Powershell Recursion with Return

Question

I am trying to write a recursive function that will return information in an array, however when I put a return statement into the function it misses certain entries.

I am trying to recursively look through a specified depth of folders getting the acl's associated with the folder. I know getChildItem has a recurse option, but I only want to step through 3 levels of folders.

The excerpt of code below is what I have been using for testing. When getACLS is called without a return statement (commented out below) the results are:

Folder 1

Folder 12

Folder 13

Folder 2

When the return statement is used I get the following output:

Folder 1

Folder 12

So it looks like the return statement is exiting out from the recursive loop?

The idea is that I want to return a multidimensional array like [folder name, [acls], [[subfolder, [permissions],[[...]]]]] etc.

cls

function getACLS ([string]$path, [int]$max, [int]$current) {

    $dirs = Get-ChildItem -Path $path | Where { $_.psIsContainer }
    $acls = Get-Acl -Path $path
    $security = @()

    foreach ($acl in $acls.Access) {
        $security += ($acl.IdentityReference, $acl.FileSystemRights)
    }   

    if ($current -le $max) {
        if ($dirs) {
            foreach ($dir in $dirs) {
                $newPath = $path + '\' + $dir.Name
                Write-Host $dir.Name
   #            return ($newPath, $security, getACLS $newPath $max ($current+1))
   #            getACLS $newPath $max ($current+1)
                return getACLS $newPath $max ($current+1)
            }   
        }
    } elseif ($current -eq $max ) {
        Write-Host max
        return ($path, $security)
    }
}

$results = getACLS "PATH\Testing" 2 0

Answer 1

The problem was the location of the return. I had it inside the foreach loop, meaning it was trying to return multiple times in the one function. I moved it outside the foreach, into the if statement instead.

function getACLS ([string]$path, [int]$max, [int]$current) {

$dirs = Get-ChildItem -Path $path | Where { $_.psIsContainer }
$acls = Get-Acl -Path $path
$security = @()
$results = @()

foreach ($acl in $acls.Access) {
    $security += ($acl.IdentityReference, $acl.FileSystemRights)
}   

if ($current -lt $max) {
    if ($dirs) {
        foreach ($dir in $dirs) {
            $newPath = $path + '\' + $dir.Name
            $next = $current + 1
            $results += (getACLS $newPath $max $next)
        }   
    } else {
        $results = ($path, $security)
    }
    return ($path, $security, $results)
} elseif ($current -eq $max ) {
    return ($path, $security)
}
}

Answer 2

In recursion, I would only use a return statement where I needed to end the recursion - just for clarity. I've done a good bit of recursion in PowerShell and it works well. However you need to remember that PowerShell functions do behave differently. The following:

return 1,2

is equivalent to:

1,2
return

In other words, anything you don't capture in a variable or redirect to a file (or $null) is automatically considered output of the function. Here's a simple example of a working, recursive function:

function recursive($path, $max, $level = 1)
{
    $path = (Resolve-Path $path).ProviderPath
    Write-Host "$path - $max - $level"
    foreach ($item in @(Get-ChildItem $path))
    {
        if ($level -eq $max) { return }

        recursive $item.PSPath $max ($level + 1) 
    }
}

recursive ~ 3