Add ability to wait for a specific process (instead of the current one)

samples/CPlusPlusWidgets/main.cpp

@@ -179,7 +179,7 @@ private:
 
         try
         {
-            updateManager->WaitExitThenApplyUpdate(updateInfo.value());
+            updateManager->WaitExitThenApplyUpdates(updateInfo.value());
             wxTheApp->ExitMainLoop();
         }
         catch (...) { /* exception will print in log */ }

samples/CPlusPlusWin32/CppWin32Sample.cpp

@@ -188,7 +188,7 @@ LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
                     MessageBoxCentered(hWnd, L"Download an update first.", szTitle, MB_OK);
                 }
                 else {
-                    manager->WaitExitThenApplyUpdate(updInfo.value());
+                    manager->WaitExitThenApplyUpdates(updInfo.value());
                     exit(0);
                 }
             }

src/lib-cpp/include/Velopack.h

@@ -294,12 +294,26 @@ bool vpkc_download_updates(vpkc_update_manager_t *p_manager,
  * You should then clean up any state and exit your app. The updater will apply updates and then
  * optionally restart your app. The updater will only wait for 60 seconds before giving up.
  */
-bool vpkc_wait_exit_then_apply_update(vpkc_update_manager_t *p_manager,
+bool vpkc_wait_exit_then_apply_updates(vpkc_update_manager_t *p_manager,
-                                      struct vpkc_asset_t *p_asset,
+                                       struct vpkc_asset_t *p_asset,
-                                      bool b_silent,
+                                       bool b_silent,
-                                      bool b_restart,
+                                       bool b_restart,
-                                      char **p_restart_args,
+                                       char **p_restart_args,
-                                      size_t c_restart_args);
+                                       size_t c_restart_args);
+
+/**
+ * This will launch the Velopack updater and optionally wait for a program to exit gracefully.
+ * This method is unsafe because it does not necessarily wait for any / the correct process to exit
+ * before applying updates. The `vpkc_wait_exit_then_apply_updates` method is recommended for most use cases.
+ * If dw_wait_pid is 0, the updater will not wait for any process to exit before applying updates (Not Recommended).
+ */
+bool vpkc_unsafe_apply_updates(vpkc_update_manager_t *p_manager,
+                               struct vpkc_asset_t *p_asset,
+                               bool b_silent,
+                               uint32_t dw_wait_pid,
+                               bool b_restart,
+                               char **p_restart_args,
+                               size_t c_restart_args);
 
 /**
  * Frees a vpkc_update_manager_t instance.

src/lib-cpp/include/Velopack.hpp

@@ -583,10 +583,19 @@ public:
      * You should then clean up any state and exit your app. The updater will apply updates and then
      * optionally restart your app. The updater will only wait for 60 seconds before giving up.
      */
-    void WaitExitThenApplyUpdate(const VelopackAsset& asset, bool silent = false, bool restart = true, std::vector<std::string> restartArgs = {}) {
+    void WaitExitThenApplyUpdates(const UpdateInfo& asset, bool silent = false, bool restart = true, std::vector<std::string> restartArgs = {}) {
+        this->WaitExitThenApplyUpdates(asset.TargetFullRelease, silent, restart, restartArgs);
+    };
+
+    /**
+     * This will launch the Velopack updater and tell it to wait for this program to exit gracefully.
+     * You should then clean up any state and exit your app. The updater will apply updates and then
+     * optionally restart your app. The updater will only wait for 60 seconds before giving up.
+     */
+    void WaitExitThenApplyUpdates(const VelopackAsset& asset, bool silent = false, bool restart = true, std::vector<std::string> restartArgs = {}) {
         char** pRestartArgs = allocate_cstring_array(restartArgs);
         vpkc_asset_t vpkc_asset = to_c(asset);
-        bool result = vpkc_wait_exit_then_apply_update(m_pManager, &vpkc_asset, silent, restart, pRestartArgs, restartArgs.size());
+        bool result = vpkc_wait_exit_then_apply_updates(m_pManager, &vpkc_asset, silent, restart, pRestartArgs, restartArgs.size());
         free_cstring_array(pRestartArgs, restartArgs.size());
         
         if (!result) {
@@ -595,12 +604,20 @@ public:
     };
 
