Module systemd_dbus 

A minimal D-Bus client for the user session bus, for the provisioning’s two calls. What: A minimal D-Bus client for the user session bus: authenticate as the current user, say Hello, and call methods of org.freedesktop.systemd1.Manager with string arguments, each bounded by one deadline for the whole exchange. Why: The wrapper provisions socket activation itself, and may start no program to do it (systemctl would be one). The supported surface of the user manager is its D-Bus API (org.freedesktop.systemd1(5)), reached through the session bus; the manager’s own private socket is documented as private to systemd. Only Reload, ResetFailedUnit, StartUnit, StopUnit and the state query (GetUnit, then a property read) are needed, all with at most two string arguments, so the writer and the reader below cover exactly the types those calls and the bus’s replies use (s, o, g, u, and a variant holding s) and stop at anything else. The reader is total over arbitrary bytes (a fuzz target holds it to that). The comparison with a D-Bus crate is in doc/planning/cli-git-resident-service.md, “Provisioning”.

In TS you’d write (pseudocode):

const bus = await connect(address, 5000); await bus.startUnit('cli-git.socket', 'replace'); // throws with the error name

Structs

Bus

An authenticated connection to the session bus, past Hello.

Reply

A reply: its type, the error name its header carries, and the first string of its body.

Target

Where a method call goes.

Enums

CallError

Why a call did not succeed.

Constants

EXCHANGE_WAIT

How long the whole exchange (connect, authenticate, say hello, make the calls) may take; a stuck bus never holds a commit longer.

GET_UNIT

GetUnit on the user manager: the object path of a loaded unit.

HELLO

Hello on the bus daemon, the first call of every connection.

MANAGER_INTERFACE

The manager’s interface.

MANAGER_NAME

The manager’s bus name.

MANAGER_PATH

The manager’s object path.

NO_SUCH_UNIT

The error name of a unit the manager does not hold (never loaded, or unloaded after it stopped).

RELOAD

Reload on the user manager.

RESET_FAILED_UNIT

ResetFailedUnit on the user manager.

START_UNIT

StartUnit on the user manager.

STOP_UNIT

StopUnit on the user manager.

Functions

decode_reply

What: Reads a complete reply message. Why: Only the type, the error name and the first string of the body matter; a header field of a kind this reader does not know ends the walk of the header, which is safe because the fields it needs come first in what the manager sends or are looked for before any unknown kind.

encode_call

What: The bytes of a method call with string arguments. Why: Kept apart from the socket so a test can read them back and compare them with the specification’s layout.

session_bus_path

The path of the session bus socket: the unix:path= entry of the address variable, else $XDG_RUNTIME_DIR/bus.