Initial import of the Chrome Frame codebase. Integration in chrome.gyp coming...

chrome_frame/vtable_patch_manager.cc

Index: chrome_frame/vtable_patch_manager.cc
===================================================================
--- chrome_frame/vtable_patch_manager.cc	(revision 0)
+++ chrome_frame/vtable_patch_manager.cc	(revision 0)
@@ -0,0 +1,82 @@
+// Copyright (c) 2009 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.
+
+#include "chrome_frame/vtable_patch_manager.h"
+
+#include "base/logging.h"
+
+#include "chrome_frame/function_stub.h"
+
+namespace vtable_patch {
+
+// Convenient definition of a VTABLE
+typedef PROC* Vtable;
+
+// Returns a pointer to the VTable of a COM interface.
+// @param unknown [in] The pointer of the COM interface.
+inline Vtable GetIFVTable(void* unknown) {
+  return reinterpret_cast<Vtable>(*reinterpret_cast<void**>(unknown));
+}
+
+HRESULT PatchInterfaceMethods(void* unknown, MethodPatchInfo* patches) {
+  // Do some sanity checking of the input arguments.
+  if (NULL == unknown || NULL == patches) {
+    NOTREACHED();
+    return E_INVALIDARG;
+  }
+
+  Vtable vtable = GetIFVTable(unknown);
+  DCHECK(vtable);
+
+  for (MethodPatchInfo* it = patches; it->index_ != -1; ++it) {
+    PROC original_fn = vtable[it->index_];
+    FunctionStub* stub = FunctionStub::FromCode(original_fn);
+    if (stub != NULL) {
+      DLOG(ERROR) << "attempt to patch a function that's already patched";
+      DCHECK(stub->absolute_target() ==
+             reinterpret_cast<uintptr_t>(it->method_)) <<
+             "patching the same method multiple times with different hooks?";
+      continue;
+    }
+
+    stub = FunctionStub::Create(reinterpret_cast<uintptr_t>(original_fn),
+                                it->method_);
+    if (!stub) {
+      NOTREACHED();
+      return E_OUTOFMEMORY;
+    } else {
+      DWORD protect = 0;
+      if (::VirtualProtect(&vtable[it->index_], sizeof(PROC),
+                           PAGE_EXECUTE_READWRITE, &protect)) {
+        it->stub_ = stub;  // save the stub
+        vtable[it->index_] = stub->code();
+        ::VirtualProtect(&vtable[it->index_], sizeof(PROC), protect,
+                         &protect);
+      } else {
+        NOTREACHED();
+      }
+    }
+  }
+
+  return S_OK;
+}
+
+HRESULT UnpatchInterfaceMethods(MethodPatchInfo* patches) {
+  for (MethodPatchInfo* it = patches; it->index_ != -1; ++it) {
+    if (it->stub_) {
+      DCHECK(it->stub_->absolute_target() == 
+          reinterpret_cast<uintptr_t>(it->method_));
+      // Modify the stub to just jump directly to the original function.
+      it->stub_->BypassStub(reinterpret_cast<void*>(it->stub_->argument()));
+      it->stub_ = NULL;
+      // Leave the stub in memory so that we won't break any possible chains.
+    } else {
+      DLOG(WARNING) << "attempt to unpatch a function that wasn't patched";
+    }
+  }
+
+  return S_OK;
+}
+
+}  // namespace vtable_patch