     /**
-     * This will launch the Velopack updater and tell it to wait for this program to exit gracefully.
+     * This will launch the Velopack updater and optionally wait for a program to exit gracefully.
-     * You should then clean up any state and exit your app. The updater will apply updates and then
+     * This method is unsafe because it does not necessarily wait for any / the correct process to exit 
-     * optionally restart your app. The updater will only wait for 60 seconds before giving up.
+     * before applying updates. The `WaitExitThenApplyUpdates` method is recommended for most use cases.
+     * If waitPid is 0, the updater will not wait for any process to exit before applying updates (Not Recommended).
      */
-    void WaitExitThenApplyUpdate(const UpdateInfo& asset, bool silent = false, bool restart = true, std::vector<std::string> restartArgs = {}) {
+    void UnsafeApplyUpdates(const VelopackAsset& asset, bool silent, uint32_t waitPid, bool restart, std::vector<std::string> restartArgs) {
-        this->WaitExitThenApplyUpdate(asset.TargetFullRelease, silent, restart, restartArgs);
+        char** pRestartArgs = allocate_cstring_array(restartArgs);
+        vpkc_asset_t vpkc_asset = to_c(asset);
+        bool result = vpkc_unsafe_apply_updates(m_pManager, &vpkc_asset, silent, waitPid, restart, pRestartArgs, restartArgs.size());
+        free_cstring_array(pRestartArgs, restartArgs.size());
+        
+        if (!result) {
+            throw_last_error();
+        }
     };
 };
 

src/lib-cpp/src/lib.rs

@@ -15,7 +15,7 @@ use anyhow::{anyhow, bail};
 use libc::{c_char, c_void, size_t};
 use log_derive::{logfn, logfn_inputs};
 use std::{ffi::CString, ptr};
-use velopack::{sources, Error as VelopackError, UpdateCheck, UpdateManager, VelopackApp};
+use velopack::{sources, ApplyWaitMode, Error as VelopackError, UpdateCheck, UpdateManager, VelopackApp};
 
 /// Create a new FileSource update source for a given file path.
 #[no_mangle]
@@ -295,7 +295,7 @@ pub extern "C" fn vpkc_download_updates(
 #[no_mangle]
 #[logfn(Trace)]
 #[logfn_inputs(Trace)]
-pub extern "C" fn vpkc_wait_exit_then_apply_update(
+pub extern "C" fn vpkc_wait_exit_then_apply_updates(
     p_manager: *mut vpkc_update_manager_t,
     p_asset: *mut vpkc_asset_t,
     b_silent: bool,
@@ -316,6 +316,36 @@ pub extern "C" fn vpkc_wait_exit_then_apply_update(
     })
 }
 
+/// This will launch the Velopack updater and optionally wait for a program to exit gracefully.
+/// This method is unsafe because it does not necessarily wait for any / the correct process to exit 
+/// before applying updates. The `vpkc_wait_exit_then_apply_updates` method is recommended for most use cases.
+/// If dw_wait_pid is 0, the updater will not wait for any process to exit before applying updates (Not Recommended).
+#[no_mangle]
+#[logfn(Trace)]
+#[logfn_inputs(Trace)]
+pub extern "C" fn vpkc_unsafe_apply_updates(
+    p_manager: *mut vpkc_update_manager_t,
+    p_asset: *mut vpkc_asset_t,
+    b_silent: bool,
+    dw_wait_pid: u32,
+    b_restart: bool,
+    p_restart_args: *mut *mut c_char,
+    c_restart_args: size_t,
+) -> bool {
+    wrap_error(|| {
+        let manager = match p_manager.to_opaque_ref() {
+            Some(manager) => manager,
+            None => bail!("pManager must not be null"),
+        };
+
+        let asset = c_to_velopackasset_opt(p_asset).ok_or(anyhow!("pAsset must not be null"))?;
+        let restart_args = c_to_string_array_opt(p_restart_args, c_restart_args).unwrap_or_default();
+        let wait_mode = if dw_wait_pid > 0 { ApplyWaitMode::WaitPid(dw_wait_pid) } else { ApplyWaitMode::NoWait };
+        manager.unsafe_apply_updates(&asset, b_silent, wait_mode, b_restart, &restart_args)?;
+        Ok(())
+    })
+}
+
 /// Frees a vpkc_update_manager_t instance.
 #[no_mangle]
 #[logfn(Trace)]

