How to Pass a structure as a parameter in a dbus signal?

Question

How to pass a structure as a parameter to a dbus signal through command line?

Dbus-send --system --type=signal / com.example.signal_name string:"hello"

In the place of string, I want to pass structure foo.

typedef enum {MODE1, MODE2, MODE3} MODE;
typedef enum {TYPE1, TYPE2} TYPE;

struct foo
{
    MODE mode;
    TYPE type;
};

Answer 1

Firstly, you need to work out how to represent that structure as a D-Bus value. Its most likely representation would be as a value of type (uu) where the first u is the mode (using some well-defined and stable mapping of C enum values to integers) and the second u is the type.

Secondly, you need to work out how to write that on the command line. However, dbus-send doesn’t currently support structs, so it’s not possible using dbus-send. I suggest using gdbus instead, as per this StackOverflow question.