Fix enumerating zip with deleted entries (#53)

Previously, if a zip had deleted entries then enumerating the entries in the zip would throw an exception - the ReadEntry call on a deleted entry would thrown an exception. With this change, deleted entries are instead skipped in the enumeration.
Co-authored-by: Jonathan Pryor <jonpryor@vt.edu>

Author: Bret Johnson

LibZipSharp.UnitTest/ZipTests.cs

@@ -1,5 +1,6 @@
 usingNUnit.Framework;
 usingSystem;
+usingSystem.Collections.Generic;
 usingSystem.IO;
 usingSystem.Text;
 usingSystem.Threading;
@@ -157,5 +158,64 @@ public void SmallTextFile ()
 }
 }
 }
+
+[TestCase(false)]
+[TestCase(true)]
+publicvoidEnumerateSkipDeletedEntries(booldeleteFromExistingFile)
+{
+varms=newMemoryStream(Encoding.UTF8.GetBytes(TEXT));
+File.WriteAllText("file1.txt","1111");
+stringfilePath=Path.GetFullPath("file1.txt");
+if(File.Exists("test-archive-write.zip"))
+File.Delete("test-archive-write.zip");
+
+ZipArchivezip=null;
+try{
+zip=ZipArchive.Open("test-archive-write.zip",FileMode.CreateNew);
+
+ZipEntrye;
+e=zip.AddFile(filePath,"/path/ZipTestCopy1.exe");
+e=zip.AddFile(filePath,"/path/ZipTestCopy2.exe");
+vartext="Hello World";
+e=zip.AddEntry("/data/foo1.txt",text,Encoding.UTF8,CompressionMethod.Store);
+e=zip.AddEntry("/data/foo2.txt",File.OpenRead(filePath),CompressionMethod.Store);
+
+if(deleteFromExistingFile){
+zip.Close();
+zip=ZipArchive.Open("test-archive-write.zip",FileMode.Open);
+}
+
+ValidateEnumeratedEntries(zip,"path/ZipTestCopy1.exe","path/ZipTestCopy2.exe","data/foo1.txt","data/foo2.txt");
+
+// Delete first
+zip.DeleteEntry("path/ZipTestCopy1.exe");
+ValidateEnumeratedEntries(zip,"path/ZipTestCopy2.exe","data/foo1.txt","data/foo2.txt");
+
+// Delete last
+zip.DeleteEntry("data/foo2.txt");
+ValidateEnumeratedEntries(zip,"path/ZipTestCopy2.exe","data/foo1.txt");
+
+// Delete middle
+zip.DeleteEntry("path/ZipTestCopy2.exe");
+ValidateEnumeratedEntries(zip,"data/foo1.txt");
+
+// Delete all
+zip.DeleteEntry("data/foo1.txt");
+ValidateEnumeratedEntries(zip);
+}
+finally{
+zip?.Dispose();
+}
+}
+
+voidValidateEnumeratedEntries(ZipArchivezip,paramsstring[]expectedEntries)
+{
+varactualEntries=newList<string>();
+foreach(varentryinzip){
+actualEntries.Add(entry.FullName);
+}
+
+Assert.AreEqual(expectedEntries,actualEntries.ToArray());
+}
 }
-}
+}

ZipArchive.cs

@@ -368,8 +368,8 @@ public ZipEntry AddFileToDirectory (string sourcePath, string archiveDirectory =
 stringdestDir=NormalizeArchivePath(true,archiveDirectory);
 stringdestFile=useFileDirectory?GetRootlessPath(sourcePath):Path.GetFileName(sourcePath);
 returnAddFile(sourcePath,
-String.IsNullOrEmpty(destDir)?null:destDir+"/"+destFile,
-permissions,compressionMethod,overwriteExisting);
+String.IsNullOrEmpty(destDir)?null:destDir+"/"+destFile,
+permissions,compressionMethod,overwriteExisting);
 }
 
 /// <summary>
@@ -692,11 +692,40 @@ public ZipEntry ReadEntry (string entryName, bool caseSensitive = false)
 }
 
 publicZipEntryReadEntry(ulongindex)
+{
+returnReadEntry(index,throwIfDeleted:true);
+}
+
+/// <summary>
+/// Read a zip entry, given an index.
+/// 
+/// When throwIfDeleted is true, if the entry is deleted then an exception is thrown (the error will be
+/// ErrorCode.Deleted or ErrorCode.Inval, depending on whether the deleted entry previously existed in
+/// the zip or was newly added - that's just how libzip handles that). If throwIfDeleted is false then
+/// null is returned for deleted entries and an exception is just thrown for other errors.
+/// </summary>
+/// <param name="index">index to read</param>
+/// <param name="throwIfDeleted">whether to return null or throw an exception for deleted entries</param>
+/// <returns></returns>
+publicZipEntryReadEntry(ulongindex,boolthrowIfDeleted)
 {
 Native.zip_stat_tstat;
 intret=Native.zip_stat_index(archive,index,OperationFlags.None,outstat);
-if(ret<0)
+if(ret<0){
+if(!throwIfDeleted){
+IntPtrerror=Native.zip_get_error(archive);
+
+if(error!=IntPtr.Zero){
+intzip_error=Native.zip_error_code_zip(error);
+// Deleted is returned when the deleted entry existed when the zip was opened
+// Inval is returned when the deleted entry was newly added to the zip, then deleted
+if(zip_error==(int)ErrorCode.Deleted||zip_error==(int)ErrorCode.Inval)
+returnnull;
+}
+}
+
 throwGetErrorException();
+}
 
 varze=ZipEntry.Create(this,stat);
 ze.Init();

ZipEntryEnumerator.cs

@@ -62,7 +62,15 @@ public bool MoveNext ()
 
 // Calling it each time because the archive can change in the meantime
 longnentries=archive.EntryCount;
-if(nentries<0||index>=(ulong)nentries)
+if(nentries<0)
+returnfalse;
+
+// Skip past any deleted entires
+while(index<(ulong)nentries&&ReadEntry(index)==null){
+++index;
+}
+
+if(index>=(ulong)nentries)
 returnfalse;
 returntrue;
 }
@@ -87,7 +95,7 @@ ZipEntry ReadEntry (ulong index)
 if(current!=null&&current.Index==index)
 returncurrent;
 
-current=archive.ReadEntry(index);
+current=archive.ReadEntry(index,throwIfDeleted:false);
 returncurrent;
 }
 }