src/lib-csharp/UpdateExe.cs

@@ -58,11 +58,11 @@ namespace Velopack
         /// Runs Update.exe in the current working directory with the 'start' command which will simply start the application.
         /// Combined with the `waitForExit` parameter, this can be used to gracefully restart the application.
         /// </summary>
-        /// <param name="waitForExit">If true, Update.exe will wait for the current process to exit before re-starting the application.</param>
+        /// <param name="waitPid">Optionally wait for the specified process to exit before continuing.</param>
         /// <param name="locator">The locator to use to find the path to Update.exe and the packages directory.</param>
         /// <param name="startArgs">The arguments to pass to the application when it is restarted.</param>
         /// <param name="logger">The logger to use for diagnostic messages</param>
-        public static void Start(IVelopackLocator? locator = null, bool waitForExit = true, string[]? startArgs = null, ILogger? logger = null)
+        public static void Start(IVelopackLocator? locator = null, uint waitPid = 0, string[]? startArgs = null, ILogger? logger = null)
         {
             logger ??= NullLogger.Instance;
             locator ??= VelopackLocator.GetDefault(logger);
@@ -70,9 +70,9 @@ namespace Velopack
             var args = new List<string>();
             args.Add("start");
 
-            if (waitForExit) {
+            if (waitPid > 0) {
                 args.Add("--waitPid");
-                args.Add(Process.GetCurrentProcess().Id.ToString());
+                args.Add(waitPid.ToString());
             }
 
             if (startArgs != null && startArgs.Length > 0) {
@@ -85,8 +85,8 @@ namespace Velopack
             StartUpdateExe(logger, locator, args);
         }
 
-        private static Process ApplyImpl(IVelopackLocator? locator, VelopackAsset? toApply, bool silent, bool restart, string[]? restartArgs = null,
+        private static Process ApplyImpl(IVelopackLocator? locator, VelopackAsset? toApply, bool silent, uint waitPid, bool restart,
-            ILogger? logger = null)
+            string[]? restartArgs = null, ILogger? logger = null)
         {
             logger ??= NullLogger.Instance;
             locator ??= VelopackLocator.GetDefault(logger);
@@ -104,8 +104,10 @@ namespace Velopack
                 }
             }
 
-            args.Add("--waitPid");
+            if (waitPid > 0) {
-            args.Add(Process.GetCurrentProcess().Id.ToString());
+                args.Add("--waitPid");
+                args.Add(waitPid.ToString());
+            }
 
             if (!restart) args.Add("--norestart"); // restarting is now the default Update.exe behavior
 
@@ -128,13 +130,14 @@ namespace Velopack
         /// <param name="restart">If true, restarts the application after updates are applied (or if they failed)</param>
         /// <param name="locator">The locator to use to find the path to Update.exe and the packages directory.</param>
         /// <param name="toApply">The update package you wish to apply, can be left null.</param>
+        /// <param name="waitPid">Optionally wait for the specified process to exit before continuing.</param>
         /// <param name="restartArgs">The arguments to pass to the application when it is restarted.</param>
         /// <param name="logger">The logger to use for diagnostic messages</param>
         /// <exception cref="Exception">Thrown if Update.exe does not initialize properly.</exception>
-        public static void Apply(IVelopackLocator? locator, VelopackAsset? toApply, bool silent, bool restart, string[]? restartArgs = null,
+        public static void Apply(IVelopackLocator? locator, VelopackAsset? toApply, bool silent, uint waitPid, bool restart, 
-            ILogger? logger = null)
+            string[]? restartArgs = null, ILogger? logger = null)
         {
-            var process = ApplyImpl(locator, toApply, silent, restart, restartArgs, logger);
+            var process = ApplyImpl(locator, toApply, silent, waitPid, restart, restartArgs, logger);
             Thread.Sleep(500);
 
             if (process.HasExited) {
@@ -143,10 +146,10 @@ namespace Velopack
         }
 
         /// <inheritdoc cref="Apply"/>
-        public static async Task ApplyAsync(IVelopackLocator? locator, VelopackAsset? toApply, bool silent, bool restart, string[]? restartArgs = null,
+        public static async Task ApplyAsync(IVelopackLocator? locator, VelopackAsset? toApply, bool silent, uint waitPid, bool restart, string[]? restartArgs = null,
             ILogger? logger = null)
         {
-            var process = ApplyImpl(locator, toApply, silent, restart, restartArgs, logger);
+            var process = ApplyImpl(locator, toApply, silent, waitPid, restart, restartArgs, logger);
             await Task.Delay(500).ConfigureAwait(false);
 
             if (process.HasExited) {

src/lib-csharp/UpdateManager.Helpers.cs

@@ -45,13 +45,13 @@ namespace Velopack
         /// <param name="restartArgs">The arguments to pass to the application when it is restarted.</param>
         public void WaitExitThenApplyUpdates(VelopackAsset? toApply, bool silent = false, bool restart = true, string[]? restartArgs = null)
         {
-            UpdateExe.Apply(Locator, toApply, silent, restart, restartArgs, Log);
+            UpdateExe.Apply(Locator, toApply, silent, VelopackRuntimeInfo.ProcessId, restart, restartArgs, Log);
         }
         
