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POImpersonation in ASP.NET MVC
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copied!<p>I have an Action that needs to read a file from a secure location, so I have to use impersonation to read the file.</p> <p>This code WORKS:</p> <pre><code>[AcceptVerbs(HttpVerbs.Get)] public ActionResult DirectDownload(Guid id) { if (Impersonator.ImpersonateValidUser()) { try { var path = "path to file"; if (!System.IO.File.Exists(path)) { return View("filenotfound"); } var bytes = System.IO.File.ReadAllBytes(path); return File(bytes, "application/octet-stream", "FileName"); } catch (Exception e) { Log.Exception(e); }finally { Impersonator.UndoImpersonation(); } } return View("filenotfound"); } </code></pre> <p>The only problem with the above code is that I have to read the entire file into memory and I am going to be dealing with VERY large files, so this is not a good solution. But if I replace these 2 lines:</p> <pre><code>var bytes = System.IO.File.ReadAllBytes(path); return File(bytes, "application/octet-stream", "FileName"); </code></pre> <p>with this:</p> <pre><code>return File(path, "application/octet-stream", "FileName"); </code></pre> <p>It does NOT work and I get the error message:</p> <blockquote> <p>Access to the path 'c:\projects\uploads\1\aa2bcbe7-ea99-499d-add8-c1fdac561b0e\Untitled 2.csv' is denied.</p> </blockquote> <p>I guess using the File results with a path, tries to open the file at a later time in the request pipeline when I have already "undone" the impersonation.</p> <p>Remember, the impersonation code works because I can read the file in the bytes array. What I want to do though is stream the file to the client.</p> <p>Any idea how I can work around this?</p> <p>Thanks in advance.</p>

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