From cfe8ee463d6f3a6aaeb819e4044e56f13c534bde Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Date: Thu, 26 Jul 2018 20:00:36 +0200 Subject: man: add sd_bus_message_new_call(3) --- man/print-unit-path.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 man/print-unit-path.c (limited to 'man/print-unit-path.c') diff --git a/man/print-unit-path.c b/man/print-unit-path.c new file mode 100644 index 0000000000..23b58a26e2 --- /dev/null +++ b/man/print-unit-path.c @@ -0,0 +1,64 @@ +#include +#include +#include +#include + +#include +#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); +} -- cgit v1.2.1