Develop Reference

Long path \\?\ workaround not working on some installs

The app I'm working on needs to handle files with very long file/path names. It's a .Net 4.6 application so I've implemented the pre-4.6.2 workaround to allow the \\?\ syntax as outlined here and here.
This is the code I'm using to enable the feature (I can't modify the app.config so this has to be set in code):
var type = Type.GetType("System.AppContext");
if (type != null)
{
AppContext.SetSwitch("Switch.System.IO.UseLegacyPathHandling", false);
AppContext.SetSwitch("Switch.System.IO.BlockLongPaths", false);
var switchType = Type.GetType("System.AppContextSwitches");
if (switchType != null)
{
// We also have to reach into System.AppContextSwitches and manually update the cached private versions of these properties (don't ask me why):
var legacyField = switchType.GetField("_useLegacyPathHandling", System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic);
legacyField?.SetValue(null, (Int32)(-1)); // <- caching uses 0 to indicate no value, -1 for false, 1 for true.
var blockingField = switchType.GetField("_blockLongPaths", System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic);
blockingField?.SetValue(null, (Int32)(-1)); // <- caching uses 0 to indicate no value, -1 for false, 1 for true.
}
}
This works (yay!) on all the machines we've tested on, except one (boo!). The machine in question is a Windows 10 Pro installation, like the others, and has the same registry settings in the [Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem] namespace.
The error message on this particular machine is:
The given path format is not supported
The one difference we can see on that machine is that when looking at a very long file in Windows File Explorer, the 'Location' field uses the \\?\ syntax in the r-click > Properties menu.
I'm guessing that there's some registry key that is causing both that difference in File Explorer, and the failure of my fix, but somewhere other than the FileSystem namespace mentioned above.
Has anyone encountered a similar issue, or have an idea of other registry areas that might be relevant?

You can set those AppContext switches on a machine-wide basis via the registry if you don't want to set them in each App.config file individually:
These settings will affect all .NET apps that don't specify a different value in their App.config file. That is, the registry setting only changes the default value, which can still be overridden with app-specific values by specifying <AppContextSwitchOverrides value="..." />
EnableLongPath.reg :
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\AppContext]
"Switch.System.IO.BlockLongPaths"="false"
"Switch.System.IO.UseLegacyPathHandling"="false"
C:\>regedit.exe EnableLongPath.reg

How to set all cookies to secure at runtime instead of using web.config?

I know I can set this in the web.config but I want to set it conditionally depending on environment and add it to our core library. I have tried the below code but it does not work.
HttpCookiesSection cookieSection = (HttpCookiesSection)ConfigurationManager.GetSection("system.web/httpCookies");
cookieSection.HttpOnlyCookies = true;
cookieSection.RequireSSL = true;
The error is:
System.Configuration.ConfigurationErrorsException
The configuration is read only.
This kind of approach works fine for app settings. Note: I am not wanting to save the web.config, just change the setting in memory.
It appears from the documentation that this property is get-set.
From the docs:
// Set the RequireSSL.
httpCookiesSection.RequireSSL = false;

Why is the ConfigurationManager.GetSection "system.webServer/handlers" not available?

I'm trying to read some configuration in my global.aspx Application_Start method. When I read ConfigurationManager.GetSection("system.web/httpHandlers") everything is fine:
ConfigurationManager.GetSection("system.web/httpHandlers")
{System.Web.Configuration.HttpHandlersSection}
base {System.Configuration.ConfigurationSection}: {System.Web.Configuration.HttpHandlersSection}
Handlers: Count = 48
But when I read ConfigurationManager.GetSection("system.webServer/handlers") (which contains my custom handlers, it returns null. What am I doing wrong?
The section looks like this:
<system.webServer>
<handlers>
<add verb="*" path="*.loc" name="LocalizedResourceStreamer"
type="CFW.WebUI.HttpHandlers.LocalizedResourceStreamer,WebUI" />
</handlers>
</system.webServer>
Notes:
Web.configs are nested, ConfigurationManager.GetSection takes nesting into account by default.
The overall problem is trying to see if *.loc files are being served.
So far:
Looks like the system.webServer is ignored.

