# Copyright (c) Microsoft Corporation
# SPDX-License-Identifier: MIT

<#
.SYNOPSIS
    Generate a native driver from a BPF program.

.DESCRIPTION
    This script generates a native driver (.sys file) from a BPF program. The native program can be used to load BPF
    programs into the kernel when Hypervisor-protected Code Integrity (HVCI) is enabled.

.PARAMETER FileName
    Specifies the name of the ELF file containing the BPF program.

.PARAMETER Type
    Specifies the type of the BPF program. Valid values include "xdp", "bind", "sockops", and other BPF program types.

.PARAMETER IncludeDir
    Specifies the directory containing the bpf2c include files.

.PARAMETER BinDir
    Specifies the directory containing the bpf2c binaries.

.PARAMETER OutDir
    Specifies the directory where the generated driver will be placed.

.PARAMETER Platform
    Specifies the target platform. Valid values include "x64".

.PARAMETER Configuration
    Specifies the build configuration. Valid values include "Release", "FuzzerDebug", and "Debug".

.PARAMETER SkipVerification
    Specifies whether to skip verification of the generated driver. This parameter is only supported for Debug builds.

.PARAMETER KernelMode
    Specifies whether to generate a kernel-mode driver. If this parameter is false, a user DLL will be generated.

.PARAMETER ResourceFile
    Specifies the path to a resource file to embed in the generated driver.

.EXAMPLE
    .\Convert-BpfToNative.ps1 -FileName bindmonitor

    This example generates a native driver from the BPF program bindmonitor.o.

.EXAMPLE
    .\Convert-BpfToNative.ps1 -FileName bindmonitor -Type bind

    This example generates a native driver from the BPF program bindmonitor.o. The
    program type is set to "bind".

.EXAMPLE
    .\Convert-BpfToNative.ps1 -FileName bindmonitor -Type bind -Configuration Debug

    This example generates a native driver from the BPF program bindmonitor.o. The program type is set to "bind".
    The driver is built in Debug configuration.

.EXAMPLE
    .\Convert-BpfToNative.ps1 -FileName bindmonitor -Type bind -Configuration Debug -KernelMode $false

    This example generates a user-mode DLL from the BPF program bindmonitor.o. The program type is set to "bind".
    The driver is built in Debug configuration.

.NOTES
    Author: Microsoft Corporation
    Website: https://github.com/microsoft/ebpf-for-windows

#>

param([parameter(Mandatory = $true)] [string] $FileName,
    [parameter(Mandatory = $false)] [string] $Type,
    [parameter(Mandatory = $false)] [string] $IncludeDir = "$PSScriptRoot\..\include",
    [parameter(Mandatory = $false)] [string] $BinDir = "$PSScriptRoot",
    [parameter(Mandatory = $false)] [string] $OutDir = "$PWD",
    [parameter(Mandatory = $false)] [string] $Platform = "x64",
    [ValidateSet("Release", "NativeOnlyRelease", "FuzzerDebug", "Debug", "NativeOnlyDebug")][parameter(Mandatory = $false)] [string] $Configuration = "Release",
    [parameter(Mandatory = $false)] [bool] $SkipVerification = $false,
    [parameter(Mandatory = $false)] [bool] $KernelMode = $true,
    [parameter(Mandatory = $false)] [string] $ResourceFile = "")

Push-Location $OutDir

$KernelModeProject = '___KERNEL_MODE_VCXPROJ___'
$UserModeProject = '___USER_MODE_VCXPROJ___'

# If program name ends with .o, remove the suffix
if ($FileName.EndsWith(".o")) {
    $FileName = $FileName.Substring(0, $FileName.Length - 2)
}

# SkipVerification is only supported for Debug builds.
if ($Configuration -eq "Release" -and $SkipVerification) {
    throw "Invalid parameter. SkipVerification is only supported for Debug builds"
}

if ($null -eq (Get-Command 'msbuild.exe' -ErrorAction SilentlyContinue)) {
    throw "Unable to locate msbuild.exe. This command needs to run within a 'Developer Command Prompt'"
}

$fileExists = Test-Path -Path ("$FileName.o")
if (!$fileExists) {
    $errorString = "Can't find program file: " + "$FileName.o"
    throw $errorString
}

$TempDir = "$OutDir\$FileName"

if ($KernelMode) {
    $TempDir += "_km"
}
else {
    $TempDir += "_um"
}

mkdir -Force $TempDir
Copy-Item -Path "$FileName.o" -Destination "$TempDir\"
cd $TempDir

if ($KernelMode) {
    $ProjectFile = "$FileName.vcxproj"
    Set-Content -Path $ProjectFile -Value $KernelModeProject
}
else {
    $ProjectFile = "$FileName_um.vcxproj"
    Set-Content -Path $ProjectFile -Value $UserModeProject
}

$AdditionalOptions = If ($SkipVerification) {"--no-verify"} Else {""}

if ($PSBoundParameters.ContainsKey("Type")) {
    $AdditionalOptions += " --type $Type"
}

msbuild /p:BinDir="$BinDir\" /p:OutDir="$OutDir\" /p:IncludeDir="$IncludeDir" /p:Configuration="$Configuration" /p:Platform="$Platform" /p:FileName="$FileName" /p:AdditionalOptions="$AdditionalOptions" /p:ResourceFile="$ResourceFile" $ProjectFile

if ($LASTEXITCODE -ne 0) {
    throw "Build failed for $FileName.o"
}

Pop-Location