Archive for the ‘.NET 4.5’ Category
Posted by jpluimers on 2014/04/09
Interesting read:
The C language specification describes an abstract computer, not a real one – The Old New Thing – Site Home – MSDN Blogs.
In other words: any language that merges null behaviour in the underlying storage will have a problem somwehere.
So if you want to have true nullable types, your null flag should be stored outside the underlying storage.
The .NET framework 2 and up, most database management systems and many other environment support that.
But most languages don’t support it for pointer types. So there will be portions of address spaces either inaccessible, or only accessible when skipping the null pointer checks.
Note that the thread above contains some very interesting bits, for instance this one:
Matt 28 Mar 2013 5:58 PM #
@MarkY “Dereferencing null is undefined? Cool! I thought it was guaranteed to crash, just like a false assertion or something. So crashing is the OS guarantee, not the language guarantee apparently.”
Nope. It’s not an OS guarantee either. The OS won’t ever normally allocate memory at address zero, but there’s nothing to stop you telling it to. Try doing “VirtualAlloc(1, 4096, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE)” on your pre-Windows8 machine.
In fact, this is the reason why null-dereferences in kernel mode are often exploitable as elevation of privilege attacks. The null-page is mappable and within the user-addressable region of memory, so if the kernel dereferences a null pointer, it reads attacker controllable data.
And btw, this is the reason why on Linux and Windows8+ you can’t map the null-page.
–jeroen
via: The C language specification describes an abstract computer, not a real one – The Old New Thing – Site Home – MSDN Blogs.
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, Borland C++, Borland Pascal, C, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, C++, C++ Builder, Database Development, Delphi, Development, Pascal, Quick Pascal, Software Development, Turbo Pascal, VB.NET, VB.NET 10.0, VB.NET 11.0, VB.NET 8.0, VB.NET 9.0 | Leave a Comment »
Posted by jpluimers on 2014/04/02
Every once in a while, someone hoses their computer far enough that it has to be reinstalled, but the original Microsoft product keys are misplaced, and some creepy anti-virus tool disallows the running of standard product key recovery tools like nirsoft’s.
Well, there is enough sourcecode that does recover it, just look for any of these strings:
Some hits:
The below full executables can trigger a virus warning (ordered from less often to most often):
–jeroen
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, CommandLine, Delphi, Development, PowerShell, Software Development | Leave a Comment »
Posted by jpluimers on 2014/03/29
Brilliant piece of open source:
SmallestDotNet – SmallestDotNet.com is a single page site that does one thing. It tells you the smallest, easiest download you’d need to get the .NET Framework on your system.
Even on Mac OS X it is helpful and recommends Mono and on iOS it recommends looking at MonoTouch.
Thanks Scott Hanselman for making this available!
–jeroen
via:
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, Apple, Development, Mac, Mac OS X / OS X / MacOS, Mac OS X 10.4 Tiger, Mac OS X 10.5 Leopard, Mac OS X 10.6 Snow Leopard, Mac OS X 10.7 Lion, MacBook, MacBook Retina, MacBook-Air, MacBook-Pro, OS X 10.8 Mountain Lion, OS X 10.9 Mavericks, Power User, Software Development, Windows, Windows 7, Windows 8, Windows 8.1, Windows Server 2003, Windows Server 2003 R2, Windows Server 2008, Windows Server 2008 R2, Windows Vista, Windows XP | Tagged: .NET Framework, scott hanselman | Leave a Comment »
Posted by jpluimers on 2014/03/24
When using a FlowLauyoutPanel, I always forget on which control the FlowBreak design time property / SetFlowBreak run time method operates.
Then I always end up writing a short demo program like Container Controls 5: FlowLayoutPanel.
It operates after the control on which you set it.
It is like text in a Word Processor: it breaks after the place where you set the break. Read the rest of this entry »
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development, WinForms | Leave a Comment »
Posted by jpluimers on 2014/03/11
Edit 20250107: added various [Wayback/Archive] archived links (dated as close to the blog post as possible) because of link-rot; marked some keywords as code; found the current .NET DiscUtils repository at [Wayback/Archive] GitHub – DiscUtils/DiscUtils: Utility libraries to interact with discs, filesystem formats and more where you also can download it.
