"Object can be disposed of more than once" error

user_447567 0
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When I run code analysis on the following chunk of code I get this message:

Object 'stream' can be disposed more than once in method 'upload.Page_Load(object, EventArgs)'. To avoid generating a System.ObjectDisposedException you should not call Dispose more than one time on an object.

using(var stream = File.Open(newFilename, FileMode.CreateNew))
using(var reader = new BinaryReader(file.InputStream))
using(var writer = new BinaryWriter(stream))
{
    var chunk = new byte[ChunkSize];
    Int32 count;
    while((count = reader.Read(chunk, 0, ChunkSize)) > 0)
    {
        writer.Write(chunk, 0, count);
    }
}

I don't understand why it might be called twice, and how to fix it to eliminate the error. Any help?

dispose c#
6 Answers

Suppress CA2202 whenever you are sure that the object in question handles multiple Dispose calls correctly and that your control flow is impeccably readable. BCL objects generally implement Dispose correctly. Streams are famous for that.

But don't necessarily trust third party or your own streams if you don't have unit tests probing that scenario yet. An API which returns a Stream may be returning a fragile subclass.

user_12355650
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