         /// <inheritdoc cref="WaitExitThenApplyUpdates"/>
         public async Task WaitExitThenApplyUpdatesAsync(VelopackAsset? toApply, bool silent = false, bool restart = true, string[]? restartArgs = null)
         {
-            await UpdateExe.ApplyAsync(Locator, toApply, silent, restart, restartArgs, Log).ConfigureAwait(false);
+            await UpdateExe.ApplyAsync(Locator, toApply, silent, VelopackRuntimeInfo.ProcessId, restart, restartArgs, Log).ConfigureAwait(false);
         }
     }
 }

src/lib-csharp/VelopackApp.cs

@@ -224,7 +224,7 @@ namespace Velopack
                 log.Info($"Launching app is out-dated. Current: {myVersion}, Newest Local Available: {latestLocal.Version}");
                 if (!restarted && _autoApply) {
                     log.Info("Auto apply is true, so restarting to apply update...");
-                    UpdateExe.Apply(locator, latestLocal, false, true, args, log);
+                    UpdateExe.Apply(locator, latestLocal, false, VelopackRuntimeInfo.ProcessId, true, args, log);
                     Exit(0);
                 } else {
                     log.Info("Pre-condition failed, we will not restart to apply updates. (restarted: " + restarted + ", autoApply: " + _autoApply + ")");

src/lib-csharp/VelopackRuntimeInfo.cs

@@ -90,6 +90,9 @@ namespace Velopack
 
         /// <summary> The path on disk of the entry assembly. </summary>
         public static string EntryExePath { get; }
+        
+        /// <summary> The current executing process ID. </summary>
+        public static uint ProcessId { get; }
 
         /// <summary> The current machine architecture, ignoring the current process / pe architecture. </summary>
         public static RuntimeCpu SystemArch { get; private set; }
@@ -122,7 +125,9 @@ namespace Velopack
 
         static VelopackRuntimeInfo()
         {
-            EntryExePath = System.Diagnostics.Process.GetCurrentProcess().MainModule.FileName;
+            var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
+            EntryExePath = currentProcess.MainModule.FileName;
+            ProcessId = (uint)currentProcess.Id;
 
 #if DEBUG
             InUnitTestRunner = CheckForUnitTestRunner();

src/lib-rust/src/manager.rs

@@ -6,24 +6,36 @@ use std::{
     sync::mpsc::Sender,
 };
 
+use semver::Version;
+use serde::{Deserialize, Serialize};
+
 #[cfg(feature = "async")]
 use async_std::channel::Sender as AsyncSender;
 #[cfg(feature = "async")]
 use async_std::task::JoinHandle;
-use semver::Version;
-use serde::{Deserialize, Serialize};
 
 use crate::{
-    locator::{self, VelopackLocatorConfig, LocationContext, VelopackLocator},
+    locator::{self, LocationContext, VelopackLocator, VelopackLocatorConfig},
     sources::UpdateSource,
-    Error,
+    util, Error,
-    util,
 };
 
+/// Configure how the update process should wait before applying updates.
+pub enum ApplyWaitMode {
+    /// NOT RECOMMENDED: Will not wait for any process before continuing. This could result in the update process being
+    /// killed, or the update process itself failing.
+    NoWait,
+    /// Will wait for the current process to exit before continuing. This is the default and recommended mode.
+    WaitCurrentProcess,
+    /// Wait for the specified process ID to exit before continuing. This is useful if you are updating a program
+    /// different from the one that is currently running.
+    WaitPid(u32),
+}
+
+/// A feed of Velopack assets, usually retrieved from a remote location.
 #[allow(non_snake_case)]
 #[derive(Serialize, Deserialize, Debug, Clone, Default)]
 #[serde(default)]
-/// A feed of Velopack assets, usually retrieved from a remote location.
 pub struct VelopackAssetFeed {
     /// The list of assets in the (probably remote) update feed.
     pub Assets: Vec<VelopackAsset>,
@@ -36,11 +48,11 @@ impl VelopackAssetFeed {
     }
 }
 
