[Mac] Disable Mach IPC between renderers and cfprefsd.

content/renderer/renderer_main_platform_delegate_mac.mm

Index: content/renderer/renderer_main_platform_delegate_mac.mm
diff --git a/content/renderer/renderer_main_platform_delegate_mac.mm b/content/renderer/renderer_main_platform_delegate_mac.mm
index 9f6172e71e1ff7800de39c96c4a5e36cbc57287c..df47f3d0e1072629559b5cea71258d4e54c18af5 100644
--- a/content/renderer/renderer_main_platform_delegate_mac.mm
+++ b/content/renderer/renderer_main_platform_delegate_mac.mm
@@ -13,6 +13,7 @@
 #import "base/mac/foundation_util.h"
 #import "base/mac/mac_util.h"
 #include "base/mac/scoped_cftyperef.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/sys_string_conversions.h"
 #include "content/common/sandbox_mac.h"
 #include "content/public/common/content_switches.h"
@@ -68,6 +69,87 @@ void CrRendererCFLog(int32_t level, CFStringRef format, ...) {
   va_end(args);
 }
 
+// You are about to read a pretty disgusting hack. In a static initializer,

[Avi (use Gerrit), 2014/02/25 19:54:47]

Yes, this is disgusting.

+// CoreFoundation decides to connect with cfprefsd(8) using Mach IPC. There is
+// no public way to close this Mach port after-the-fact, nor a way to stop it
+// from happening since it is done pre-main in dyld. But the address of the
+// CFMachPort can be found in the run loop's string description. Below, that
+// address is parsed, cast, and then used to invalidate the Mach port to
+// disable communication with cfprefsd.
+void DisconnectCFNotificationCenter() {
+  base::ScopedCFTypeRef<CFStringRef> run_loop_description(
+      CFCopyDescription(CFRunLoopGetCurrent()));
+  const CFIndex length = CFStringGetLength(run_loop_description);
+  for (CFIndex i = 0; i < length; ) {
+    // Find the start of a CFMachPort run loop source, which looks like this,
+    // without new lines:
+    // 1 : <CFRunLoopSource 0x7d16ea90 [0xa160af80]>{signalled = No,
+    // valid = Yes, order = 0, context =
+    // <CFMachPort 0x7d16fe00 [0xa160af80]>{valid = Yes, port = 3a0f,
+    // source = 0x7d16ea90, callout =
+    // _ZL14MessageHandlerP12__CFMachPortPvlS1_ (0x96df59c2), context =
+    // <CFMachPort context 0x1475b>}}
+    CFRange run_loop_source_context_range;
+    if (!CFStringFindWithOptions(run_loop_description,
+            CFSTR(", context = <CFMachPort "), CFRangeMake(i, length - i),
+            0, &run_loop_source_context_range)) {
+      break;
+    }
+    i = run_loop_source_context_range.location +
+        run_loop_source_context_range.length;
+
+    // The address of the CFMachPort is the first hexadecimal address after the
+    // CF type name.
+    CFRange port_address_range = CFRangeMake(i, 0);
+    for (CFIndex j = port_address_range.location; j < length; ++j) {
+      UniChar c = CFStringGetCharacterAtIndex(run_loop_description, j);
+      if (c == ' ')
+        break;
+      ++port_address_range.length;
+    }
+
+    base::ScopedCFTypeRef<CFStringRef> port_address_string(
+        CFStringCreateWithSubstring(NULL, run_loop_description,
+            port_address_range));
+    if (!port_address_string)
+      continue;
+
+    // Convert the string to an address.
+    std::string port_address_std_string =
+        base::SysCFStringRefToUTF8(port_address_string);
+#if __LP64__
+    uint64 port_address = 0;
+    if (!base::HexStringToUInt64(port_address_std_string, &port_address))
+      continue;
+#else
+    uint32 port_address = 0;
+    if (!base::HexStringToUInt(port_address_std_string, &port_address))
+      continue;
+#endif
+
+    // Cast the address to an object.
+    CFMachPortRef mach_port = reinterpret_cast<CFMachPortRef>(port_address);
+    if (CFGetTypeID(mach_port) != CFMachPortGetTypeID())
+      continue;
+
+    // Verify that this is the Mach port that needs to be disconnected by the
+    // name of its callout function. Example description (no new lines):
+    // <CFMachPort 0x7d16fe00 [0xa160af80]>{valid = Yes, port = 3a0f, source =
+    // 0x7d16ea90, callout = __CFXNotificationReceiveFromServer (0x96df59c2),
+    // context = <CFMachPort context 0x1475b>}
+    base::ScopedCFTypeRef<CFStringRef> port_description(
+        CFCopyDescription(mach_port));
+    if (CFStringFindWithOptions(port_description,
+            CFSTR(", callout = __CFXNotificationReceiveFromServer ("),
+            CFRangeMake(0, CFStringGetLength(port_description)),
+            0,
+            NULL)) {
+      CFMachPortInvalidate(mach_port);
+      return;
+    }
+  }
+}
+
 }  // namespace
 
 RendererMainPlatformDelegate::RendererMainPlatformDelegate(
@@ -173,6 +255,8 @@ bool RendererMainPlatformDelegate::EnableSandbox() {
         source_list, arraysize(source_list), &kCFTypeArrayCallBacks);
   }
 
+  DisconnectCFNotificationCenter();
+
   return sandbox_initialized;
 }