The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘Software Development’ Category

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Ancient Unix based keyboard shortcuts

Posted by jpluimers on 2019/02/14

Somehow I’ve been doing Unix like work off and on for most of my life. So I know many ancient shell shortcuts (like Ctrl-E for end-of-line and Ctrl-A for start-of-line) by heart.

Many don’t, or even list shortcuts as if they are for the shell, but in fact aren’t.

So here are some links that distinguish between various kinds of keyboard shortcuts and give some insight in the history of these shortcuts (that go back into the 1970s, yes I’m that old).

–jeroen

via:

Posted in *nix, *nix-tools, Development, Power User, Software Development | Leave a Comment »

VCL Root units

Posted by jpluimers on 2019/02/13

Delphi VCL units that are not using any other VCL units:

  • Vcl.Bind.Consts
  • Vcl.Consts
  • Vcl.ComStrs
  • Vcl.HtmlHelpViewer
  • Vcl.IdAntiFreeze
  • Vcl.Imaging.GIFConsts
  • Vcl.Imaging.JConsts
  • Vcl.Imaging.pnglang
  • Vcl.OleConst
  • Vcl.ShellAnimations
  • Vcl.Shell.ShellConsts
  • Vcl.Touch.GestureConsts
  • Vcl.Touch.KeyboardTypes
  • Vcl.VDBConsts
  • Vcl.XPMan

–jeroen

Posted in Delphi, Development, Software Development | Leave a Comment »

Accessing storage (NAS) over the Internet via FTP | FRITZ!Box 7490 | AVM International

Posted by jpluimers on 2019/02/13

Of course you don’t want this. So by the time you read this, the connection has been closed.

For testing some Internet of Shit stuff from a client that cannot do SFTP, I needed a temporary FTP accessible connection.

These links helped:

TL;DR:

  1. Preparing the USB stick:
    1. Ensure the USB disk is FAT/FAT32/NTFS
    2. Create a directory in the root of the USB disk for the FTP user (for now: FtpDirectory)
    3. Insert the USB disk in the Fritz!Box
  2. Logon to the Fritz!Box web UI
    1. Configure a user for FTP:
      1. In the menu, go to System, then FRITZ!Box Users
      2. Click Add user
      3. Name the user (for now: MyFtpUser)
      4. Ensure that user *only* has a checkmark for `Access to NAS contents`
      5. Click the button Add directory
      6. In the popup click Select folder
      7. Choose the FtpDirectory you just made
      8. Click OK
      9. Ensure the read and write checkboxes are enabled
      10. Click OK
    2. Configure the USB stick for FPT access
      1. In the menu, go to Home Network, then USB Devices
      2. Observe if the device is visible and has the correct file system (if not: ask AVM)
      3. In the menu, go to Internet, then Permit Access
      4. Click on the FRITZ!Box Services
      5. Ensure there is a checkmark at Internet access to your storage media via FTP/FTPS enabled
      6. At TCP Port for FTP/FTPS, fill in 21 (many IoT devices cannot use a different port)
      7. Ensure there is *no* checkmark at Allow only secure FTP connections (FTPS)
      8. Make a note of the value after FTP address (something like ftp://example.org:21`)
      9. Click Apply
  3. Test

–jeroen

Posted in Communications Development, Development, Fritz!, Fritz!Box, FTP, Internet protocol suite, IoT Internet of Things, Network-and-equipment, Power User, Software Development, TCP | Leave a Comment »

Berlin 10.1.2 Vcl.RibbonConsts removed, so now Vcl.ScreenTips compilation fails – Pascal Today

Posted by jpluimers on 2019/02/12

The Ribbon controls got removed since Delphi 10.1 Berlin, but the dependency in Vcl.ScreenTips remained, so:

After installing the official Delphi Berlin Update 2 I have faced nasty problem. One of my unit was using the Vcl.ScreenTips unit (for TScreenTipsWindow). And when you compile such a project you ge…

Source: Berlin 10.1.2 Vcl.ScreenTips compilation fail – Pascal Today

In the mean time however, it has been moved to GetIt: [WayBack] Ribbon Controls in RAD Studio 10.1 Berlin.

Note that the XE8 introduced [Archive.is] GetIt package manager is under the Tools menu, which is not covered by [Archive.is] IDE Insight – RAD Studio.

Anyway: here you can get it in Delphi 10.1 Berlin (now also in 10.2 Tokyo, where at first it was not available through GetIt):

—jeroen

Posted in Delphi, Delphi 10.1 Berlin (BigBen), Delphi 10.2 Tokyo (Godzilla), Development, Software Development | Leave a Comment »

Quantum Computing for Computer Scientists – YouTube

Posted by jpluimers on 2019/02/08

On my list of videos to watch:

Via: [WayBack] Quantum computing for computer scientists, explained by Microsoft. Despite the pop lecturing style the explanation is deep enough. I’ve wondered before… – Sergey Kasandrov – Google+

–jeroen

Posted in Development, Software Development | Leave a Comment »

Why the New V8 is so Damn Fast – NodeSource

Posted by jpluimers on 2019/02/07

Wow, impressive work, and a very good explanation of some of the optimizations that take place and how you can check which ones work on your code: [WayBack] Why the New V8 is so Damn Fast – NodeSource:

The entire V8 compiler pipeline was overhauled and shipped with Node.js version 8. This post investigates what speed improvements we can expect as a result.

