I recently had the job of writing an application using the .NET Framework for work that would walk through the folders at a given location and return the total of all the file sizes so we can track changes in certain directories.  I quickly found out that the .NET Framework does not allow for folder paths that are beyond 260 characters and you get an exception if you try.  Well that is a pain.

So working from an example from pinvoke.net(read it here) I started building an app based on the Windows API.  This was completely new territory for me and some surprises were encountered.

WIN32_FIND_DATA is the data structure that is passed into the FindFirstFile and FindNextFile methods and is filled with the found files information.  The two properties I was examining were  nFileSizeLow and nFileSizeHigh to get the file sizes.  But I noticed that for some files I was getting a negative file size returned.  Huh?!?

MSDN says that to get the correct file size you need to get the file size this way: (nFileSizeHigh * (MAXDWORD+1)) + nFileSizeLow

Tried that and still got negative file sizes.  WTF?  I tried a Google search to see if anyone had encountered this.  There were a few suggestions but after trying them I was still getting negative file sizes for really large files.  I finally found a solution that worked even when it encountered files that were 10GB in size.

Below is my explanation of the why and my solution.  This worked great for me but if any one encounters this and has suggestions please let me know in comments.  I figured this was worth the post since I haven’t seen this solution yet.

Explanation:

WIN32_FIND_DATA holds the file sizes in the nFileSizeLow property in bytes. nFileSizeHigh is meant to be greater than zero if the file size is greater than the data type can hold.  In this case the properties hold a DWORD, Windows version of a 32-bit signed unsigned integer (EDIT: originally this as incorrect).

1.1 The maximum of a signed 32-bit integer

The maximum for a signed 32-bit integer is (2^³¹⁾ - 1 = 2,147,483,647. Image 1.1 shows the bit pattern for this.
So if we add one to this number we get the bit pattern that is shown in Image 1.2.
We get the result of -2147483648 when we should get +2147483648.  To rectify this we need to add back in the correct value.  This would be 4294967296 or 2147483648 * 2.

1.2 Overflowed 32-bit integer

There are four possible outcomes for WIN32_FIND_DATA’s file size info

1. nFileSizeLow < 0 and nFileSizeHigh > 0
2. nFileSizeLow > 0 and nFileSizeHigh > 0
3. nFileSizeLow < 0 and nFileSizeHigh !> 0
4. nFilesSizeLow is > 0

So MSDN’s solution does not account for all possibilities. Below is my solution.

notes:

• 4294967296 = [(AbsVal|32bit signed int max|)+1] * 2 = [([2^31]-1)+1] * 2 = 2147483648 * 2
• +2147483647 = 32bit signed int max ——-> 0111 1111 1111 1111
• -2147483648 = 32bit signed int max + 1 —> 1000 0000 0000 0000 –> sign change! Should be +2147483648
• -2147483648 + 2147483648 + 2147483648 = -2147483648 + (2147483648 * 2) = -2147483648 + 4294967296  = 2147483648 –> sweet!

The WIN32_FIND_DATA struct looks like this:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
 public struct WIN32_FIND_DATA
 {
 public FileAttributes dwFileAttributes;
 public FILETIME ftCreationTime;
 public FILETIME ftLastAccessTime;
 public FILETIME ftLastWriteTime;
 public int nFileSizeHigh; //EDIT: this should be a UINT, not INT
 public int nFileSizeLow; //EDIT: this should be a UINT, not INT
 public int dwReserved0; //EDIT: this should be a UINT, not INT
 public int dwReserved1; //EDIT: this should be a UINT, not INT
 [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAX_PATH)]
 public string cFileName;
 [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAX_ALTERNATE)]
 public string cAlternate;
 }

I have declared this as findData below.

My solution:

//store nFileSizeLow
long fDataFSize = (long)findData.nFileSizeLow;

//store individual file size for later accounting usage
long fileSize = 0;

if (fDataFSize < 0 && (long)findData.nFileSizeHigh > 0)
{
   fileSize = fDataFSize + 4294967296 + ((long)findData.nFileSizeHigh * 4294967296);
}
else
{
  if ((long)findData.nFileSizeHigh > 0)
  {
     fileSize = fDataFSize + ((long)findData.nFileSizeHigh * 4294967296);
  }
  else if (fDataFSize < 0)
  {
     fileSize = (fDataFSize + 4294967296);
  }
  else
  {
     fileSize = fDataFSize;
  }
}

But it was pretty gnarly:

rundll32 printui.dll,PrintUIEntry /ga /n\\serverName\printerName

All options can be seen by using:

rundll32 printui.dll,PrintUIEntry /?

Recieving Mail Tab:

Server Type: POP (dropdown menu)
Server: POP3.live.com
Username: youremail@msn.com
Security: SSL encryption
Authentication Type: password
the box to remember passord is checked.

Server Type: SMTP (dropdown menu)
Server:  smtp.live.com
Server Requires Authentication (box is checked)
Security: Use Secure Connection (TLS)
Authentication Type: Login
Username: youremail@msn.com
box to remember password is checked.

Worked for me.  Sending and receiving.

So now you have to realize A is column 1 and Z is column 26.  AA is 27, AB is 28 and so on.  To access a certain column you need its number.  But you also need to  get a column name from a number.  This can be tricky.  The columns are one based, A=1, but the indices of the data structure underneath are zero based, A=0.

