Fix the elusive invalid zip archive issue that has been a problem for ages!

.vscode/tasks.json

@@ -6,7 +6,7 @@
         {
             "label": "Build LibZipSharp",
             "type": "shell",
-            "command": "msbuild LibZipSharp/libZipSharp.csproj /restore /t:Build",
+            "command": "dotnet build LibZipSharp/libZipSharp.csproj -t:Build",
             "group": {
                 "kind": "build",
                 "isDefault": true
@@ -18,7 +18,7 @@
         {
             "label": "Pack LibZipSharp Nuget",
             "type": "shell",
-            "command": "msbuild LibZipSharp/libZipSharp.csproj /t:Pack",
+            "command": "dotnet pack LibZipSharp/libZipSharp.csproj",
             "group": {
                 "kind": "build",
                 "isDefault": true
@@ -30,7 +30,7 @@
         {
             "label": "Clean LibZipSharp",
             "type": "shell",
-            "command": "msbuild LibZipSharp/libZipSharp.csproj /restore /t:Clean",
+            "command": "dotnet build LibZipSharp/libZipSharp.csproj -t:Clean",
             "group": {
                 "kind": "build",
                 "isDefault": true
@@ -42,7 +42,7 @@
         {
             "label": "Build LibZipSharp Unit Tests",
             "type": "shell",
-            "command": "msbuild LibZipSharp.UnitTest/LibZipSharp.UnitTest.csproj /restore /t:Build /p:ReferenceNuget=False",
+            "command": "dotnet build LibZipSharp.UnitTest/LibZipSharp.UnitTest.csproj -t:Build -p:ReferenceNuget=False",
             "group": {
                 "kind": "build",
                 "isDefault": true
@@ -51,17 +51,5 @@
                 "$msCompile"
             ]
         },
-        {
-            "label": "Run LibZipSharp Unit Tests",
-            "type": "shell",
-            "command": "msbuild LibZipSharp.UnitTest/LibZipSharp.UnitTest.csproj /restore /t:RunNunitTests /p:ReferenceNuget=False",
-            "group": {
-                "kind": "test",
-                "isDefault": true
-            },
-            "problemMatcher": [
-                "$msCompile"
-            ]
-        }
     ]
 }

LibZipSharp.UnitTest/ZipTests.cs

@@ -345,7 +345,7 @@ public void InMemoryZipFile ()
 				}
 
 				stream.Position = 0;
-				using (var zip = ZipArchive.Open (stream)) {
+				using (var zip = ZipArchive.Open (stream, strictConsistencyChecks: true)) {
 					Assert.AreEqual (3, zip.EntryCount);
 					foreach (var e in zip) {
 						Console.WriteLine (e.FullName);
@@ -354,7 +354,7 @@ public void InMemoryZipFile ()
 				}
 
 				stream.Position = 0;
-				using (var zip = ZipArchive.Open (stream)) {
+				using (var zip = ZipArchive.Open (stream, strictConsistencyChecks: true)) {
 					Assert.AreEqual (2, zip.EntryCount);
 					zip.AddEntry ("info.json", File.ReadAllText (filePath), Encoding.UTF8, CompressionMethod.Deflate);
 				}
@@ -377,6 +377,40 @@ public void InMemoryZipFile ()
 			}
 		}
 
+		[Test]
+		public void EnumerateOnEmptyThenAddFiles ()
+		{
+			File.WriteAllText ("file1.txt", TEXT);
+			File.WriteAllText ("file2.txt", TEXT);
+			string filePath = Path.GetFullPath ("file1.txt");
+			if (File.Exists ("enumerateonempty.zip"))
+				File.Delete ("enumerateonempty.zip");
+
+
+			using (var stream = File.Create ("test-archive-write.zip"))
+			using (var zip = ZipArchive.Create (stream)) {
+				foreach (var entry in zip) {
+					Console.Write (entry.FullName);
+				}
+				ZipEntry e;
+				e = zip.AddFile (filePath, "/path/ZipTestCopy1.exe");
+				filePath = Path.GetFullPath ("file2.txt");
+				e = zip.AddFile (filePath, "/path/ZipTestCopy2.exe");
+
+				foreach (var entry in zip) {
+					Console.Write (entry.FullName);
+				}
+
+				zip.Close ();
+			}
+
+			using (var zip = ZipArchive.Open ("test-archive-write.zip", FileMode.Open, strictConsistencyChecks: true)) {
+				foreach (var entry in zip) {
+					Console.Write (entry.FullName);
+				}
+			}
+		}
+
 		[TestCase (false)]
 		[TestCase (true)]
 		public void EnumerateSkipDeletedEntries (bool deleteFromExistingFile)

LibZipSharp.props

@@ -1,7 +1,7 @@
 <Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <_LibZipSharpAssemblyVersionMajor>3</_LibZipSharpAssemblyVersionMajor>
-    <_LibZipSharpAssemblyVersionMinor>2</_LibZipSharpAssemblyVersionMinor>
+    <_LibZipSharpAssemblyVersionMinor>3</_LibZipSharpAssemblyVersionMinor>
     <_LibZipSharpAssemblyVersionPatch>0</_LibZipSharpAssemblyVersionPatch>
     <_LibZipSharpAssemblyVersion>$(_LibZipSharpAssemblyVersionMajor).$(_LibZipSharpAssemblyVersionMinor).$(_LibZipSharpAssemblyVersionPatch)</_LibZipSharpAssemblyVersion>
     <_NativeLibraryVersionForName>$(_LibZipSharpAssemblyVersionMajor)-$(_LibZipSharpAssemblyVersionMinor)</_NativeLibraryVersionForName>