Via: [WayBack] Adrian Marius Popa – Google+

–jeroen

 

Posted in Development, JavaScript/ECMAScript, Node.js, Scripting, Software Development | Leave a Comment »

Why you should always do documentation before development | Opensource.com

Posted by jpluimers on 2019/02/07

Food for thought, especially on the UX side of software: [WayBack] Why you should always do documentation before development | Opensource.com.

Via:

–jeroen

Read the rest of this entry »

Posted in Development, Software Development, User Experience (ux) | Leave a Comment »

Delphi threadvar: TLS thread local storage

Posted by jpluimers on 2019/02/07

Managing TLS correctly with all kinds of dynamic storage seems to be a nightmare.

From what I think it’s safe to use a TStopWatch [WayBack] System.Diagnostics.TStopwatch (introduced in Delphi XE2) as threadvar (which gets into TLS: Thread-local storage) because it’s a record type and as a bonus will be zero-initialised in something like this:

threadvar
 ThreadStopwatch: TStopwatch; // threadvars are zero-initialised, like TStopwatch.Reset was called. Ensure TStopwatch.InitStopwatchType called before using this.

... thread code:
var
  lThreadElapsedMilliseconds: string;
begin
...
  if not ThreadStopwatch.IsRunning then
    ThreadStopwatch.Start;
  try
    lThreadElapsedMilliseconds := ThreadStopwatch.ElapsedMilliseconds.ToString();
    // log duration of call-to-call somewhere
... logic
    lThreadElapsedMilliseconds := ThreadStopwatch.ElapsedMilliseconds.ToString();
    // log duration of logic somewhere
  finally
    ThreadStopwatch := TStopwatch.StartNew; // resets new count
  end;

As long as I perform this in the main thread somwehere to pre-initialise the class variable, then no thread should have the penalty for that:

TStopwatch.Create(); // ensures non-public TStopwatch.InitStopwatchType is called, enabling the threadvar ThreadStopwatch get the penalty for that

If I ever need to dig deeper into TLS with Delphi, then these are starters:

–jeroen

Posted in Delphi, Development, Software Development | Leave a Comment »

Some links on keystore, encryption and decryption on Android

Posted by jpluimers on 2019/02/06

For my link archive:

 

Basically:

  • storing encrypted data plus IV in preferences is OK
  • store the symmetric encryption key (for instance an AES one) in the keystore for the application
  • likely a salt is also needed, then store the salt with the IV and encrypted data

–jeroen

Presumptions:

  • The keystore of a specific application UUID is only accessible by only that application UUID when the device has been unlocked by the user
  • The keystore saves credentials in a secure way
  • It is OK to save both the encrypted data and associated IV

Approach (plain data is “hashed application PIN”, encrypted data is “encrypted hashed application PIN”:

  1. store a symmetric AES key in the application key store
  2. after entering application PIN:
    1. hash the application PIN
    2. use the hashed application PIN to to enter the application
    3. from the keystore, obtain the symmetric AES key
    4. create a cipher based on the AES key
    5. use the cipher to obtain an IV, and to encrypt the hashed application PIN
    6. store the encrypted hashed application PIN and IV both in the application preferences
  3. when needing to enter the application, present the user to either enter the application PIN again or proof that they can pass the device unlock sequence (using an unlock activity)
    1. if the user provided the application PIN, then:
      1. hash the application PIN
      2. try to enter the application with the hashed application PIN
    2. proved the device unlock, then:
      1. from the preferences, obtain the IV and encrypted hashed application PIN
      2. from the keystore, obtain the symmetric AES key
      3. create a cipher based on the AES key
      4. decrypt the encrypted hashed application PIN using the cipher and the IV into the hashed application PIN
      5. try to enter the application with the hashed application PIN

Posted in Android, Development, Mobile Development, Software Development | Leave a Comment »

Delphi Declarations and Statements: Hinting Directives

Posted by jpluimers on 2019/02/06

From [WayBack] Declarations and Statements: Hinting Directives you might remember this:

The ‘hint’ directives platform, deprecated, and library may be appended to any declaration. These directives will produce warnings at compile time. Hint directives can be applied to type declarations, variable declarations, class, interface and structure declarations, field declarations within classes or records, procedure, function and method declarations, and unit declarations.

However, it doesn’t as at least these fail:

type
{ [dcc32 Error] ClassConstUsageConsoleProject.dpr(14): E1030 Invalid compiler directive: 'DEPRECATED' }
  TMyProcedure = procedure() of object deprecated 'do not use TMyProcedure';
{ [dcc32 Error] E1030 Invalid compiler directive: 'DEPRECATED' }
  TMyReference = reference to procedure() deprecated 'do not use TMyReference';

These two helped me though:

This fails too:

type
{ [dcc32 Error] E2029 '=' expected but ';' found }
  TArrayChars = array of Char; deprecated;
{ [dcc32 Error] E2029 ';' expected but identifier 'deprecated' found }
  TArrayChars = array of Char deprecated;

But this is a workaround:

type
  TArrayCharsOld = array of Char;
  TArrayChars = TArrayCharsOld deprecated;

Which works for the procedure types as well:

type
  TMyProcedureOld = procedure() of object;
  TMyProcedure = TMyProcedureOld deprecated 'do not use TMyProcedure';
  TMyReferenceOld = reference to procedure();
  TMyReference = TMyReferenceOld deprecated 'do not use TMyReference';

Bug https://quality.embarcadero.com/browse/RSP-18316

–jeroen

Posted in Delphi, Development, Software Development | 1 Comment »

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