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/* server.c */

#include <dbus/dbus.h>
#include <stdbool.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

static DBusHandlerResult
filter_func(DBusConnection *connection, DBusMessage *message, void *usr_data)
{
    dbus_bool_t handled = false;
    char *word = NULL;
    DBusError dberr;

    if (dbus_message_is_signal(message, "client.signal.Type", "Test")) {
        dbus_error_init(&dberr);
        dbus_message_get_args(message, &dberr, DBUS_TYPE_STRING,
            &word, DBUS_TYPE_INVALID);
        if (dbus_error_is_set(&dberr)) {
            dbus_error_free(&dberr);
        } else {
            printf("receive message %s\n", word);
            handled = true;
        }
    }
    return (handled ? DBUS_HANDLER_RESULT_HANDLED : DBUS_HANDLER_RESULT_NOT_YET_HANDLED);
}

int main(int argc, char *argv[])
{
    DBusError dberr;
    DBusConnection *dbconn;

    dbus_error_init(&dberr);

    dbconn = dbus_bus_get(DBUS_BUS_SESSION, &dberr);
    if (dbus_error_is_set(&dberr)) {
        dbus_error_free(&dberr);
        return -1;
    }

    if (!dbus_connection_add_filter(dbconn, filter_func, NULL, NULL)) {
        return -1;
    }

    dbus_bus_add_match(dbconn, "type='signal',interface='client.signal.Type'", &dberr);
    if (dbus_error_is_set(&dberr)) {
        dbus_error_free(&dberr);
        return -1;
    }

    while(dbus_connection_read_write_dispatch(dbconn, -1)) {
        /* loop */
    }
    return 0;
}

#include <dbus/dbus.h>
#include <stdbool.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

int db_send(DBusConnection *dbconn)
{
    DBusMessage *dbmsg;
    char *word;
    int i;

    dbmsg = dbus_message_new_signal("/client/signal/Object", // object name of the signal
                                  "client.signal.Type",      // interface name of the signal
                                  "Test");                   // name of the signal
    if (!dbmsg) {
        return -1;
    }

    word = "hello world";
    if (!dbus_message_append_args(dbmsg, DBUS_TYPE_STRING, &word, DBUS_TYPE_INVALID)) {
        return -1;
    }

    if (!dbus_connection_send(dbconn, dbmsg, NULL)) {
        return -1;
    }
    dbus_connection_flush(dbconn);
    printf("send message %s\n", word);

    dbus_message_unref(dbmsg);
    return 0;
}

int main(int argc, char *argv[])
{
    DBusError dberr;
    DBusConnection *dbconn;
    int i;

    dbus_error_init(&dberr);

    dbconn = dbus_bus_get(DBUS_BUS_SESSION, &dberr);
    if (dbus_error_is_set(&dberr)) {
        return -1;
    }

    db_send(dbconn);

    dbus_connection_unref(dbconn);

    return 0;
}

#include <stdio.h>

int func(int *p)
{
        *p = 0;
}

int main()
{
        func(NULL);
        return 0;
}

SIGQUIT：终端退出符

SIGILL：非法硬件指令

SIGTRAP：平台相关的硬件错误，现在多用在实现调试时的断点

SIGBUS：与平台相关的硬件错误，一般是内存错误

SIGABRT：调用abort函数时产生此信号，进程异常终止

SIGFPE：算术异常

SIGSEGV：segment violation，无效内存引用

SIGXCPU：超过了cpu使用资源限制（setrlimit）

SIGXFSZ：超过了文件长度限制（setrlimit）

SIGSYS：无效的系统调用