卸载C ++中的USB驱动器 [英] unmount USB drive in C++

问题描述

我正在开发用于Linux(Ubuntu)的Qt应用程序，其中使用USB驱动器备份一些内容.复制内容后，应用程序应卸载目标驱动器.我有一个udev规则文件，用于通过ENV{mount_options}="relatime,users,umask=0,uid=user,gid=user"将USB挂载到特定位置，其中用户代表我的用户名.

I am developing a Qt application for Linux (Ubuntu) in which I use USB drive to backup some content. Application should unmount the target drive after copying stuff. I have a udev rule file to mount USB at a specific location with ENV{mount_options}="relatime,users,umask=0,uid=user,gid=user" where user represents my user name.

我尝试使用它没有任何运气.

I tried using this without any luck.

const char* usb = "/mnt/mountpoint/usbdrive";
if (!umount(usb))
{
  qDebug() << "Device unmounted";
}
else
{
  qDebug() << "Can't unmount" << strerror(errno); //this prints Operation not permitted
}

有人可以在这里帮助我吗?我在使用umount正确吗?

Could someone please help me here? Am I using umount right?

谢谢.

推荐答案

适当的特权(Linux: CAP_SYS_ADMIN 功能)是 卸载文件系统所需.

Appropriate privilege (Linux: the CAP_SYS_ADMIN capability) is required to unmount file systems.

每个 umount 都可以.但是，您需要特权才能卸载设备.

Per umount the code is fine. However you need privilege to umount devices.

CAP_SYS_ADMIN 功能允许进程执行各种管理任务，即:调用mount() ，umount().这里有两篇有关 capabilities 的有价值的文章:

The CAP_SYS_ADMIN capability allows a process to perform various administrative tasks, namely: calling mount(), umount(). There are two worth articles about capabilities here:

• CAP_SYS_ADMIN:新的根目录
• Linux功能概述(功能列表)

• CAP_SYS_ADMIN: the new root
• Overview of Linux capabilities (List of capabilities)

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