Add pre install/uninstall checks to planners (#561)

* Add pre install/uninstall checks to planners

* Refine checks

* fmt

* Make sure checks run before install/uninstall described as well

* Make nix-darwin error expected

* Fix import

* Fix import

* Report expected errors properly

* format

src/action/base/create_user.rs

@@ -304,7 +304,7 @@ impl Action for CreateUser {
                     Some(40) if stderr.contains("-14120") => {
                         // The user is on an ephemeral Mac, like detsys uses
                         // These Macs cannot always delete users, as sometimes there is no graphical login
-                        tracing::warn!("Encountered an exit code 40 with -14120 error while removing user, this is likely because the initial executing user did not have a secure token, or that there was no graphical login session. To delete the user, log in graphically, then run `/usr/bin/dscl . -delete /Users/{}", self.name);
+                        tracing::warn!("Encountered an exit code 40 with -14120 error while removing user, this is likely because the initial executing user did not have a secure token, or that there was no graphical login session. To delete the user, log in graphically, then run `/usr/bin/dscl . -delete /Users/{}`", self.name);
                     },
                     _ => {
                         // Something went wrong

src/action/base/delete_user.rs

@@ -100,7 +100,7 @@ impl Action for DeleteUser {
                     Some(40) if stderr.contains("-14120") => {
                         // The user is on an ephemeral Mac, like detsys uses
                         // These Macs cannot always delete users, as sometimes there is no graphical login
-                        tracing::warn!("Encountered an exit code 40 with -14120 error while removing user, this is likely because the initial executing user did not have a secure token, or that there was no graphical login session. To delete the user, log in graphically, then run `/usr/bin/dscl . -delete /Users/{}", self.name);
+                        tracing::warn!("Encountered an exit code 40 with -14120 error while removing user, this is likely because the initial executing user did not have a secure token, or that there was no graphical login session. To delete the user, log in graphically, then run `/usr/bin/dscl . -delete /Users/{}`", self.name);
                     },
                     _ => {
                         // Something went wrong

src/cli/subcommand/install.rs

@@ -199,6 +199,14 @@ impl CommandExecute for Install {
             (Some(_), Some(_)) => return Err(eyre!("`--plan` conflicts with passing a planner, a planner creates plans, so passing an existing plan doesn't make sense")),
         };
 
+        if let Err(err) = install_plan.pre_install_check().await {
+            if let Some(expected) = err.expected() {
+                eprintln!("{}", expected.red());
+                return Ok(ExitCode::FAILURE);
+            }
+            Err(err)?
+        }
+
         if !no_confirm {
             let mut currently_explaining = explain;
             loop {

src/cli/subcommand/uninstall.rs

@@ -113,6 +113,14 @@ impl CommandExecute for Uninstall {
             .wrap_err("Reading receipt")?;
         let mut plan: InstallPlan = serde_json::from_str(&install_receipt_string)?;
 
+        if let Err(err) = plan.pre_uninstall_check().await {
+            if let Some(expected) = err.expected() {
+                eprintln!("{}", expected.red());
+                return Ok(ExitCode::FAILURE);
+            }
+            Err(err)?
+        }
+
         if !no_confirm {
             let mut currently_explaining = explain;
             loop {

src/plan.rs

@@ -53,6 +53,9 @@ impl InstallPlan {
         #[cfg(feature = "diagnostics")]
         let diagnostic_data = Some(planner.diagnostic_data().await?);
 
+        // Some Action `plan` calls may fail if we don't do these checks
+        planner.pre_install_check().await?;
+
         let actions = planner.plan().await?;
         Ok(Self {
             planner: planner.boxed(),
@@ -62,6 +65,17 @@ impl InstallPlan {
             diagnostic_data,
         })
     }
+
+    pub async fn pre_uninstall_check(&self) -> Result<(), NixInstallerError> {
+        self.planner.pre_uninstall_check().await?;
+        Ok(())
+    }
+
+    pub async fn pre_install_check(&self) -> Result<(), NixInstallerError> {
+        self.planner.pre_install_check().await?;
+        Ok(())
+    }
+
     #[tracing::instrument(level = "debug", skip_all)]
     pub async fn describe_install(&self, explain: bool) -> Result<String, NixInstallerError> {
         let Self {
@@ -143,6 +157,8 @@ impl InstallPlan {
         cancel_channel: impl Into<Option<Receiver<()>>>,
     ) -> Result<(), NixInstallerError> {
         self.check_compatible()?;
+        self.planner.pre_install_check().await?;
+
         let Self { actions, .. } = self;
         let mut cancel_channel = cancel_channel.into();
 