Depending on your OS/setup, the system.webServer element may be configured to be ignored - and so the config system will not be constructing any inner configuration items from it. E.g. on my machine (WinXP, IIS 5.1), it's set to ignored by default.
Check the machine.config on the machine where this code is running, and see how the system.webServer element is configured. I don't have machines available with suitable later OSes at the moment, but it may be that this element is always set to be ignored - after all, that part of the config is for IIS' use, rather than our own.

try :
**p.s. my web.config contains : <httpHandlers> and not handlers as yours. change as necessarily :) - also the webserver vs system.web **
Configuration webConfig = WebConfigurationManager.OpenWebConfiguration(Request.ApplicationPath);
ConfigurationSection webConfigSections = webConfig.GetSection("system.web/httpHandlers");
if (webConfigSections != null)
{
// PropertyInformationCollection t = webConfigSections.ElementInformation.Properties;
XDocument xmlFile = XDocument.Load(new StringReader(webConfigSections.SectionInformation.GetRawXml()));
IEnumerable<XElement> query = from c in xmlFile.Descendants("add") select c;
foreach (XElement band in query)
{
}
}
p.s. thats the problem with this section - he doesnt have a uniquee element name that can be taken. thats why you take it whole("add" element) and parse it.

How to change location of app.config

I want to change the location where my application looks for the app.config file.
I know that I can use ConfigurationManager.OpenExeConfiguration() to access an arbitrary config file - however, when the .Net Framework reads the config file (for ConnectionStrings or EventSources, for instance), it will look at the default location. I want to actually change the location, globally for the entire .Net Framework (for my application, of course).
I also know that I can use AppDomainSetup to change the location of the app.config for a new AppDomain. However, that doesn't apply to the primary AppDomain of the application.
I also know that I can override function Main() and create a new AppDomain as above and run my application in that new AppDomain. However, that has other side-effects - for instance, Assembly.GetEntryAssembly() will return a null reference.
Given how everything else works in .Net, I would expect there to be some way to configure the startup environment of my application - via a Application Manifest, or some such - but I have been unable to find even a glimmer of hope in that direction.
Any pointer would be helpful.
David Mullin

I used the approach with starting another AppDomain from Main(), specifying the "new" location of the configuration file.
No issues with GetEntryAssembly(); it only returns null, when being called from unmanaged code - or at least it doesn't for me, as I use ExecuteAssembly() to create/run the second AppDomain, much like this:
int Main(string[] args)
{
string currentExecutable = Assembly.GetExecutingAssembly().Location;
bool inChild = false;
List<string> xargs = new List<string>();
foreach (string arg in xargs)
{
if (arg.Equals("-child"))
{
inChild = true;
}
/* Parse other command line arguments */
else
{
xargs.Add(arg);
}
}
if (!inChild)
{
AppDomainSetup info = new AppDomainSetup();
info.ConfigurationFile = /* Path to desired App.Config File */;
Evidence evidence = AppDomain.CurrentDomain.Evidence;
AppDomain domain = AppDomain.CreateDomain(friendlyName, evidence, info);
xargs.Add("-child"); // Prevent recursion
return domain.ExecuteAssembly(currentExecutable, evidence, xargs.ToArray());
}
// Execute actual Main-Code, we are in the child domain with the custom app.config
return 0;
}
Note that we are effectively rerunning the EXE, just as a AppDomain and with a different config. Also note that you need to have some "magic" option that prevents this from going on endlessly.
I crafted this out from a bigger (real) chunk of code, so it might not work as is, but should illustrate the concept.

