!1725 去除警告

Merge pull request !1725 from aquan/N/A

Admin.NET/Admin.NET.Core/Utils/VerifyFileExtensionName.cs

@@ -109,7 +109,7 @@ public static class VerifyFileExtensionName
             foreach (var len in dic)
             {
                 byte[] b = new byte[len];
-                stream.Read(b, 0, b.Length);
+                stream.ReadExactly(b);
                 // string fileType = System.Text.Encoding.UTF8.GetString(b);
                 string fileKey = GetFileHeader(b);
                 if (DicsExt.ContainsKey(fileKey))