Give ZipOutputStream an INameTransform property, and use it to transf…

…orm the names of newly added entries

src/ICSharpCode.SharpZipLib/Zip/FastZip.cs

@@ -368,6 +368,7 @@ public void CreateZip(Stream outputStream, string sourceDirectory, bool recurse,
 			using (outputStream_ = new ZipOutputStream(outputStream))
 			{
 				outputStream_.SetLevel((int)CompressionLevel);
+				outputStream_.NameTransform = null; // all required transforms handled by us
 
 				if (password_ != null)
 				{

src/ICSharpCode.SharpZipLib/Zip/ZipNameTransform.cs

@@ -247,4 +247,76 @@ public static bool IsValidName(string name)
 
 		#endregion Class Fields
 	}
+
+	/// <summary>
+	/// An implementation of INameTransform that transforms entry paths as per the Zip file naming convention.
+	/// Strips path roots and puts directory separators in the correct format ('/')
+	/// </summary>
+	public class PathTransformer : INameTransform
+	{
+		/// <summary>
+		/// Initialize a new instance of <see cref="PathTransformer"></see>
+		/// </summary>
+		public PathTransformer()
+		{
+		}
+
+		/// <summary>
+		/// Transform a windows directory name according to the Zip file naming conventions.
+		/// </summary>
+		/// <param name="name">The directory name to transform.</param>
+		/// <returns>The transformed name.</returns>
+		public string TransformDirectory(string name)
+		{
+			name = TransformFile(name);
+
+			if (name.Length > 0)
+			{
+				if (!name.EndsWith("/", StringComparison.Ordinal))
+				{
+					name += "/";
+				}
+			}
+			else
+			{
+				throw new ZipException("Cannot have an empty directory name");
+			}
+
+			return name;
+		}
+
+		/// <summary>
+		/// Transform a windows file name according to the Zip file naming conventions.
+		/// </summary>
+		/// <param name="name">The file name to transform.</param>
+		/// <returns>The transformed name.</returns>
+		public string TransformFile(string name)
+		{
+			if (name != null)
+			{
+				// Put separators in the expected format.
+				name = name.Replace(@"\", "/");
+
+				// Remove the path root.
+				name = WindowsPathUtils.DropPathRoot(name);
+
+				// Drop any leading and trailing slashes.
+				name = name.Trim('/');
+
+				// Convert consecutive // characters to /
+				int index = name.IndexOf("//", StringComparison.Ordinal);
+				while (index >= 0)
+				{
+					name = name.Remove(index, 1);
+					index = name.IndexOf("//", StringComparison.Ordinal);
+				}
+			}
+			else
+			{
+				name = string.Empty;
+			}
+
+			return name;
+		}
+	}
 }

src/ICSharpCode.SharpZipLib/Zip/ZipOutputStream.cs

@@ -1,4 +1,5 @@
 using ICSharpCode.SharpZipLib.Checksum;
+using ICSharpCode.SharpZipLib.Core;
 using ICSharpCode.SharpZipLib.Zip.Compression;
 using ICSharpCode.SharpZipLib.Zip.Compression.Streams;
 using System;
@@ -146,6 +147,12 @@ public UseZip64 UseZip64
 			set { useZip64_ = value; }
 		}
 
+		/// <summary>
+		/// Used for transforming the names of entries added by <see cref="PutNextEntry(ZipEntry)"/>.
+		/// Defaults to <see cref="PathTransformer"/>, set to null to disable transforms and use names as supplied.
+		/// </summary>
+		public INameTransform NameTransform { get; set; } = new PathTransformer();
+
 		/// <summary>
 		/// Write an unsigned short in little endian byte order.
 		/// </summary>
@@ -182,6 +189,34 @@ private void WriteLeLong(long value)
 			}
 		}
 
+		// Apply any configured transforms/cleaning to the name of the supplied entry.
+		private string TransformEntryName(ZipEntry entry)
+		{
+			string transformedName = entry.Name;
+
+			if (this.NameTransform != null)
+			{
+				if (entry.IsDirectory)
+				{
+					transformedName = this.NameTransform.TransformDirectory(entry.Name);
+				}
+				else
+				{
+					transformedName = this.NameTransform.TransformFile(entry.Name);
+				}
+			}
+
+			return transformedName;
+		}
+
+		// Convert an entry name to a byte array, and apply any transforms
+		private byte[] TransformEntryNameToArray(ZipEntry entry)
+		{
+			string transformedName = TransformEntryName(entry);
+			byte[] name = ZipStrings.ConvertToArray(entry.Flags, transformedName);
+			return name;
+		}
+
 		/// <summary>
 		/// Starts a new Zip entry. It automatically closes the previous
 		/// entry if present.
@@ -367,7 +402,7 @@ public void PutNextEntry(ZipEntry entry)
 				}
 			}
 
-			byte[] name = ZipStrings.ConvertToArray(entry.Flags, entry.Name);
+			byte[] name = TransformEntryNameToArray(entry);
 
 			if (name.Length > 0xFFFF)
 			{
@@ -787,7 +822,7 @@ public override void Finish()
 					WriteLeInt((int)entry.Size);
 				}
 
-				byte[] name = ZipStrings.ConvertToArray(entry.Flags, entry.Name);
+				byte[] name = TransformEntryNameToArray(entry);
 
 				if (name.Length > 0xffff)
 				{