I am not sure why you want to change the location of your config file - perhaps there can be different approach for solving your actual problem. I had a requirement where I wanted to share configuration file across related applications - I had chosen to use own xml file as it had given me extra benefit of having complete control over the schema.
In your case, it's possible to externalize sections of your config file to a separate file using configSource property. See here under "Using External Configuration Files" to check how it has been done for connection strings section. Perhaps, this may help you.

var configPath = YOUR_PATH;
if (!Directory.Exists(ProductFolder))
{
Directory.CreateDirectory(ProductFolder);
}
if (!File.Exists(configPath))
{
File.WriteAllText(configPath, Resources.App);
}
var map = new ExeConfigurationFileMap
{
ExeConfigFilename = configPath,
LocalUserConfigFilename = configPath,
RoamingUserConfigFilename = configPath
};
Configuration config = ConfigurationManager.OpenMappedExeConfiguration(map, ConfigurationUserLevel.None);
Then use config member as you want.

Another approach is to leave the config file with the executable file and move the relevant changeable sections to external xml files which can be in whatever location you choose.
If you are using your config file in a readonly capacity, then you can add the relevant chunks to an XML file in a different location using XML Inlcude. This won't work if you are trying to write values back directly to app.config using the Configuration.Save method.
app.config:
<?xml version="1.0"?>
<configuration xmlns:xi="http://www.w3.org/2001/XInclude">
<appSettings>
<xi:include href="AppSettings.xml"/>
</appSettings>
<connectionStrings>
<xi:include href="ConnectionStrings.xml"/>
</connectionStrings>
<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7"/></startup>
</configuration>
ConnectionStrings.xml:
<?xml version="1.0"?>
<add name="Example1ConnectionString"
connectionString="Data Source=(local)\SQLExpress;Initial Catalog=Example1DB;Persist Security Info=True;User ID=sa;Password=password"
providerName="System.Data.SqlClient" />
<add name="Example2ConnectionString"
connectionString="Data Source=(local)\SQLExpress;Initial Catalog=Example2DB;Persist Security Info=True;User ID=sa;Password=password"
providerName="System.Data.SqlClient" />
AppSettings.xml:
<?xml version="1.0"?>
<add key="Setting1" value="Value1"/>
<add key="Setting2" value="Value2"/>
A file URI looks like this:
file:///C:/whatever.txt
You can even define failover files in case the one you are trying to reference is missing. This pattern is from https://www.xml.com/pub/a/2002/07/31/xinclude.html:
<xi:include href="http://www.whitehouse.gov/malapropisms.xml">
<xi:fallback>
<para>
This administration is doing everything we can to end the stalemate in
an efficient way. We're making the right decisions to bring the solution
to an end.
</para>
</xi:fallback>

Reloading configuration without restarting application using ConfigurationManager.RefreshSection

Has anyone got this working in a web application?
No matter what I do it seems that my appSettings section (redirected from web.config using appSettings file=".\Site\site.config") does not get reloaded.
Am I doomed to the case of having to just restart the application? I was hoping this method would lead me to a more performant solution.
Update:
By 'reloading' I mean refreshing ConfigurationManager.AppSettings without having to completely restart my ASP.NET application and having to incur the usual startup latency.

Make sure you are passing the correct case sensitive value to RefreshSection, i.e.
ConfigurationManager.RefreshSection("appSettings");

This seems to be a flaw (maybe a bug) when using an external config file for your appSettings. I've tried it using the configSource attribute and RefreshSection simply never works, I'm assuming this is the same when using the file attribute.
If you move your appSettings back inside your web.config RefreshSection will work perfectly but otherwise I'm afraid you're doomed.

For some reason ConfigurationManager.RefreshSection("appSettings") wasn't working for me. Reloading the Web.Config into a Configuration object seems to work correctly. The following code assumes the Web.Config file is one directory below the executing (bin) folder.
ExeConfigurationFileMap configMap = new ExeConfigurationFileMap();
Uri uriAssemblyFolder = new Uri(System.IO.Path.GetDirectoryName(Assembly.GetExecutingAssembly().GetName().CodeBase));
string appPath = uriAssemblyFolder.LocalPath;
configMap.ExeConfigFilename = appPath + #"\..\" + "Web.config";
Configuration config = ConfigurationManager.OpenMappedExeConfiguration(configMap, ConfigurationUserLevel.None);
And is used like:
string webConfigVariable = config.AppSettings.Settings["webConfigVariable"].Value;

.RefreshSection() does not work when the appSettings is external.
You can however use the following to change a value:
ConfigurationManager.AppSettings.Set(key, value)
This will NOT change the setting on file, only the loaded value in memory.
So instead of using RefreshSection I did the following:
string configFile="path to your config file";
XmlDocument xml = new XmlDocument();
xml.Load(configFile);
foreach (XmlNode node in xml.SelectNodes("/appSettings/add"))
{
string key = node.Attributes["key"].Value;
string value= node.Attributes["value"].Value;
ConfigurationManager.AppSettings.Set(key, value);
}
Any subsequent calls to AppSettings.Get will contain the updated value.
The appSettings will then be updated without needing to restart the application.

As an alternative you could write your own ConfigSection and set restartOnExternalChanges="false".
Then, when reading the section with ConfigurationManager.GetSection("yourSection") the settings will be auto-refreshed without an application restart.
And you could implement your settings strongly typed or as NameValueCollection.

Yes. you are stuck with iis restarting.
There is a feature with asp.net 4.0 and iis 7.5 where the initial startup is removed.

I am not sure if this is possible in a web app, but it works in a desktop app. Try using ConfigurationSettings rather than ConfigurationManager (it will yell at you for using outdated classes...), then reading all the data into a class. When you wish to refresh, simply create a new instance and drop all references to the old instance. My theory for why this works (might be wrong): when you don't directly access the app.config file the entire time you are running, the file lock is dropped by the application. Then, edits can be made when you are not accessing the file.

The App.Config settings are cached in memory when the application starts. For this reason, I don't think you'll be able to change those settings without restarting your application. One alternative that should be pretty straight forward would be to create a separate, simple XML configuration file, and handle loading/caching/reloading it yourself.

To write, call it this way:
Dim config As System.Configuration.Configuration = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~")
Return AddOrUpdateAppSetting(config, "YourSettingKey", "YourValueForTheKey")
To read and be sure you get the values in file, instead of those in cache, read it this way:
Dim config As System.Configuration.Configuration = WebConfigurationManager.OpenWebConfiguration("~")
Return config.AppSettings.Settings("TheKeyYouWantTheValue").Value
Full example:
Protected Shared Function AddOrUpdateAppSetting( _
ByVal Config As System.Configuration.Configuration _
, ByVal TheKey As String _
, ByVal TheValue As String _
) As Boolean</p>
Dim retval As Boolean = True
Dim Itm As System.Configuration.KeyValueConfigurationElement = _
Config.AppSettings.Settings.Item(TheKey)
If Itm Is Nothing Then
If Config.AppSettings.Settings.IsReadOnly Then
retval = False
Else
Config.AppSettings.Settings.Add(TheKey, TheValue)
End If
Else
' config.AppSettings.Settings(thekey).Value = thevalue
If Itm.IsReadOnly Then
retval = False
Else
Itm.Value = TheValue
End If
End If
If retval Then
Try
Config.Save(ConfigurationSaveMode.Modified)
Catch ex As Exception
retval = False
End Try
End If
Return retval
End Function

Have you tried storing your AppSettings in its own external file?
From app.config/web.config:
<appSettings configSource="appSettings.config"></appSettings>
appSettings.config:
<?xml version="1.0"?>
<appSettings>
<add key="SomeKey" value="SomeValue" />
</appSettings>
Changes made to appSettings.config should be reflected instantly.
More info:
http://msdn.microsoft.com/en-us/library/system.configuration.sectioninformation.configsource.aspx