Elektra: Plugin: dump

Elektra 0.8.24

Plugin: dump

- infos = Information about the dump plugin is in keys below
- infos/author = Markus Raab elekt.nosp@m.ra@l.nosp@m.ibele.nosp@m.ktra.nosp@m..org
- infos/licence = BSD
- infos/needs =
- infos/provides = storage/dump
- infos/recommends =
- infos/placements = getstorage setstorage
- infos/status = productive maintained conformant unittest tested nodep -1000
- infos/metadata =
- infos/description = Dumps into a format tailored for complete KeySet semantics

This plugin is a storage plugin that supports full Elektra semantics. Combined with a resolver plugin it already assembles a fully featured backend. No other plugins are needed.

## Format

The file format edf (Elektra dump format) consists of a simple command language with arguments. When an argument is binary or string data the length needs to be passed first. Because the size is known in advance, any binary dump is accepted. Terminating characters present no problem. The commands are assembled similar to the ones present in Elektra’s API.

The file starts with the magic word `kdbOpen` followed by a version number. Processing can be stopped immediately when it is not in Elektra’s dump format at all. A wrong version number most likely indicates that the version of the plugin is too old to recognize all commands in the file. The basic idea of the dump plugin is to write out the way that the KeySet needs to be constructed. The dump plugin interprets such a file. The file also looks similar to C code that would create the KeySet. Keys can contain any binary values and arbitrary metadata and are still stored and parsed correctly. The dump plugin can even reconstruct pointers to metadata to save memory. When a pointer to the same region of memory is found, a special command `keyCopyMeta` is written out that is able to reconstruct the data structure the way it was before. The commands were designed to make parsing of the file an easy task.

### Format Examples

The serialized configuration can look like (0 bytes at end of strings are omitted):

    kdbOpen 1
    ksNew 207
    keyNew 27 1
    system/elektra/mountpoints
    keyMeta 8 27
    commentBelow are the mountpoints.
    keyEnd
    keyNew 32 19
    system/elektra/mountpoints/dbusserialized Backend
    keyEnd keyNew 39 1
    system/elektra/mountpoints/dbus/config
    keyMeta 8 72
    commentThis is a configuration for a backend, see subkeys for more information
    keyEnd
    keyNew 53 1
    system/elektra/mountpoints/fstab/config/struct/FStab
    keyCopyMeta 59 11
    system/elektra/mountpoints/file
    systems/config/struct/FStabcheck/type
    keyEnd
    ksEnd

## Limitations

(status -1000)

- It is quite slow
- Files cannot easily edited by hand

## Examples

Export a KeySet using `dump`:

    kdb export system/example dump > example.ecf

Import a KeySet using `dump`:

    cat example.ecf | kdb import system/example dump

Using grep/diff or other Unix tools on the dump file. Make sure that you treat it as text file, e.g.:

    grep --text mountpoints example.ecf