Unable to read an open file with binary reader - powershell

Question

I have this function to read the SQL Server errorlog but the problem is that I'm not able to read the errorlog that the server is using at the time. I have been google-ing and it seems that the Fileshare flag isn't working for powershell. Is there some way to set the the Fileshare flag when I try to open the file?
function check_logs{
param($logs)
$pos
foreach($log in $logpos){
if($log.host -eq $logs.host){
$currentLog = $log
break
}
}
if($currentLog -eq $null){
$currentLog = #{}
$logpos.Add($currentLog)
$currentLog.host = $logs.host
$currentLog.event = $logs.type
$currentLog.lastpos = 0
}
$path = $logs.file
if($currentLog.lastpos -ne $null){$pos = $currentLog.lastpos}
else{$pos = 0}
if($logs.enc -eq $null){$br = New-Object System.IO.BinaryReader([System.IO.File]::Open($path, [System.IO.FileMode]::Open))}
else{
$encoding = $logs.enc.toUpper().Replace('-','')
if($encoding -eq 'UTF16'){$encoding = 'Unicode'}
$br = New-Object System.IO.BinaryReader([System.IO.File]::Open($path, [System.IO.FileMode]::Open), [System.Text.Encoding]::$encoding)
}
$required = $br.BaseStream.Length - $pos
if($required -lt 0){
$pos = 0
$required = $br.BaseStream.Length
}
if($required -eq 0){$br.close(); return $null}
$br.BaseStream.Seek($pos, [System.IO.SeekOrigin]::Begin)|Out-Null
$bytes = $br.ReadBytes($required)
$result = [System.Text.Encoding]::Unicode.GetString($bytes)
$split = $result.Split("`n")
foreach($s in $split)
{
if($s.contains(" Error:"))
{
$errorLine = [regex]::Split($s, "\s\s+")
$err = [regex]::Split($errorLine[1], "\s+")
if(log_filter $currentLog.event $err[1..$err.length]){$Script:events = $events+ [string]$s + "`n" }
}
}
$currentLog.lastpos = $br.BaseStream.Position
$br.close()
}
To be clear the error comes when I try to open the file. The error message is:
Exception calling "Open" with "2" argument(s): "The process cannot access the file
'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\Log\ERRORLOG'
because it is being used by another process."
Gísli

Answer 1

So I found the answer and it was pretty simple.
The binary reader constructor takes as input a stream. I didn't define the stream seperately and that's why I didn't notice that you set the FileShare flag in the stream's constructor.
What I had to do was to change this:
{$br = New-Object System.IO.BinaryReader([System.IO.File]::Open($path, [System.IO.FileMode]::Open))}
To this:
{$br = New-Object System.IO.BinaryReader([System.IO.File]::Open($path, [System.IO.FileMode]::Open, [System.IO.FileAccess]::Read, [System.IO.FileShare]::ReadWrite))}
And then it worked like a charm.
Gísli