3 files changed, 30 insertions, 9 deletions
diff --git a/chrome/installer/mini_installer/decompress.cc b/chrome/installer/mini_installer/decompress.cc
index ced226d..ed9098a 100644
--- a/chrome/installer/mini_installer/decompress.cc
+++ b/chrome/installer/mini_installer/decompress.cc
@@ -179,11 +179,32 @@ FDICopyFn g_FDICopy = NULL;
 
 bool InitializeFdi() {
   if (!g_fdi) {
+    // It has been observed that some users do not have the expected
+    // environment variables set, so we try a couple that *should* always be
+    // present and fallback to the default Windows install path if all else
+    // fails.
+    // The cabinet.dll should be available on all supported versions of Windows.
+    static const wchar_t* const candidate_paths[] = {
+      L"%WINDIR%\\system32\\cabinet.dll",
+      L"%SYSTEMROOT%\\system32\\cabinet.dll",
+      L"C:\\Windows\\system32\\cabinet.dll",
+    };
+
     wchar_t path[MAX_PATH] = {0};
-    ::ExpandEnvironmentStringsW(L"%WINDIR%\\system32\\cabinet.dll", path,
-                                MAX_PATH);
-    // This DLL should be available on all supported versions of Windows.
-    g_fdi = ::LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
+    for (int i = 0; i < arraysize(candidate_paths); ++i) {
+      path[0] = L'\0';
+      DWORD result = ::ExpandEnvironmentStringsW(candidate_paths[i],
+                                                 path, arraysize(path));
+
+      if (result > 0 && result <= arraysize(path))
+        g_fdi = ::LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
+
+      if (g_fdi)
+        break;
+    }
+  }
+
+  if (g_fdi) {
     g_FDICreate =
         reinterpret_cast<FDICreateFn>(::GetProcAddress(g_fdi, "FDICreate"));
     g_FDIDestroy =
diff --git a/chrome/installer/mini_installer/decompress.h b/chrome/installer/mini_installer/decompress.h
index 8e093aa..579ee3c 100644
--- a/chrome/installer/mini_installer/decompress.h
+++ b/chrome/installer/mini_installer/decompress.h
@@ -6,6 +6,11 @@
 #define CHROME_INSTALLER_MINI_INSTALLER_DECOMPRESS_H_
 #pragma once
 
+// arraysize borrowed from basictypes.h
+template <typename T, size_t N>
+char (&ArraySizeHelper(T (&array)[N]))[N];
+#define arraysize(array) (sizeof(ArraySizeHelper(array)))
+
 namespace mini_installer {
 
 // Same as the tool, expand.exe.  Decompresses a file that was compressed
diff --git a/chrome/installer/mini_installer/mini_installer.cc b/chrome/installer/mini_installer/mini_installer.cc
index 44a17e2..ea3add3 100644
--- a/chrome/installer/mini_installer/mini_installer.cc
+++ b/chrome/installer/mini_installer/mini_installer.cc
@@ -31,11 +31,6 @@
 #include "chrome/installer/mini_installer/mini_string.h"
 #include "chrome/installer/mini_installer/pe_resource.h"
 
-// arraysize borrowed from basictypes.h
-template <typename T, size_t N>
-char (&ArraySizeHelper(T (&array)[N]))[N];
-#define arraysize(array) (sizeof(ArraySizeHelper(array)))
-
 namespace mini_installer {
 
 typedef StackString<MAX_PATH> PathString;