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systemd/man/vtable-example.c
Luca Boccassi 0cfb00d9da man: improve VtableExample
The methods published by the example have a reply in the signature, but
the code was not sending any, so the client gets stuck waiting for a
response that doesn't arrive. Echo back the input string.

Update the object path to follow what would be the canonical format.

Request a service name on the bus, so that the code can be dropped in a
service and it can be dbus-activatable. It also makes it easier to see
on busctl list.
2022-05-11 19:12:24 +01:00

113 lines
3.3 KiB
C

/* SPDX-License-Identifier: CC0-1.0 */
#include <errno.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <systemd/sd-bus.h>
#define _cleanup_(f) __attribute__((cleanup(f)))
#define check(x) ({ \
int r = (x); \
errno = r < 0 ? -r : 0; \
printf(#x ": %m\n"); \
if (r < 0) \
return EXIT_FAILURE; \
})
typedef struct object {
char *name;
uint32_t number;
} object;
static int method(sd_bus_message *m, void *userdata, sd_bus_error *error) {
printf("Got called with userdata=%p\n", userdata);
if (sd_bus_message_is_method_call(m,
"org.freedesktop.systemd.VtableExample",
"Method4"))
return 1;
const char *string;
check(sd_bus_message_read(m, "s", &string));
check(sd_bus_reply_method_return(m, "s", string));
return 1;
}
static const sd_bus_vtable vtable[] = {
SD_BUS_VTABLE_START(0),
SD_BUS_METHOD(
"Method1", "s", "s", method, 0),
SD_BUS_METHOD_WITH_NAMES_OFFSET(
"Method2",
"so", SD_BUS_PARAM(string) SD_BUS_PARAM(path),
"s", SD_BUS_PARAM(returnstring),
method, offsetof(object, number),
SD_BUS_VTABLE_DEPRECATED),
SD_BUS_METHOD_WITH_ARGS_OFFSET(
"Method3",
SD_BUS_ARGS("s", string, "o", path),
SD_BUS_RESULT("s", returnstring),
method, offsetof(object, number),
SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD_WITH_ARGS(
"Method4",
SD_BUS_NO_ARGS,
SD_BUS_NO_RESULT,
method,
SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_SIGNAL(
"Signal1",
"so",
0),
SD_BUS_SIGNAL_WITH_NAMES(
"Signal2",
"so", SD_BUS_PARAM(string) SD_BUS_PARAM(path),
0),
SD_BUS_SIGNAL_WITH_ARGS(
"Signal3",
SD_BUS_ARGS("s", string, "o", path),
0),
SD_BUS_WRITABLE_PROPERTY(
"AutomaticStringProperty", "s", NULL, NULL,
offsetof(object, name),
SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
SD_BUS_WRITABLE_PROPERTY(
"AutomaticIntegerProperty", "u", NULL, NULL,
offsetof(object, number),
SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
SD_BUS_VTABLE_END
};
int main(int argc, char **argv) {
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
sd_bus_default(&bus);
object object = { .number = 666 };
check((object.name = strdup("name")) != NULL);
check(sd_bus_add_object_vtable(bus, NULL,
"/org/freedesktop/systemd/VtableExample",
"org.freedesktop.systemd.VtableExample",
vtable,
&object));
check(sd_bus_request_name(bus,
"org.freedesktop.systemd.VtableExample",
0));
for (;;) {
check(sd_bus_wait(bus, UINT64_MAX));
check(sd_bus_process(bus, NULL));
}
check(sd_bus_release_name(bus, "org.freedesktop.systemd.VtableExample"));
free(object.name);
return 0;
}