`get_installed_apps` messes up string offsets

[phistep]

Running following code should show me my installed apps:

require "pebblewatch"
require 'pp'

watch = Pebble::Watch.new("4F92", "/dev/rfcomm0")

watch.connect
pp watch.get_installed_apps
watch.disconnect

prints:

{:banks_count=>8,
 :apps=>
  [{:id=>12,
    :index=>0,
    :name=>"Counter",
    :author=>"Ps0ke",
    :flags=>0,
    :version=>3956},
   {:id=>13,
    :index=>1,
    :name=>"MtG Life Points",
    :author=>"Ps0ke",
    :flags=>0,
    :version=>8392},
   {:id=>14,
    :index=>2,
    :name=>"Dotz",
    :author=>"Zalew",
    :flags=>1,
    :version=>42359},
   {:id=>15,
    :index=>3,
    :name=>"Noms",
    :author=>"Fuzzie",
    :flags=>1,
    :version=>3224},
   {:id=>16,
    :index=>4,
    :name=>"Nyan Watch",
    :author=>"Jeff Pitchell",
    :flags=>1,
    :version=>41153},
   {:id=>0,
    :index=>1347,
    :name=>
     "alendar\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00W",
    :author=>"illiam Heaton",
    :flags=>162,
    :version=>11776},
   {:id=>4608,
    :index=>1607,
    :name=>
     "low\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00d",
    :author=>"otar",
    :flags=>258,
    :version=>21504},
   {:id=>0,
    :index=>478821,
    :name=>
     "olog\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00Ps",
    :author=>"0ke",
    :flags=>nil,
    :version=>1}]}

The first ones work well, but starting at ID 0 The Strings get all messed up. The app with ID 0 has the name Calendar, but the first char got lost somewhere. Instead the first char of the author field got at the end of the name field (William). As a result, the nullbytes did not get stripped. My guess is, that the offsets got wrong as you still read 32 byte.

Just for the record: ID 4608's name should be "Glow", the author "dotar" I guess. ID 0 (two identical IDs? Maybe something went wrong here, too?) should have the name "Neolog", and the author is me, "Ps0ke". We're two bytes off by now.

[DouweM]

So evidently the way we're unpacking the installed apps message isn't correct anymore, see lib/pebble/watch.rb#L150.

My Pebble charging cable actually broke a little while ago, so I can't fix and test it myself. I would be very happy to accept a pull request addressing this, though.

[phistep]

The unpack syntax is quite unreadable. I haven't really looked into it, but do you think moving to bindata (now that I pulled it in anyway) makes sense?

Where can I find documentation to the messaging/protocol syntax? Did you just extract it from the Python code?

[DouweM]

The #unpack syntax is just as unreadable as anything you don't know yet ;-) I can see how bindata is useful for larger structures like bundles (which I why I let you pull it in), but for smaller blobs with just a small number of values, my vote goes to #unpack.