LibZipSharp/Xamarin.Tools.Zip/ZipArchive.cs

@@ -28,6 +28,7 @@
 using System.Buffers;
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Runtime.InteropServices;
 using System.Text;
@@ -195,19 +196,26 @@ ErrorCode Open (string path, OpenFlags flags)
 		/// </summary>
 		/// <param name="stream">The stream to open</param>
 		/// <param name="options">Platform-specific options</param>
-		public static ZipArchive Open (Stream stream, IPlatformOptions options = null)
+		/// <param name="strictConsistencyChecks"></param>
+		public static ZipArchive Open (Stream stream, IPlatformOptions options = null, bool strictConsistencyChecks = false)
 		{
-			return ZipArchive.CreateInstanceFromStream (stream, OpenFlags.None, options);
+			OpenFlags flags = OpenFlags.None;
+			if (strictConsistencyChecks)
+				flags |= OpenFlags.CheckCons;
+			return ZipArchive.CreateInstanceFromStream (stream, flags, options);
 		}
 
 		/// <summary>
 		/// Create a new archive using the Stream provided. The steam should be an empty stream, any existing data will be overwritten.
 		/// </summary>
 		/// <param name="stream">The stream to create the arhive in</param>
 		/// <param name="options">Platform-specific options</param>
-		public static ZipArchive Create (Stream stream, IPlatformOptions options = null)
+		public static ZipArchive Create (Stream stream, IPlatformOptions options = null, bool strictConsistencyChecks = false)
 		{
-			return ZipArchive.CreateInstanceFromStream (stream, OpenFlags.Create | OpenFlags.Truncate, options);
+			OpenFlags flags = OpenFlags.Create | OpenFlags.Truncate;
+			if (strictConsistencyChecks)
+				flags |= OpenFlags.CheckCons;
+			return ZipArchive.CreateInstanceFromStream (stream, flags, options);
 		}
 
 		/// <summary>
@@ -788,6 +796,7 @@ internal ZipException GetErrorException ()
 		internal static unsafe Int64 stream_callback (IntPtr state, IntPtr data, UInt64 len, SourceCommand cmd)
 		{
 			byte [] buffer = null;
+			Native.zip_error_t error;
 			int length = (int)len;
 			var handle = GCHandle.FromIntPtr (state);
 			if (!handle.IsAllocated)
@@ -833,30 +842,26 @@ internal static unsafe Int64 stream_callback (IntPtr state, IntPtr data, UInt64
 						return -1;
 					}
 
-					long firstOffset, secondOffset;
+					SeekOrigin seek = Native.ConvertWhence (args.whence);
 					if (args.offset > Int64.MaxValue) {
 						// Stream.Seek uses a signed 64-bit value for the offset, we need to split it up
-						firstOffset = Int64.MaxValue;
-						secondOffset = (long)(args.offset - Int64.MaxValue);
+						if (!Seek (destination, seek, Int64.MaxValue) || !Seek (destination, seek, (long)(args.offset - Int64.MaxValue))) {
+							return -1;
+						}
 					} else {
-						firstOffset = (long)args.offset;
-						secondOffset = 0;
-					}
-
-					SeekOrigin seek = Native.ConvertWhence (args.whence);
-					Native.zip_error_t error;
-
-					if (!SeekIfNeeded (destination, seek, firstOffset) || !SeekIfNeeded (destination, seek, secondOffset)) {
-						return -1;
+						if (!Seek (destination, seek, (long)args.offset)) {
+							return -1;
+						}
 					}
+
 					break;
 
 				case SourceCommand.Seek:
 					long offset = Native.zip_source_seek_compute_offset ((UInt64)stream.Position, (UInt64)stream.Length, data, len, out error);
 					if (offset < 0) {
 						return offset;
 					}
-					if (offset != stream.Seek (offset, SeekOrigin.Begin)) {
+					if (!Seek (stream, SeekOrigin.Begin, offset)) {
 						return -1;
 					}
 					break;
@@ -962,12 +967,8 @@ internal static unsafe Int64 stream_callback (IntPtr state, IntPtr data, UInt64
 
 			return 0;
 
-			bool SeekIfNeeded (Stream s, SeekOrigin origin, long offset)
+			bool Seek (Stream s, SeekOrigin origin, long offset)
 			{
-				if (offset == 0) {
-					return true;
-				}
-
 				return s.Seek (offset, origin) == offset;
 			}
 		}

azure-pipelines.yml

@@ -105,6 +105,11 @@ extends:
                 archiveType: 7z
                 replaceExistingArchive: true
                 archiveFile: $(Build.ArtifactStagingDirectory)\libzip-windows-arm-x64.7z
+            - script: |
+                7z t $(Build.ArtifactStagingDirectory)\libzip-windows-arm-x64.7z
+                7z t $(Build.ArtifactStagingDirectory)\libzip-windows-x64.7z
+                7z t $(Build.ArtifactStagingDirectory)\libzip-windows-x86.7z
+              displayName: Test Archives
 
         - job: buildLinux
           pool: