C / C++ / MFC

26-Nov-09 15:02

Hi,

Given a Mapped Drive i.e.'F:\' Is itpossible to recover the Server Name and Path .

Regards,

Bram van Kampen

Garth J Lancaster26-Nov-09 16:51

26-Nov-09 16:51

I thought the information was available in the 'Netshare' API's - these days its likely to be available through WMI as well - if only a bit more convoluted to access

'g'

See this ..

Garth J Lancaster26-Nov-09 16:57

26-Nov-09 16:57

http://www.codeguru.com/cpp/i-n/network/basicnetworkoperations/article.php/c5429/[^]

Might even have been posted here on CP - GetUNC may be what you're looking for

'g'

T210226-Nov-09 19:33

T2102

26-Nov-09 19:33

You also can read the RemotePath key in HKEY_CURRENT_USER\Network\DRIVE_LETTER to get the mapping information

Garth J Lancaster26-Nov-09 19:47

26-Nov-09 19:47

Thanks for that info - filed away for future use

'G'/Remote/via Blackberry

Bram van Kampen28-Nov-09 13:03

28-Nov-09 13:03

Thanks.

I used this to write an "API" as follows:-

<br />
SGAPI BOOL GetUNCA(LPCSTR DriveSpec, LPSTR pstrResult,LPDWORD pcbSize){<br />
       if((DriveSpec==NULL)||(pstrResult==NULL)||(pcbSize==NULL)){<br />
          SetLastError(ERROR_INVALID_PARAMETER);<br />
          return FALSE;<br />
         }<br />
        if(strlen(DriveSpec)!=3){<br />
               SetLastError(ERROR_BAD_FORMAT);<br />
               return FALSE;<br />
        }<br />
        if((DriveSpec[1]!=':')||(DriveSpec[2]!='\\')){<br />
                SetLastError(ERROR_BAD_FORMAT);<br />
                return FALSE;<br />
        }<br />
<br />
        char ch=toupper(DriveSpec[0]);<br />
        if((ch<'A')||(ch>'Z')){<br />
                SetLastError(ERROR_BAD_FORMAT);<br />
                return FALSE;<br />
        }<br />
        CString SubKey="Network\\";<br />
	SubKey+=ch;<br />
<br />
        HKEY hkResult;<br />
        if(RegOpenKeyExA(HKEY_CURRENT_USER,SubKey,NULL,NULL,&hkResult)!=ERROR_SUCCESS){<br />
<br />
                SetLastError(ERROR_INVALID_CATEGORY);<br />
                return FALSE;<br />
        }<br />
<br />
        DWORD Type=REG_SZ;<br />
        DWORD dwRes=RegQueryValueExA(hkResult,"RemotePath",NULL,&Type,(LPBYTE)pstrResult,pcbSize);<br />
        RegCloseKey(hkResult);<br />
<br />
        if(dwRes==ERROR_SUCCESS)return TRUE;<br />
		<br />
        SetLastError(ERROR_INVALID_CATEGORY);<br />
<br />
        return FALSE;<br />
}<br />

One of the Things is: How do those Subkeys Translate in Foreign Languages... ???

Thanks A lot for the Info Smile | :)

Bram van Kampen

Bram van Kampen28-Nov-09 13:06

28-Nov-09 13:06

hmmm!

GetUNC is a Commandline Utility. Maybe as a Last Resort.

Thanks for your comment though. Smile | :)

Regards,

Bram van Kampen

Garth J Lancaster28-Nov-09 13:22

28-Nov-09 13:22

the CNetservice I showed from CodeGuru is NOT a command line utility - why would I have shown you something sooo useless, hmmmm ???

If you look for CNetService by Jay Wheeler, and get the download, you'll see GetUNC() uses APU WNetGetUniversalName

I was thinking one of is crazy, glad its not me, ok, for once Wink | ;-)

'g'

Bram van Kampen29-Nov-09 14:15

29-Nov-09 14:15

Hi,

Garth J Lancaster wrote:
the CNetservice I showed from CodeGuru is NOT a command line utility - why would I have shown you something sooo useless, hmmmm ??

Well, that's what the link appeared to be pointed to. I asked myself the same question.

Garth J Lancaster wrote:
If you look for CNetService by Jay Wheeler, and get the download, you'll see GetUNC() uses APU WNetGetUniversalName

I was thinking one of is crazy, glad its not me, ok, for once

Well maybe the gremlins...
Found that site, its very usefull.

Thanks. Smile | :)

Bram van Kampen

Randor 27-Nov-09 15:23

Randor

27-Nov-09 15:23

Hi Bram,

Are you looking for the WNetGetUniversalName Function[^]?

Best Wishes,
-David Delaune

Bram van Kampen28-Nov-09 12:54

28-Nov-09 12:54

Bingo!

Just the Ticket. Thanks.

As a Side Line, The MS Windows API is growing that wide that even googeling, or MSDN becomes difficult, if you don't remember the name of an API in the first place. Many of the 10,000 or so Microsoft engineers seem to be having the same problem. They have another weapon though, access to the windows code, and it occurs to me that if they cannot find quikly what they need, that they just introduce another API to add to the pile.

In the mean time I wrote:

<br />
     SGAPI BOOL GetUNC(LPCSTR DriveSpec, LPSTR pstrResult,LPDWORD pcbSize)<br />

based on the previous replies. That was not difficult, but WNetGetUniversalName() is more universal, and less likely to break in future versions.

Thanks, Smile | :)

Bram van Kampen

Garth J Lancaster28-Nov-09 13:23

28-Nov-09 13:23

rats - he beat me to it - see my prev response - lest you got there in the end - have fun Smile | :)

'g'

Bram van Kampen28-Nov-09 14:27

28-Nov-09 14:27

Hi,

BTW.

