Geth build script for Windows Powershell

geth-posh-build.ps1

<#
.SYNOPSIS
    Geth build script for Windows
.DESCRIPTION
    A Powershell script to install dependencies for Windows and build go-ethereum binaries.
    Make sure to run `Set-ExecutionPolicy RemoteSigned` in an Adminisrative Powershell window first
    if you intend to run this as a script instead of in a console
.NOTES
    File Name      : geth-posh-install.ps1
    Author         : Taylor Gerring (taylor.gerring@gmail.com)
    Prerequisite   : PowerShell V3
    Copyright 2015 - Ethereum
#>

<##############################################
  Customize options here
###############################################>
$vergeth = "v1.2.2"
$vergo = "1.5.1"
$vermsys = "20150916"

<##############################################
  Probably nothing needs to be modified below
###############################################>

Function InstallMsys2($vermsys)
{
  # Set directories
  $downloaddir = $env:TEMP
  $url = "http://repo.msys2.org/distrib/$arch/msys2-$arch-$vermsys.exe"
  $url2 = "https://raw.githubusercontent.com/Alexpux/MSYS2-packages/master/msys2-installer/auto-install.js"

  # Determine type of system
  if ($ENV:PROCESSOR_ARCHITECTURE -eq "AMD64") {
    $arch = "x86_64"
    $archpath = "msys64"
  } else {
    $arch = "i686"
    $archpath = "msys32"
  }
  $msys2path =  "C:\$archpath" # BUG This is not currently used by the install script
  $url = "http://repo.msys2.org/distrib/$arch/msys2-$arch-$vermsys.exe"
  $url2 = "https://raw.githubusercontent.com/Alexpux/MSYS2-packages/master/msys2-installer/auto-install.js"
  
  # Download and install
  Invoke-WebRequest $url  -UseBasicParsing -OutFile "$downloaddir\msys2-setup.exe"
  Invoke-WebRequest $url2  -UseBasicParsing -OutFile "$downloaddir\auto-install.js"
  #$clnt = new-object System.Net.WebClient
  #$clnt.DownloadFile($url,"$downloaddir\msys2-setup.exe")
  #$clnt.DownloadFile($url2, "$downloaddir\auto-install.js")

  cd $downloaddir
  .\msys2-setup.exe --script auto-install.js -v --platform minimal # This does not wait for exit and pollutes console output

  $env:PATH = "$msys2path\usr\bin;$env:PATH"
  [Environment]::SetEnvironmentVariable("PATH", $env:PATH, "User")
  
  #
  # Because we cannot be sure that msys2-setup.exe is done installing, postpone dependency installation until build
  #
}

Function InstallGo ($vergo)
{
  # Set directories
  $basedir = $env:USERPROFILE
  $golangroot = "$basedir\golang"
  $gosrcroot = "$basedir\go"
  $downloaddir = $env:TEMP

  # Determine type of system
  if ($ENV:PROCESSOR_ARCHITECTURE -eq "AMD64") {
    $arch = "amd64"
  } else {
    $arch = "386"
  }

  # Download and extract
  $golangdl = -Join("https://storage.googleapis.com/golang/go", $vergo, ".windows-", $arch, ".zip")
  Invoke-WebRequest $golangdl -UseBasicParsing -OutFile "$downloaddir\golang.zip"
  #$clnt.DownloadFile($golangdl,"$downloaddir\golang.zip")
  #$clnt = new-object System.Net.WebClient
  
  Add-Type -AssemblyName System.IO.Compression.FileSystem
  [System.IO.Compression.ZipFile]::ExtractToDirectory("$downloaddir\golang.zip", $golangroot)
  #unzip .\golang.zip -d $golangroot

  # Set environment variables
  $env:GOROOT = "$golangroot\go"
  $env:GOPATH = $gosrcroot
  $env:PATH = "$env:PATH;$golangroot\go\bin;$gosrcroot\bin"
  [Environment]::SetEnvironmentVariable("GOROOT", $env:GOROOT, "User")
  [Environment]::SetEnvironmentVariable("GOPATH", $env:GOPATH, "User")
  [Environment]::SetEnvironmentVariable("PATH", $env:PATH, "User")
}

Function InstallDeps ($msys2path)
{
  # Determine type of system
  if ($ENV:PROCESSOR_ARCHITECTURE -eq "AMD64") {
    $arch = "x86_64"
    $archpath = "mingw64"
  } else {
    $arch = "i686"
    $archpath = "mingw32"
  }
  # Install dependencies
  pacman --noconfirm -S unzip git gcc gmp-devel mingw-w64-$arch-gcc
  
  # Path order is very important. Must use gcc from mingw64 not mysys2
  $env:PATH = "$msys2path\$archpath\bin;$env:PATH"  
}

Function BuildGeth ($vergeth)
{
  $packagepath = "github.com/ethereum/go-ethereum"
  # Download source
  go get github.com/tools/godep
  mkdir -p $env:GOPATH\src\$packagepath
  git clone https://$packagepath $env:GOPATH\src\$packagepath
  # Build
  cd $env:GOPATH/src/$packagepath
  git checkout $vergeth
  git pull
  godep go install .\cmd\geth
}

# Install POSIX tools
InstallMsys2($vermsys)
# Install Go
InstallGo($vergo)
# Install late deps
InstallDeps("C:\msys64")
# Download and build
BuildGeth($vergeth)