/* SPDX-License-Identifier: MIT-0 */ /* This is equivalent to: * busctl call org.freedesktop.systemd1 /org/freedesktop/systemd1 \ * org.freedesktop.systemd1.Manager GetUnitByPID $$ * * Compile with 'cc print-unit-path-call-method.c -lsystemd' */ #include <errno.h> #include <stdio.h> #include <sys/types.h> #include <unistd.h> #include <systemd/sd-bus.h> #define _cleanup_(f) __attribute__((cleanup(f))) #define DESTINATION "org.freedesktop.systemd1" #define PATH "/org/freedesktop/systemd1" #define INTERFACE "org.freedesktop.systemd1.Manager" #define MEMBER "GetUnitByPID" static int log_error(int error, const char *message) { fprintf(stderr, "%s: %s\n", message, strerror(-error)); return error; } int main(int argc, char **argv) { _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL; _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL; _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL; int r; r = sd_bus_open_system(&bus); if (r < 0) return log_error(r, "Failed to acquire bus"); r = sd_bus_call_method(bus, DESTINATION, PATH, INTERFACE, MEMBER, &error, &reply, "u", (unsigned) getpid()); if (r < 0) return log_error(r, MEMBER " call failed"); const char *ans; r = sd_bus_message_read(reply, "o", &ans); if (r < 0) return log_error(r, "Failed to read reply"); printf("Unit path is \"%s\".\n", ans); return 0; }