That Reg Entry. If you delete that, does that 'Undo' Drive mapping. I know of no way to 'Unmap' a drive in XP. Does not bother me much, I never realy use this 'Drive Mapping Feature' I personally think that it is a leftover from the DOS days, (maybe you don't remember those)
Those where the days that God was with us in Paradise, and all of us had Floppies. Lo and Behold, Someone invented the CD. Everybody took a step back and admired in awe, and all those guru's, came up with further int14's and complicated code, to assign those horrid things a drive letter, using a device called MSCDEX, etc. Afterall, DOS could only deal with Block devices if they had a Drive Letter, so a drive letter it got.

Then some Nasty bugger invented Networking! Not to worry, MS had already a Mechanism to map Drives... Just another Interrupt, And, Presto, we had 'Share', with, guess it... A Drive Letter!

Me thinks, No real need for all that crap. UNC Names are about as good as it gets.

The problem occurs, where XP supports this anachronism. Some of my customers use Network Shares assigned to a Mapped Drive. Over Time, Things break, and I have to unravel the mess in a Fix, but, Idealy trap it during the Setup.

Thanks for your Contribution.

Regards Smile | :)

Bram van Kampen

Garth J Lancaster28-Nov-09 14:35

Overlap Message on WM_TIMER

28-Nov-09 14:35

Bram van Kampen wrote:
I know of no way to 'Unmap' a drive in XP

chuckle - in the old days it used to be (command line)

net use drive: path to map
net use drive: /delete to unmap/delete

still works on xp last time I looked - I suspect (going back to the 'NetShare API' you can do it programmtically through them as well)

shows ya what an ol' fart I am - but willing to learn new tricks, like as you suggest, deleting that reg entry - didnt know that one

'g'

Max++26-Nov-09 15:01

26-Nov-09 15:01

In the case we setting WM__TIMER to the small value for example 20 msec that mean the thread will work on OnTimer function every 20 msec.

Assume that, during the thread work on the first period time message in OnTimer function but still not finish, then the second period time message overlap happen so that this message should wait for the first message finish before it continue.
Again assume that, the first message not finish and the second message wait for first message, then the third period time message happen.

How windows manage this situation.

Thanks.

«_Superman_»26-Nov-09 16:07

«_Superman_»

26-Nov-09 16:07

WM_TIMER is only posted once.
That means that if there is already a WM_TIMER in the message queue it is not posted again.
So at any time there is only one WM_TIMER in the message queue.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Max++26-Nov-09 16:20

26-Nov-09 16:20

What about another message, for example WM_MOUSTMOVE if we have a lot of code within OnMouseMove function the first message not finish but another one come in.

How windows manage this situation or just ignore it?

JohnCz26-Nov-09 19:57

JohnCz

26-Nov-09 19:57

There are certain rules involved:
1. Main window procedure can process only one message at the time.
2. WM_TIMER message is posted to a thread’s queue.
3. Messages posted to the queue are retrieved and removed in a main message loop by GetMessage. There is always one global message loop per process. Local message loops can be created but that is not a case here and it does not change this set of rules.
4. Retrieved messages are delivered to a window procedure by DispatchMessage call.
5. When message is processed, system posted messages are not delivered to a message queue, since the thread is blocked.

Let’s assume you register timer calling SetTimer. After time elapses, system posts the WM_TIMER message to a queue.
Message is then removed and window procedure or callback is called.
If timer message is processed for a time much longer that time interval used to register timer, thread id blocked and no messages are added to a queue.
If processing time is very long, it will render application unresponsive.
After processing is done, queue receives all new messages that are posted by the system.

WM_MOUSEMOVE message as other mouse messages are also posted to the queue, hence if thread is blocked by long processing of any message window will loose WM_MOUSEMOVE, resuming receiving after processing is done.

Timer is not precise. It has low priority and GetMessage can retrieve other messages first before WM_TIMER is retrieved; it is really at the bottom of the food chain.

There is also a set of messages that are delivered by SendMessage directly to a window procedure without being posted.
Considering this and low priority of the WM_TIMER it should not be used when timing is crucial. If that is a case, use another thread to handle such a case.

JohnCz
MS C++ MVP

Max++27-Nov-09 1:50

27-Nov-09 1:50

Thanks a lot JohnCz

KarstenK26-Nov-09 23:28

KarstenK

26-Nov-09 23:28

This is a misuse of WM_TIMER, because it is to often so it will lower performance with its overhead. Cry | :((

If you need such high frequencies of calling write a seperate thread which handles such stuff. Thumbs Up | :thumbsup:

Press F1 for help or google it.
Greetings from Germany

JohnCz27-Nov-09 6:14

JohnCz

27-Nov-09 6:14

Well, I do not think this is a WM_TIMER misuse issue. Timer is not posted as high priority message and is retrieved as the last after all others and only during a system idle, that is why is not guaranteed that it will be delivered in intervals it was registered with.
The issue here is the fact that timer can be used to handle some long processing and that is what can cause problems.

JohnCz
MS C++ MVP

Max++27-Nov-09 14:41

27-Nov-09 14:41

Is it posible to change the priority message in the process?
What's function can support this issue ?

JohnCz27-Nov-09 20:14

JohnCz

27-Nov-09 20:14

No, it is not possible, that is the way OS works.
Why is it so important to you?
AS I havew already indicated, if you have to do some long processing you would be much better off, moving processing to a dedicated thread, freeing main thread to do GUI updates and process all other messages without freezing.

JohnCz
MS C++ MVP