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WiX Tips

Some tips on using WiX to generate MSI installers:


The GUID used as Product Id has to be unique for each release of the package. That is version 1.0 & 1.1 should have different product ids. So it's best to use auto-generated GUIDs for this like this:
<product Id="*"... />In other words do not hard code the product id.
MSI only recognizes three quadrant product version numbers.Product upgrades essentially work by uninstalling the current version and then installing the new version.From MSI v3.5 onward upgrades are supported through the <MajorUpgrade.. />tag.MSI does not define special actions for uninstallation. In fact, uninstallation is also treated as a type of installation. So if you want to run a custom action during uninstall, you have to use Condition predicates that cause them to run only during uninstallation. For example the following custom action is only run during uninstall as REMOVE="ALL" evaluates to TRUE only when all components are…

Setting up a Windows VM for Kernel Debugging

If you search the web using the title of this post, you'll get many links to articles most of which explain how to set this up using a virtual COM port on the VM. Coming from driver background that goes back over 20 years, at first this seemed quite natural. But then I remembered that using WinDBG over COM port to be painfully slow. And recent adventures in OSX land using LLDB led me to wonder if WinDBG over network would to be possible?

Well it turns out that WinDBG over Ethernet is indeed possible and is documented by Microsoft here. However, they miss out on certain key steps, which won't be obvious for the casual reader unless one reads the entire driver debugging documentation from the beginning.

This post captures all the requisite steps as a quick reference guide. I used one of the freely available MSEdge on Windows 10 VM for  VirtualBox. It's only valid for 90 days, but 90 days was more than enough for my little excursion into the driver land. If you want a more p…

Javascript Promises

While explaining Promises to a friend I remembered reading a blog post couple of years back that explained the concept very well and made it all clear to me. However, I never bookmarked and searching for it, I can't find the specific post. Then I thought why not recreate some of the samples that the blog author had used to explain the concepts.

Here's what I came up with:

// Function to convert setTimeout into a Promise based // abstraction function delaySeconds(seconds) { return new Promise((resolve, reject) => { setTimeout(resolve, seconds*1000); }); } /* * A simple function that converts clunky setTimeout * callback based interface to a promise based * abstraction. */ function delayAndReturn(seconds, retval) { return new Promise((resolve, reject) => { setTimeout(() => { resolve(retval); }, seconds*1000); }); } // example of how to use the above abstraction console.log("Calling delaySeconds with 10 seconds delay"…

Setting up OS X for kernel debugging

Here are the steps to prepare an OS X system for debugging kernel modules such as drivers. The instructions are deliberately brief to save the reader from tons of text.
If you search the web, you will come across may resources that point to using GDB to debug the kernel. These resources were written in the early days of OS X when versions 10.4 or 10.5 were prevalent. Since around v10.9 (or thereabouts), Mac moved to lldb as their debugger of choice and have continually improved it to enable easier setup & more efficient workflow.

This short post has the instructions to setting up lldb for debugging OS X kernel versions 10.11 and above.

My setup is using a Parallels VM as the target on the development system. But it should work on a separate hardware that is connected via network to the host.

Debuggee is the target system where drivers are deployed and tested. This also referred to as the target system. Debugger is the host system, typically running your development tools with the …

How to view kernel logs in OS X

How to view kernel logs is OS X You can use the command line tool log for this.

This command accepts a predicate argument that can be used to , well build predicates, that when evaluates to true, the log message will be printed. It takes a command argument that decides how the logs are to be displayed. For instance

log stream

produces a streaming output of the log. That is new log messages are displayed as they come (asynchronously).

log show

displays messages from the log history.

log --process 0

displays messages from process with ID 0, which is kernel. This can be used to display all kext log messages.

log show --predicate 'processID == 0'

displays messages printed by processID 0, which is the kernel process. This is the same as the previous command.

