The Wiert Corner – irregular stream of stuff

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

  • My badges

  • Twitter Updates

  • My Flickr Stream

  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 2,977 other subscribers

Archive for the ‘Java’ Category

Google Cloud Shell: tools, languages and “safe mode”

Posted by jpluimers on 2023/01/19

After publishing Free Linux cloud shell for Gmail users – shell in the browser that works in all locations I’ve been so far, the Google Cloud Shell got extended quite a bit.

There is now [Wayback/Archive] Safe Mode (which skips initialisation scripts):

If there’s a problem in your .bashrc or .tmux.conf files, Cloud Shell immediately close after connection. To resolve this, open Cloud Shell in safe mode by appending cloudshellsafemode=true to the URL. This restarts your Cloud Shell instance and logs you in as root, allowing you to fix any issues in the files.

To permanently delete all files in your home directory and restore your Cloud Shell home directory to a clean state, you can reset your Cloud Shell VM.

And there is support for way more [Wayback/Archive] tools and languages:

Read the rest of this entry »

Posted in .NET, C#, Cloud, Development, Go (golang), Google, GoogleCloudShell, Infrastructure, Java, Java Platform, JavaScript/ECMAScript, Node.js, Perl, PHP, Power User, Python, Ruby, Scripting, Software Development | Leave a Comment »

Type safe versus interpreted languages: which ones are safer?

Posted by jpluimers on 2022/10/06

An interesting thread by Kristian Köhntopp last year:

[Archive.is] Kristian Köhntopp on Twitter: “Python: >>> print(1+2+” = “+2+1) Traceback (most recent call last): File “”, line 1, in TypeError: unsupported operand type(s) for +: ‘int’ and ‘str’ Java: System.out.println(1+2+” = “+1+2); 3=12”

The examples from him and others in the thread:

Python:
>>> print(1+2+" = "+2+1)
Traceback (most recent call last):
  File "", line 1, in 
TypeError: unsupported operand type(s) for +: 'int' and 'str'

Java:
System.out.println(1+2+" = "+1+2);
3=12

php8.1  -r 'print 1+2+" = "+2+1;'
PHP Fatal error:  Uncaught TypeError: Unsupported operand types: int + string in Command line code:1
Stack trace:
#0 {main}
  thrown in Command line code on line 1

php7.3  -r 'print 1+2+" = "+2+1;'
PHP Warning:  A non-numeric value encountered in Command line code on line 1

Node?
Chrome & FF dev console:
window.alert(1+2+" = "+1+2)
3 = 12

Sind ja immerhin verschiedene Sprachen.

SELECT Wert1 
FROM table1
WHERE Wert1 < AVG(Wert1);

DB2 vs. Oracle vs. MSSQL vs. ....

The joke is that Python actually does better than Java.

But in practice, this is a problem on many platforms, so it deserves constant attention, that’s why Kristian pointed to [Archive] Anna “Legacy Archaeologist” Filina on Twitter: “My annotated slides “Fantastic Bugs and How to Avoid Them” from @LonghornPHP:  #LonghornPHP”

[Wayback/Archive] Fantastic Bugs and How to Avoid Them – Speaker Deck

I’ve expanded the examples from the thread below. The results are interesting and consistent over versions of the various languages.

–jeroen

Read the rest of this entry »

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

GitHub – metasfresh/metasfresh: We do Open Source ERP – Fast, Flexible & Free Software to scale your Business.

Posted by jpluimers on 2021/09/22

For my link archive: [WayBack] GitHub – metasfresh/metasfresh: We do Open Source ERP – Fast, Flexible & Free Software to scale your Business.

It’s mainly written in JavaScript and Java with a PostgreSQL database and elasticsearch search.

There is plenty of [WayBack] metasfresh documentation (for users, administrators and developers), all with markdown source.

