Develop Reference

Title: C# File.Exist returning false when file can be read from/written to

Development Environment: .Net Framework 4.7.2 using VS 2022 on Win 10 Pro x64
Preface: I've reviewed the two similar questions I found at SO; the first deals with permissions and the second with restrictions on using the root directory. Neither contained info that enabled me to resolve my issue.
I'm working on a C# winforms app which uses a SQLite database. I recently discovered "PRAGMA integrity_check" will create an empty DB and return “ok” if the target DB file is missing so I need to ensure the file’s not gone missing before executing the PRAGMA. My simple solution is to wrap integrity_check in an IF (File.Exist) ELSE but the Exist method is returning ”false”.
In MSDN documentation there 7 stated reasons why a false might be returned in addition to the file actually not existing (listed to avoid the need to follow a link):
path is null
path is invalid
path exceeds maximum length (260)
path is a zero-length string
path has invalid characters
storage media is failing/missing
caller has insufficient permissions to read the specified file
My operating assumption is none of those are the root cause since I can read from and write to the DB programmatically in the app.
Code building the path:
namespace BURS_Library
{
public class MISC
{
public const string DBName = "BURS.db";
}
}
using System;
using System.IO;
using System.Reflection;
using System.Text;
using System.Windows.Forms;
namespace BURS_Library
{
public class BURS_Path
{
public static string AppData()
{
string userAppDataDir = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
userAppDataDir = userAppDataDir.Replace("Roaming", "LocalLow");
if ( ! Directory.Exists(Path.Combine(userAppDataDir, "BURS_Data_tst")))
{
// display error MessageBox
Environment.Exit(1);
}
return Path.Combine(userAppDataDir, "BURS_Data_tst");
}
public static string DB()
{
return Path.Combine(AppData(), MISC.DBName);
}
{
}
Resultant path: C:\Users\Art\AppData\LocalLow\BURS_Data_tst\BURS.db
Code with File.Exist
using _Library;
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Windows.Forms;
namespace BURS_UI
{
public static class Program
{
[STAThread]
public static void Main(string[] tsArgs)
{
if (File.Exists(BURS_Path.DB()))
{
// perform db Integrity Check
}
else
{
// display error MessageBox
Environment.Exit(2);
}
BURS_Connections.SetConnection(BURS_Path.DB());
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Discover());
}
}
}
If my operating assumption is valid why is File.Exist returning false?
Thank you for your time & expertise.

Following #BentTranberg's suggestion a test was run using the following code (in case its useful to somebody):
if (Directory.Exists(#"C:\Users"))
Save2Log(#"FOUND: C:\Users", true);
if (Directory.Exists(#"C:\Users\Art"))
Save2Log(#"FOUND: C:\Users\Art", true);
if (Directory.Exists(#"C:\Users\Art\AppData"))
Save2Log(#"FOUND: C:\Users\Art\AppData", true);
if (Directory.Exists(#"C:\Users\Art\AppData\LocalLow"))
Save2Log(#"FOUND: C:\Users\Art\AppData\LocalLow", true);
if (Directory.Exists(#"C:\Users\Art\AppData\LocalLow\BURS_Data_tst"))
Save2Log(#"FOUND: C:\Users\Art\AppData\LocalLow\BURS_Data_tst", true);
if (File.Exists(#"C:\Users\Art\AppData\LocalLow\BURS_Data_tst\BURS.db"))
Save2Log(#"FOUND: C:\Users\Art\AppData\LocalLow\BURS_Data_tst\BURS.db", true);
Save2Log($"METHOD: {BURS_Path.DB()}", true);
Which produced the following result:
FOUND: C:\Users
FOUND: C:\Users\Art
FOUND: C:\Users\Art\AppData
FOUND: C:\Users\Art\AppData\LocalLow
FOUND: C:\Users\Art\AppData\LocalLow\BURS_Data_tst
FOUND: C:\Users\Art\AppData\LocalLow\BURS_Data_tst\BURS.db
METHOD: C:\Users\Art\AppData\LocalLow\BURS_Data_tst\BURS.db
Next I reran my original code which surprisingly now worked as expected. To validate that result I ran more test:
int existFail = 0;
for (int i = 0; i < 10000; i++)
{
if ( ! File.Exists(BURS_Path.DB())) existFail++;
}
Save2Log($"number of exist fail in 10,000 = {existFail}", true);
I did that 5 times and in 50,000 iterations there were zero incorrect returns. At this point the error has not been reproduced.
My computer was shut down over night which may have impacted the findings. I will rerun this each morning for the next 3 days and post the results as an edit.

