转自：

 

通过property_set("ctl.start", service_xx);

来启动init.rc中的service是一个很方便方法来调用某个可执行程序或某个脚本程序

service service_xx  /system/bin/xx

disabled

    oneshot

但在非AID_ROOT、AID_SYSTEM 用户的进程中调用ctl.start ctl.stop会碰到权限问题:

system/core/init/property_service.c

/*  

 * White list of UID that are allowed to start/stop services.  

 * Currently there are no user apps that require.  

 */  

struct {   

    const char *service;   

    unsigned int uid;   

    unsigned int gid;   

} control_perms[] = {   

    { "dumpstate",AID_SHELL, AID_LOG },   

     {NULL, 0, 0 }   

};   

  

/*  

 * Checks permissions for starting/stoping system services.  

 * AID_SYSTEM and AID_ROOT are always allowed.  

 *  

 * Returns 1 if uid allowed, 0 otherwise.  

 */  

static int check_control_perms(const char *name, int uid, int gid) {   

    int i;   

    if (uid == AID_SYSTEM || uid == AID_ROOT)   

        return 1;   

  

    /* Search the ACL */  

    for (i = 0; control_perms[i].service; i++) {   

        if (strcmp(control_perms[i].service, name) == 0) {   

            if ((uid && control_perms[i].uid == uid) ||   

                (gid && control_perms[i].gid == gid)) {   

                return 1;   

            }   

        }   

    }   

    return 0;   

} 

本文来自CSDN博客，转载请标明出处：

只有uid == AID_SYSTEM || uid == AID_ROOT

或符合 control_perms[] = {

    { "dumpstate",AID_SHELL, AID_LOG },

     {NULL, 0, 0 }

}; 的uid进程才有权限star/stop services

因此，如果我们碰到了权限问题，根据log提示，在/system/core/include/private/_filesystem_config.h

中查到进程定义，添加到control_perms[]列表

比如，uid ==AID_WIFI的某个程序需要权限启动service_xx

control_perms[] = {

    { "dumpstate",AID_SHELL, AID_LOG },

+  { "service_xx ",AID_WIFI, AID_WIFI},

     {NULL, 0, 0 }

};