C D-bus:无法创建属性:sd_总线_添加_对象_vtable失败
我试图在系统总线上创建一个属性,使用复杂签名,在我的示例中是两个有符号整数。源文件test.c:C D-bus:无法创建属性:sd_总线_添加_对象_vtable失败,c,properties,ipc,systemd,dbus,C,Properties,Ipc,Systemd,Dbus,我试图在系统总线上创建一个属性,使用复杂签名,在我的示例中是两个有符号整数。源文件test.c: #include <stdio.h> #include <stdint.h> #include <systemd/sd-bus.h> #include <systemd/sd-bus-vtable.h> #define DATA_INTERFACE "com.myexample.myproject" #define DATA_PATH "/com/m
#include <stdio.h>
#include <stdint.h>
#include <systemd/sd-bus.h>
#include <systemd/sd-bus-vtable.h>
#define DATA_INTERFACE "com.myexample.myproject"
#define DATA_PATH "/com/myexample/myproject"
#define DATA_PROPERTY "data"
#define DATA_SIGNATURE "ii"
static int get_property_cb(sd_bus*_bus,
const char* path,
const char* interface,
const char* property,
sd_bus_message* reply,
void* userdata,
sd_bus_error* ret_error)
{
int ret = 1;
sd_bus_message_open_container(reply, 'r', DATA_SIGNATURE);
sd_bus_message_append(reply, "i", 111);
sd_bus_message_append(reply, "i", 222);
sd_bus_message_close_container(reply);
return ret;
}
static const sd_bus_vtable prop_spec[3] = {
SD_BUS_VTABLE_START(0),
SD_BUS_PROPERTY(DATA_PROPERTY, DATA_SIGNATURE, get_property_cb, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
SD_BUS_VTABLE_END
};
int main ()
{
sd_bus* _bus = NULL;
sd_bus_slot* _slot = NULL;
int ret = 0;
ret = sd_bus_open_system(&_bus);
if(ret < 0) {
fprintf(stderr, "Error: sd_bus_open ret %d\n", ret);
return -1;
}
ret = sd_bus_request_name(_bus, DATA_INTERFACE, 0);
if(ret < 0) {
fprintf(stderr, "Error: sd_bus_request_name ret %d\n", ret);
return -1;
}
ret = sd_bus_add_object_vtable(_bus, &_slot, DATA_PATH, DATA_INTERFACE, prop_spec, NULL);
if(ret < 0) {
fprintf(stderr, "Error: sd_bus_add_object_vtable ret %d\n", ret);
return -1;
}
printf("!!!Success!!!\n");
sd_bus_slot_unref(_slot);
sd_bus_unref(_bus);
return 0;
}
我以root用户身份运行它:
sudo ./test
绞尽脑汁为什么sd_总线_添加_对象_vtable返回-22(-EINVAL)
有人知道怎么回事吗?签名必须写在括号内:
#define DATA_SIGNATURE "(ii)"
此外,不需要文件/usr/share/dbus-1/services/com.myexample.myproject.service和/usr/share/dbus-1/interfaces/com.myexample.myproject.xml
[D-BUS Service]
Name=com.myexample.myproject
Exec=/home/user/test
sudo ./test
#define DATA_SIGNATURE "(ii)"