--- name: "sd_bus_emit_object_removed" section: "3" platform: "linux" package: "libsystemd-dev" version: "257.13-1~deb13u1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/sd_bus_emit_signal" --- # sd\_bus\_emit\_object\_removed(3) Convenience functions for emitting (standard) D-Bus signals Part of [sd\_bus\_emit\_signal(3)](/sd_bus_emit_signal/3.md). ## NAME sd\_bus\_emit\_signal, sd\_bus\_emit\_signalv, sd\_bus\_emit\_signal\_to, sd\_bus\_emit\_signal\_tov, sd\_bus\_emit\_interfaces\_added, sd\_bus\_emit\_interfaces\_added\_strv, sd\_bus\_emit\_interfaces\_removed, sd\_bus\_emit\_interfaces\_removed\_strv, sd\_bus\_emit\_properties\_changed, sd\_bus\_emit\_properties\_changed\_strv, sd\_bus\_emit\_object\_added, sd\_bus\_emit\_object\_removed - Convenience functions for emitting (standard) D-Bus signals ## SYNOPSIS ``` #include ``` **int sd\_bus\_emit\_signal(sd\_bus \****bus***, const char \****path***, const char \****interface***, const char \****member***, const char \****types***, ...);** **int sd\_bus\_emit\_signalv(sd\_bus \****bus***, const char \****path***, const char \****interface***, const char \****member***, const char \****types***, va\_list** *ap***);** **int sd\_bus\_emit\_signal\_to(sd\_bus \****bus***, const char \****destination***, const char \****path***, const char \****interface***, const char \****member***, const char \****types***, ...);** **int sd\_bus\_emit\_signal\_tov(sd\_bus \****bus***, const char \****destination***, const char \****path***, const char \****interface***, const char \****member***, const char \****types***, va\_list** *ap***);** **int sd\_bus\_emit\_interfaces\_added(sd\_bus \****bus***, const char \****path***, const char \****interface***, ...);** **int sd\_bus\_emit\_interfaces\_added\_strv(sd\_bus \****bus***, const char \****path***, char \*\****interfaces***);** **int sd\_bus\_emit\_interfaces\_removed(sd\_bus \****bus***, const char \****path***, const char \****interface***, ...);** **int sd\_bus\_emit\_interfaces\_removed\_strv(sd\_bus \****bus***, const char \****path***, char \*\****interfaces***);** **int sd\_bus\_emit\_properties\_changed(sd\_bus \****bus***, const char \****path***, const char \****interface***, const char \****name***, ...);** **int sd\_bus\_emit\_properties\_changed\_strv(sd\_bus \****bus***, const char \****path***, const char \****interface***, char \*\****names***);** **int sd\_bus\_emit\_object\_added(sd\_bus \****bus***, const char \****path***);** **int sd\_bus\_emit\_object\_removed(sd\_bus \****bus***, const char \****path***);** ## DESCRIPTION **sd\_bus\_emit\_signal()** is a convenience function for initializing a bus message object and emitting the corresponding D-Bus signal. It combines the [**sd\_bus\_message\_new\_signal**(3)](/sd_bus_message_new_signal/3.md), [**sd\_bus\_message\_append**(3)](/sd_bus_message_append/3.md) and [**sd\_bus\_send**(3)](/sd_bus_send/3.md) functions into a single function call. **sd\_bus\_emit\_signalv()** is equivalent to **sd\_bus\_message\_append()**, except that it is called with a "va\_list" instead of a variable number of arguments. **sd\_bus\_emit\_signal\_to()** and **sd\_bus\_emit\_signal\_tov()** are identical to **sd\_bus\_emit\_signal()** and **sd\_bus\_emit\_signalv()**, except that they can emit the signal to a single destination. Give *destination* as **NULL** to broadcast the signal. **sd\_bus\_emit\_interfaces\_added()** and **sd\_bus\_emit\_interfaces\_removed()** are used to implement the **InterfacesAdded** and **InterfacesRemoved** signals of the **org.freedesktop.DBus.ObjectManager** interface. They take a path whose interfaces have been modified as an argument and a variable list of interfaces that have been added or removed, respectively. The final argument passed to **sd\_bus\_emit\_interfaces\_added()** and **sd\_bus\_emit\_interfaces\_removed()** *must* be **NULL**. This allows both functions to safely determine the number of passed interface arguments. **sd\_bus\_emit\_interfaces\_added\_strv()** and **sd\_bus\_emit\_interfaces\_removed\_strv()** are identical to their respective counterparts but both take the list of interfaces as a single argument instead of a variable number of arguments. **sd\_bus\_emit\_properties\_changed()** is used to implement the **PropertiesChanged** signal of the **org.freedesktop.DBus.Properties** interface. It takes an object path, interface and a variable list of property names as its arguments. The final argument passed to **sd\_bus\_emit\_properties\_changed()** *must* be **NULL**. This allows it to safely determine the number of passed property names. **sd\_bus\_emit\_properties\_changed\_strv()** is identical to **sd\_bus\_emit\_properties\_changed()** but takes the list of property names as a single argument instead of a variable number of arguments. **sd\_bus\_emit\_object\_added()** and **sd\_bus\_emit\_object\_removed()** are convenience functions for emitting the **InterfacesAdded** or **InterfacesRemoved** signals for all interfaces registered on a specific object path, respectively. This includes any parent fallback vtables if they are not overridden by a more applicable child vtable. It also includes all the standard D-Bus interfaces implemented by sd-bus itself on any registered object. Note that **sd\_bus\_emit\_interfaces\_added()**, **sd\_bus\_emit\_interfaces\_removed()**, **sd\_bus\_emit\_object\_added()** and **sd\_bus\_emit\_object\_removed()** require an object manager to have been registered on the given object path or one of its parent object paths using [**sd\_bus\_add\_object\_manager**(3)](/sd_bus_add_object_manager/3.md). ## RETURN VALUE On success, these functions return a non-negative integer. On failure, they return a negative errno-style error code. ### Errors Returned errors may indicate the following problems: **-EINVAL** One of the required parameters is **NULL** or invalid. A reserved D-Bus interface was passed as the *interface* parameter. **-ENOPKG** The bus cannot be resolved. **-ECHILD** The bus was created in a different process, library or module instance. **-ENOMEM** Memory allocation failed. **-ESRCH** One of **sd\_bus\_emit\_interfaces\_added()**, **sd\_bus\_emit\_interfaces\_removed()**, **sd\_bus\_emit\_object\_added()** or **sd\_bus\_emit\_object\_removed()** was called on an object without an object manager registered on its own object path or one of its parent object paths. See the man pages of [**sd\_bus\_message\_new\_signal**(3)](/sd_bus_message_new_signal/3.md), [**sd\_bus\_message\_append**(3)](/sd_bus_message_append/3.md) and [**sd\_bus\_send**(3)](/sd_bus_send/3.md) for more possible errors. ## NOTES Functions described here are available as a shared library, which can be compiled against and linked to with the **libsystemd** [**pkg-config**(1)](/pkg-config/1.md) file. The code described here uses [**getenv**(3)](/getenv/3.md), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not call [**setenv**(3)](/setenv/3.md) from a parallel thread. It is recommended to only do calls to **setenv()** from an early phase of the program when no other threads have been started. ## HISTORY **sd\_bus\_emit\_signal()**, **sd\_bus\_emit\_interfaces\_added()**, **sd\_bus\_emit\_interfaces\_added\_strv()**, **sd\_bus\_emit\_interfaces\_removed()**, **sd\_bus\_emit\_interfaces\_removed\_strv()**, **sd\_bus\_emit\_properties\_changed()**, **sd\_bus\_emit\_properties\_changed\_strv()**, were added in version 221. **sd\_bus\_emit\_object\_added()**, and **sd\_bus\_emit\_object\_removed()** were added in version 222. **sd\_bus\_emit\_signalv()** was added in version 246. **sd\_bus\_emit\_signal\_to()** and **sd\_bus\_emit\_signal\_tov()** were added in version 253. ## SEE ALSO [**sd-bus**(3)](/sd-bus/3.md), [**busctl**(1)](/busctl/1.md), [**sd\_bus\_message\_new\_signal**(3)](/sd_bus_message_new_signal/3.md), [**sd\_bus\_message\_append**(3)](/sd_bus_message_append/3.md), [**sd\_bus\_send**(3)](/sd_bus_send/3.md), [**sd\_bus\_call\_method**(3)](/sd_bus_call_method/3.md)