Hacking / Customizing a Kobo Touch ebook reader: Part I, sqlite (Shallow Thoughts)

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Thu, 03 Sep 2015

Hacking / Customizing a Kobo Touch ebook reader: Part I, sqlite

I've been enjoying reading my new Kobo Touch quite a lot. The screen is crisp, clear and quite a bit whiter than my old Nook; the form factor is great, it's reasonably responsive (though there are a few places on the screen where I have to tap harder than other places to get it to turn the page), and I'm happy with the choice of fonts.

But as I mentioned in my previous Kobo article, there were a few tweaks I wanted to make; and I was very happy with how easy it was to tweak, compared to the Nook. Here's how.

Mount the Kobo

When you plug the Kobo in to USB, it automatically shows up as a USB-Storage device once you tap "Connect" on the Kobo -- or as two storage devices, if you have an SD card inserted.

Like the Nook, the Kobo's storage devices show up without partitions. For instance, on Linux, they might be /dev/sdb and /dev/sdc, rather than /dev/sdb1 and /dev/sdc1. That means they also don't present UUIDs until after they're already mounted, so it's hard to make an entry for them in /etc/fstab if you're the sort of dinosaur (like I am) who prefers that to automounters.

Instead, you can use the entry in /dev/disk/by-id. So fstab entries, if you're inclined to make them, might look like:

/dev/disk/by-id/usb-Kobo_eReader-3.16.0_N905K138254971:0 /kobo   vfat user,noauto,exec,fmask=133,shortname=lower 0 0
/dev/disk/by-id/usb-Kobo_eReader-3.16.0_N905K138254971:1 /kobosd vfat user,noauto,exec,fmask=133,shortname=lower 0 0

One other complication, for me, was that the Kobo is one of a few devices that don't work through my USB2 powered hub. Initially I thought the Kobo wasn't working, until I tried a cable plugged directly into my computer. I have no idea what controls which devices work through the hub and which ones don't. (The Kobo also doesn't give any indication when it's plugged in to a wall charger, nor does

The sqlite database

Once the Kobo is mouted, ls -a will show a directory named .kobo. That's where all the good stuff is: in particular, KoboReader.sqlite, the device's database, and Kobo/Kobo eReader.conf, a human-readable configuration file.

Browse through Kobo/Kobo eReader.conf for your own amusement, but the remainder of this article will be about KoboReader.sqlite.

I hadn't used sqlite before, and I'm certainly no SQL expert. But a little web searching and experimentation taught me what I needed to know.

First, make a local copy of KoboReader.sqlite, so you don't risk overwriting something important during your experimentation. The Kobo is apparently good at regenerating data it needs, but you might lose information on books you're reading.

To explore the database manually, run: sqlite3 KoboReader.sqlite

Some useful queries

Here are some useful sqlite commands, which you can generalize to whatever you want to search for on your own Kobo. Every query (not .tables) must end with a semicolon.

Show all tables in the database:

.tables
The most important ones, at least to me, are content (all your books), Shelf (a list of your shelves/collections), and ShelfContent (the table that assigns books to shelves).

Show all column names in a table:

PRAGMA table_info(content);
There are a lot of columns in content, so try PRAGMA table_info(content); to see a much simpler table.

Show the names of all your shelves/collections:

SELECT Name FROM Shelf;

Show everything in a table:

SELECT * FROM Shelf;

Show all books assigned to shelves, and which shelves they're on:

SELECT ShelfName,ContentId FROM ShelfContent;
ContentId can be a URL to a sideloaded book, like file:///mnt/sd/TheWitchesOfKarres.epub, or a UUID like de98dbf6-e798-4de2-91fc-4be2723d952f for books from the Kobo store.

Show all books you have installed:

SELECT Title,Attribution,ContentID FROM content WHERE BookTitle is null ORDER BY Title;
One peculiarity of Kobo's database: each book has lots of entries, apparently one for each chapter. The entries for chapters have the chapter name as Title, and the book title as BookTitle. The entry for the book as a whole has BookTitle empty, and the book title as Title. For example, I have file:///mnt/sd/earnest.epub sideloaded:
sqlite> SELECT Title,BookTitle from content WHERE ContentID LIKE "%hamlet%";
HAMLET, PRINCE OF DENMARK|Hamlet
PERSONS REPRESENTED.|Hamlet
ACT I.|Hamlet
Scene II. Elsinore. A room of state in the Castle.|Hamlet
Scene III. A room in Polonius's house.|Hamlet
Scene IV. The platform.|Hamlet
Scene V. A more remote part of the Castle.|Hamlet
Act II.|Hamlet
  [ ... and so on ... ]
ACT V.|Hamlet
Scene II. A hall in the Castle.|Hamlet
Hamlet|
Each of these entries has Title set to the name of the chapter (an act in the play) and BookTitle set to Hamlet, except for the final entry, which has Title set to Hamlet and BookTitle set to nothing. That's why you need that query WHERE BookTitle is null if you just want a list of your books.

Show all books by an author:

SELECT Title,Attribution,ContentID FROM content WHERE BookTitle is null
AND Attribution LIKE "%twain%" ORDER BY Title;
Attribution is where the author's name goes. LIKE %% searches are case insensitive.

Update: how to change a field

I realized I didn't include how to change a field, and that seems to fit better with this article rather than writing a whole new blog post just for that.

The Kobo doesn't show series order. So to find a specific book, and then update its title to include the series and series number, do something like this:

SELECT Title,Attribution,ContentID,BookTitle FROM content WHERE Attribution LIKE "%Doyle%" AND Title LIKE "%Adventures%";
UPDATE content SET Title="Sherlock Stories 1: The Adventures of Sherlock Holmes" WHERE Attribution LIKE "%Doyle%" AND Title LIKE "%Adventures%";
    

To delete an entry -- in this case I had two copies of the same book and needed to specify the ContentID of the older one:

DELETE from content WHERE Attribution LIKE "%Doyle%" AND ContentID="file:///mnt/sd/memoirs-holmes.epub";
    

Of course, it's a lot handier to have a program that knows these queries so you don't have to type them in every time (especially since the sqlite3 app has no history or proper command-line editing). But this has gotten long enough, so I'll write about that separately.

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[ 19:11 Sep 03, 2015    More tech | permalink to this entry | ]

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