+/// An individual Velopack asset, could refer to an asset on-disk or in a remote package feed.
 #[allow(non_snake_case)]
 #[derive(Serialize, Deserialize, Debug, Clone, Default)]
 #[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
 #[serde(default)]
-/// An individual Velopack asset, could refer to an asset on-disk or in a remote package feed.
 pub struct VelopackAsset {
     /// The name or Id of the package containing this release.
     pub PackageId: String,
@@ -62,11 +74,11 @@ pub struct VelopackAsset {
     pub NotesHtml: String,
 }
 
+/// Holds information about the current version and pending updates, such as how many there are, and access to release notes.
 #[allow(non_snake_case)]
 #[derive(Serialize, Deserialize, Debug, Clone, Default)]
 #[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
 #[serde(default)]
-/// Holds information about the current version and pending updates, such as how many there are, and access to release notes.
 pub struct UpdateInfo {
     /// The available version that we are updating to.
     pub TargetFullRelease: VelopackAsset,
@@ -88,11 +100,11 @@ impl AsRef<VelopackAsset> for VelopackAsset {
     }
 }
 
+/// Options to customise the behaviour of UpdateManager.
 #[allow(non_snake_case)]
 #[derive(Serialize, Deserialize, Debug, Clone, Default)]
 #[cfg_attr(feature = "typescript", derive(ts_rs::TS))]
 #[serde(default)]
-/// Options to customise the behaviour of UpdateManager.
 pub struct UpdateOptions {
     /// Allows UpdateManager to update to a version that's lower than the current version (i.e. downgrading).
     /// This could happen if a release has bugs and was retracted from the release feed, or if you're using
@@ -166,11 +178,7 @@ impl UpdateManager {
         } else {
             locator::auto_locate_app_manifest(LocationContext::FromCurrentExe)?
         };
-        Ok(UpdateManager {
+        Ok(UpdateManager { options: options.unwrap_or_default(), source, locator })
-            options: options.unwrap_or_default(),
-            source,
-            locator,
-        })
     }
 
     fn get_practical_channel(&self) -> String {
@@ -189,7 +197,7 @@ impl UpdateManager {
     pub fn get_current_version_as_string(&self) -> String {
         self.locator.get_manifest_version_full_string()
     }
-    
+
     /// The currently installed app version as a semver Version.
     pub fn get_current_version(&self) -> Version {
         self.locator.get_manifest_version()
@@ -206,7 +214,7 @@ impl UpdateManager {
         self.locator.get_is_portable()
     }
 
-    /// Returns None if there is no local package waiting to be applied. Returns a VelopackAsset 
+    /// Returns None if there is no local package waiting to be applied. Returns a VelopackAsset
     /// if there is an update downloaded which has not yet been applied. In that case, the
     /// VelopackAsset can be applied by calling apply_updates_and_restart or wait_exit_then_apply_updates.
     pub fn get_update_pending_restart(&self) -> Option<VelopackAsset> {
@@ -235,10 +243,9 @@ impl UpdateManager {
         self.source.get_release_feed(&channel, &self.locator.get_manifest())
     }
 
-    #[cfg(feature = "async")]
     /// Get a list of available remote releases from the package source.
-    pub fn get_release_feed_async(&self) -> JoinHandle<Result<VelopackAssetFeed, Error>>
+    #[cfg(feature = "async")]
-    {
+    pub fn get_release_feed_async(&self) -> JoinHandle<Result<VelopackAssetFeed, Error>> {
         let self_clone = self.clone();
         async_std::task::spawn_blocking(move || self_clone.get_release_feed())
     }
@@ -299,11 +306,10 @@ impl UpdateManager {
         }
     }
 
-    #[cfg(feature = "async")]
     /// Checks for updates, returning None if there are none available. If there are updates available, this method will return an
     /// UpdateInfo object containing the latest available release, and any delta updates that can be applied if they are available.
-    pub fn check_for_updates_async(&self) -> JoinHandle<Result<UpdateCheck, Error>>
+    #[cfg(feature = "async")]
-    {
+    pub fn check_for_updates_async(&self) -> JoinHandle<Result<UpdateCheck, Error>> {
         let self_clone = self.clone();
         async_std::task::spawn_blocking(move || self_clone.check_for_updates())
     }
@@ -331,7 +337,7 @@ impl UpdateManager {
         let old_nupkg_pattern = format!("{}/*.nupkg", packages_dir.to_string_lossy());
         let old_partial_pattern = format!("{}/*.partial", packages_dir.to_string_lossy());
         let mut to_delete = Vec::new();
-        
+
         fn find_files_to_delete(pattern: &str, to_delete: &mut Vec<String>) {
             info!("Searching for packages to clean: '{}'", pattern);
             match glob::glob(pattern) {
@@ -345,13 +351,13 @@ impl UpdateManager {
                 }
             }
         }
-        
+
         find_files_to_delete(&old_nupkg_pattern, &mut to_delete);
         find_files_to_delete(&old_partial_pattern, &mut to_delete);
 
