Do not modify stream position in ZipPluginPackageReader (#327)

* Do not modify stream position in ZipPluginPackageReader

* Check stream canread and canseek

* Remove catching ArgumentException when creating zip archive

src/PluginsSystem/Microsoft.Performance.Toolkit.Plugins.Runtime.Tests/ZipPluginPackageReaderTests.cs

@@ -49,7 +49,7 @@ namespace Microsoft.Performance.Toolkit.Plugins.Runtime.Tests
             var package = await sut.TryReadPackageAsync(stream, CancellationToken.None);
 
             Assert.IsNull(package);
-            fakeLogger.Verify(logger => logger.Error(It.IsAny<ArgumentException>(), It.IsAny<string>()));
+            fakeLogger.Verify(logger => logger.Error(It.IsAny<string>()));
         }
 
         [TestMethod]

src/PluginsSystem/Microsoft.Performance.Toolkit.Plugins.Runtime/Package/ZipPluginPackageReader.cs

@@ -57,27 +57,35 @@ namespace Microsoft.Performance.Toolkit.Plugins.Runtime.Package
         {
             Guard.NotNull(stream, nameof(stream));
 
+            if (!stream.CanRead)
+            {
+                this.logger.Error($"The stream is not readable.");
+                return null;
+            }
+
+            if (!stream.CanSeek)
+            {
+                this.logger.Error($"The stream is not seekable.");
+                return null;
+            }
+
             bool success = false;
+            long originalPosition = stream.Position;
 
             // Try to open the stream as a zip archive
-            ZipArchive zip;
+            ZipArchive zip = null;
             try
             {
-                zip = new ZipArchive(stream, ZipArchiveMode.Read, true);
+                try
-            }
+                {
-            catch (ArgumentException e)
+                    zip = new ZipArchive(stream, ZipArchiveMode.Read, true);
-            {
+                }
-                this.logger.Error(e, $"Unable to read from the stream.");
+                catch (InvalidDataException e)
-                return null;
+                {
-            }
+                    this.logger.Error(e, $"The stream could not be interpreted as a zip archive.");
-            catch (InvalidDataException e)
+                    return null;
-            {
+                }
-                this.logger.Error(e, $"The stream could not be interpreted as a zip archive.");
-                return null;
-            }
 
-            try
-            {
                 // Check that the plugin content folder exists
                 bool hasContentFolder = zip.Entries.Any(
                     e => e.FullName.Replace('\\', '/').StartsWith(PackageConstants.PluginContentFolderName, StringComparison.OrdinalIgnoreCase));
@@ -139,7 +147,9 @@ namespace Microsoft.Performance.Toolkit.Plugins.Runtime.Package
             }
             finally
             {
-                if (!success)
+                stream.Position = originalPosition;
+
+                if (!success && zip != null)
                 {
                     zip.Dispose();
                 }