fakeXrmEasy for crm testing initialization issues

I'm trying to follow the basic tutorial for FakeXrmEasy, but I'm not sure why I'm getting errors. I installed everything that needs to be installed to mock Dynamics 365, but I'm still getting errors. I can't figure out what I'm missing, I really want to be able to use this tool.
CS1950 The best overloaded Add method 'List.Add(Entity)' for the collection initializer has some invalid arguments unitTest c:\Users\acapell\documents\visual studio 2015\Projects\unitTest\unitTest\Program.cs 48 Active
CS0246 The type or namespace name 'Account' could not be found (are you missing a using directive or an assembly reference?) unitTest c:\Users\acapell\documents\visual studio 2015\Projects\unitTest\unitTest\Program.cs 45 Active
Didn't know if I was suppose to create an account class, I also tried that but that didn't work either. I got
CS1503 Argument 1: cannot convert from 'unitTest.Account' to 'Microsoft.Xrm.Sdk.Entity' unitTest c:\Users\acapell\documents\visual studio 2015\Projects\unitTest\unitTest\Program.cs 48 Active
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xunit;
using FakeItEasy;
using FakeXrmEasy;
using Microsoft.Xrm.Sdk;
namespace unitTest
{
class Program
{
static void Main(string[] args)
{
}
}
class unitTest
{
public object ProxyTypesAssembly { get; private set; }
public void MyFirstTest()
{//test method body
var context = new XrmFakedContext();
//You can think of a context like an Organisation database which stores entities In Memory.
//We can also use TypedEntities but we need to tell the context where to look for them,
//this could be done, easily, like this:
context.ProxyTypesAssembly = Assembly.GetAssembly(typeof(Account));
//We have to define our initial state now,
//by calling the Initialize method, which expects a list of entities.
var account = new Account() { Id = Guid.NewGuid(), Name = "My First Faked Account yeah!" };
context.Initialize(new List<Entity>() {
account
});
}
}
}

Do you use early binding in your CRM project and got the references right? If you do not use early binding, you can try late binding, e.g.
//context.ProxyTypesAssembly = Assembly.GetAssembly(typeof(Account));
var account = new Entity();
account.LogicalName = "account";
account.Attributes["name"] = "your account name";

How to fix ambiguous reference errors?

I have a web app that allows importing of contacts from Hotmail, Yahoo and GMail. I finally have it almost completed but since I added the importing of GMail, I am getting ambiguous reference errors and I am unsure how to fix them without breaking any code.
Here is a screen shot of the errors:

Try to use unique class names as much as possible. This will be the better solution in the end.
Write the entire namespace when referencing
OAuth.OAuthBase a = new ...;
Google.GData.Client.OAuthBase b = new ...;
Make an using alias for one or both:
using n2 = OAuth;
using Google.GData.Client;
n2.OAuthBase a = new ...; // referenced using namespace
OAuthBase b = new ...; // referenced through existing `using`

you can try something like this..
using GoogleOAuthBase = Google.GData.Client.OAuthBase;
namespace abc
{
public class Program
{
//make sure this Google.GData.Client.OAuthBase is instansiateable
var googleBase = new GoogleOAuthBase();
}
}
you can try entire name space as well.
var googleBase = new Google.GData.Client.OAuthBase();