To display messages from a driver, you may use the sender predicate filter argument. So if your driver is named mytestdriver, you may display messages from it using the command:

log stream --predicate 'sender == "mytestdri…

Ionic 4 HTTP CORS Issue

Ionic 4 is a major upgrade to previous version of Ionic. One of the primary differences between Ionic 4 and its previous incarnations is that Ionic 4 uses web components, which are custom HTML elements written using web standards (as opposed to using a slap-on framework such as Angular).
Ionic 4 also makes a fundamental change in how the created app is rendered (I use rendered as apps are essentially HTML which is rendered using the native WebView control of the device's UI framework) in a device. While earlier versions used to refer to the top level index.html using file:// URI scheme, Ionic 4 internally spins up an HTTP server on localhost (yes for each app) and then loads the index.html through a standard HTTP request such as http://localhost:port/index.html.
Problem I'm not sure what necessitated this change, but I reckon it probably had something to do with native API restrictions, which in turn was prompted by need for improved security. This, however, introduces a new (…

Notes of the day

A recent project requirement from a customer for a cross-platform solution prompted me to look into viable frameworks for this. Based on my knowledge of languages (C++, Python & Javascript), I narrowed the potential solutions to wxWidgets & Git Electron. Since I have been spending some time with Python over the last two years and given its ease of use, I through I'll look into wxPython, the Python projection of wxWidgets framework.

Here are my notes from this research today morning:
wxPython provides a genuine means to build cross platform GUI apps (installed through PyPi pip install wxpython).Python code can be compiled into distributable binaries using cx_Freeze, another cross-platform tool that can generate binaries for Windows, Mac & Linux. cx_Freeze can provide executable files as well as installable binaries such as MSI or DMG files.cx_Freeze source repo has sample code for various deployment scenarios. One of them is wxPython based application.Py2Exe is a popula…

Downloading & opening a file in an Ionic app

If you search the Internet for examples to achieve the above, you'll get a number of resources that suggest using the cordova-file-transfer plugin. However, with Ionic 3+ and its native API, you can do this directly using a mix of Angular and Ionic File API.

Essentially, you need to use Angular HttpClient to download a URL as a Blob using the responseType option and then save the resultant Blob to a file on the device using the File API. Finally, open the saved file using the Ionic native FileOpener API.

Here's the method in a provider that is used to download files from a website. Note that this.http is an instance of HttpClient.

/** * Download a file from the given url. * * Params: * url - the URL to download the file from * Returns: * A promise which upon resolution returns a dictionary * { * fileEntry: FileEntry, * type: The content-type string for the file * } */ download(url): Promise<{ fileEntry: FileEntry, type: s…

Cordova build errors

Had this unusual errors crop up when building a cordova app for android. This started appearing after I installed cordova-plugin-file-opener2.

ERROR: In <declare-styleable> FontFamilyFont, unable to find attribute android:fontVariationSettings ERROR: In <declare-styleable> FontFamilyFont, unable to find attribute android:ttcIndex
Going through platforms/android/project.properties file, I realized that there was something quite odd about it.

cordova.system.library.1=com.android.support:support-v13:26.+ cordova.system.library.2=me.leolin:ShortcutBadger:1.1.17@aar cordova.system.library.3=com.google.firebase:firebase-messaging:11.0.1 cordova.system.library.4=com.android.support:support-v4:27.1.0 cordova.system.library.5=com.android.support:support-v4:24.1.1+ cordova.system.library.6=com.android.support:support-v4:+
There were multiple versions of the same library being defined.

I removed the last three lines -- library.4, library.5 & library.6, ensuring that the the high…

Celery on Windows

Running celery on Windows, shows the following error when tasks are queued to be executed:
ValueError: not enough values to unpack (expected 3, got 0)
The way to fix this is to add --pool=solo to the celery daemon command line. This makes celery run as a solo process and without concurrency, which for development purposes shouldn't be a big deal.

So the entire daemon command would look something like this:
python -m celery -A config worker --pool=solo -l info
Taken from this Github thread.