feat(install): Add PIXI_NO_PATH_UPDATE for PATH update suppression (#…

…692)

Close #686 

The PR mainly adds the option of using a `PIXI_NO_PATH_UPDATE`
environment variable to suppress PATH update, when installing pixi from
install script.

Besides the option added, since the PR is about environment variable,
the way of updating PATH in the PowerShell install script has also been
modified from using `[Environment]::SetEnvironmentVariable` to set
environment variable to get and update environment variable from Windows
registry.

This change doesn't affect pixi installation directly and is primarily
to address a potential issue that `SetEnvironmentVariable` expands all
environment variables and this behavior may not be welcomed in some
cases.

```pwsh
$Env:PATH
#> %USERPROFILE%\bin;

# when using `SetEnvironmentVariable` to update PATH, `%USERPROFILE%` will be expanded
#> C:\Users\userA\bin;C:\pixi\bin

# when using registry to update PATH, `%USERPROFILE%` will be kept unexpanded
#> %USERPROFILE%\bin;C:\pixi\bin
```

Related code are copied from
[ScoopInstaller/Install](https://github.com/ScoopInstaller/Install/blob/master/install.ps1#L362)
I'm maintaining.

Signed-off-by: Chawye Hsu <[email protected]>

install/install.ps1

@@ -11,18 +11,91 @@
     Specifies Pixi's home directory.
     The default value is '$Env:USERPROFILE\.pixi'. You can also specify it by
     setting the environment variable 'PIXI_HOME'.
+.PARAMETER NoPathUpdate
+    If specified, the script will not update the PATH environment variable.
 .LINK
     https://pixi.sh
 .LINK
     https://github.com/prefix-dev/pixi
 #>
 param (
     [string] $PixiVersion = 'latest',
-    [string] $PixiHome = "$Env:USERPROFILE\.pixi"
+    [string] $PixiHome = "$Env:USERPROFILE\.pixi",
+    [switch] $NoPathUpdate
 )
 
 Set-StrictMode -Version Latest
 
+function Publish-Env {
+    if (-not ("Win32.NativeMethods" -as [Type])) {
+        Add-Type -Namespace Win32 -Name NativeMethods -MemberDefinition @"
+[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
+public static extern IntPtr SendMessageTimeout(
+    IntPtr hWnd, uint Msg, UIntPtr wParam, string lParam,
+    uint fuFlags, uint uTimeout, out UIntPtr lpdwResult);
+"@
+    }
+
+    $HWND_BROADCAST = [IntPtr] 0xffff
+    $WM_SETTINGCHANGE = 0x1a
+    $result = [UIntPtr]::Zero
+
+    [Win32.Nativemethods]::SendMessageTimeout($HWND_BROADCAST,
+        $WM_SETTINGCHANGE,
+        [UIntPtr]::Zero,
+        "Environment",
+        2,
+        5000,
+        [ref] $result
+    ) | Out-Null
+}
+
+function Write-Env {
+    param(
+        [String] $name,
+        [String] $val,
+        [Switch] $global
+    )
+
+    $RegisterKey = if ($global) {
+        Get-Item -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager'
+    } else {
+        Get-Item -Path 'HKCU:'
+    }
+
+    $EnvRegisterKey = $RegisterKey.OpenSubKey('Environment', $true)
+    if ($null -eq $val) {
+        $EnvRegisterKey.DeleteValue($name)
+    } else {
+        $RegistryValueKind = if ($val.Contains('%')) {
+            [Microsoft.Win32.RegistryValueKind]::ExpandString
+        } elseif ($EnvRegisterKey.GetValue($name)) {
+            $EnvRegisterKey.GetValueKind($name)
+        } else {
+            [Microsoft.Win32.RegistryValueKind]::String
+        }
+        $EnvRegisterKey.SetValue($name, $val, $RegistryValueKind)
+    }
+    Publish-Env
+}
+
+function Get-Env {
+    param(
+        [String] $name,
+        [Switch] $global
+    )
+
+    $RegisterKey = if ($global) {
+        Get-Item -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager'
+    } else {
+        Get-Item -Path 'HKCU:'
+    }
+
+    $EnvRegisterKey = $RegisterKey.OpenSubKey('Environment')
+    $RegistryValueOption = [Microsoft.Win32.RegistryValueOptions]::DoNotExpandEnvironmentNames
+    $EnvRegisterKey.GetValue($name, $null, $RegistryValueOption)
+}
+
 if ($Env:PIXI_VERSION) {
     $PixiVersion = $Env:PIXI_VERSION
 }
@@ -31,6 +104,10 @@ if ($Env:PIXI_HOME) {
     $PixiHome = $Env:PIXI_HOME
 }
 
+if ($Env:PIXI_NO_PATH_UPDATE) {
+    $NoPathUpdate = $true
+}
+
 # Repository name
 $REPO = 'prefix-dev/pixi'
 $ARCH = 'x86_64'
@@ -57,26 +134,34 @@ try {
 
     # Create the install dir if it doesn't exist
     if (!(Test-Path -Path $BinDir)) {
-        New-Item -ItemType directory -Path $BinDir
+        New-Item -ItemType Directory -Path $BinDir | Out-Null
     }
 
     $ZIP_FILE = $TEMP_FILE + ".zip"
     Rename-Item -Path $TEMP_FILE -NewName $ZIP_FILE
 
     # Extract pixi from the downloaded zip file
     Expand-Archive -Path $ZIP_FILE -DestinationPath $BinDir -Force
-
-    # Add pixi to PATH if the folder is not already in the PATH variable
-    $PATH = [Environment]::GetEnvironmentVariable("Path", "User")
-    if ($PATH -notlike "*$BinDir*") {
-        Write-Output "Adding $BinDir to PATH`n"
-        [Environment]::SetEnvironmentVariable("Path", "$BinDir;" + [Environment]::GetEnvironmentVariable("Path", "User"), "User")
-    } else {
-        Write-Output "$BinDir is already in PATH`n"
-    }
 } catch {
     Write-Host "Error: '$DOWNLOAD_URL' is not available or failed to download"
     exit 1
 } finally {
     Remove-Item -Path $ZIP_FILE
 }
+
+# Add pixi to PATH if the folder is not already in the PATH variable
+if (!$NoPathUpdate) {
+    $PATH = Get-Env 'PATH'
+    if ($PATH -notlike "*$BinDir*") {
+        Write-Output "Adding $BinDir to PATH"
+        # For future sessions
+        Write-Env -name 'PATH' -val "$BinDir;$PATH"
+        # For current session
+        $Env:PATH = "$BinDir;$PATH"
+        Write-Output "You may need to restart your shell"
+    } else {
+        Write-Output "$BinDir is already in PATH"
+    }
+} else {
+    Write-Output "You may need to update your PATH manually to use pixi"
+}

install/install.sh

@@ -79,6 +79,9 @@ update_shell() {
     FILE=$1
     LINE=$2
 
+    # shell update can be suppressed by `PIXI_NO_PATH_UPDATE` env var
+    [[ ! -z "$PIXI_NO_PATH_UPDATE" ]] && return
+
     # Create the file if it doesn't exist
     if [ -f "$FILE" ]; then
         touch "$FILE"