.NET DiscUtils is an interesting open source .NET library for accessing and manipulating virtual disk images. Since it is entirely written in C# (without the need for P/Invoke), you should even be able to run this on non-Windows machines using mono. Later on, you will see the 0.11.0 build fails this, but it gives good hope it eventually will.
Virtual disk formats supported are DMG, ISO, RAW (IMG/IMA/VFD/FLP/BIF), VDI, VHD, VHDX, VMDK, and [Wayback/Archive] XVA, regular disks like Physical, iSCSI and NFS.
There are two ways of getting the .NET DiscUtils tools to run:
- [Wayback/Archive] download pre-build binaries (at the time of writing: version 0.10) from via [Wayback/Archive] .NET DiscUtils – Home, or
- from the [Wayback/Archive] latest source page, click the download button, then build the binaries from the source package. At the time of writing, that version is 0.11.
This post describes the second way, and requires PowerShell to be installed on your system (which probably is, as Windows 7 and Windows Server 2008 R2 include it). Read the rest of this entry »
Posted in .NET, .NET 4.0, .NET 4.5, C#, C# 4.0, C# 5.0, CommandLine, Development, PowerShell, Software Development | 1 Comment »
Posted by jpluimers on 2014/02/27
I’m more and more amazed (actually I’m not, this is how life on forum-like communities when moderatorss take over) about which StackOverflow questsions get closed, and which ones stay alive.
It seems the best way is to ask longer questions way beyond what most moderatorss can grasp.
Closed:
Still open:
A great point in the comments of the first question is that
you can technically can write .NET 4.0 / C# 4 applications on a .NET 4.5 / C#5 equiped machine and deploy them on machines that only have .NET 4.0 and C# support.
Don’t. I learned that in the .NET 3.0/3.5 and C# 3.0/2.0 era that combining is bad as the version matrix allows for subtle combinations that are hard to test.
.NET 3.0 with C# 2.0 applications written on a system that had .NET 3.5 and C# 3.0 installed would occasionally fail on systems that only had .NET 3.0 and C# 2.0 installed.
–jeroen
Posted in .NET, .NET 4.0, .NET 4.5, C#, C# 4.0, C# 5.0, Development, Software Development | Tagged: stack overflow | Leave a Comment »
Posted by jpluimers on 2014/02/13
ForNeVeR now maintains ManagedSpy, see his answer on StackOverflow
BTW, I’ve cloned the original ManagedSpy source code and maintaining the code today (for example, ported it to .NET4).
See project on GitHub.
–jeroen
via: managed – What happened to ManagedSpy? – Stack Overflow.
Posted in .NET, .NET 4.0, .NET 4.5, C#, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2014/02/11
The DBNull type is a very special type in .NET. It represents null values in databases, which are slightly different than null values in .NET.
The biggest confusion that people have with it is that it won’t convert to anything. Which means that you see a lot of questions like “System.InvalidCastException: Conversion from type ‘DBNull’ to type” “is not valid”.
You’d think the full name would be System.Data.DBNull, it is actually named System.DBNull. The reason is that various other functionality of the System namespace depend on it, for instance the System.Convert class.
DBNull was already present in .NET 1.x, so it predates nullable types that were introduced in C# 2 / .NET 2.
A null value on the database side will result in a DBNull instance.
If you want to explicitly pass a null value to a database, you use a DBNull.Value, which is a singleton.
Why DBNull
There is a very interestin question/answer series on StackOverflow about this: via .net – What is the point of DBNull? – Stack Overflow.
There are a few good arguments both for and against DBNull.
But the baseline is that DBNull predates the introduction in the .NET framework of genuine nullable types. Both their behaviour is slightly different, so DBNull had to stay.
Which means you have to deal with it every now and then.
Invalid casts
A bit more background on the invalid casts.
