add writable checks

src/SharpCompress/StreamValidationExtensions.cs

@@ -31,6 +31,18 @@ internal static class StreamValidationExtensions
         return stream;
     }
 
+    internal static Stream RequireWritable(this Stream stream)
+    {
+        stream.NotNull(nameof(stream));
+
+        if (!stream.CanWrite)
+        {
+            throw new ArgumentException("Stream must be writable", nameof(stream));
+        }
+
+        return stream;
+    }
+
     internal static IReadOnlyList<Stream> RequireSeekable(this IReadOnlyList<Stream> streams)
     {
         streams.NotNull(nameof(streams));

src/SharpCompress/Writers/GZip/GZipWriter.Factory.cs

@@ -22,7 +22,7 @@ public partial class GZipWriter : IWriterOpenable<GZipWriterOptions>
 
     public static IWriter OpenWriter(Stream stream, GZipWriterOptions writerOptions)
     {
-        stream.NotNull(nameof(stream));
+        stream.RequireWritable();
         return new GZipWriter(stream, writerOptions);
     }
 

src/SharpCompress/Writers/SevenZip/SevenZipWriter.Factory.cs

@@ -36,7 +36,7 @@ public partial class SevenZipWriter : IWriterOpenable<SevenZipWriterOptions>
     /// </summary>
     public static IWriter OpenWriter(Stream stream, SevenZipWriterOptions writerOptions)
     {
-        stream.NotNull(nameof(stream));
+        stream.RequireWritable();
         return new SevenZipWriter(stream, writerOptions);
     }
 

src/SharpCompress/Writers/Tar/TarWriter.Factory.cs

@@ -22,7 +22,7 @@ public partial class TarWriter : IWriterOpenable<TarWriterOptions>
 
     public static IWriter OpenWriter(Stream stream, TarWriterOptions writerOptions)
     {
-        stream.NotNull(nameof(stream));
+        stream.RequireWritable();
         return new TarWriter(stream, writerOptions);
     }
 

src/SharpCompress/Writers/WriterFactory.cs

@@ -75,6 +75,8 @@ public static class WriterFactory
         IWriterOptions writerOptions
     )
     {
+        stream.RequireWritable();
+
         var factory = Factories
             .Factory.Factories.OfType<IWriterFactory>()
             .FirstOrDefault(item => item.KnownArchiveType == archiveType);
@@ -102,6 +104,8 @@ public static class WriterFactory
         CancellationToken cancellationToken = default
     )
     {
+        stream.RequireWritable();
+
         var factory = Factories
             .Factory.Factories.OfType<IWriterFactory>()
             .FirstOrDefault(item => item.KnownArchiveType == archiveType);

src/SharpCompress/Writers/Zip/ZipWriter.Factory.cs

@@ -22,7 +22,7 @@ public partial class ZipWriter : IWriterOpenable<ZipWriterOptions>
 
     public static IWriter OpenWriter(Stream stream, ZipWriterOptions writerOptions)
     {
-        stream.NotNull(nameof(stream));
+        stream.RequireWritable();
         return new ZipWriter(stream, writerOptions);
     }
 

tests/SharpCompress.Test/WriterFactoryTests.cs

@@ -0,0 +1,34 @@
+using System;
+using System.IO;
+using System.Threading.Tasks;
+using SharpCompress.Common;
+using SharpCompress.Test.Mocks;
+using SharpCompress.Writers;
+using Xunit;
+
+namespace SharpCompress.Test;
+
+public class WriterFactoryTests
+{
+    [Fact]
+    public void OpenWriter_Stream_Throws_On_Unwritable_Stream()
+    {
+        using var unwritable = new TestStream(new MemoryStream(), true, false, true);
+
+        Assert.Throws<ArgumentException>(() =>
+            WriterFactory.OpenWriter(unwritable, ArchiveType.Zip, WriterOptions.ForZip())
+        );
+    }
+
+    [Fact]
+    public async ValueTask OpenAsyncWriter_Stream_Throws_On_Unwritable_Stream()
+    {
+        using var unwritable = new TestStream(new MemoryStream(), true, false, true);
+
+        await Assert.ThrowsAsync<ArgumentException>(() =>
+            WriterFactory
+                .OpenAsyncWriter(unwritable, ArchiveType.Zip, WriterOptions.ForZip())
+                .AsTask()
+        );
+    }
+}