Bug 1435827 part 4/9: Adding GetModuleFullPath to WinUtils.cpp;r=aklotz

A wrapper for ::GetModuleFileNameW() is needed in multiple places for the
purpose of evaluating and processing untrusted DLLs. This adds the appropriate
wrapper to WinUtils.cpp

Depends on D6240

Differential Revision: https://phabricator.services.mozilla.com/D9163

--HG--
extra : moz-landing-system : lando

widget/windows/WinUtils.cpp

@@ -2151,6 +2151,30 @@ WinUtils::RunningFromANetworkDrive()
   return (::GetDriveTypeW(volPath) == DRIVE_REMOTE);
 }
 
+/* static */
+bool
+WinUtils::GetModuleFullPath(HMODULE aModuleHandle, nsAString& aPath)
+{
+  size_t bufferSize = MAX_PATH;
+  size_t len = 0;
+  while (true) {
+    aPath.SetLength(bufferSize);
+    len = (size_t)::GetModuleFileNameW(aModuleHandle,
+                                       (char16ptr_t)aPath.BeginWriting(),
+                                       bufferSize);
+    if (!len) {
+      return false;
+    }
+    if (len == bufferSize && ::GetLastError() == ERROR_INSUFFICIENT_BUFFER) {
+      bufferSize *= 2;
+      continue;
+    }
+    aPath.Truncate(len);
+    break;
+  }
+  return true;
+}
+
 /* static */
 bool WinUtils::CanonicalizePath(nsAString& aPath)
 {

widget/windows/WinUtils.h

@@ -511,6 +511,15 @@ public:
   // Use the one above!
   static nsresult WriteBitmap(nsIFile* aFile, imgIContainer* aImage);
 
+  /**
+   * Wrapper for ::GetModuleFileNameW().
+   * @param  aModuleHandle [in] The handle of a loaded module
+   * @param  aPath         [out] receives the full path of the module specified
+   *                       by aModuleBase.
+   * @return true if aPath was successfully populated.
+   */
+  static bool GetModuleFullPath(HMODULE aModuleHandle, nsAString& aPath);
+
   /**
    * Wrapper for PathCanonicalize().
    * Upon success, the resulting output string length is <= MAX_PATH.