From 3b8a3fad8f720fc6ee18d3cbbbef9e40cb377bab Mon Sep 17 00:00:00 2001
From: Toshihito Kikuchi <tkikuchi@mozilla.com>
Date: Fri, 28 Aug 2020 21:27:22 +0000
Subject: [PATCH] Bug 1657208 - Dynamic-load urlmon.dll for x86 system. 
 r=freddyb,mhowell

Our data indicates a few users of x86 system hit failure to load urlmon.dll
for unknown reasons.  Since we don't always require urlmon.dll,
we delay-load it, which causes a crash if loading urlmon.dll fails.

A proposed fix is to dynamically load urlmon.dll on x86.

Differential Revision: https://phabricator.services.mozilla.com/D88534
---
 dom/security/nsContentSecurityUtils.cpp |  6 +++---
 widget/windows/UrlmonHeaderOnlyUtils.h  |  3 ++-
 widget/windows/WinHeaderOnlyUtils.h     | 17 +++++++++++++++++
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/dom/security/nsContentSecurityUtils.cpp b/dom/security/nsContentSecurityUtils.cpp
index 77b924960d3c..c3acac0c213f 100644
--- a/dom/security/nsContentSecurityUtils.cpp
+++ b/dom/security/nsContentSecurityUtils.cpp
@@ -303,9 +303,9 @@ FilenameTypeAndDetails nsContentSecurityUtils::FilenameToFilenameType(
   if (widget::WinUtils::PreparePathForTelemetry(strSanitizedPath, flags)) {
     DWORD cchDecodedUrl = INTERNET_MAX_URL_LENGTH;
     WCHAR szOut[INTERNET_MAX_URL_LENGTH];
-    HRESULT hr =
-        ::CoInternetParseUrl(fileName.get(), PARSE_SCHEMA, 0, szOut,
-                             INTERNET_MAX_URL_LENGTH, &cchDecodedUrl, 0);
+    HRESULT hr;
+    SAFECALL_URLMON_FUNC(CoInternetParseUrl, fileName.get(), PARSE_SCHEMA, 0,
+                         szOut, INTERNET_MAX_URL_LENGTH, &cchDecodedUrl, 0);
     if (hr == S_OK && cchDecodedUrl) {
       nsAutoString sanitizedPathAndScheme;
       sanitizedPathAndScheme.Append(szOut);
diff --git a/widget/windows/UrlmonHeaderOnlyUtils.h b/widget/windows/UrlmonHeaderOnlyUtils.h
index e55af55c81f3..dd9209f78f04 100644
--- a/widget/windows/UrlmonHeaderOnlyUtils.h
+++ b/widget/windows/UrlmonHeaderOnlyUtils.h
@@ -48,7 +48,8 @@ inline LauncherResult<_bstr_t> UrlmonValidateUri(const wchar_t* aUri) {
       Uri_CREATE_CRACK_UNKNOWN_SCHEMES | Uri_CREATE_PRE_PROCESS_HTML_URI |
       Uri_CREATE_IE_SETTINGS;
   RefPtr<IUri> uri;
-  HRESULT hr = CreateUri(aUri, flags, 0, getter_AddRefs(uri));
+  HRESULT hr;
+  SAFECALL_URLMON_FUNC(CreateUri, aUri, flags, 0, getter_AddRefs(uri));
   if (FAILED(hr)) {
     return LAUNCHER_ERROR_FROM_HRESULT(hr);
   }
diff --git a/widget/windows/WinHeaderOnlyUtils.h b/widget/windows/WinHeaderOnlyUtils.h
index 33747779f726..18599e1fc6db 100644
--- a/widget/windows/WinHeaderOnlyUtils.h
+++ b/widget/windows/WinHeaderOnlyUtils.h
@@ -51,6 +51,23 @@ typedef struct _FILE_ID_INFO {
 #  define STATUS_SUCCESS ((NTSTATUS)0x00000000L)
 #endif  // !defined(STATUS_SUCCESS)
 
+// Our data indicates a few users of Win7 x86 hit failure to load urlmon.dll
+// for unknown reasons.  Since we don't always require urlmon.dll on Win7,
+// we delay-load it, which causes a crash if loading urlmon.dll fails.  This
+// macro is to safely load and call urlmon's API graciously without crash.
+#if defined(_X86_)
+#  define SAFECALL_URLMON_FUNC(FuncName, ...)                                  \
+    do {                                                                       \
+      static const mozilla::StaticDynamicallyLinkedFunctionPtr<decltype(       \
+          &::FuncName)>                                                        \
+          func(L"urlmon.dll", #FuncName);                                      \
+      hr =                                                                     \
+          func ? func(__VA_ARGS__) : HRESULT_FROM_WIN32(ERROR_PROC_NOT_FOUND); \
+    } while (0)
+#else
+#  define SAFECALL_URLMON_FUNC(FuncName, ...) hr = ::FuncName(__VA_ARGS__)
+#endif
+
 namespace mozilla {
 
 class WindowsError final {