Marshal Problems with ByValArray

Question

Hi!

i have an array that not will working...

Here is the structure:

   <StructLayout(LayoutKind.Sequential)> Public Structure MySatz
        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=25)> Public MyArrayGrKo() As MYKopfTabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=10)> Public MyKopfAnzahl As String
         <MarshalAs(UnmanagedType.ByValArray, SizeConst:=25)> Public MyArrayGrZeilen() As MYGridZeilen
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=51)> Public MyZeilenAnzahl As String
    End Structure
    <StructLayout(LayoutKind.Sequential)> Public Structure MYGridZeilen
        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=999)> Public MyArray2() As MYZeilen
    End Structure
    <StructLayout(LayoutKind.Sequential)> Public Structure MYZeilen
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=81)> Public TABGridElement As String
    End Structure

If i male a call wit this Array i becom a .Net Error that the structure is not suportet!?

Is the array to big?

How big can be say the array?

Or is ther a Bug in my Code?

With a smaler Array will it working!?

Have anyone an Idea?

Best Regards

Bernd

Answer 1

Does the error message also say why the structure is not supported?

What's the declaration of MYKopfTabelle?

The type of the array which you pass is MySatz()?

What's the declaration of the function to which you pass the array? (although I won't be able to test it)

For testing, if I declare the missing type simply as

   Structure MYKopfTabelle
      Public i As Integer
   End Structure

retrieving the size does not fail

      Dim size = Marshal.SizeOf(GetType(MySatz))

so I think passing it shouldn't fail either.

---

Armin

Answer 2

here is the complete structure:

    <StructLayout(LayoutKind.Sequential)> Public Structure AVW13SATZ
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=31)> Public AVWSTFUNKTION As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=11)> Public AVWSTASTE As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=2)> Public AVWSTASTEOK As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=31)> Public AVWSBUTTON As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=51)> Public AVWSZIELFELD As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=31)> Public AVWSHGFarbe As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=31)> Public AVWSVGFarbe As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=31)> Public AVWSORTIERUNG As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=11)> Public AVWSANZAHL As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=1001)> Public AVWSAUSWAHL As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=80)> Public AVWSTEF00STZ1A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=11)> Public AVWSTEF00STZ2A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=6)> Public AVWSTEF00STZ3A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=2)> Public AVWSTEF00STZ4A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=2)> Public AVWSTEF00STZ5A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=11)> Public AVWSTEF00STZ6A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=6)> Public AVWSTEF00STZ7A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=11)> Public AVWSTEF00STZ8A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=11)> Public AVWSTEF00STZ9A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=4)> Public AVWSTEF00STZ10A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=4)> Public AVWSTEF00STZ11A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=9)> Public AVWSTEF00STZ12A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=101)> Public AVWSTEF00STZ13A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=4)> Public AVWSTEF00STZ14A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=4)> Public AVWSTEF00STZ15A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=4)> Public AVWSTEF00STZ16A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=6)> Public AVWSTEF00STZ17A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=11)> Public AVWSTEF00STZ18A As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=10)> Public AVWSTEF00STZ19A As String
        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=99)> Public MyArraySB() As MYSBTabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=10)> Public MySBAnzahl As String
        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=99)> Public MyArrayTA() As MYTATabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=10)> Public MyTAAnzahl As String
        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=99)> Public MyArrayERF() As MYERFTabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=10)> Public MyERFAnzahl As String
        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=25)> Public MyArrayGrKo() As MYKopfTabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=10)> Public MyKopfAnzahl As String
        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=99)> Public MyArrayGrZe() As MYGridTabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=10)> Public MyTabAnzahl As String
    End Structure
    <StructLayout(LayoutKind.Sequential)> Public Structure MYSBTabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=4)> Public TABSB As String
    End Structure
    <StructLayout(LayoutKind.Sequential)> Public Structure MYTATabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=4)> Public TABTA As String
    End Structure
    <StructLayout(LayoutKind.Sequential)> Public Structure MYERFTabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=9)> Public TABERF As String
    End Structure
    <StructLayout(LayoutKind.Sequential)> Public Structure MYKopfTabelle
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=81)> Public TABGridKopf As String
    End Structure
    <StructLayout(LayoutKind.Sequential)> Public Structure MYGridTabelle
        ' Maximal 25 Spalten
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=2)> Public TABGridX As String
        <MarshalAs(UnmanagedType.ByValArray, SizeConst:=25)> Public TabGridZeile() As MYGridTabelleSpalte
    End Structure
    <StructLayout(LayoutKind.Sequential)> Public Structure MYGridTabelleSpalte
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=81)> Public TABGridZeileSpalte As String
    End Structure

and here is the call that will not working:

        Dim CblStatus As Integer
        Dim AVW13SATZ001 = New AVW13SATZ
        AVW13SATZ001.AVWSTFUNKTION = "USETABLE"
        CblStatus = AVW13CALL(AVW13SATZ001)

The size of the comlpete structure is 2028236 characters

How can i say that the structure is so big?

Best Regards

Bernd

Answer 3

Does the error message also say why the structure is not supported?

What's the declaration of the AVW13CALL? Maybe you want to pass the record ByVal instead of ByRef?

The size I get from Marshal.SizeOf(GetType(AVW13SATZ)) is 205,959, not 2,028,236

I don't see a reason why it doesn't work. There shouldn't be a size limit (probably not before 2^31). The marshaller is also able to report the offset of each item correctly:

      Dim satz As AVW13SATZ
      Dim t = satz.GetType
      Dim infos = t.GetFields(Reflection.BindingFlags.Public Or Reflection.BindingFlags.Instance)

      For Each info In infos
         Dim offset = Marshal.OffsetOf(t, info.Name)
         Debug.Print("{0,10}: {1}", offset, info.Name)
      Next

So, I'm afraid, I don't see what's going wrong. Maybe the exception shows more details?

---

Armin

Answer 4

Here is the VB:

https://skydrive.live.com/redir.aspx?cid=1313463dde8bb0db&resid=1313463DDE8BB0DB!114&parid=1313463DDE8BB0DB!109&authkey=!AM7sM_hpQzY6UIw

The call without the last array will working fine!

Best regards

Bernd

Answer 5

I was asking you twice what's the exact exception message. You were guessing the structure might be too big, but you should have clearly stated that this was not your own guessing. If you had straight posted the exception message, it would have simplified it without keeping me guessing if there is a limit for the marshaller. The exception message is:

System.Runtime.InteropServices.MarshalDirectiveException wurde nicht behandelt.
  Message=""parameter #1" kann nicht gemarshallt werden: Interne Einschränkung: Die Struktur ist zu komplex oder zu groß.."

Translated:

System.Runtime.InteropServices.MarshalDirectiveException has not been handled.
  Message=""parameter #1" can not be marshalled: Internal limitation: The structure is too complex or too big."

Now I'm only unable to add anything to what the message already says.

Search for MarshalDirectiveException and possible workarounds (globalloc, copy, pass pointer)

---

Armin

Answer 6

The Error is not easy to handle because there is not help about the error...

Whats about the "Internal limitation"??

What are the limitation?

Answer 7

According to the web search results, there might be a 64K limit. I do not know why. Use the other approach mentioned: Marshal.AllocHGlobal, Marshal.StructureToPtr. However, I don't know if StructureToPtr can handle it. If not, you must write data piece by piece (also using the Marshal class), then pass the pointer to the allocated block to the API function.

---

Armin