Bug 1709969 Part 1 - Add a utility function to retrieve the current package's family name. r=agashlin

Differential Revision: https://phabricator.services.mozilla.com/D120529

widget/windows/WinUtils.cpp

@@ -2294,5 +2294,41 @@ bool WinUtils::PreparePathForTelemetry(nsAString& aPath,
   return true;
 }
 
+nsString WinUtils::GetPackageFamilyName() {
+  nsString rv;
+
+  if (!HasPackageIdentity()) {
+    return rv;
+  }
+
+  HMODULE kernel32Dll = ::GetModuleHandleW(L"kernel32");
+  if (!kernel32Dll) {
+    return rv;
+  }
+
+  typedef LONG(WINAPI * GetCurrentPackageFamilyNameProc)(UINT32*, PWSTR);
+  GetCurrentPackageFamilyNameProc pGetCurrentPackageFamilyName =
+      (GetCurrentPackageFamilyNameProc)::GetProcAddress(
+          kernel32Dll, "GetCurrentPackageFamilyName");
+  if (!pGetCurrentPackageFamilyName) {
+    return rv;
+  }
+
+  UINT32 packageNameSize = 0;
+  if (pGetCurrentPackageFamilyName(&packageNameSize, nullptr) !=
+      ERROR_INSUFFICIENT_BUFFER) {
+    return rv;
+  }
+
+  UniquePtr<wchar_t[]> packageIdentity = MakeUnique<wchar_t[]>(packageNameSize);
+  if (pGetCurrentPackageFamilyName(&packageNameSize, packageIdentity.get()) !=
+      ERROR_SUCCESS) {
+    return rv;
+  }
+
+  rv = packageIdentity.get();
+  return rv;
+}
+
 }  // namespace widget
 }  // namespace mozilla

widget/windows/WinUtils.h

@@ -223,6 +223,18 @@ class WinUtils {
 
   static bool HasPackageIdentity() { return sHasPackageIdentity; }
 
+  /*
+   * The "family name" of a Windows app package is the full name without any of
+   * the components that might change during the life cycle of the app (such as
+   * the version number, or the architecture). This leaves only those properties
+   * which together serve to uniquely identify the app within one Windows
+   * installation, namely the base name and the publisher name. Meaning, this
+   * string is safe to use anywhere that a string uniquely identifying an app
+   * installation is called for (because multiple copies of the same app on the
+   * same system is not a supported feature in the app framework).
+   */
+  static nsString GetPackageFamilyName();
+
   /**
    * Logging helpers that dump output to prlog module 'Widget', console, and
    * OutputDebugString. Note these output in both debug and release builds.