         self.source.download_release_entry(&update.TargetFullRelease, &partial_file.to_string_lossy(), progress)?;
         info!("Successfully placed file: '{}'", partial_file.to_string_lossy());
-        
+
         info!("Renaming partial file to final target: '{}'", final_target_file.to_string_lossy());
         fs::rename(&partial_file, &final_target_file)?;
 
@@ -378,13 +384,13 @@ impl UpdateManager {
         Ok(())
     }
 
-    #[cfg(feature = "async")]
     /// Downloads the specified updates to the local app packages directory. Progress is reported back to the caller via an optional Sender.
     /// This function will acquire a global update lock so may fail if there is already another update operation in progress.
     /// - If the update contains delta packages and the delta feature is enabled
     ///   this method will attempt to unpack and prepare them.
     /// - If there is no delta update available, or there is an error preparing delta
     ///   packages, this method will fall back to downloading the full version of the update.
+    #[cfg(feature = "async")]
     pub fn download_updates_async(&self, update: &UpdateInfo, progress: Option<AsyncSender<i16>>) -> JoinHandle<Result<(), Error>> {
         let mut sync_progress: Option<Sender<i16>> = None;
 
@@ -424,7 +430,7 @@ impl UpdateManager {
     where
         A: AsRef<VelopackAsset>,
         S: AsRef<str>,
-        C: IntoIterator<Item=S>,
+        C: IntoIterator<Item = S>,
     {
         self.wait_exit_then_apply_updates(to_apply, false, true, restart_args)?;
         exit(0);
@@ -449,7 +455,27 @@ impl UpdateManager {
     where
         A: AsRef<VelopackAsset>,
         S: AsRef<str>,
-        C: IntoIterator<Item=S>,
+        C: IntoIterator<Item = S>,
+    {
+        self.unsafe_apply_updates(to_apply, silent, ApplyWaitMode::WaitCurrentProcess, restart, restart_args)?;
+        Ok(())
+    }
+
+    /// This will launch the Velopack updater and optionally wait for a program to exit gracefully.
+    /// This method is unsafe because it does not necessarily wait for any / the correct process to exit 
+    /// before applying updates. The `wait_exit_then_apply_updates` method is recommended for most use cases.
+    pub fn unsafe_apply_updates<A, C, S>(
+        &self,
+        to_apply: A,
+        silent: bool,
+        wait_mode: ApplyWaitMode,
+        restart: bool,
+        restart_args: C,
+    ) -> Result<(), Error>
+    where
+        A: AsRef<VelopackAsset>,
+        S: AsRef<str>,
+        C: IntoIterator<Item = S>,
     {
         let to_apply = to_apply.as_ref();
         let pkg_path = self.locator.get_packages_dir().join(&to_apply.FileName);
@@ -457,10 +483,26 @@ impl UpdateManager {
 
         let mut args = Vec::new();
         args.push("apply".to_string());
-        args.push("--waitPid".to_string());
+
-        args.push(format!("{}", std::process::id()));
         args.push("--package".to_string());
-        args.push(pkg_path_str.into_owned());
+        args.push(pkg_path_str.to_string());
+
+        if !pkg_path.exists() {
+            error!("Package does not exist on disk: '{}'", &pkg_path_str);
+            return Err(Error::FileNotFound(pkg_path_str.to_string()));
+        }
+
+        match wait_mode {
+            ApplyWaitMode::NoWait => {}
+            ApplyWaitMode::WaitCurrentProcess => {
+                args.push("--waitPid".to_string());
+                args.push(format!("{}", std::process::id()));
+            }
+            ApplyWaitMode::WaitPid(pid) => {
+                args.push("--waitPid".to_string());
+                args.push(format!("{}", pid));
+            }
+        }
 
         if silent {
             args.push("--silent".to_string());
@@ -495,4 +537,4 @@ impl UpdateManager {
         p.spawn()?;
         Ok(())
     }
-}
+}