treewide: fix nvd diffing; omit warnings on non-VM builds

Author: NotAShelf

src/commands.rs

@@ -29,6 +29,7 @@ pub struct Command {
     args: Vec<OsString>,
     elevate: bool,
     ssh: Option<String>,
+    show_output: bool,
 }
 
 impl Command {
@@ -40,6 +41,7 @@ impl Command {
             args: vec![],
             elevate: false,
             ssh: None,
+            show_output: false,
         }
     }
 
@@ -53,6 +55,11 @@ impl Command {
         self
     }
 
+    pub const fn show_output(mut self, show_output: bool) -> Self {
+        self.show_output = show_output;
+        self
+    }
+
     pub fn ssh(mut self, ssh: Option<String>) -> Self {
         self.ssh = ssh;
         self
@@ -113,8 +120,15 @@ impl Command {
         } else {
             Exec::cmd(&self.command).args(&self.args)
         };
-        let cmd =
-            ssh_wrap(cmd.stderr(Redirection::None), self.ssh.as_deref()).stdout(Redirection::None);
+        // Configure output redirection based on show_output setting
+        let cmd = ssh_wrap(
+            if self.show_output {
+                cmd.stderr(Redirection::Merge)
+            } else {
+                cmd.stderr(Redirection::None).stdout(Redirection::None)
+            },
+            self.ssh.as_deref(),
+        );
 
         if let Some(m) = &self.message {
             info!("{}", m);

src/darwin.rs

@@ -103,13 +103,24 @@ impl DarwinRebuildArgs {
 
         let target_profile = out_path.get_path().to_owned();
 
+        // Take a strong reference to out_path to prevent premature dropping
+        // We need to keep this alive through the entire function scope to prevent
+        // the tempdir from being dropped early, which would cause nvd diff to fail
+        #[allow(unused_variables)]
+        let keep_alive = out_path.get_path().to_owned();
+        debug!(
+            "Registered keep_alive reference to: {}",
+            keep_alive.display()
+        );
+
         target_profile.try_exists().context("Doesn't exist")?;
 
         Command::new("nvd")
             .arg("diff")
             .arg(CURRENT_PROFILE)
             .arg(&target_profile)
             .message("Comparing changes")
+            .show_output(true)
             .run()?;
 
         if self.common.ask && !self.common.dry && !matches!(variant, Build) {
@@ -151,6 +162,10 @@ impl DarwinRebuildArgs {
 
         // Make sure out_path is not accidentally dropped
         // https://docs.rs/tempfile/3.12.0/tempfile/index.html#early-drop-pitfall
+        debug!(
+            "Completed operation with output path: {:?}",
+            out_path.get_path()
+        );
         drop(out_path);
 
         Ok(())

src/generations.rs

@@ -43,7 +43,7 @@ pub fn from_dir(generation_dir: &Path) -> Option<u64> {
         })
 }
 
-pub fn describe(generation_dir: &Path, current_profile: &Path) -> Option<GenerationInfo> {
+pub fn describe(generation_dir: &Path, _current_profile: &Path) -> Option<GenerationInfo> {
     let generation_number = from_dir(generation_dir)?;
 
     // Get metadata once and reuse for both date and existence checks

src/home.rs

@@ -112,10 +112,17 @@ impl HomeRebuildArgs {
 
         debug!("target_specialisation: {target_specialisation:?}");
 
-        let target_profile: Box<dyn crate::util::MaybeTempPath> = match &target_specialisation {
-            None => out_path,
-            Some(spec) => Box::new(out_path.get_path().join("specialisation").join(spec)),
-        };
+        let target_profile: Box<dyn crate::util::MaybeTempPath> =
+            if let Some(spec) = &target_specialisation {
+                Box::new(out_path.get_path().join("specialisation").join(spec))
+            } else {
+                out_path
+            };
+
+        // Take a strong reference to ensure the TempDir isn't dropped
+        // This prevents early dropping of the tempdir, which causes nvd diff to fail
+        #[allow(unused_variables)]
+        let keep_alive = target_profile.get_path().to_owned();
 
         // just do nothing for None case (fresh installs)
         if let Some(generation) = prev_generation {
@@ -124,6 +131,7 @@ impl HomeRebuildArgs {
                 .arg(generation)
                 .arg(target_profile.get_path())
                 .message("Comparing changes")
+                .show_output(true)
                 .run()?;
         }
 
@@ -154,6 +162,10 @@ impl HomeRebuildArgs {
 
         // Make sure out_path is not accidentally dropped
         // https://docs.rs/tempfile/3.12.0/tempfile/index.html#early-drop-pitfall
+        debug!(
+            "Completed operation with output path: {:?}",
+            target_profile.get_path()
+        );
         drop(target_profile);
 