@@ -313,6 +329,8 @@ impl InstallPlan {
         cancel_channel: impl Into<Option<Receiver<()>>>,
     ) -> Result<(), NixInstallerError> {
         self.check_compatible()?;
+        self.planner.pre_uninstall_check().await?;
+
         let Self { actions, .. } = self;
         let mut cancel_channel = cancel_channel.into();
         let mut errors = vec![];

src/planner/linux.rs

@@ -38,18 +38,8 @@ impl Planner for Linux {
     }
 
     async fn plan(&self) -> Result<Vec<StatefulAction<Box<dyn Action>>>, PlannerError> {
-        check_not_nixos()?;
-
-        check_nix_not_already_installed().await?;
-
-        check_not_wsl1()?;
-
         let has_selinux = detect_selinux().await?;
 
-        if self.init.init == InitSystem::Systemd && self.init.start_daemon {
-            check_systemd_active()?;
-        }
-
         let mut plan = vec![];
 
         plan.push(
@@ -141,6 +131,29 @@ impl Planner for Linux {
             self.settings.ssl_cert_file.clone(),
         )?)
     }
+    async fn pre_uninstall_check(&self) -> Result<(), PlannerError> {
+        check_not_wsl1()?;
+
+        if self.init.init == InitSystem::Systemd && self.init.start_daemon {
+            check_systemd_active()?;
+        }
+
+        Ok(())
+    }
+
+    async fn pre_install_check(&self) -> Result<(), PlannerError> {
+        check_not_nixos()?;
+
+        check_nix_not_already_installed().await?;
+
+        check_not_wsl1()?;
+
+        if self.init.init == InitSystem::Systemd && self.init.start_daemon {
+            check_systemd_active()?;
+        }
+
+        Ok(())
+    }
 }
 
 impl Into<BuiltinPlanner> for Linux {
@@ -150,7 +163,7 @@ impl Into<BuiltinPlanner> for Linux {
 }
 
 // If on NixOS, running `nix_installer` is pointless
-fn check_not_nixos() -> Result<(), PlannerError> {
+pub(crate) fn check_not_nixos() -> Result<(), PlannerError> {
     // NixOS always sets up this file as part of setting up /etc itself: https://github.com/NixOS/nixpkgs/blob/bdd39e5757d858bd6ea58ed65b4a2e52c8ed11ca/nixos/modules/system/etc/setup-etc.pl#L145
     if Path::new("/etc/NIXOS").exists() {
         return Err(PlannerError::NixOs);
@@ -158,7 +171,7 @@ fn check_not_nixos() -> Result<(), PlannerError> {
     Ok(())
 }
 
-fn check_not_wsl1() -> Result<(), PlannerError> {
+pub(crate) fn check_not_wsl1() -> Result<(), PlannerError> {
     // Detection strategies: https://patrickwu.space/wslconf/
     if std::env::var("WSL_DISTRO_NAME").is_ok() && std::env::var("WSL_INTEROP").is_err() {
         return Err(PlannerError::Wsl1);
@@ -166,7 +179,7 @@ fn check_not_wsl1() -> Result<(), PlannerError> {
     Ok(())
 }
 
-async fn detect_selinux() -> Result<bool, PlannerError> {
+pub(crate) async fn detect_selinux() -> Result<bool, PlannerError> {
     if Path::new("/sys/fs/selinux").exists() && which("sestatus").is_ok() {
         // We expect systems with SELinux to have the normal SELinux tools.
         let has_semodule = which("semodule").is_ok();
@@ -181,7 +194,7 @@ async fn detect_selinux() -> Result<bool, PlannerError> {
     }
 }
 
-async fn check_nix_not_already_installed() -> Result<(), PlannerError> {
+pub(crate) async fn check_nix_not_already_installed() -> Result<(), PlannerError> {
     // For now, we don't try to repair the user's Nix install or anything special.
     if let Ok(_) = Command::new("nix-env")
         .arg("--version")
@@ -195,7 +208,7 @@ async fn check_nix_not_already_installed() -> Result<(), PlannerError> {
     Ok(())
 }
 
-fn check_systemd_active() -> Result<(), PlannerError> {
+pub(crate) fn check_systemd_active() -> Result<(), PlannerError> {
     if !Path::new("/run/systemd/system").exists() {
         if std::env::var("WSL_DISTRO_NAME").is_ok() {
             return Err(LinuxErrorKind::Wsl2SystemdNotActive)?;

src/planner/macos.rs

@@ -3,8 +3,10 @@ use std::{collections::HashMap, io::Cursor, path::PathBuf};
 #[cfg(feature = "cli")]
 use clap::ArgAction;
 use tokio::process::Command;
+use which::which;
 
 use super::ShellProfileLocations;
+use crate::planner::HasExpectedErrors;
 
