the other hand, might as well do it properly. Done.

+      std::string new_path(old_path);
+      new_path.append(";");
+      new_path.append(x64_crt_path);
+      env->SetVar(kPath, new_path);
+    }
+#endif  // _DLL
   }
 #endif