         Ok(())

src/nixos.rs

@@ -56,6 +56,7 @@ enum OsRebuildVariant {
 impl OsBuildVmArgs {
     fn build_vm(self) -> Result<()> {
         let final_attr = get_final_attr(true, self.with_bootloader);
+        debug!("Building VM with attribute: {}", final_attr);
         self.common
             .rebuild(OsRebuildVariant::BuildVm, Some(final_attr))
     }
@@ -97,7 +98,16 @@ impl OsRebuildArgs {
             Some(h) => h.to_owned(),
             None => match &system_hostname {
                 Some(hostname) => {
-                    tracing::warn!("Guessing system is {hostname} for a VM image. If this isn't intended, use --hostname to change.");
+                    // Only show the warning if we're explicitly building a VM
+                    // by directly calling build_vm(), not when the BuildVm variant
+                    // is used internally via other code paths
+                    if matches!(variant, OsRebuildVariant::BuildVm)
+                        && final_attr
+                            .as_deref()
+                            .map_or(false, |attr| attr == "vm" || attr == "vmWithBootLoader")
+                    {
+                        tracing::warn!("Guessing system is {hostname} for a VM image. If this isn't intended, use --hostname to change.");
+                    }
                     hostname.clone()
                 }
                 None => return Err(eyre!("Unable to fetch hostname, and no hostname supplied.")),
@@ -143,7 +153,6 @@ impl OsRebuildArgs {
             BuildVm => "Building NixOS VM image",
             _ => "Building NixOS configuration",
         };
-
         commands::Build::new(toplevel)
             .extra_arg("--out-link")
             .extra_arg(out_path.get_path())
@@ -168,20 +177,49 @@ impl OsRebuildArgs {
             Some(spec) => out_path.get_path().join("specialisation").join(spec),
         };
 
-        debug!("exists: {}", target_profile.exists());
+        debug!("Output path: {}", out_path.get_path().display());
+        debug!("Target profile path: {}", target_profile.display());
+        debug!("Target profile exists: {}", target_profile.exists());
+
+        // Take a strong reference to out_path to prevent premature dropping
+        // This prevents the tempdir from being dropped early, which would cause nvd diff to fail
+        #[allow(unused_variables)]
+        let keep_alive = out_path.get_path().to_owned();
 
-        target_profile.try_exists().context("Doesn't exist")?;
+        if !target_profile
+            .try_exists()
+            .context("Failed to check if target profile exists")?
+        {
+            return Err(eyre!(
+                "Target profile path does not exist: {}",
+                target_profile.display()
+            ));
+        }
 
         if self.build_host.is_none()
             && self.target_host.is_none()
             && system_hostname.map_or(true, |h| h == target_hostname)
         {
-            Command::new("nvd")
-                .arg("diff")
-                .arg(CURRENT_PROFILE)
-                .arg(&target_profile)
-                .message("Comparing changes")
-                .run()?;
+            // Verify the target_profile path exists before attempting to use it
+            if matches!(target_profile.try_exists(), Ok(true)) {
+                debug!(
+                    "Comparing with target profile: {}",
+                    target_profile.display()
+                );
+
+                Command::new("nvd")
+                    .arg("diff")
+                    .arg(CURRENT_PROFILE)
+                    .arg(&target_profile)
+                    .message("Comparing changes")
+                    .show_output(true)
+                    .run()?;
+            } else {
+                warn!(
+                    "Cannot compare changes - target profile path does not exist: {}",
+                    target_profile.display()
+                );
+            }
         } else {
             debug!("Not running nvd as the target hostname is different from the system hostname.");
         }
@@ -253,8 +291,12 @@ impl OsRebuildArgs {
                 .run()?;
         }
 
-        // Make sure out_path is not accidentally dropped
+        // Make sure out_path is not acidentally dropped
         // https://docs.rs/tempfile/3.12.0/tempfile/index.html#early-drop-pitfall
+        debug!(
+            "Completed operation with output path: {:?}",
+            out_path.get_path()
+        );
         drop(out_path);
 
         Ok(())
@@ -305,6 +347,7 @@ impl OsRollbackArgs {
             .arg(CURRENT_PROFILE)
             .arg(&generation_link)
             .message("Comparing changes")
+            .show_output(true)
             .run()?;
 
         if self.dry {
@@ -345,9 +388,6 @@ impl OsRollbackArgs {
             .message("Setting system profile")
             .run()?;
 
-        // Set up rollback protection flag
-        let mut rollback_profile = false;
-
         // Determine the correct profile to use with specialisations
         let final_profile = match &target_specialisation {
             None => generation_link,
@@ -383,10 +423,8 @@ impl OsRollbackArgs {
                 );
             }
             Err(e) => {
-                rollback_profile = true;
-
                 // If activation fails, rollback the profile
-                if rollback_profile && current_gen_number > 0 {
+                if current_gen_number > 0 {
                     let current_gen_link =
                         profile_dir.join(format!("system-{current_gen_number}-link"));