It is thrown like this:
throw new InvalidCastException(Environment.GetResourceString("InvalidCast_DBNull"));
from
Convert.DefaultToType();
which is called from the DBNull method
object IConvertible.ToType(Type type, IFormatProvider provider);
All other IConvertible methods are implementated like
bool IConvertible.ToBoolean(IFormatProvider provider)
{
throw new InvalidCastException(Environment.GetResourceString("InvalidCast_FromDBNull"));
}
So these all throw the same exception:
bool IConvertible.ToBoolean(IFormatProvider provider);
byte IConvertible.ToByte(IFormatProvider provider);
char IConvertible.ToChar(IFormatProvider provider);
DateTime IConvertible.ToDateTime(IFormatProvider provider);
decimal IConvertible.ToDecimal(IFormatProvider provider);
double IConvertible.ToDouble(IFormatProvider provider);
short IConvertible.ToInt16(IFormatProvider provider);
int IConvertible.ToInt32(IFormatProvider provider);
long IConvertible.ToInt64(IFormatProvider provider);
sbyte IConvertible.ToSByte(IFormatProvider provider);
float IConvertible.ToSingle(IFormatProvider provider);
ushort IConvertible.ToUInt16(IFormatProvider provider);
uint IConvertible.ToUInt32(IFormatProvider provider);
ulong IConvertible.ToUInt64(IFormatProvider provider);
–jeroen
via:
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2014/02/06
A while ago, I had this error when running an application on a hardened server:
Unhandled Exception:System.InvalidOperationException:
Unable to generate a temporary class (result=1).
error CS2001: Source file 'C:\windows\TEMP\0hocq2nq.0.cs' could not be found error CS2008: No inputs specified
at System.Xml.Serialization.Compiler.Compile(Assembly parent, String ns, XmlSerializerCompilerParameters xmlParameters, Evidence evidence)
at System.Xml.Serialization.TempAssembly.GenerateAssembly(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, Evidence evidence, XmlSerializerCompilerParameters parameters, Assembly assembly, Hashtable assemblies)
at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, String location, Evidence evidence)
at System.Xml.Serialization.XmlSerializer..ctor(Type type, XmlAttributeOverrides overrides, Type[] extraTypes, XmlRootAttribute root, String defaultNamespace, String location, Evidence evidence)
at System.Xml.Serialization.XmlSerializer..ctor(Type type, XmlAttributeOverrides overrides, Type[] extraTypes, XmlRootAttribute root, String defaultNamespace, String location)
at System.Xml.Serialization.XmlSerializer..ctor(Type type, Type[] extraTypes)
Usually I’m not the first with strange errors, but searching for “Unhandled Exception:System.InvalidOperationException: Unable to generate a temporary class” didn’t get many results.
This was a program running from SSIS under a non-system domain account with very little access.
My first guess was the right now: the XmlSerializer wants to generate a temporary C# file, then compile it into a temporary assembly. Since it cannot generate the C# file because the account does not have access to %windir\TEMP%, the compiler cannot find the (not generated) C# file.
After a few tries, I searched for XmlSerializer without GenerateAssembly, where the first hit ended at Changing where XmlSerializer Outputs Temporary Assemblies – Scott Hanselman.
That post indicated I should try looking for tempFilesLocation in the XmlSerializer context.
That got me these posts: Read the rest of this entry »
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2014/02/05
Looking for the pesky little differences between C# and VB.NET, I stumbled over this nice question by Micah Martin on default values for generics in VB.NET as compared to C#. Actually there were 3 questions, so I did a bit of post-editing:
How do I create the default for a generic in VB.NET? in C# I can call:
T variable = default(T);
- How do I do this in VB?
- If this just returns null (C#) or nothing (VB.NET) then what happens to value types?
- Is there a way to specify for a custom type what the default value is? For instance what if I want the default value to be the equivalent to calling a parameterless constructor on my class.
User Konrad Rudolph – Stack Overflow. promptly gave three answers:
Question 1:
Dim variable As T ‘ or ‘ Dim variable As T = Nothing ‘ or ‘ Dim variable As New T() Notice that the latter only works if you specifiy either the New or the Structure constraint for the generic type.
Question 2:
For value types all members of the struct are “nulled” out, i.e. all reference type members are set to null (Nothing) and all value types are in turn nulled out. And no, since string is a reference type, it does not result in "" for strings as suggested in the other answer.
Question 3:
No, there’s no way to specify this. There are some threads about this on Stack Overflow already, e.g. here. Jon has posted an excellent explanation why this is.
–jeroen
via: c# – Default value for generics – Stack Overflow.
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development, VB.NET, VB.NET 10.0, VB.NET 11.0, VB.NET 7.0, VB.NET 7.1, VB.NET 8.0, VB.NET 9.0 | Leave a Comment »
The Wiert Corner - irregular stream of stuff 