The developer documentation starts with a nice diagram of the [WayBack] metasfresh Architecture:

Markdown source of the architecture page: [WayBack] metasfresh-documentation/metasfresh_architecture.md at gh-pages · metasfresh/metasfresh-documentation · GitHub: Docs and Manuals for Devs, Users, Admins.

Via:

–jeroen

Posted in Development, Java, Java Platform, JavaScript/ECMAScript, Scripting, Software Development | Leave a Comment »

Still unsolved since 2015 NetBeans: Bug 251538 – Your Installer is Creating Invalid Data for the NoModify DWORD Key which crashes enumeration of the Uninstall Key in at least PowerShell

Posted by jpluimers on 2021/03/23

Lovely. Having a bug reported to you in 2015, and acknowledged, that makes software crash and not fixing it.

 

For NetBeans (still one of the major IDEs) and related stuff like GlassFish, this is too true (a workaround is in the Solution steps) below: [WayBack] Bug 251538 – Your Installer is Creating Invalid Data for the NoModify DWORD Key which crashes enumeration of the Uninstall Key in at least PowerShell, and copied to [WayBack] [NETBEANS-2523] Netbeans 64-bit creates invalid nomodify value in windows registry for years – ASF JIRA.

This one appears for instance when running choco install --yes jre8 (but is certainly not limited to it) as it inspects uninstall registry values which have been corrupted and resulted into [WayBack] “Specified cast is not valid” on jre8 upgrade · Issue #18 · proudcanadianeh/ChocoPackages · GitHub.

Anyway: back to the NoModify issue:

phansson 2015-06-23 13:35:00 UTC
Yep, I can see this problem as well. I believe the problem (bug) has indeed always existed.

What happens is that someone (in this case NetBeans Installer) has put an 8-byte value into a Registry field that should only contain a 4-byte value. DWORDs are 4-byte.

If you use Registry Editor you can clearly see the problem if you look at something NBI has installed. You must look under either
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall (64-bit installers) or HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall (32-bit installers). For some reason I don't see the problem for those NBI applications installed with a 32-bit installer, meaning the stuff in HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall. This can probably be explained when you read the next bit.

NBI actually sets a number of Registry key values but all of them are strings, with the exception of NoModify value. As far as I know this value already defaults to true (=1) if not present so the fact that Windows cannot interpret what NBI has put into the Registry does not have much effect .... until all other kinds of tools will start to explain as you've encountered.

So, what's the problem?  As far as I can see this is really just a very simple bug. In the NBI project (NetBeans Platform source) you have a file called jni_WindowsRegistry.c which defines various JNI methods that can then be used from within Java. One of these is called 'set32BitValue0(....)'.

It looks like this:

JNIEXPORT void JNICALL Java_org_netbeans_installer_utils_system_windows_WindowsRegistry_set32BitValue0(JNIEnv *jEnv, jobject jObject, jint jMode, jint jSection, jstring jKey, jstring jName, jint jValue) {
    unsigned short*  key       = getWideChars(jEnv, jKey);
    unsigned short*  name      = getWideChars(jEnv, jName);
    DWORD  dword     = (DWORD) jValue;
    LPBYTE byteValue = (LPBYTE) &dword;
    
    if (!setValue(getMode(jMode),getHKEY(jSection), key, name, REG_DWORD, byteValue, sizeof(name), 0)) {
        throwException(jEnv, "Cannot set value");
    }
    
    FREE(key);
    FREE(name);
}

One of the parameters passed to the setValue() function is the size (bytes) of the value. Unfortunately whoever made this has made a blunder by using 'sizeof(name)' for that parameter. It should have been the size of the value, not the size of the name, meaning sizeof(dword) or just a hard-coded value of 4.  Just imagine what sizeof(name) will give you if name happens to be 'NoModify'. Yep, that's right: It will be 8.

As I said, I believe this blunder has been in the code from the very beginning. It just hasn't had much effect until now.
Comment 3phansson 2015-06-24 22:12:06 UTC
See https://bitbucket.org/phansson/nbi-native-jnilib-windows
for a fix to this problem. 

