[chrome_elf] NTRegistry - added wow64 redirection support.

chrome_elf/nt_registry/nt_registry.h

Index: chrome_elf/nt_registry/nt_registry.h
diff --git a/chrome_elf/nt_registry/nt_registry.h b/chrome_elf/nt_registry/nt_registry.h
index 0451fc536ec4fe4c266ccbb88b05f91f8f4c8104..3872b50bd2ec13fbac8f2696b000fdee420b6646 100644
--- a/chrome_elf/nt_registry/nt_registry.h
+++ b/chrome_elf/nt_registry/nt_registry.h
@@ -38,6 +38,18 @@ extern wchar_t HKCU_override[];
 // Use HKLM or HKCU to override.
 typedef enum _ROOT_KEY { AUTO = 0, HKLM, HKCU } ROOT_KEY;

[robertshield, 2016/09/28 23:49:23]

thoughts re: AUTO: it seems to be used in only once place (install_util.cc). It
minutely complicates some of the implementations and requires an extra global
bool. 

Also, install_util.cc already has an implementation of IsSystemInstall()
(https://codesearch.chromium.org/chromium/src/chrome/install_static/install_ut...)
which could be called at the place in install_util.cc where AUTO is now passed. 

This would simplify the interface here and allow us to have a bit less code in
the implementation.

[penny, 2016/10/01 01:44:25]

Wow.  Way to swoop in with the profound thinking Robert.

It just makes sense to me for an NTDLL Registry library to offer the AUTO
feature.  I know install_static existed before this lib, and constantly checks
whether it's system or not (it should probably cache it once), so it doesn't
really need to use AUTO.  But I imagine if I wrote something new, I would want
to let NtRegistry handle whether I should be accessing HKLM or HKCU.  So I'm
inclined to leave it in for now.

But you've inspired me.  I've made sure to resolve nt::AUTO in the external API
functions, so that private internal functions do not have to consider AUTO.

[robertshield, 2016/10/04 05:22:09]

Ok. My line of reasoning was based on separation of concerns. Modulo nt::AUTO,
this is a nice leafish drop-in replacement library for a subset of advapi32's
logic. 

With nt::AUTO, an arguably-Chromium-specific implementation detail (namely that
you might want to pick HKLM vs. HKCU depending on process image path) works its
way in.

You can make the case that automatic hive-selection based on image path is a
handy feature for a generic library but figured I'd explain where I was coming
from :-)
Awesome, thanks!

[penny, 2016/10/04 17:55:53]

Thank you!  I hear you.

 
+// Used with wrapper functions to request registry redirection override.
+// Maps to KEY_WOW64_32KEY and KEY_WOW64_64KEY access flags.
+enum WOW64_OVERRIDE {
+  NONE = 0L,
+  WOW6432 = KEY_WOW64_32KEY,
+  WOW6464 = KEY_WOW64_64KEY
+};
+
+//------------------------------------------------------------------------------
+// Create, open, delete, close functions
+//------------------------------------------------------------------------------
+
 // Create and/or open a registry key.
 // - This function will recursively create multiple sub-keys if required for
 //   |key_path|.
@@ -66,7 +78,10 @@ bool DeleteRegKey(HANDLE key);
 
 // Delete a registry key.
 // - WRAPPER: Function opens and closes the target key for caller.
-bool DeleteRegKey(ROOT_KEY root, const wchar_t* key_path);
+// - Use |wow64_override| to force redirection behaviour, or pass 0/nt::NONE.
+bool DeleteRegKey(ROOT_KEY root,
+                  WOW64_OVERRIDE wow64_override,
+                  const wchar_t* key_path);
 
 // Close a registry key handle that was opened with CreateRegKey or OpenRegKey.
 void CloseRegKey(HANDLE key);
@@ -96,7 +111,9 @@ bool QueryRegValueDWORD(HANDLE key,
 // Query DWORD value.
 // - WRAPPER: Function opens and closes the target key for caller, and works
 // with DWORD data type.
+// - Use |wow64_override| to force redirection behaviour, or pass 0/nt::NONE.

[robertshield, 2016/09/28 23:49:23]

nit: figure we should express a stronger opinion that the enum should be used:
e.g.: "or pass nt::NONE".

[grt (UTC plus 2), 2016/09/29 10:30:22]

yes, please

[penny, 2016/10/01 01:44:25]

Done.

 bool QueryRegValueDWORD(ROOT_KEY root,
+                        WOW64_OVERRIDE wow64_override,
                         const wchar_t* key_path,
                         const wchar_t* value_name,
                         DWORD* out_dword);
@@ -112,7 +129,9 @@ bool QueryRegValueSZ(HANDLE key,
 // Query SZ (string) value.
 // - WRAPPER: Function opens and closes the target key for caller, and works
 // with SZ data type.
+// - Use |wow64_override| to force redirection behaviour, or pass 0/nt::NONE.
 bool QueryRegValueSZ(ROOT_KEY root,
+                     WOW64_OVERRIDE wow64_override,
                      const wchar_t* key_path,
                      const wchar_t* value_name,
                      std::wstring* out_sz);
@@ -128,7 +147,9 @@ bool QueryRegValueMULTISZ(HANDLE key,
 // Query MULTI_SZ (multiple strings) value.
 // - WRAPPER: Function opens and closes the target key for caller, and works
 // with MULTI_SZ data type.
+// - Use |wow64_override| to force redirection behaviour, or pass 0/nt::NONE.
 bool QueryRegValueMULTISZ(ROOT_KEY root,
+                          WOW64_OVERRIDE wow64_override,
                           const wchar_t* key_path,
                           const wchar_t* value_name,
                           std::vector<std::wstring>* out_multi_sz);
@@ -155,7 +176,9 @@ bool SetRegValueDWORD(HANDLE key, const wchar_t* value_name, DWORD value);
 // Set DWORD value.
 // - WRAPPER: Function opens and closes the target key for caller, and works
 // with DWORD data type.
+// - Use |wow64_override| to force redirection behaviour, or pass 0/nt::NONE.
 bool SetRegValueDWORD(ROOT_KEY root,
+                      WOW64_OVERRIDE wow64_override,
                       const wchar_t* key_path,
                       const wchar_t* value_name,
                       DWORD value);
@@ -171,7 +194,9 @@ bool SetRegValueSZ(HANDLE key,
 // Set SZ (string) value.
 // - WRAPPER: Function opens and closes the target key for caller, and works
 // with SZ data type.
+// - Use |wow64_override| to force redirection behaviour, or pass 0/nt::NONE.
 bool SetRegValueSZ(ROOT_KEY root,
+                   WOW64_OVERRIDE wow64_override,
                    const wchar_t* key_path,
                    const wchar_t* value_name,
                    const std::wstring& value);
@@ -187,7 +212,9 @@ bool SetRegValueMULTISZ(HANDLE key,
 // Set MULTI_SZ (multiple strings) value.
 // - WRAPPER: Function opens and closes the target key for caller, and works
 // with MULTI_SZ data type.
+// - Use |wow64_override| to force redirection behaviour, or pass 0/nt::NONE.
 bool SetRegValueMULTISZ(ROOT_KEY root,
+                        WOW64_OVERRIDE wow64_override,
                         const wchar_t* key_path,
                         const wchar_t* value_name,
                         const std::vector<std::wstring>& values);