powershell 2.0 重定向文件句柄异常

Question

我正在寻找The OS handle's position is not what FileStream expected. Do not use a handle simultaneously in one FileStream and in Win32 code or another FileStream. 异常的解决方案，该解决方案也适用于在包含"the fix" 的脚本中调用的脚本。

就这个问题而言，假设我有两个脚本：

foo.ps1

# <fix>
$bindingFlags = [Reflection.BindingFlags] "Instance,NonPublic,GetField"
$objectRef = $host.GetType().GetField( "externalHostRef", $bindingFlags ).GetValue( $host )
$bindingFlags = [Reflection.BindingFlags] "Instance,NonPublic,GetProperty"
$consoleHost = $objectRef.GetType().GetProperty( "Value", $bindingFlags ).GetValue( $objectRef, @() )
[void] $consoleHost.GetType().GetProperty( "IsStandardOutputRedirected", $bindingFlags ).GetValue( $consoleHost, @() )
$bindingFlags = [Reflection.BindingFlags] "Instance,NonPublic,GetField"
$field = $consoleHost.GetType().GetField( "standardOutputWriter", $bindingFlags )
$field.SetValue( $consoleHost, [Console]::Out )
$field2 = $consoleHost.GetType().GetField( "standardErrorWriter", $bindingFlags )
$field2.SetValue( $consoleHost, [Console]::Out )
# </fix>

write-host "normal"
write-error "error"
write-host "yay"
.\bar.ps1

bar.ps1

write-host "normal"
write-error "error"
write-host "yay"

foo.ps1 是这样运行的：

powershell .\foo.ps1 > C:\temp\redirecct.log 2>&1

预期的输出应该是：

normal
C:\foo.ps1 : error
At line:1 char:10
+ .\foo.ps1 <<<<
    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException
    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,foo.ps1

yay
normal
C:\bar.ps1 : error
At C:\foo.ps1:17 char:6
+ .\bar <<<<  2>&1
    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException
    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,bar.ps1

yay

但是，由于已知的错误，输出实际上是：

normal
C:\foo.ps1 : error
At line:1 char:10
+ .\foo.ps1 <<<< 
    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException
    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,foo.ps1

yay
normal
out-lineoutput : The OS handle's position is not what FileStream expected. Do not use a handle simultaneously in one FileStream and in Win3
2 code or another FileStream. This may cause data loss.
    + CategoryInfo          : NotSpecified: (:) [out-lineoutput], IOException
    + FullyQualifiedErrorId : System.IO.IOException,Microsoft.PowerShell.Commands.OutLineOutputCommand

所以观察到的行为是“修复”所做的更改没有被“子”脚本继承（bar.ps1，在这种情况下）。当 bar.ps1 尝试写入时，它会严重崩溃。如果我在foo.ps1 中不以某种方式防范它，它也会严重崩溃。在调用bar.ps1 之前/调用中我可以做些什么来防止bar.ps1 在尝试写入时崩溃？

约束：

• Powershell 2.0
• 脚本必须按上述方式运行
• 我无法修改 bar.ps1（写入 stderr 时它不应该崩溃）。

更新

下面是一个可以接受的解决方案。我说一半是因为它只能防止“父”脚本崩溃。 'child' 脚本在尝试写入时仍然失败。从好的方面来说，它可以识别出该条失败。

foo.ps1：

function savepowershellfromitself {
    $bindingFlags = [Reflection.BindingFlags] "Instance,NonPublic,GetField"
    $objectRef = $host.GetType().GetField( "externalHostRef", $bindingFlags ).GetValue( $host )
    $bindingFlags = [Reflection.BindingFlags] "Instance,NonPublic,GetProperty"
    $consoleHost = $objectRef.GetType().GetProperty( "Value", $bindingFlags ).GetValue( $objectRef, @() )
    [void] $consoleHost.GetType().GetProperty( "IsStandardOutputRedirected", $bindingFlags ).GetValue( $consoleHost, @() )
    $bindingFlags = [Reflection.BindingFlags] "Instance,NonPublic,GetField"
    $field = $consoleHost.GetType().GetField( "standardOutputWriter", $bindingFlags )
    $field.SetValue( $consoleHost, [Console]::Out )
    $field2 = $consoleHost.GetType().GetField( "standardErrorWriter", $bindingFlags )
    $field2.SetValue( $consoleHost, [Console]::Out )
}

savepowershellfromitself
write-host "normal"
write-error "error"
write-host "yay"
$output = .\bar.ps1 2>&1
savepowershellfromitself
write-host "$output"
if( $errors = $output | ?{$_.gettype().Name -eq "ErrorRecord"} ){
    write-host "there were errors in bar!"
}
write-error "error2"
write-host "done"

Answer 1

如果你在 foo.ps1 中这样做，它可以解决问题：

# <fix>
$bindingFlags = [Reflection.BindingFlags] "Instance,NonPublic,GetField"
$objectRef = $host.GetType().GetField( "externalHostRef", $bindingFlags ).GetValue( $host )
$bindingFlags = [Reflection.BindingFlags] "Instance,NonPublic,GetProperty"
$consoleHost = $objectRef.GetType().GetProperty( "Value", $bindingFlags ).GetValue(     $objectRef, @() )
[void] $consoleHost.GetType().GetProperty( "IsStandardOutputRedirected", $bindingFlags).GetValue( $consoleHost, @() )
$bindingFlags = [Reflection.BindingFlags] "Instance,NonPublic,GetField"
$field = $consoleHost.GetType().GetField( "standardOutputWriter", $bindingFlags )
$field.SetValue( $consoleHost, [Console]::Out )
$field2 = $consoleHost.GetType().GetField( "standardErrorWriter", $bindingFlags )
$field2.SetValue( $consoleHost, [Console]::Out )
# </fix>

write-host "normal"
write-error "error"
write-host "yay"

powershell .\bar.ps1 2>&1 | more

通过 more 管道输出隐藏了这样一个事实，即它最终会从 Powershell 的子实例转到文件，从而绕过错误。

事实上，如果你创建一个只运行 foo.ps1 的祖父脚本 foobar.ps1：

powershell .\foo.ps1 2>&1 | more

那么你根本不需要“修复”，而 foo.ps1 就可以了

write-host "normal"
write-error "error"
write-host "yay"

.\bar.ps1

因为管道解决了所有后代脚本的问题。