NAME
sd_bus_call_method, sd_bus_call_methodv, sd_bus_call_method_async, sd_bus_call_method_asyncv - Initialize a bus message object and invoke the corresponding D-Bus method callSYNOPSIS
#include <systemd/sd-bus.h>
typedef
int (*sd_bus_message_handler_t)(sd_bus_message *m,
void *userdata,
sd_bus_error *ret_error);
int
sd_bus_call_method(sd_bus *bus,
const char *destination,
const char *path,
const char *interface,
const char *member,
sd_bus_error *ret_error,
sd_bus_message **reply,
const char *types, ...);
int
sd_bus_call_methodv(sd_bus *bus,
const char *destination,
const char *path,
const char *interface,
const char *member,
sd_bus_error *ret_error,
sd_bus_message **reply,
const char *types,
va_list ap);
int
sd_bus_call_method_async(sd_bus *bus,
sd_bus_slot **slot,
const char *destination,
const char *path,
const char *interface,
const char *member,
sd_bus_message_handler_t callback,
void *userdata,
const char *types, ...);
int
sd_bus_call_method_asyncv(sd_bus *bus,
sd_bus_slot **slot,
const char *destination,
const char *path,
const char *interface,
const char *member,
sd_bus_message_handler_t callback,
void *userdata,
const char *types,
va_list ap);
DESCRIPTION
sd_bus_call_method() is a convenience function for initializing a bus message object and calling the corresponding D-Bus method. It combines the sd_bus_message_new_method_call(3), sd_bus_message_append(3) and sd_bus_call(3) functions into a single function call. sd_bus_call_method_async() is a convenience function for initializing a bus message object and calling the corresponding D-Bus method asynchronously. It combines the sd_bus_message_new_method_call(3), sd_bus_message_append(3) and sd_bus_call_async(3) functions into a single function call.RETURN VALUE
On success, these functions return a non-negative integer. On failure, they return a negative errno-style error code.Errors
See the man pages of sd_bus_message_new_method_call(3), sd_bus_message_append(3), sd_bus_call(3) and sd_bus_call_async(3) for a list of possible errors.NOTES
These APIs are implemented as a shared library, which can be compiled and linked to with the libsystemd pkg-config(1) file.EXAMPLES
Example 1. Make a call to a D-Bus method that takes a single parameter/* 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; }
SEE ALSO
systemd(1), sd-bus(3), sd_bus_message_new_method_call(3), sd_bus_message_append(3), sd_bus_call(3), sd_bus_set_property(3), sd_bus_emit_signal(3)systemd 252 |