Make GetUserName() return more specific error code, so that we could know how the function failed.

rlz/win/lib/process_info.cc

 // Copyright (c) 2012 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.
 //
 // Information about the current process.
 
 #include "rlz/win/lib/process_info.h"
 
 #include <windows.h>
 #include <Sddl.h>  // For ConvertSidToStringSid.
 #include <LMCons.h>  // For UNLEN
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/process/process_handle.h"
 #include "base/win/scoped_handle.h"
 #include "base/win/windows_version.h"
 #include "rlz/lib/assert.h"
 
 namespace {
 
 HRESULT GetCurrentUser(std::wstring* name,
                        std::wstring* domain,
                        std::wstring* sid) {
   DWORD err;
+  DWORD zero = 0;
 
   // Get the current username & domain the hard way.  (GetUserNameEx would be
   // nice, but unfortunately requires connectivity to a domain controller.
   // Useless.)
 
   // (Following call doesn't work if running as a Service - because a Service
   // runs under special accounts like LOCAL_SYSTEM, not as the logged in user.
   // In which case, search for and use the process handle of a running
   // Explorer.exe.)
   HANDLE token;
-  if (!::OpenProcessToken(::GetCurrentProcess(), TOKEN_QUERY, &token))
-    return E_FAIL;
+
+  HANDLE process_handle = ::GetCurrentProcess();
+  if (!process_handle)
+    CHECK(process_handle);
+
+  if (!::OpenProcessToken(process_handle, TOKEN_QUERY, &token)) {
+    err = ::GetLastError();
+    // Check should fail.
+    CHECK_EQ(err, zero);
+    return err;
+  }

[Roger Tawa OOO till Jul 10th, 2014/02/28 19:34:00]

From the docs, I don't believe getting a handle to yourself can fail.  So I
think you can replace all the above with something like:

  CHECK(::OpenProcessToken(::GetCurrentProcess(), TOKEN_QUERY, &token));

I think you can do something similar for calls to ::GetTokenInformation() and
::LookupAccountSidW() below.

[yao, 2014/02/28 21:28:19]

Done.

 
   base::win::ScopedHandle scoped_process_token(token);
 
   // (Following call will fail with ERROR_INSUFFICIENT_BUFFER and give us the
   // required size.)
   scoped_ptr<char[]> token_user_bytes;
   DWORD token_user_size;
   DWORD token_user_size2;
   BOOL result = ::GetTokenInformation(token, TokenUser, NULL, 0,
                                       &token_user_size);
   err = ::GetLastError();
   CHECK(!result && err == ERROR_INSUFFICIENT_BUFFER);
 
   token_user_bytes.reset(new char[token_user_size]);
-  if (!token_user_bytes.get())
+  if (!token_user_bytes.get()) {
+    // Check should fail.
+    CHECK_EQ(E_OUTOFMEMORY, 0);
     return E_OUTOFMEMORY;
+  }

[Roger Tawa OOO till Jul 10th, 2014/02/28 19:34:00]

Can probably replace lines 62-66 with:

   CHECK(token_user_bytes.get());

Similar comment for line 83 below.  I don't think you need a |zero| local
variable.

[yao, 2014/02/28 21:28:19]

Done.

 
   if (!::GetTokenInformation(token, TokenUser, token_user_bytes.get(),
                              token_user_size, &token_user_size2)) {
-    return E_FAIL;
+    err = ::GetLastError();
+    // Check should fail.
+    CHECK_EQ(err, zero);
+    return err;
   }
 
   WCHAR user_name[UNLEN + 1];  // max username length
   WCHAR domain_name[UNLEN + 1];
   DWORD user_name_size = UNLEN + 1;
   DWORD domain_name_size = UNLEN + 1;
   SID_NAME_USE sid_type;
   TOKEN_USER* token_user =
       reinterpret_cast<TOKEN_USER*>(token_user_bytes.get());
-  if (!token_user)
-    return E_FAIL;
+  if (!token_user) {
+    err = ::GetLastError();
+    // Check should fail.
+    CHECK_EQ(err, zero);
+    return err;
+  }
   PSID user_sid = token_user->User.Sid;
   if (!::LookupAccountSidW(NULL, user_sid, user_name, &user_name_size,
                            domain_name, &domain_name_size, &sid_type)) {
-    return E_FAIL;
+    err = ::GetLastError();
+    // Check should fail.
+    CHECK_EQ(err, zero);
+    return err;
   }
 
   if (name != NULL) {
     *name = user_name;
   }
   if (domain != NULL) {
     *domain = domain_name;
   }
   if (sid != NULL) {
     LPWSTR string_sid;
@@ skipping 103 matching lines @@
   }
 
   evaluated = true;
   if (!has_rights)
     ASSERT_STRING("ProcessInfo::HasAdminRights: Does not have admin rights.");
 
   return has_rights;
 }
 
 };  // namespace