Merge #243

243: systemd/bus: provide an example and mark some Message fields optional r=jmesmon a=jmesmon Resolves #242 Co-authored-by: Cody P Schafer <[email protected]>
codyps · Dec 14, 2021 · 92925bd · 92925bd
2 parents 2b17eb3 + b43332f
commit 92925bd
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diff --git a/Cargo.lock b/Cargo.lock
diff --git a/examples/systemd-start-service.rs b/examples/systemd-start-service.rs
@@ -0,0 +1,37 @@
+#![warn(rust_2018_idioms)]
+// WARNING: you may want to use a more tested/complete dbus library, or one that is pure rust.
+// `zbus` may be a reasonable choice, and there are others too
+
+use utf8_cstr::Utf8CStr;
+// approximately this command:
+//     busctl --system call  org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager StartUnit "ss" "foo.service" "fail"
+#[cfg(feature = "bus")]
+fn main() {
+    let mut bus = systemd::bus::Bus::default_system().unwrap();
+
+    let mut method_call = bus
+        .new_method_call(
+            systemd::bus::BusName::from_bytes(b"org.freedesktop.systemd1\0").unwrap(),
+            systemd::bus::ObjectPath::from_bytes(b"/org/freedesktop/systemd1\0").unwrap(),
+            systemd::bus::InterfaceName::from_bytes(b"org.freedesktop.systemd1.Manager\0").unwrap(),
+            systemd::bus::MemberName::from_bytes(b"StartUnit\0").unwrap(),
+        )
+        .unwrap();
+
+    // args
+    method_call
+        .append(Utf8CStr::from_bytes(b"foo.service\0").unwrap())
+        .unwrap();
+    method_call
+        .append(Utf8CStr::from_bytes(b"fail\0").unwrap())
+        .unwrap();
+
+    let res = method_call.call(0).unwrap();
+
+    eprintln!("done, result={:?}", *res);
+}
+
+#[cfg(not(feature = "bus"))]
+fn main() {
+    println!("bus disabled");
+}
diff --git a/src/bus/mod.rs b/src/bus/mod.rs
@@ -1447,31 +1447,37 @@ impl MessageRef {
     /// This corresponds to [`sd_bus_message_get_path`]
     ///
     /// [`sd_bus_message_get_path`]: https://www.freedesktop.org/software/systemd/man/sd_bus_message_get_path.html
-    pub fn path(&self) -> &CStr {
+    pub fn path(&self) -> Option<&CStr> {
         let p = unsafe { ffi::bus::sd_bus_message_get_path(self.as_ptr()) };
-        assert!(!p.is_null());
-
-        unsafe { CStr::from_ptr(p) }
+        if p.is_null() {
+            None
+        } else {
+            Some(unsafe { CStr::from_ptr(p) })
+        }
     }
 
     /// This corresponds to [`sd_bus_message_get_interface`]
     ///
     /// [`sd_bus_message_get_interface`]: https://www.freedesktop.org/software/systemd/man/sd_bus_message_get_interface.html
-    pub fn interface(&self) -> &CStr {
+    pub fn interface(&self) -> Option<&CStr> {
         let p = unsafe { ffi::bus::sd_bus_message_get_interface(self.as_ptr()) };
-        assert!(!p.is_null());
-
-        unsafe { CStr::from_ptr(p) }
+        if p.is_null() {
+            None
+        } else {
+            Some(unsafe { CStr::from_ptr(p) })
+        }
     }
 
     /// This corresponds to [`sd_bus_message_get_member`]
     ///
     /// [`sd_bus_message_get_member`]: https://www.freedesktop.org/software/systemd/man/sd_bus_message_get_member.html
-    pub fn member(&self) -> &CStr {
+    pub fn member(&self) -> Option<&CStr> {
         let p = unsafe { ffi::bus::sd_bus_message_get_member(self.as_ptr()) };
-        assert!(!p.is_null());
-
-        unsafe { CStr::from_ptr(p) }
+        if p.is_null() {
+            None
+        } else {
+            Some(unsafe { CStr::from_ptr(p) })
+        }
     }
 
     /// This corresponds to [`sd_bus_message_get_sender`]