A Google search came up with plenty of examples but all that I found only worked in a certain range of numbers.  My buddy and I came up with the following algorithm that worked much nicer.  Below is the implementation in Java.  Casting to a char from an int in Java uses ASCII values.  You may need to play with this part of the example in other languages.

public String getColName (int colNum) {

   String res = "";

   int quot = colNum;
   int rem;        
    /*1. Subtract one from number.
    *2. Save the mod 26 value.
   *3. Divide the number by 26, save result.
   *4. Convert the remainder to a letter.
   *5. Repeat until the number is zero.
   *6. Return that bitch...
   */
    while(quot > 0)
    {
        quot = quot - 1;
        rem = quot % 26;
        quot = quot / 26;
       
        //cast to a char and add to the beginning of the string
        //add 97 to convert to the correct ASCII number
        res = (char)(rem+97) + res;            
    }   
    return res;
}

In addition to this using the arrow keys to move up and down was also a iffy prospect.  One day when I was low on sleep and using my computer this happened.  I had simply been ignoring it for so long.  I finally typed this sentence into Google search:

firefox page up page down fuck

And obviously I wasn’t the only one who was incredibly irritated by this because one of the first forum posts I read had my answer.

Go to Tools–>Options–>Advanced–>General.  Turn off the option to “Always use cursor keys to navigate within pages”.  Also try turning off the “Search for text when I start typing” option.

After this your Page up/Down buttons should function like normal.  You can toggle between this caret browsing mode by simply hitting the F7 key.  And alternatively in Firefox you can page down with the Space bar and page up with Shift+Space bar.

I’m not sure if I was the one who enabled this function or it comes that way by default but whoever thought it was a good idea should be flogged.

Try deleting this file:

%userprofile%\appdata\Roaming\Microsoft\MMC\dsa

It will be recreated after you shut down your MMC console.

Thanks to frymaster for the update!

I installed the newest version of RSAT for Vista Service Pack 1.  I am running the 64-bit Version of Vista.

After installing this newest version I got this error when trying to start Active Directory Users and Computers:

Microsoft Visual C++ Runtime Library
“the application has requested the runtime to terminate it in an unusual way”

I could not find an answer anywhere, I was able to open up the Management Console (mmc.exe) and browse to the .msc file (dsa.msc) manually and it would open just fine.

I went looking for command line parameters for mmc.exe and here is what I found:

MMC command-line options

Using MMC command-line options, you can open a specific MMC console, open MMC in author mode, or specify that the 32-bit or 64-bit version of MMC is opened.

Syntax

mmcpath\filename.msc[/a] [/64] [/32]

Parameters

path \ filename.msc

Starts MMC and opens a saved console. You need to specify the complete path and file name for the saved console file. If you do not specify a console file, MMC opens a new console.

/a

Opens a saved console in author mode. Used to make changes to saved consoles.

/64

Opens the 64-bit version of MMC (MMC64). Use this option only if you are running a Microsoft 64-bit operating system and want to use a 64-bit snap-in.

/32

Opens the 32-bit version of MMC (MMC32). When running a Microsoft 64-bit operating system, you can run 32-bit snap-ins by opening MMC with this command-line option when you have 32-bit only snap-ins.

• Source: http://technet.microsoft.com/en-us/library/cc757725.aspx

The short cut for Active Directory Users and Computers points to:

%SystemRoot%\system32\dsa.msc

Adding the “/64″ flag to the Target of the shortcut fixed the problem

%SystemRoot%\system32\dsa.msc /64

After that, no more errors!

$ldap = “your ldap path here“
$de = new-object directoryservices.directoryentry(“LDAP://” + $ldap)
$ds = new-object directoryservices.directorysearcher($de)
$ds.filter = ‘(&(samaccountname=*))’
$rc = $ds.findall()
$rc[0].properties(‘member’)

They wanted to use the HP Director software, which is fine it just wouldn’t start when you clicked on the program icon.  I was pretty stumped until I thought “Why not look at HP’s site?”  So I did.

And there it was a patch to fix this very problem (link)

It turns out that IE 7 causes a problem.  Why??!?!  I have no idea but the patch fixed it.

Every once in a while I have to remind my self that the soultion is probably easier than I think AND someone else has already fixed it.

Sometimes you want to grab a property from an Active Directory entry.  I wanted to be able to do it from Powershell.

One of the cool things about PowerShell is that you can access the Namespaces in the .net framework.  So you can put together a script that can access Active Directory the same way you do it from .net Code using Directory Services.

Here is what I came up with:

Write-Host “”
$id = Read-Host “Which username?”
$prop = Read-Host “Which Property(Leave blank for all or type ‘list’ for property names)?”

$de = new-object directoryservices.directoryentry(“LDAP://your_LDAP_path“)
$ds = new-object directoryservices.directorysearcher($de)
$ds.filter = ‘(&(samaccountname=’ + $id + ‘))’
$results = $ds.findall()

if ($prop -eq “”)
{
Write-Host “”
$results.item(0).properties | more
}
elseif ($prop -eq “list”)
{
Write-Host “”
$results.item(0).properties.propertynames | more
}
else
{
Write-Host “”
$results.item(0).properties.item($prop)
}
Write-Host “”
Write-Host “”

So you just save this script as your_filename.ps1 and run it.

The LDAP filter is set to filter by the “samaccountname” which is usually the user name/id of the user.  If you wanted to filter by something else you could do so by changing the filter string.

After you run it you will be prompted for the variables and presto!  Some kick-assery ensues.

Check it here: http://blogs.msdn.com/b/powershell/archive/2007/01/24/powershell-cheat-sheet.aspx