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systemd-stable/man/print-unit-path-call-method.c
Luca Boccassi 7245c4bdba man: add example for sd_bus_call_method
(cherry picked from commit ce199d12e9a88286271dec6f22cd2c61f1cd7f54)
(cherry picked from commit 8b1cc644c5c80b85d170cbb7c6745cf75915ad2f)
(cherry picked from commit 75ee851a416caae424b3c3c37f399138f8044d20)
2023-04-29 11:36:49 +01:00

52 lines
1.4 KiB
C

/* 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) {
errno = -error;
fprintf(stderr, "%s: %m\n", message);
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;
}