打印DBUS连接对应的进程的PID和名字

1） C 语言实现：

#include <gio/gio.h>#include <stdlib.h>#include <stdio.h>#include <sys/types.h>#include <fcntl.h>#ifdef G_OS_UNIX//#include <gio/gunixfdlist.h>/* For STDOUT_FILENO */#include <unistd.h>#endifGDBusProxy *dbus_proxy;GMainLoop * g_main_loop;char *dbus_name;#define PROCESS_NAME_LENGTH 255int sysfs_read(char *proc_file_name, char *cmdline, int len){int fd = open(proc_file_name, O_RDONLY);int n = read(fd, cmdline, len);close(fd);return n;}voidget_pid_from_dbus_name_cb(GObject *source_object,               GAsyncResult *res,               gpointer user_data){    GError *error = NULL;    GVariant *result = NULL;    guint pid;    gchar process_name[PROCESS_NAME_LENGTH] = "";    gchar proc_path[64] = "";    int ret;    result = g_dbus_proxy_call_finish (dbus_proxy, res, &error);    if (error) {        printf("get_pid_from_dbus_name_cb failed: %s\n", error->message);        g_error_free(error);    }    else if (result) {        g_variant_get(result, "(u)", &pid);        g_variant_unref(result);        /* safety check */        if (pid != 0) {            sprintf(proc_path, "/proc/%u/cmdline", pid);            ret = sysfs_read(proc_path, process_name, PROCESS_NAME_LENGTH);            if (ret < 0)            {                printf("error reading process name from %s: %d",                    proc_path, ret);                strcpy(process_name, "UNKNOWN");            }            //g_debug("PID: %u, Process Name: %s", pid, process_name);            printf("PID: %u, Process Name: %s\n", pid, process_name);        }        else {            /* not sure this can happen */           printf("unable to get pid info\n");        }    }g_main_loop_quit(g_main_loop);exit(0);}voiddbus_proxy_connect_cb(GObject *source_object,               GAsyncResult *res,               gpointer user_data){    GError *error = NULL;    dbus_proxy = g_dbus_proxy_new_finish (res, &error);    if (error) {        g_warning("dbus_proxy_connect_cb failed: %s", error->message);        g_error_free(error);        dbus_proxy = NULL;    }    else {        g_debug("dbus_proxy_connect_cb succeeded");    g_dbus_proxy_call(dbus_proxy,        "GetConnectionUnixProcessID",        g_variant_new("(s)", dbus_name),        G_DBUS_CALL_FLAGS_NONE,        -1,        NULL,        (GAsyncReadyCallback)get_pid_from_dbus_name_cb,        NULL);    }}int main (int argc, char **argv){GDBusConnection *bcon;GMainLoop *loop;if(argc != 2){return -1;}dbus_name = argv[1];g_type_init ();//bcon = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, NULL);g_dbus_proxy_new_for_bus (G_BUS_TYPE_SYSTEM, G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES,NULL, "org.freedesktop.DBus", "/org/freedesktop/DBus", "org.freedesktop.DBus", NULL, (GAsyncReadyCallback)dbus_proxy_connect_cb, NULL);//g_dbus_proxy_call (bproxy, "HelloWorld", g_variant_new ("(s)", "Wow"), G_DBUS_CALL_FLAGS_NONE, -1, NULL, (GAsyncReadyCallback) mycallback, NULL);g_main_loop = g_main_loop_new(NULL, FALSE);g_main_loop_run(g_main_loop);return 0;}

编译：

gcc gdbus-get-pid.c `pkg-config --cflags --libs gio-2.0 gio-unix-2.0` -g -o gdbus-get-pid

运行方式：

$ ./gdbus-get-pid :1.6PID: 953, Process Name: /lib/systemd/systemd-logind

 ./gdbus-get-pid org.freedesktop.UDisks2PID: 2887, Process Name: /usr/lib/udisks2/udisksd

输入可以是 DBUS连接的 unique name，或者是 well-known name.

2. 使用 dbus-send 命令：

e$ dbus-send --print-reply  --dest=org.freedesktop.DBus /org/freedesktop/DBus org.freedesktop.DBus.GetConnectionUnixProcessID string::1.6 method return sender=org.freedesktop.DBus -> dest=:1.166 reply_serial=2   uint32 2517

$ dbus-send --system --print-reply  --dest=org.freedesktop.DBus /org/freedesktop/DBus org.freedesktop.DBus.GetConnectionUnixProcessID string::1.6 method return sender=org.freedesktop.DBus -> dest=:1.113 reply_serial=2   uint32 953

$ dbus-send --system --print-reply  --dest=org.freedesktop.DBus /org/freedesktop/DBus org.freedesktop.DBus.GetConnectionUnixProcessID string:org.freedesktop.UDisks2method return sender=org.freedesktop.DBus -> dest=:1.114 reply_serial=2   uint32 2887

3. python代码：

#!/usr/bin/pythonimport dbusimport sysbus=dbus.SystemBus().get_object('org.freedesktop.DBus', '/org/freedesktop/DBus');print dbus.Interface(bus, 'org.freedesktop.DBus').GetConnectionUnixProcessID(sys.argv[1])

References:

1. http://www.mattfischer.com/blog/?p=494