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f4d74c6105
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.
67 lines
1.8 KiB
C
67 lines
1.8 KiB
C
/* SPDX-License-Identifier: CC0-1.0 */
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <systemd/sd-bus.h>
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#define _cleanup_(f) __attribute__((cleanup(f)))
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/* This is equivalent to:
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* busctl call org.freedesktop.systemd1 /org/freedesktop/systemd1 \
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* org.freedesktop.systemd1.Manager GetUnitByPID $$
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*
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* Compile with 'cc -lsystemd print-unit-path.c'
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*/
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#define DESTINATION "org.freedesktop.systemd1"
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#define PATH "/org/freedesktop/systemd1"
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#define INTERFACE "org.freedesktop.systemd1.Manager"
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#define MEMBER "GetUnitByPID"
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static int log_error(int error, const char *message) {
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fprintf(stderr, "%s: %s\n", message, strerror(-error));
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return error;
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}
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static int print_unit_path(sd_bus *bus) {
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_cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
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_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
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_cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
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int r;
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r = sd_bus_message_new_method_call(bus, &m,
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DESTINATION, PATH, INTERFACE, MEMBER);
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if (r < 0)
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return log_error(r, "Failed to create bus message");
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r = sd_bus_message_append(m, "u", (unsigned) getpid());
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if (r < 0)
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return log_error(r, "Failed to append to bus message");
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r = sd_bus_call(bus, m, -1, &error, &reply);
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if (r < 0)
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return log_error(r, "Call failed");
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const char *ans;
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r = sd_bus_message_read(reply, "o", &ans);
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if (r < 0)
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return log_error(r, "Failed to read reply");
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printf("Unit path is \"%s\".\n", ans);
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return 0;
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}
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int main(int argc, char **argv) {
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_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
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int r;
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r = sd_bus_open_system(&bus);
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if (r < 0)
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return log_error(r, "Failed to acquire bus");
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print_unit_path(bus);
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}
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