# sd_event_source_set_description

## NAME



           sd_event_source_set_description, sd_event_source_get_description -
           Set or retrieve descriptive names of event sources
    


## SYNOPSIS



           **#include <systemd/sd-event.h>**
    
           **int sd_event_source_set_description(sd_event_source ***_source_**,**
                                               **const char ***_description_**);**
    
           **int sd_event_source_get_description(sd_event_source ***_source_**,**
                                               **const char ****_ret_**);**
    


## DESCRIPTION



           **sd_event_source_set_description()** may be used to set an arbitrary
           descriptive name for the event source object specified as _source_.
           This name will be used in debugging messages generated by
           sd-event(3) for this event source, and may be queried using
           **sd_event_source_get_description()** for debugging purposes. The
           _description_ parameter shall point to a **NUL** -terminated string or be
           **NULL**. In the latter case, the descriptive name will be unset. The
           string is copied internally, hence the _description_ argument is not
           referenced after the function returns.
    
           **sd_event_source_get_description()** may be used to query the current
           descriptive name assigned to the event source object _source_. It
           returns a pointer to the current name in _ret_ , stored in memory
           internal to the event source. The memory is invalidated when the
           event source is destroyed or the descriptive name is changed.
    
           Event source objects generally have no description set when they
           are created, except for UNIX signal event sources created with
           sd_event_add_signal(3), whose descriptive name is initialized to
           the signal's C constant name (e.g.  "SIGINT" or "SIGTERM").
    


## RETURN VALUE



           On success, **sd_event_source_set_description()** and
           **sd_event_source_get_description()** return a non-negative integer.
           On failure, they return a negative errno-style error code.
    
       **Errors**
           Returned errors may indicate the following problems:
    
           **-EINVAL**
               _source_ is not a valid pointer to an sd_event_source object or
               the _description_ argument for **sd_event_source_get_description()**
               is **NULL**.
    
           **-ENOMEM**
               Not enough memory to copy the name.
    
           **-ECHILD**
               The event loop has been created in a different process,
               library or module instance.
    
           **-ENXIO**
               No name was set for the event source.
    


## NOTES



           Functions described here are available as a shared library, which
           can be compiled against and linked to with the
           **libsystemd pkg-config**(1) file.
    
           The code described here uses getenv(3), which is declared to be
           not multi-thread-safe. This means that the code calling the
           functions described here must not call setenv(3) 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.
    


* * *