get GuiApplication of running Sap logon vb6 to c#

I have to migrate a vb6 program to C# .net 3.5
the user starts SAP logon and authenticates,
then he can use the tool to fetch and insert the data using the tool
the problem:
i can create a new GuiApplication with reflection, but i can't fetch currently opened GuiSessions with it :/
here is the vb6 part of the code that gets currently opened GuiApplication with all opened GuiSessions
Dim obj As Object
Set obj = CreateObject("SAPGUI")
Set obj = obj.GetScriptingEngine
If TypeName(obj) = "GuiApplication" Then
Set SapAutomationObject = obj
SapAutomationObject.AllowSystemMessages = False
Debug.Print "SAP Automation OK"
End If
i tried it with reflection:
GuiApplication Application = (GuiApplication)System.Activator.CreateInstance(Type.GetTypeFromProgID("SapGui.S‌​criptingCtrl.1"));
i got an instance but no existing sessions

public static void testConnection()
{
SapROTWr.CSapROTWrapper sapROTWrapper = new SapROTWr.CSapROTWrapper();
object SapGuilRot = sapROTWrapper.GetROTEntry("SAPGUI");
object engine = SapGuilRot.GetType().InvokeMember("GetSCriptingEngine", System.Reflection.BindingFlags.InvokeMethod,
null, SapGuilRot, null);
SAPconnection.sapGuiApp = engine as GuiApplication;
GuiConnection connection = sapGuiApp.Connections.ElementAt(0) as GuiConnection;
GuiSession session = connection.Children.ElementAt(0) as GuiSession;
MessageBox.Show(session.Info.User + " !!||!! " + session.Info.Transaction);
}
Use This method, you have to reference SapROTWr.DLL which is in the sapgui folder of your SAP installation.

This works for me (SAP 730 / Win7):
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using SAPFEWSELib;
using SapROTWr;
namespace FIT.SapHelper
{
public static class stcSapHelper
{
public static void testConnection()
{
SapROTWr.CSapROTWrapper sapROTWrapper = new SapROTWr.CSapROTWrapper();
object SapGuilRot = sapROTWrapper.GetROTEntry("SAPGUI");
object engine = SapGuilRot.GetType().InvokeMember("GetScriptingEngine", System.Reflection.BindingFlags.InvokeMethod, null, SapGuilRot, null);
GuiConnection connection = (engine as GuiApplication).OpenConnection("BOX DESCRIPTION");
GuiSession session = connection.Children.ElementAt(0) as GuiSession;
}
}
}

Assuming that SAPGUI is a COM object then you should be able to take a reference to it and create it as a new object without using reflection. i.e. Use early binding and not late binding even though the original VB6 code is using 'late binding'
Secondly, assuming late binding, shouldn't the Type.GetTypeFromProgID("SapGui.S‌criptingCtrl.1") fragment be Type.GetTypeFromProgID("SapGui") to match the original VB6? you might need to check on the object model for SAPGUI to make sure you're referencing the right object.

the only solution that i found to work with running sessions is to load that code in a dll and access it via c#

SAP released SAP .NET connector to provide standartized way to interact with SAP system from within of .NET application. Look at http://service.sap.com/connectors, you must be SAP partner to be able access to the page

Restrict plugin access to file system and network via appdomain

I asked a while ago how to restrict plugins access ( I want to prevent them from writing to the disk or network ) and i was told to use AppDomain. I have searched and tried and failed on how to get this working.
Can anyone provide some information so i can get started, simply put make a AppDomain that does not allows writing to the file or network.

