[PATCH 3/3] mpr: Implement WNetUseConnectionA(). (try 4)

[Pierre Schweitzer]

On 23/01/2016 14:00, Nikolay Sivov wrote:
> On 23.01.2016 15:47, Pierre Schweitzer wrote:
>> On 22/01/2016 09:58, Alexandre Julliard wrote:
>>> Pierre Schweitzer <pierre at reactos.org> writes:
>>>
>>>> +    ret = WNetUseConnectionW(hwndOwner, pRes, passW, userIDW, dwFlags,
>>>> +                             accessNameW, lpBufferSize, lpResult);
>>>> +    if (lpAccessName && lpBufferSize && *lpBufferSize && accessNameW)
>>>> +    {
>>>> +        len = WideCharToMultiByte(CP_ACP, 0, accessNameW, -1, NULL, 0, NULL, NULL);
>>>> +        if (len && len <= *lpBufferSize)
>>>> +            WideCharToMultiByte(CP_ACP, 0, accessNameW, -1, lpAccessName, len, NULL, NULL);
>>>> +    }
>>>
>>> You need to handle failures, and a possibly different lpBufferSize for
>>> the W function. It could also use some test cases, which would probably
>>> require the W function to do something useful first.
>>
>> Thanks for your review.
>>
>> There's no need, in my understanding of MSDN of a different
>> lpBufferSize. It contains the size in chars of the buffer. So, be it for
>> A or W, we pass the same,
> 
> That's a wrong assumption. In this case you need to get length of
> W-buffer with WNetUseConnectionW() first, allocate buffer, call
> WNetUseConnectionW(), then convert W->A and at this point
> WideCharToMultiByte will return required A-buffer length that you can
> compare with WNetUseConnectionA argument value to check if passed buffer
> was large enough.

I'm not sure I understand your point. We're talking about a length in
chars. So let's have a view on how my current implementation currently
works. Let's say the caller calls A with a CHAR buf[256] and len = 256.
This is legit: buffer can store 256 chars (including the null char). In
my implementation, I take the len, and allocate a WCHAR buf[256]. And
pass it with len, to W.

Two cases, buffer is big enough: W will write up to 256 chars in buf.
When W is over, I can get the len in chars of the A string with the
first WideCharToMultiByte. I don't see a reason why it should be higher
than 256 (but in this case, I return an error - this is perhaps the case
you don't like?). And then, I can write in the buffer, which is big
enough to hold up to 256.

On the contrary, buffer is too small. Let's say, W wants to write 260
chars. It will write in len that it needs 260 chars, and return
WN_MORE_DATA. Job done, that's what the A caller needs to know. It can
then, recall with a CHAR buf[260].

-- 
Pierre Schweitzer <pierre at reactos.org>
System & Network Administrator
Senior Kernel Developer
ReactOS Deutschland e.V.

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