From 0badf072e0e0c44c99412f2236adc1b29364bd18 Mon Sep 17 00:00:00 2001
From: Sven Baars <sbaars@codeweavers.com>
Date: Tue, 8 Nov 2022 12:42:28 +0100
Subject: [PATCH] kernelbase: Factor opening a subkey out of open_key().

---
 dlls/kernelbase/registry.c | 125 ++++++++++++++++++++++---------------
 1 file changed, 75 insertions(+), 50 deletions(-)

diff --git a/dlls/kernelbase/registry.c b/dlls/kernelbase/registry.c
index a78aea82fc1..133214c84d4 100644
--- a/dlls/kernelbase/registry.c
+++ b/dlls/kernelbase/registry.c
@@ -221,26 +221,84 @@ static NTSTATUS create_key( HKEY *retkey, HKEY root, UNICODE_STRING name, ULONG
     return status;
 }
 
-/* wrapper for NtOpenKeyEx to handle Wow6432 nodes */
-static NTSTATUS open_key( HKEY *retkey, HKEY root, UNICODE_STRING name, DWORD options, ACCESS_MASK access )
+static NTSTATUS open_subkey( HKEY *subkey, HKEY root, UNICODE_STRING *name, DWORD options, ACCESS_MASK access )
 {
+    DWORD i = 0, len = name->Length / sizeof(WCHAR);
+    WCHAR *buffer = name->Buffer;
     OBJECT_ATTRIBUTES attr;
-    NTSTATUS status;
-    HANDLE subkey;
-    WCHAR *buffer = name.Buffer;
-    DWORD i, len = name.Length / sizeof(WCHAR);
-
-    *retkey = NULL;
+    UNICODE_STRING str;
+    NTSTATUS status = 0;
 
     attr.Length = sizeof(attr);
     attr.RootDirectory = root;
-    attr.ObjectName = &name;
+    attr.ObjectName = &str;
     attr.Attributes = 0;
     attr.SecurityDescriptor = NULL;
     attr.SecurityQualityOfService = NULL;
 
+    if (buffer[0] == '\\') return STATUS_OBJECT_PATH_INVALID;
+    while (i < len && buffer[i] != '\\') i++;
+
+    str.Buffer = name->Buffer;
+    str.Length = i * sizeof(WCHAR);
+
+    if (i == len)
+    {
+        if (options & REG_OPTION_OPEN_LINK) attr.Attributes |= OBJ_OPENLINK;
+    }
+    else
+    {
+        if (!(options & REG_OPTION_OPEN_LINK)) attr.Attributes &= ~OBJ_OPENLINK;
+        options &= ~REG_OPTION_OPEN_LINK;
+    }
+
+    status = NtOpenKeyEx( (HANDLE *)subkey, access, &attr, options );
+    if (status == STATUS_PREDEFINED_HANDLE)
+    {
+        *subkey = get_perflib_key( *subkey );
+        status = STATUS_SUCCESS;
+    }
+
+    if (!status)
+    {
+        while (i < len && buffer[i] == '\\') i++;
+
+        name->Buffer += i;
+        name->Length -= i * sizeof(WCHAR);
+
+        if (!is_wow6432node( name ))
+        {
+            HKEY wow6432node = open_wow6432node( *subkey );
+            if (wow6432node)
+            {
+                NtClose( *subkey );
+                *subkey = wow6432node;
+            }
+        }
+    }
+
+    return status;
+}
+
+/* wrapper for NtOpenKeyEx to handle Wow6432 nodes */
+static NTSTATUS open_key( HKEY *retkey, HKEY root, UNICODE_STRING name, DWORD options, ACCESS_MASK access )
+{
+    HKEY subkey, subkey_root = root;
+    NTSTATUS status = 0;
+
+    *retkey = NULL;
+
     if (!(is_win64 && (access & KEY_WOW64_32KEY)))
     {
+        OBJECT_ATTRIBUTES attr;
+
+        attr.Length = sizeof(attr);
+        attr.RootDirectory = root;
+        attr.ObjectName = &name;
+        attr.Attributes = 0;
+        attr.SecurityDescriptor = NULL;
+        attr.SecurityQualityOfService = NULL;
+
         if (options & REG_OPTION_OPEN_LINK) attr.Attributes |= OBJ_OPENLINK;
         status = NtOpenKeyEx( (HANDLE *)retkey, access, &attr, options );
         if (status == STATUS_PREDEFINED_HANDLE)
@@ -251,49 +309,16 @@ static NTSTATUS open_key( HKEY *retkey, HKEY root, UNICODE_STRING name, DWORD op
         return status;
     }
 
-    while (len)
+    while (!status && name.Length)
     {
-        i = 0;
-        if (buffer[0] == '\\') return STATUS_OBJECT_PATH_INVALID;
-        while (i < len && buffer[i] != '\\') i++;
-
-        name.Buffer = buffer;
-        name.Length = i * sizeof(WCHAR);
-
-        if (i == len)
-        {
-            if (options & REG_OPTION_OPEN_LINK) attr.Attributes |= OBJ_OPENLINK;
-            status = NtOpenKeyEx( &subkey, access, &attr, options );
-        }
-        else
-        {
-            if (!(options & REG_OPTION_OPEN_LINK)) attr.Attributes &= ~OBJ_OPENLINK;
-            status = NtOpenKeyEx( &subkey, access, &attr, options & ~REG_OPTION_OPEN_LINK );
-        }
-        if (attr.RootDirectory != root) NtClose( attr.RootDirectory );
-        if (status) return status;
-        attr.RootDirectory = subkey;
-        while (i < len && buffer[i] == '\\') i++;
-        buffer += i;
-        len -= i;
-
-        name.Buffer = buffer;
-        name.Length = len * sizeof(WCHAR);
-        if (!is_wow6432node( &name ))
-        {
-            if ((subkey = open_wow6432node( attr.RootDirectory )))
-            {
-                NtClose( attr.RootDirectory );
-                attr.RootDirectory = subkey;
-            }
-        }
+        status = open_subkey( &subkey, subkey_root, &name, options, access );
+        if (subkey_root && subkey_root != root) NtClose( subkey_root );
+        subkey_root = subkey;
     }
-    if (status == STATUS_PREDEFINED_HANDLE)
-    {
-        attr.RootDirectory = get_perflib_key( attr.RootDirectory );
-        status = STATUS_SUCCESS;
-    }
-    *retkey = attr.RootDirectory;
+
+    if (!status)
+        *retkey = subkey_root;
+
     return status;
 }