dotnet security: .Net Code Access Imperative Security -- dotnet security

Re: .Net Code Access Imperative Security

Sameeksha
9/9/2004 5:21:06 AM

Hello,

Thanks a lot. When I tried opening file chosen in the open file dialog, it
did give security exception.

I've one more similar piece of code with similar problem. It is as follows:

CodeAccessPermission perm = new
FileIOPermission(FileIOPermissionAccess.Write,"C:\\");
try
{
perm.Deny();
StreamWriter sw = new StreamWriter("C:\\myfile.txt",true);
sw.WriteLine("***************************************");
sw.Close();
}
catch (SecurityException ex)
{
MessageBox.Show(ex.Message);
}
This code ALWAYS writes to the specified file without any SecurityException.
What could be the reason?

Thanks in advance
Sameeksha

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Re: .Net Code Access Imperative Security

Nicole Calinoiu
9/9/2004 7:41:53 AM

Sameeksha,

The OpenFileDialog class only demands the FileDialogPermission when its
OpenFile method is called, not when the dialog is displayed. Doesn't
necessarily make much sense, but that's the the way it's implemented...
That said, you can get your desired result by denying UIPermission, but
that's not necessarily worthwhile since denials can be overridden by
assertions on the same call stack.

HTH,
Nicole

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Re: .Net Code Access Imperative Security

Nicole Calinoiu
9/9/2004 8:43:40 AM

If you want to block appending to an existing file, use
FileIOPermissionAccess.Append, not FileIOPermissionAccess.Write. You can,
of course, use both. e.g.:

CodeAccessPermission perm = new
FileIOPermission(FileIOPermissionAccess.Write |
FileIOPermissionAccess.Append ,"C:\\");

HTH,
Nicole

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Re: .Net Code Access Imperative Security

Sameeksha
9/9/2004 8:53:02 PM

Great!!!! It did work. Thanks a lot.

[quoted text, click to view]

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