[yabridgectl] Check notify-send install status

Since it's used for yabridge's desktop notifications.

CHANGELOG.md

@@ -36,6 +36,8 @@ Versioning](https://semver.org/spec/v2.0.0.html).
   update. If you use a distro packaged version of yabridge, then that means
   yabridge can now be updated safely without requiring any action from your
   side.
+- Added support for the `effBeginLoadBank` and `effBeginLoadProgram` VST2
+  opcodes for loading state as a program or a program bank.
 
 ### Changed
 
@@ -103,6 +105,10 @@ Versioning](https://semver.org/spec/v2.0.0.html).
   idea. I've come across at least one binary this new parser can't handle
   (https://github.com/m4b/goblin/issues/307), so it will still fall back to
   winedump in some cases.
+- After `yabridgectl sync` has finished setting up plugins, yabridgectl will now
+  also check whether `notify-send` is installed as part of its post-install
+  verification process. If `notify-send` is missing then yabridge won't be able
+  to send any notifications when things are going terribly wrong.
 - `yabridgectl status` now shows the locations where bridged VST2 and VST3
   plugins will be set up.
 - `yabridgectl sync --prune` now also considers broken symlinks.

tools/yabridgectl/src/actions.rs

@@ -28,7 +28,7 @@ use crate::config::{
 };
 use crate::files::{self, NativeFile, Plugin, Vst2Plugin};
 use crate::util::{self, get_file_type};
-use crate::util::{verify_path_setup, verify_wine_setup};
+use crate::util::{verify_external_dependencies, verify_path_setup, verify_wine_setup};
 use crate::vst3_moduleinfo::ModuleInfo;
 
 pub mod blacklist;
@@ -682,6 +682,10 @@ pub fn do_sync(config: &mut Config, options: &SyncOptions) -> Result<()> {
     // This check is only performed once per combination of Wine and yabridge versions
     verify_wine_setup(config)?;
 
+    // Yabridge uses notify-send to relay important information when something's very wrong, so
+    // we'll check whether this is installed
+    verify_external_dependencies()?;
+
     Ok(())
 }
 

tools/yabridgectl/src/util.rs

@@ -29,6 +29,7 @@ use std::os::unix::process::CommandExt;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
 use textwrap::Wrapper;
+use which::which;
 
 use crate::config::{self, Config, KnownConfig, YABRIDGE_HOST_32_EXE_NAME, YABRIDGE_HOST_EXE_NAME};
 use crate::files::{LibArchitecture, NativeFile};
@@ -463,6 +464,25 @@ pub fn verify_wine_setup(config: &mut Config) -> Result<()> {
     Ok(())
 }
 
+/// Check whether `notify-send` is installed, as this is used to relay important information when
+/// something's very wrong.
+pub fn verify_external_dependencies() -> Result<()> {
+    if which("notify-send").is_err() {
+        eprintln!(
+            "\n{}",
+            wrap(&format!(
+                "Warning: Could not find '{}'. This will not prevent yabridge from working, but \
+                 you will also not receive any notifcations when something is wrong. It is \
+                 usually part of the libnotify package, but your distro might have moved it into a \
+                 separate libnotify-tools package.",
+                "notify-send".bright_white(),
+            ))
+        );
+    }
+
+    Ok(())
+}
+
 /// Wrap a long paragraph of text to terminal width, or 80 characters if the width of the terminal
 /// can't be determined. Everything after the first line gets indented with four spaces.
 pub fn wrap(text: &str) -> String {