├── Differ ├── DiffResult.cs ├── Differ.csproj ├── Program.cs └── DiffRunner.cs ├── README.md ├── LICENSE ├── Differ.sln └── .gitignore /Differ/DiffResult.cs: -------------------------------------------------------------------------------- 1 | namespace Differ 2 | { 3 | public readonly record struct DiffResult(string Path, DiffStatus Status); 4 | 5 | public enum DiffStatus 6 | { 7 | Error, 8 | Identical, 9 | Modified, 10 | Added, 11 | Deleted 12 | } 13 | } 14 | -------------------------------------------------------------------------------- /Differ/Differ.csproj: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | Exe 5 | net6.0 6 | enable 7 | enable 8 | true 9 | true 10 | 11 | 12 | 13 | -------------------------------------------------------------------------------- /Differ/Program.cs: -------------------------------------------------------------------------------- 1 | using Differ; 2 | using System.Threading.Channels; 3 | 4 | ExecutionContext.SuppressFlow(); // we're a simple tool; don't bother flowing EC 5 | 6 | Channel channel = Channel.CreateUnbounded(); 7 | 8 | var runner = new DiffRunner( 9 | left: new DirectoryInfo(args[0]), 10 | right: new DirectoryInfo(args[1]), 11 | writer: channel.Writer); 12 | 13 | runner.Process(); 14 | 15 | await foreach (var item in channel.Reader.ReadAllAsync()) 16 | { 17 | Console.WriteLine($"{item.Path} >>> {item.Status}"); 18 | } 19 | 20 | Console.WriteLine(); 21 | Console.WriteLine(">> COMPLETE <<"); 22 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # differ 2 | 3 | Simple command-line tool to see if directories contain identical files 4 | 5 | ## Usage 6 | 7 | ```txt 8 | differ 9 | ``` 10 | 11 | The tool will recursively iterate through both the _left_ and the _right_ directories, comparing the contents of files in each directory. It writes to the console a status for each file. 12 | 13 | * __Added__ - The file is present only in _right_. 14 | * __Deleted__ - The file is present only in _left_. 15 | * __Identical__ - The file is present in both _left_ and _right_ and the contents have not changed. 16 | * __Modified__ - The file is present in both _left_ and _right_ and the contents have changed. 17 | 18 | The tool compares filenames using a case-insensitive comparer. File renames are not tracked. If a file is renamed from _a.txt_ to _b.txt_ between the two directories, this will be reported as an addition (for _b.txt_) and a deletion (for _a.txt_). 19 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | MIT License 2 | 3 | Copyright (c) 2022 Levi Broderick 4 | 5 | Permission is hereby granted, free of charge, to any person obtaining a copy 6 | of this software and associated documentation files (the "Software"), to deal 7 | in the Software without restriction, including without limitation the rights 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 | copies of the Software, and to permit persons to whom the Software is 10 | furnished to do so, subject to the following conditions: 11 | 12 | The above copyright notice and this permission notice shall be included in all 13 | copies or substantial portions of the Software. 14 | 15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 21 | SOFTWARE. 22 | -------------------------------------------------------------------------------- /Differ.sln: -------------------------------------------------------------------------------- 1 | 2 | Microsoft Visual Studio Solution File, Format Version 12.00 3 | # Visual Studio Version 17 4 | VisualStudioVersion = 17.2.32216.311 5 | MinimumVisualStudioVersion = 10.0.40219.1 6 | Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Differ", "Differ\Differ.csproj", "{BDE1C00A-E6AB-4A8D-8E43-9F416C087DB1}" 7 | EndProject 8 | Global 9 | GlobalSection(SolutionConfigurationPlatforms) = preSolution 10 | Debug|Any CPU = Debug|Any CPU 11 | Release|Any CPU = Release|Any CPU 12 | EndGlobalSection 13 | GlobalSection(ProjectConfigurationPlatforms) = postSolution 14 | {BDE1C00A-E6AB-4A8D-8E43-9F416C087DB1}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 15 | {BDE1C00A-E6AB-4A8D-8E43-9F416C087DB1}.Debug|Any CPU.Build.0 = Debug|Any CPU 16 | {BDE1C00A-E6AB-4A8D-8E43-9F416C087DB1}.Release|Any CPU.ActiveCfg = Release|Any CPU 17 | {BDE1C00A-E6AB-4A8D-8E43-9F416C087DB1}.Release|Any CPU.Build.0 = Release|Any CPU 18 | EndGlobalSection 19 | GlobalSection(SolutionProperties) = preSolution 20 | HideSolutionNode = FALSE 21 | EndGlobalSection 22 | GlobalSection(ExtensibilityGlobals) = postSolution 