sd_bus_message_at_end — Check if a message has been fully read
#include <systemd/sd-bus.h>
| int sd_bus_message_at_end( | sd_bus_message *m, | 
| int complete ); | 
sd_bus_message_at_end() returns whether all data from the currently opened
    container in m or all data from all containers in m has
    been read. If complete is zero, this function returns whether all data from the
    currently opened container has been read. If complete is non-zero, this function
    returns whether all data from all containers in m has been read.
If all data from all containers or the current container (depending on the value of
    complete) has been read, sd_bus_message_at_end() returns a
    positive integer. If there is still data left to be read, it returns zero. On failure, it returns a
    negative errno-style error code.
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.