Honestly the sole reason why that project exists was that I had to have this problem fixed as our corporate customers were complaining about our software "messing up their Registry" and we could not wait for NetBeans team to fix the problem.
Comment 4oldium 2017-03-03 21:28:13 UTC
Any update on this? I lost 1 hour finding why the Get-ItemProperty of Chocolatey failed and found this. Then I remembered that I had the same issue one year ago...

This issue is now 2 years old, the fix is a one-liner. Is there any plan to fix this or (I am just curious) is Netbeans project dead?
Comment 5scott.fagg 2018-04-27 03:13:04 UTC
We encounter this too. Machines with Netbeans installed on our network often encounter issues when IT roll out software installs. Fix has been to remove and recreate the offending key.

If this has been known since 2015, is there any intention of fixing it ?

I encountered it in 2019, when switching my JRE installations to become chocolatey based.

Solution steps

  1. Run the script mentioned in [WayBack] powershell – How to resolve “ERROR: Specified cast is not valid.” error during installation? – Super User:

    Run the below:

    Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | % { write-host "Key Name:" $_.PSChildName }
    

    This should return some results, then, will return the Specified cast error. The error will occur on the key harboring the invalid subkey.

  2. Then inspect the keys after that in regedit, and watch for any value of type REG_DWORD with a value (invalid DWORD (32-bit) value) (usually named NoModify
  3. Note those keys, and find them in appwiz.cpl
  4. Uninstall the accompanying software

On my systems

Delete the below pieces of crap.

Then run choco install --yes jre8 again.

  • Glassfish

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\nbi-glassfish-mod-3.1.43.0.0

  • NetBeans IDE

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\nbi-nb-base-7.0.0.0.0

Luckily, the NetBeans uninstaller can uninstall GlassFish at the same time:

Do not re-install, as they re-insert the corrupt data.

–jeroen

Posted in Development, Java, Java Platform, Software Development | Leave a Comment »

Android passwords: store as transient as possible using arrays in stead of strings

Posted by jpluimers on 2020/08/06

Sometimes you cannot avoid handling passwords in your application. When you do,

  • keep them around as short as possible
  • store them in data types that are not garbage collected
  • wipe the storage as soon as you are done

In practice, this usually comes down to storing them as arrays (character or byte arrays), not strings.

This holds for many other platforms outside Java as well: strings are usually managed in one way or the other, so they cannot be wiped

References:

For actual storage of passwords, you always have the risk of retrieval: when a “bad guy” gets physical access to a device, it is basically hosed.

A KeyStore can only do so much against it: if your APK can be downloaded, it can be reverse-engineered revealing the exact steps how the store is accessed, reproducing the steps needed to hack into the underlying protected data/functionality.

The keystore can be forgetful…

You’ve just moved in to a new house and have been given the master key for the front door. You only have one of these so you know you need to keep it safe. Your really paranoid so you hire an armed guard, whose sole job is to protect this key, in fact, this is all he has been trained to do and has a catchy slogan of “need to protect a key, its what I was born to do!”. You install an extra lock on your front door as you feel the bodyguard isn’t enough, this is a rough area anyway and who’s going to make sure no-ones about to break in and steal all your crap. You return to your key guard only to be informed he has thrown the key away. You shout and scream at him but he just blankly says “I don’t have it anymore, I didn’t think it was important”. You can’t contain your anger “What the hell, your a jerk! You had one thing to do and you failed, this causes me a lot of problems, why didn’t you tell me you might do this?! What do I do now?!”

[WayBack] Android Security: The Forgetful Keystore – SystemDotRun – Dorian Cussen’s Super Blog

–jeroen

Posted in Android, Development, Java, Java Platform, Mobile Development, Power User, Security, Software Development | Leave a Comment »

 
%d bloggers like this: