[PATCH v2 1/3] kernelbase: Implement compatibility mode for GetVersionEx.

[Nikolay Sivov]

On 3/17/20 7:50 PM, Gabriel Ivăncescu wrote:
> On 17/03/2020 18:28, Nikolay Sivov wrote:
>> On 3/17/20 7:07 PM, Gabriel Ivăncescu wrote:
>>> +/*********************************************************************** 
>>>
>>> + * Win8 info, reported if app doesn't provide compat GUID in manifest.
>>> + */
>>> +static const RTL_OSVERSIONINFOEXW windows8_version_data =
>>> +{
>>> +    sizeof(RTL_OSVERSIONINFOEXW), 6, 2, 0x23f0, VER_PLATFORM_WIN32_NT,
>>> +    {0}, 0, 0, VER_SUITE_SINGLEUSERTS, VER_NT_WORKSTATION, 0
>>> +};
>>> +
>>> +
>>> +/*********************************************************************** 
>>>
>>> + * Windows versions that need compatibility GUID specified in manifest
>>> + * in order to be reported by the APIs.
>>> + */
>>> +static const struct
>>> +{
>>> +    RTL_OSVERSIONINFOEXW info;
>>> +    GUID guid;
>>> +} version_data[] =
>>> +{
>>> +    /* Windows 8.1 */
>>> +    {
>>> +        {
>>> +            sizeof(RTL_OSVERSIONINFOEXW), 6, 3, 0x2580, 
>>> VER_PLATFORM_WIN32_NT,
>>> +            {0}, 0, 0, VER_SUITE_SINGLEUSERTS, VER_NT_WORKSTATION, 0
>>> +        },
>>> + {0x1f676c76,0x80e1,0x4239,{0x95,0xbb,0x83,0xd0,0xf6,0xd0,0xda,0x78}}
>>> +    },
>>> +    /* Windows 10 */
>>> +    {
>>> +        {
>>> +            sizeof(RTL_OSVERSIONINFOEXW), 10, 0, 0x42ee, 
>>> VER_PLATFORM_WIN32_NT,
>>> +            {0}, 0, 0, VER_SUITE_SINGLEUSERTS, VER_NT_WORKSTATION, 0
>>> +        },
>>> + {0x8e0f7a12,0xbfb3,0x4fe8,{0xb9,0xa5,0x48,0xfd,0x50,0xa1,0x5a,0x9a}}
>>> +    }
>>> +};
>> For that you only need to store 3 values - major/minor/build.
>
> Ah alright, I just copy-pasted the entires from ntdll.
>
>>> +/*********************************************************************** 
>>>
>>> + * Holds the current version (including compatibility mode).
>>> + * Call init_current_version before using it.
>>> + */
>>> +static RTL_OSVERSIONINFOEXW current_version;
>>> +
>>> +
>>> +/****************************************************************************** 
>>>
>>> + *  init_current_version
>>> + *
>>> + * Initialize the current_version variable.
>>> + *
>>> + * For compatibility, Windows 8.1 and later report Win8 version 
>>> unless the app
>>> + * has a manifest that confirms its compatibility with newer 
>>> versions of Windows.
>>> + *
>>> + */
>>> +static BOOL CALLBACK init_current_version_callback(PINIT_ONCE 
>>> init_once, PVOID parameter, PVOID *context)
>>> +{
>> Should it actually be static and initialized once? What happens if 
>> you activate another context dynamically?
>>
>
> I actually have no idea, didn't know you can do that. I'm somewhat 
> unfamiliar with activation context APIs. What API should I be using to 
> test this?

There are functions to create, activate and deactivate contexts. We use 
that in tests for example.

>
>>> + /*ACTIVATION_CONTEXT_COMPATIBILITY_INFORMATION*/DWORD *acci;
>> Why not use proper type pointer?
>
> I don't know, ntdll does the same thing when filling it, for some 
> reason we don't even have that structure so I couldn't use it, 
> although I did find it in headers. So I was a bit confused and just 
> copied what ntdll does, assuming it had a good reason to.

I remember now, unfortunately public type definition is using zero 
length array.

>
>>
>>> +                if (elements[i].Type == 
>>> ACTCX_COMPATIBILITY_ELEMENT_TYPE_OS &&
>>> +                    IsEqualGUID(&elements[i].Id, 
>>> &version_data[idx].guid))
>> Type value name has a typo.
>>
>
> Right, but that's in our headers, I thought it was intentional. Should 
> I send a fix for this?