 use crate::{
     action::{
@@ -89,8 +91,6 @@ impl Planner for Macos {
     }
 
     async fn plan(&self) -> Result<Vec<StatefulAction<Box<dyn Action>>>, PlannerError> {
-        ensure_not_running_in_rosetta().await?;
-
         let root_disk = match &self.root_disk {
             root_disk @ Some(_) => root_disk.clone(),
             None => {
@@ -219,6 +219,18 @@ impl Planner for Macos {
             self.settings.ssl_cert_file.clone(),
         )?)
     }
+
+    async fn pre_uninstall_check(&self) -> Result<(), PlannerError> {
+        check_nix_darwin_not_installed().await?;
+
+        Ok(())
+    }
+
+    async fn pre_install_check(&self) -> Result<(), PlannerError> {
+        check_not_running_in_rosetta()?;
+
+        Ok(())
+    }
 }
 
 impl Into<BuiltinPlanner> for Macos {
@@ -227,7 +239,30 @@ impl Into<BuiltinPlanner> for Macos {
     }
 }
 
-async fn ensure_not_running_in_rosetta() -> Result<(), PlannerError> {
+async fn check_nix_darwin_not_installed() -> Result<(), PlannerError> {
+    let has_darwin_rebuild = which("darwin-rebuild").is_ok();
+    let has_darwin_option = which("darwin-option").is_ok();
+
+    let activate_system_present = Command::new("launchctl")
+        .arg("print")
+        .arg("system/org.nixos.activate-system")
+        .process_group(0)
+        .stdin(std::process::Stdio::null())
+        .stdout(std::process::Stdio::null())
+        .stderr(std::process::Stdio::null())
+        .status()
+        .await
+        .map(|v| v.success())
+        .unwrap_or(false);
+
+    if activate_system_present || has_darwin_rebuild || has_darwin_option {
+        return Err(MacosError::UninstallNixDarwin).map_err(|e| PlannerError::Custom(Box::new(e)));
+    };
+
+    Ok(())
+}
+
+fn check_not_running_in_rosetta() -> Result<(), PlannerError> {
     use sysctl::{Ctl, Sysctl};
     const CTLNAME: &str = "sysctl.proc_translated";
 
@@ -246,3 +281,18 @@ async fn ensure_not_running_in_rosetta() -> Result<(), PlannerError> {
 
     Ok(())
 }
+
+#[non_exhaustive]
+#[derive(thiserror::Error, Debug)]
+pub enum MacosError {
+    #[error("`nix-darwin` installation detected, it must be removed before uninstalling Nix. Please refer to https://github.com/LnL7/nix-darwin#uninstalling for instructions how to uninstall `nix-darwin`.")]
+    UninstallNixDarwin,
+}
+
+impl HasExpectedErrors for MacosError {
+    fn expected<'a>(&'a self) -> Option<Box<dyn std::error::Error + 'a>> {
+        match self {
+            this @ MacosError::UninstallNixDarwin => Some(Box::new(this)),
+        }
+    }
+}

src/planner/mod.rs

@@ -144,6 +144,14 @@ pub trait Planner: std::fmt::Debug + Send + Sync + dyn_clone::DynClone {
         Box::new(self)
     }
 
+    async fn pre_uninstall_check(&self) -> Result<(), PlannerError> {
+        Ok(())
+    }
+
+    async fn pre_install_check(&self) -> Result<(), PlannerError> {
+        Ok(())
+    }
+
     #[cfg(feature = "diagnostics")]
     async fn diagnostic_data(&self) -> Result<crate::diagnostics::DiagnosticData, PlannerError>;
 }
@@ -415,6 +423,10 @@ impl HasExpectedErrors for PlannerError {
                 if let Some(err) = _e.downcast_ref::<linux::LinuxErrorKind>() {
                     return err.expected();
                 }
+                #[cfg(target_os = "macos")]
+                if let Some(err) = _e.downcast_ref::<macos::MacosError>() {
+                    return err.expected();
+                }
                 None
             },
             this @ PlannerError::NixOs => Some(Box::new(this)),

src/planner/steam_deck.rs

@@ -398,6 +398,28 @@ impl Planner for SteamDeck {
             self.settings.ssl_cert_file.clone(),
         )?)
     }
+
+    async fn pre_uninstall_check(&self) -> Result<(), PlannerError> {
+        super::linux::check_not_wsl1()?;
+
+        // Unlike the Linux planner, the steam deck planner requires systemd
+        super::linux::check_systemd_active()?;
+
+        Ok(())
+    }
+
+    async fn pre_install_check(&self) -> Result<(), PlannerError> {
+        super::linux::check_not_nixos()?;
+
+        super::linux::check_nix_not_already_installed().await?;
+
+        super::linux::check_not_wsl1()?;
+
+        // Unlike the Linux planner, the steam deck planner requires systemd
+        super::linux::check_systemd_active()?;
+
+        Ok(())
+    }
 }
 
 impl Into<BuiltinPlanner> for SteamDeck {