systemd/man/print-unit-path.c
Luca Boccassi f4d74c6105 man: add licenses to all files that lack one
Documentation is licensed under LGPL-2.1-or-later.
Scripts are MIT to facilitate reuse.
Examples are relicensed to CC0-1.0 to maximise copy-and-paste
for users, with permission from authors.
2021-10-01 17:27:34 +01:00

67 lines
1.8 KiB
C

/* SPDX-License-Identifier: CC0-1.0 */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <systemd/sd-bus.h>
#define _cleanup_(f) __attribute__((cleanup(f)))
/* This is equivalent to:
* busctl call org.freedesktop.systemd1 /org/freedesktop/systemd1 \
* org.freedesktop.systemd1.Manager GetUnitByPID $$
*
* Compile with 'cc -lsystemd print-unit-path.c'
*/
#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;
}
static int print_unit_path(sd_bus *bus) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *m = 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_message_new_method_call(bus, &m,
DESTINATION, PATH, INTERFACE, MEMBER);
if (r < 0)
return log_error(r, "Failed to create bus message");
r = sd_bus_message_append(m, "u", (unsigned) getpid());
if (r < 0)
return log_error(r, "Failed to append to bus message");
r = sd_bus_call(bus, m, -1, &error, &reply);
if (r < 0)
return log_error(r, "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;
}
int main(int argc, char **argv) {
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
int r;
r = sd_bus_open_system(&bus);
if (r < 0)
return log_error(r, "Failed to acquire bus");
print_unit_path(bus);
}