Search order for DLLImport?

I'm trying to call a function from a plain old DLL (no COM or .NET)
which I can do by compiling some in-line c# code in a 'here string'
and then instantaiting the c# code. Works well so long as the dll I'm
trying to call is in the path, for e.g. c:\windows\system32, but
doesn't work when the dll is just in the same folder as the script
(which is what I need)

I thought the search order for things like this always try the local
folder first, and then search through the path?

Below is the function that calls the dll. The problem is when I try
and call it I get:

8# $helper::_openCommPort(1,2)
Exception calling "_openCommPort" with "2" argument(s): "Unable to
load DLL 'weatherlink.dll': The specified module could not be found.
(Exception from HRESULT: 0x8007007E)"
At line:1 char:23
+ $helper::_openCommPort( <<<< 1,2)
9#

The dll is in the same location as the ps1 script, maybe the c#
snippet is being executed in a different context - i.e. different
folder? I've tried changind the DLLImport string to specifiy the
local folder, i.e. ".\weatherlink.dll" too

Any pointers?

---function snippet---
function Process-WS {

$code = @'
using System;
using System.Runtime.InteropServices;

public class WSHelper
{
[DllImport("weatherlink.dll")]
private static extern Int32 OpenCommPort( Int32 port, Int32
baud );

public static Int32 _openCommPort( Int32 port, Int32 baud )
{
return OpenCommPort( port, baud );
}
}
'@

[WSHelper] > $null
$global:helper = [WSHelper]
trap {
$cp = new-object Microsoft.CSharp.CSharpCodeProvider

$cpar = New-Object System.CodeDom.Compiler.CompilerParameters
$cpar.GenerateInMemory = $true
$cpar.GenerateExecutable = $false
$cpar.OutputAssembly = "custom"
$cr = $cp.CompileAssemblyFromSource( $cpar, $code )
if ( $cr.Errors.Count)
{
$codeLines = $code.Split("`n");
foreach ($ce in $cr.Errors)
{
write-host "Error: $($codeLines[$($ce.Line - 1)])"
$ce | out-default
}
Throw "Compile failed..."
}
else
{
# don't report the exception
continue
}
}

[Int32]$port = 2;
[Int32]$baud = 2400;

[Int32]$retVal = $helper::_openCommPort( $port, $baud )
}
---end of function snippet--

Duncan Smith wrote: I don't know the answer, but here are some pointers that may help:

Dynamic-Link Library Search Order
http://msdn2.microsoft.com/en-US/library/ms682586.aspx

SetDllDirectory
http://msdn2.microsoft.com/en-us/library/ms686203.aspx

The first article has several different cases where the search order is
different, but all of them do contain the current directory. Maybe if you
explicitly set-location to the directory in question that would help?

--

Hal Rottenberg
blog: http://halr9000.com
powershell category:
http://halr9000.com/article/category...ng/powershell/

"Duncan Smith" <DSmith1974@xxxxxx> wrote in message
news:1189261840.762727.230780@xxxxxx Yes the local folder of the PowerShell executable with is $PSHome.
Temporarily add the local dir to the path like so:

$env:Path += ";$pwd"

then try to call your .net assembly.

--
Keith

Good answer! Thanks Keith.