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Document Storage

• Storage.conf
• Mount Point Groups
• HOME
• PREFIX
• Non Mount Point Groups
• MountTable
• Updates
• Packages
• SxeDatabase
• Non-removable vs Removable Storage
• Explicit Mount/Unmount Notifications
• Using read-only File Systems

Storage.conf

The Storage.conf configuration file defines the organization of storage devices in a Qt Extended installation. Storage.conf maps devices to human-readable names, and defines whether they are removable, read-only, and what type of data they may store and where. It also defines which devices packages and Qt Extended updates are installed to.

The information stored in the Storage.conf can be accessed at run-time using the QStorageMetaInfo and QFileSystem classes, and the QStorageDeviceSelector widget provides a user interface for selecting storage devices defined in the Storage.conf.

An example Storage.conf is available at: <qt-extended-root-dir>/devices/greenphone/Storage.conf.

Mount Point Groups

The configuration for each storage device is defined in a separate settings group in the Storage.conf. Any group key may be used for a mount point provided it's not a reserved group names, but they typically take the form of MountPointX where X is an integer (MountPoint0,MountPoint1).

The parameters defined for a mount point group are:

Example: Mount point group for an SD Card

    [MountPoint1]
    Name[] = SD Card
    Path=/dev/mmca
    Removable = 1
    Applications = 0
    Documents = 1
    ContentDatabase = 1

HOME

The HOME group is a special case mount path which holds the settings for the Qt Extended home directory. Unless specified otherwise the HOME mount is assumed to be a valid storage location which may contain both applications and documents. The HOME mount may be explicitly disabled by setting Path = HIDE, otherwise no value of Path is necessary.

Example: HOME mount that contains applications but not documents.

    [HOME]
    Name[] = HOME
    Path = HOME
    Applications = 1
    Documents = 0

PREFIX

The PREFIX is another special case mount path, which holds the settings for the directory Qt Extended is run from. It is normally not necessary to define anything for the PREFIX mount.

Note: Commercial customers please contact support before using this group.

Non Mount Point Groups

In addition to the mount point settings groups there are also reserved groups, these either index the storage devices or identify which device should be used as the storage location for a particular set of data.

MountTable

The MountTable group provides a list of all the device mount points defined in the Storage.conf and identifies which mount points are the default storage locations for application, and document data.

The parameters for the MountTable group are:

Example: MountTable group for device with two storage devices, one the default documents location.

    [MountTable]
    MountPoints="MountPoint0,MountPoint1"
    DocumentsDefault=MountPoint0
    ApplicationsDefault=HOME

Updates

The Updates group specifies where Qt Extended updates are installed to:

Example: Updates installed to the Updates sub-directory of the HOME mount.

    [Updates]
    MountPoint=HOME
    Path=Updates

Packages

The Packages group specifies where downloaded packages are installed to:

Example: Packages installed to the Packages sub-directory of the HOME mount.

    [Packages]
    MountPoint=HOME
    Path=Packages

SxeDatabase

The SxeDatabase group specifies the directory in which the SXE database is located.

Example: SXE database located in /home/Updates/etc/sxe

    [SxeDatabase]
    Path = /home/Updates/etc/sxe

Non-removable vs Removable Storage

Application data is stored only in non-removable locations, however documents can be stored in any location. Removable locations are scanned on insertion and removal.

The scanning is triggered when the Qt Extended library receives one of the following messages via the QPE/Card QCop channel:

• mtabChanged() - sent when /etc/mtab has changed
• stabChanged() - sent when /var/run/stab, /var/state/pcmcia/stab, or /var/lib/pcmcia/stab have changed. The StabMonitor server task provides a default implementation.

Note: Removable media with a content database must be Lazy unmounted to allow time for Qt Extended to release file resources; see also the umount man page.

Explicit Mount/Unmount Notifications

If monitoring mtab/stab or lazy unmounting in unsuitable, Qt Extended can also be explicitly informed of a mount or pending unmount. This is done by sending messages to the QPE/QStorage QCop channel.

The mounting(QString) message notifies Qt Extended that a storage device has been mounted, the QString argument is the device path of the storage device mounted. In response to this Qt Extended will add the storage device to the list of connected devices, load it's content database if it has one, and start a document scan.

Example: Sending a notification that the storage device with the device path /dev/mmca has been mounted:

    QtopiaChannel::send( "QPE/QStorage", "mounting(QString)", "/dev/mmca" );

The unmounting(QString) message notifies Qt Extended that a storage device is about to be unmounted, the QString argument is the device path of the storage device to be unmounted. In response to this Qt Extended will remove the storage device from the list of connected devices, and close the content database if it has one.

Example: Sending a notification that the storage device with the device path /dev/mmca is about to be unmounted:

    QtopiaChannel::send( "QPE/QStorage", "unmounting(QString)", "/dev/mmca" );

Using read-only File Systems

Using read-only file systems have a number of benefits:

• compressed read-only file systems such as cramfs and squashfs have better compression than read-write file systems such as jffs2
• read-only file systems provide a measure of protection for system files.