23 | SolutionGuid = {CAD4E4F0-C5EC-49D7-8CB0-0CA59DF297A2} 24 | EndGlobalSection 25 | EndGlobal 26 | -------------------------------------------------------------------------------- /Differ/DiffRunner.cs: -------------------------------------------------------------------------------- 1 | using System.IO.MemoryMappedFiles; 2 | using System.Threading.Channels; 3 | 4 | namespace Differ 5 | { 6 | internal sealed class DiffRunner 7 | { 8 | private readonly DirectoryInfo _left; 9 | private readonly DirectoryInfo _right; 10 | private readonly ChannelWriter _writer; 11 | 12 | public DiffRunner(DirectoryInfo left, DirectoryInfo right, ChannelWriter writer) 13 | { 14 | _left = left; 15 | _right = right; 16 | _writer = writer; 17 | } 18 | 19 | public void Process() 20 | { 21 | Task.Run(async () => 22 | { 23 | List tasks = new List(); 24 | 25 | HashSet filenames = new HashSet(StringComparer.OrdinalIgnoreCase); 26 | foreach (string filename in GetRecursiveFileList(_left).Concat(GetRecursiveFileList(_right))) 27 | { 28 | if (filenames.Add(filename)) 29 | { 30 | // first time this file has been seen - process it! 31 | var newTask = Task.Run(() => _writer.WriteAsync(new DiffResult(filename, GetStatus(filename)))); 32 | tasks.Add(newTask); 33 | } 34 | } 35 | 36 | await Task.WhenAll(tasks); 37 | _writer.Complete(); 38 | }); 39 | } 40 | 41 | private DiffStatus GetStatus(string relativeFilename) 42 | { 43 | try 44 | { 45 | FileInfo left = new FileInfo(_left.FullName + relativeFilename); 46 | FileInfo right = new FileInfo(_right.FullName + relativeFilename); 47 | 48 | bool leftExists = left.Exists; 49 | bool rightExists = right.Exists; 50 | 51 | if (leftExists && !rightExists) { return DiffStatus.Deleted; } 52 | if (rightExists && !leftExists) { return DiffStatus.Added; } 53 | if (!leftExists && !rightExists) { return DiffStatus.Error; } 54 | 55 | long leftLength = left.Length; 56 | long rightLength = right.Length; 57 | 58 | if (leftLength != rightLength) { return DiffStatus.Modified; } 59 | if (leftLength == 0 && rightLength == 0) { return DiffStatus.Identical; } 60 | if (leftLength == 0 || rightLength == 0) { return DiffStatus.Modified; } 61 | 62 | using var leftMMF = OpenFile(left); 63 | using var rightMMF = OpenFile(right); 64 | 65 | return AreFilesIdentical(leftMMF, rightMMF, leftLength) ? DiffStatus.Identical : DiffStatus.Modified; 66 | } 67 | catch 68 | { 69 | return DiffStatus.Error; 70 | } 71 | } 72 | 73 | private static MemoryMappedFile OpenFile(FileInfo file) 74 | { 75 | FileStream fs = file.Open(FileMode.Open, FileAccess.Read, FileShare.Read); 76 | return MemoryMappedFile.CreateFromFile(fs, null, 0, MemoryMappedFileAccess.Read, HandleInheritability.None, false); 77 | } 78 | 79 | private static unsafe bool AreFilesIdentical(MemoryMappedFile left, MemoryMappedFile right, long actualLength) 80 | { 81 | using var leftAccr = left.CreateViewAccessor(0, actualLength, MemoryMappedFileAccess.Read); 82 | using var rightAccr = right.CreateViewAccessor(0, actualLength, MemoryMappedFileAccess.Read); 83 | 84 | var leftHnd = leftAccr.SafeMemoryMappedViewHandle; 85 | var rightHnd = rightAccr.SafeMemoryMappedViewHandle; 86 | 87 | if (leftHnd.ByteLength != rightHnd.ByteLength) { return false; } 88 | 89 | byte* leftPtr = null; 90 | byte* rightPtr = null; 91 | 92 | try 93 | { 94 | leftHnd.AcquirePointer(ref leftPtr); 95 | rightHnd.AcquirePointer(ref rightPtr); 96 | 97 | ulong currentOffset = 0; 98 | ulong remainingByteLength = leftHnd.ByteLength; 99 | while (remainingByteLength > 0) 100 | { 101 | int thisSpanSize = (int)Math.Min(int.MaxValue, remainingByteLength); 102 | ReadOnlySpan leftSpan = new ReadOnlySpan(leftPtr + currentOffset, thisSpanSize); 103 | ReadOnlySpan rightSpan = new ReadOnlySpan(rightPtr + currentOffset, thisSpanSize); 104 | if (!leftSpan.SequenceEqual(rightSpan)) 105 | { 106 | return false; 107 | } 108 | 109 | currentOffset += (uint)thisSpanSize; 110 | remainingByteLength -= (uint)thisSpanSize; 111 | } 112 | 113 | return true; 114 | } 115 | finally 116 | { 117 | if (leftPtr != null) { leftHnd.ReleasePointer(); } 118 | if (rightPtr != null) { rightHnd.ReleasePointer(); } 119 | } 120 | } 121 | 122 | private static IEnumerable GetRecursiveFileList(DirectoryInfo path) 123 | { 124 | int pathLength = path.FullName.Length; 125 | var allFiles = Directory.EnumerateFiles(path.FullName, "*", SearchOption.AllDirectories); 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