(#747) Switch CryptoHashProvider to filestream for hashing files

Previously, when getting the checksum of a file, this read the file
into a byte array to pass to ComputeHash. However, this was limited to
files of 2gb or less, and was not efficent memory wise. This changes
the method to using a filestream which is passed to ComputeHash, which
should allow arbitrary file sizes with better memory usage.

The unit test for this method had to be removed because the mock
filesystem does not allow opening a file stream.

src/chocolatey.tests/chocolatey.tests.csproj

@@ -118,7 +118,6 @@
     <Compile Include="infrastructure\commands\CommandExecutorSpecs.cs" />
     <Compile Include="infrastructure\commands\PowershellExecutorSpecs.cs" />
     <Compile Include="infrastructure\configuration\ConfigSpecs.cs" />
-    <Compile Include="infrastructure\cryptography\CryptoHashProviderSpecs.cs" />
     <Compile Include="infrastructure\events\context\FakeEvent.cs" />
     <Compile Include="infrastructure\events\context\FakeSubscriber.cs" />
     <Compile Include="infrastructure\events\EventSubscriptionManagerSpecs.cs" />

src/chocolatey/infrastructure.app/ApplicationParameters.cs

@@ -138,7 +138,6 @@ public static class Environment
         public static readonly string ConfigFileTransformExtension = ".install.xdt";
         public static readonly string[] ShimDirectorFileExtensions = new string[] {".gui",".ignore"};
 
-        public static readonly string HashProviderFileTooBig = "UnableToDetectChanges_FileTooBig";
         public static readonly string HashProviderFileLocked = "UnableToDetectChanges_FileLocked";
 
         /// <summary>

src/chocolatey/infrastructure/cryptography/CryptoHashProvider.cs

@@ -90,21 +90,23 @@ public string hash_file(string filePath)
 
             try
             {
-                var hash = _hashAlgorithm.ComputeHash(_fileSystem.read_file_bytes(filePath));
-
-                return BitConverter.ToString(hash).Replace("-", string.Empty);
+                using (var fileStream = _fileSystem.open_file_readonly(filePath))
+                {
+                    var hash = _hashAlgorithm.ComputeHash(fileStream);
+                    return BitConverter.ToString(hash).Replace("-", string.Empty);
+                }
             }
             catch (IOException ex)
             {
-                this.Log().Warn(() => "Error computing hash for '{0}'{1} Hash will be special code for locked file or file too big instead.{1} Captured error:{1}  {2}".format_with(filePath, Environment.NewLine, ex.Message));
+                this.Log().Warn(() => "Error computing hash for '{0}'{1} Hash will be special code for locked file {1} Captured error:{1}  {2}".format_with(filePath, Environment.NewLine, ex.Message));
 
                 if (file_is_locked(ex))
                 {
                     return ApplicationParameters.HashProviderFileLocked;
                 }
 
-                //IO.IO_FileTooLong2GB (over Int32.MaxValue)
-                return ApplicationParameters.HashProviderFileTooBig;
+                //Rethrow if file is not locked
+                throw;
             }
         }