Tag: Source Code
Exciting Unlimited Register Machines
A brief and entertaining talk by an obviously excited presenter. 🙂 It goes into the same directions as Jim Weirich’s talk about the Y combinator.
Aktivieren Sie JavaScript um das Video zu sehen.
https://www.youtube.com/watch?v=7Q-UwjgZ0q4
https://www.youtube.com/watch?v=7Q-UwjgZ0q4
AR create_with
I knew there was AR’s find_or_create_by method but I didn’t know it had a very useful companion create_with .
1 | @something ||= SomeModel.create_with(some: "stuff").find_or_create_by(foo: "bar") |
This will either find a record SomeModel.where(foo: "bar") or create it with SomeModel.create(foo: "bar", some: "stuff") . Very useful.
AR Find Trickery
1 | found = ModelA.find_by(id: id) || ModelB.find(id) |
I stumbled over this during a code review. It was supposed to look for a record in two distinct tables. find_by will return nil if nothing was found while find will raise . Hence either you get something (from any model) or you raise.
Backup And Restore Your Android Phone With ADB (And rsync)
Based on my previous scripts and inspired by two blog posts that I stumbled upon I tackled the “backup all my apps, settings and data” problem for my Android devices again. The “new” solutions both use rsync instead of adb pull for file transfers. They both use ADB to start a rsync daemon on the device, forward its ports to localhost and run rsync against it from your host.
Simon’s solution assumes your phone has rsync already (e.g. because you run CyanogenMod) and can become root via adb root . It clones all files from the phone (minus /dev , /sys , /proc etc.). He also configures udev to start the backup automatically when the phone is plugged in.
pts solves the setup without necessarily becoming root. He also has a way of providing a rsync binary to phones that don’t have any (e.g. when running OxygenOS). He also has a few tricks on how to debug the rsync daemon setup on the phone.
I’ve tried to combine both methods. My approach doesn’t require adb or rsync to be run as root. It’ll use the the system’s rsync when available or temporarily upload and use a backup one extracted from Cyanogen OS (for my OnePlus One). Android won’t allow you to chmod +x a file uploaded to /sdcard , but in /data/local/tmp it works. 😀
The scripts will currently only backup and restore all of your /sdcard directory. Assuming you’re also using something like Titanium Backup you’ll be able to backup and restore all your apps, settings and data. To reduce the amount of data to copy it uses rsync filters to exclude caches and other files that you definitely don’t want synced ( .DS_Store files anyone?).
At the moment there’s one caveat: I had to disable restoring modification times (i.e. use --no-times ) because of an obnoxious error (they will be backuped fine, only restoring is the problem): 😒
mkstemp “…” (in root) failed: Operation not permitted (1)
Additionally if you’re on the paranoid side you can also build your own rsync for Android to use as the backup binary.
The code and a ton of documentation can be found on GitHub. Comments and suggestions are welcome. 😀
Build Rsync for Android Yourself
To build rsync for Android you’ll need to have the Android NDK installed already.
Then clone the rsync for android source (e.g. from CyanogenMod LineageOS) …
1 2 3 4 | git clone https://github.com/LineageOS/android_external_rsync.git cd android_external_rsync # checkout the most recent branch git checkout cm-14.1 |
… create the missing jni/Application.mk build file (e.g. from this Gist) and adapt it to your case …
… and start the build with
1 2 | export NDK_PROJECT_PATH=<code>pwd ndk-build -d rsync |
You’ll find your self-build rsync in obj/local/*/rsync . 😀
Update 2017-10-06:
- Updated sources from CyanogenMod to LineageOS.
- Added links to Gist and Andoid NDK docs
- Updated steps to work with up-to-date setups
If you get something like the following warnings and errors …
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | [...] ./flist.c:454:16: warning: implicit declaration of function 'major' is invalid in C99 [-Wimplicit-function-declaration] if ((uint32)major(rdev) == rdev_major) ^ ./flist.c:458:41: warning: implicit declaration of function 'minor' is invalid in C99 [-Wimplicit-function-declaration] if (protocol_version < 30 && (uint32)minor(rdev) <= 0xFFu) ^ ./flist.c:467:11: warning: implicit declaration of function 'makedev' is invalid in C99 [-Wimplicit-function-declaration] rdev = MAKEDEV(major(rdev), 0); ^ ./rsync.h:446:36: note: expanded from macro 'MAKEDEV' #define MAKEDEV(devmajor,devminor) makedev(devmajor,devminor) ^ 3 warnings generated. [...] ./flist.c:473: error: undefined reference to 'makedev' ./flist.c:454: error: undefined reference to 'major' ./flist.c:457: error: undefined reference to 'major' ./flist.c:458: error: undefined reference to 'minor' ./flist.c:467: error: undefined reference to 'major' ./flist.c:467: error: undefined reference to 'makedev' ./flist.c:617: error: undefined reference to 'major' ./flist.c:619: error: undefined reference to 'minor' ./flist.c:621: error: undefined reference to 'minor' ./flist.c:788: error: undefined reference to 'makedev' ./flist.c:869: error: undefined reference to 'makedev' ./flist.c:1027: error: undefined reference to 'minor' clang++: error: linker command failed with exit code 1 (use -v to see invocation) make: *** [obj/local/armeabi-v7a/rsync] Error 1 |
… you probably need to update config.h and change /* #undef MAJOR_IN_SYSMACROS */ to #define MAJOR_IN_SYSMACROS 1 .
CFSSL FTW
After reading how CloudFlare handles their PKI and that LetsEncrypt will use it I wanted to give CFSSL a shot.
Reading the project’s documentation doesn’t really help in building your own CA, but searching the Internet I found Fernando Barillas’ blog explaining how to create your own root certificate and how to create intermediate certificates from this.
I took it a step further I wrote a script generating new certificates for several services with different intermediates and possibly different configurations (e.g. depending on your distro and services certain cyphers (e.g. using ECC) may not be supported).
I also streamlined generating service specific key, cert and chain files. 😀
Have a look at the full Gist or just the most interesting part:
You’ll still have to deploy them yourself.
Update 2016-10-04:
Fixed some issues with this Gist.
- Fixed a bug where intermediate CA certificates weren’t marked as CAs any more
- Updated the example CSRs and the script so it can now be run without errors
Update 2017-10-08:
- Cleaned up
renew-certs.shby extracting functions for generating root CA, intermediate CA and service keys.
A Service Monitor built with Polymer
I tried to build a service monitor having the following features:
- showing the reachability of HTTP servers
- plotting the amount of messages in a specific RabbitMQ queue
- plotting the amount of queues with specific prefixes
- showing the status of RabbitMQ queues i.e. how many messages are in there? are there any consumers? are they hung?
- showing the availability of certain Redis clients
Well, you can find the result on GitHub.
It uses two things I published before: polymer-flot and flot-sparklines. 😀
An example dashboard:
Flot Sparklines with Polymer
After wrapping Flot for Polymer I needed an element that would present a sparklines style graph.
I made one and put it into a Gist along with a demo on how to use it.
Flot in Polymer
I was playing with Polymer at work, building a service monitor with it. At some point I needed charts and Flot seemed to be the simplest solution.
So after a little work I managed to wrap Flot for Polymer (on GitHub). 😀