QStorageInfo 不适用于只读 rootfs

Question

我在我的 debian strech 系统上使用 qt 修订版 5.7.1。我使用 overlayfs 将我的 rootfs 安装为只读，我使用 QStorageInfo 检查我的 SD 卡大小。

将 rootfs 安装为只读后，我在 QStorageInfo mountedvolumes 中只获得根目录。

下面是获取存储列表的源码：

foreach (const QStorageInfo &storage, QStorageInfo::mountedVolumes()) {
    if (storage.isValid() && storage.isReady())
        {
            qDebug() << "storage path" << storage.rootPath();
            qDebug()  << "storage name" << storage.name();
            qDebug()  << "storage readonly" << storage.isReadOnly();
            qDebug()  << "storage filesystem type " << storage.fileSystemType();
            qDebug()  << "storage device " << storage.device();
    }
}

以上来源的输出：

storage path "/"
        storage name ""
        storage readonly true
        storage filesystem type  ""
        storage device  ""

我的 /etc/fstab 文件包含：

/dev/mmcblk0p1  /               ext4    ro,noatime  0 1
mount_overlay   /var            fuse    nofail,defaults 0 0
mount_overlay   /home           fuse    nofail,defaults 0 0
mount_overlay   /etc            fuse    nofail,defaults 0 0
none            /tmp            tmpfs   defaults    0 0

如果我将 rootfs 挂载为“rw”QStorageInfo 工作正常。以下是“rw”选项作为 rootfs 的输出：

storage path "/"
storage name ""
storage readonly false
storage filesystem type  "ext4"
storage device  "/dev/root"
storage path "/run"
storage name ""
storage readonly false
storage filesystem type  "tmpfs"
storage device  "tmpfs"
storage path "/run/lock"
storage name ""
storage readonly false
storage filesystem type  "tmpfs"
storage device  "tmpfs"
storage path "/tmp"
storage name ""
storage readonly false
storage filesystem type  "tmpfs"
storage device  "none"
storage path "/home"
storage name ""
storage readonly false
storage filesystem type  "ext4"
storage device  "/dev/root"
storage path "/var"
storage name ""
storage readonly false
storage filesystem type  "ext4"
storage device  "/dev/root"
storage path "/media/data"
storage name "Data"
storage readonly false
storage filesystem type  "ext4"
storage device  "/dev/mmcblk0p3"
storage path "/run/user/0"
storage name ""
storage readonly false
storage filesystem type  "tmpfs"
storage device  "tmpfs"
storage path "/home/user/SdCard"
storage name "SDCard"
storage readonly false
storage filesystem type  "ext4"
storage device  "/dev/mmcblk1p1"
storage path "/home_org/user/SdCard"
storage name "SDCard"
storage readonly false
storage filesystem type  "ext4"
storage device  "/dev/mmcblk1p1"

当将 rootfs 设置为 read/write 权限时工作正常。当设置为只读时它不能正常工作

请帮助我理解问题 QStorageInfo with readonly rootfs。

Answer 1

QStorageInfo 正在尝试读取 /etc/mtab 以获取已安装的卷。 /etc/mtab 由于 readonly rootfs 无法生成。

/etc/mtab 是“../proc/self/mounts”的符号 link。

所以在创建只读系统之前需要生成smbolink link从“../proc/self/mounts”到/etc/mtab。

QStorageInfo 不适用于只读 rootfs

QStorageInfo is not working with read only rootfs

c++

qt

embedded-linux

c++14