[Mono-list] DllImport ... help (gethostname)

[Stewart Allen]

I did find an example here:

  http://www.c-sharpcenter.com/Tutorial/UnManaged.htm

which recommends this structure:

[DllImport("Advapi32.dll", EntryPoint="GetUserName", ExactSpelling=false,
SetLastError=true)]
static extern bool GetUserName(
[MarshalAs(UnmanagedType.LPArray)] byte[] lpBuffer,
[MarshalAs(UnmanagedType.LPArray)] Int32[] nSize );

so I tried this:

  static extern int gethostname([MarshalAs(UnmanagedType.LPArray)] 
byte[] buf, int len);

but that fails to compile (mcs under linux) with:

** (process:9763): WARNING **: unhandled exception 
System.NotImplementedException: "The requested feature is not yet 
implemented"
in <0x00032> 
System.Reflection.Emit.UnmanagedMarshal:DefineUnmanagedMarshal 
(System.Runtime.InteropServices.UnmanagedType)
in <0x005df> Mono.CSharp.Attribute:ApplyAttributes 
(Mono.CSharp.EmitContext,object,object,Mono.CSharp.Attributes,Mono.CSharp.Location)
in <0x00220> Mono.CSharp.MethodCore:LabelParameters 
(Mono.CSharp.EmitContext,System.Type[],System.Reflection.MethodBase)
in <0x00132> Mono.CSharp.Method:Emit (Mono.CSharp.TypeContainer)
in <0x001df> Mono.CSharp.TypeContainer:Emit ()
in <0x004ca> Mono.CSharp.RootContext:EmitCode ()
in <0x01cbb> Mono.CSharp.Driver:MainDriver (string[])
in <0x00009> Mono.CSharp.Driver:Main (string[])

so I guess this either isn't possible with mono in it's current state or 
  I need to find an alternate method.

any/all suggestions heartily welcomed.

thanks,

stewart


Stewart Allen wrote:
> I've been struggling with DllImport all evening just to call 
> gethostname(char *buf, int len). Seems like it should be simple. There 
> appear to be a lot of examples of sending string arguments and getting 
> string return values, but I can't find anything that addresses filling a 
> preallocated string buffer.
> 
> most tests (that I can get to compile) result in:
> 
> ** (process:7): WARNING **: unhandled exception 
> System.NullReferenceException: "A null value was found where an object 
> instance was required"
> 
> Any help is greatly appreciated.