For .net framework 4.0, please follow the following code from this MSDN article.
The following example implements the procedure in the previous section. In the example, a project named Sandboxer in a Visual Studio solution also contains a project named UntrustedCode, which implements the class UntrustedClass. This scenario assumes that you have downloaded a library assembly containing a method that is expected to return true or false to indicate whether the number you provided is a Fibonacci number. Instead, the method attempts to read a file from your computer. The following example shows the untrusted code.
using System;
using System.IO;
namespace UntrustedCode
{
public class UntrustedClass
{
// Pretend to be a method checking if a number is a Fibonacci
// but which actually attempts to read a file.
public static bool IsFibonacci(int number)
{
File.ReadAllText("C:\\Temp\\file.txt");
return false;
}
}
}
The following example shows the Sandboxer application code that executes the untrusted code.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Security;
using System.Security.Policy;
using System.Security.Permissions;
using System.Reflection;
using System.Runtime.Remoting;
//The Sandboxer class needs to derive from MarshalByRefObject so that we can create it in another
// AppDomain and refer to it from the default AppDomain.
class Sandboxer : MarshalByRefObject
{
const string pathToUntrusted = #"..\..\..\UntrustedCode\bin\Debug";
const string untrustedAssembly = "UntrustedCode";
const string untrustedClass = "UntrustedCode.UntrustedClass";
const string entryPoint = "IsFibonacci";
private static Object[] parameters = { 45 };
static void Main()
{
//Setting the AppDomainSetup. It is very important to set the ApplicationBase to a folder
//other than the one in which the sandboxer resides.
AppDomainSetup adSetup = new AppDomainSetup();
adSetup.ApplicationBase = Path.GetFullPath(pathToUntrusted);
//Setting the permissions for the AppDomain. We give the permission to execute and to
//read/discover the location where the untrusted code is loaded.
PermissionSet permSet = new PermissionSet(PermissionState.None);
permSet.AddPermission(new SecurityPermission(SecurityPermissionFlag.Execution));
//We want the sandboxer assembly's strong name, so that we can add it to the full trust list.
StrongName fullTrustAssembly = typeof(Sandboxer).Assembly.Evidence.GetHostEvidence<StrongName>();
//Now we have everything we need to create the AppDomain, so let's create it.
AppDomain newDomain = AppDomain.CreateDomain("Sandbox", null, adSetup, permSet, fullTrustAssembly);
//Use CreateInstanceFrom to load an instance of the Sandboxer class into the
//new AppDomain.
ObjectHandle handle = Activator.CreateInstanceFrom(
newDomain, typeof(Sandboxer).Assembly.ManifestModule.FullyQualifiedName,
typeof(Sandboxer).FullName
);
//Unwrap the new domain instance into a reference in this domain and use it to execute the
//untrusted code.
Sandboxer newDomainInstance = (Sandboxer) handle.Unwrap();
newDomainInstance.ExecuteUntrustedCode(untrustedAssembly, untrustedClass, entryPoint, parameters);
}
public void ExecuteUntrustedCode(string assemblyName, string typeName, string entryPoint, Object[] parameters)
{
//Load the MethodInfo for a method in the new Assembly. This might be a method you know, or
//you can use Assembly.EntryPoint to get to the main function in an executable.
MethodInfo target = Assembly.Load(assemblyName).GetType(typeName).GetMethod(entryPoint);
try
{
//Now invoke the method.
bool retVal = (bool)target.Invoke(null, parameters);
}
catch (Exception ex)
{
// When we print informations from a SecurityException extra information can be printed if we are
//calling it with a full-trust stack.
(new PermissionSet(PermissionState.Unrestricted)).Assert();
Console.WriteLine("SecurityException caught:\n{0}", ex.ToString());
CodeAccessPermission.RevertAssert();
Console.ReadLine();
}
}
}

I guess this is what you need, if I understand correctly your point.
System.Security.PermissionSet ps =
new System.Security.PermissionSet(System.Security.Permissions.PermissionState.None);
ps.AddPermission(new System.Security.Permissions.FileIOPermission(System.Security.Permissions.FileIOPermissionAccess.NoAccess, "C:\\"));
System.Security.Policy.PolicyLevel pl = System.Security.Policy.PolicyLevel.CreateAppDomainLevel();
pl.RootCodeGroup.PolicyStatement = new System.Security.Policy.PolicyStatement(ps);
AppDomain.CurrentDomain.SetAppDomainPolicy(pl);
System.Reflection.Assembly myPluginAssembly = AppDomain.CurrentDomain.Load("MyPluginAssembly");
Is this more precisely what you meant?
Notice that you may provide an array of string containg the paths where you don't want the plugin to have access. You may provide if when initializing the new instance of FileIOPermission class.
Let me know if this helps. :-)

If you're using plugins, you might perhaps know about proxies.
While loading your assembly through a proxy, you can specify the security policy level for this particular assembly through the LoadAssembly() method or so, if I remember correctly. In other words, this is done through reflection.
I know my answer isn't that much detailed, but I hope it will give you an idea of where to look for your solution. I shall take an eye out to find further details on the subject so that I may be of better help. =)
Hope you will share your findings when you've done it.