Fix XLSX loading with 64-bit ZIP data descriptors

EPPlus/Packaging/ZipPackage.cs

@@ -96,27 +96,31 @@ internal ZipPackage(Stream stream)
             {
                 var rels = new Dictionary<string, string>();
                 stream.Seek(0, SeekOrigin.Begin);                
-                using (ZipInputStream zip = new ZipInputStream(stream))
+                using (stream)
+                using (ZipFile zip = ReadZipFile(stream))
                 {
-                    var e = zip.GetNextEntry();
-                    if(e==null)
+                    var firstEntry = zip.Entries.FirstOrDefault();
+                    if (firstEntry == null)
                     {
                         throw (new InvalidDataException("The file is not an valid Package file. If the file is encrypted, please supply the password in the constructor."));
                     }
-                    if (e.FileName.Contains("\\"))
+                    if (firstEntry.FileName.Contains("\\"))
                     {
                         _dirSeparator = '\\';
                     }
                     else
                     {
                         _dirSeparator = '/';
                     }
-                    while (e != null)
+                    foreach (var e in zip)
                     {
                         if (e.UncompressedSize > 0)
                         {
                             var b = new byte[e.UncompressedSize];
-                            var size = zip.Read(b, 0, (int)e.UncompressedSize);
+                            using (var entryStream = new MemoryStream(b))
+                            {
+                                e.Extract(entryStream);
+                            }
                             if (e.FileName.Equals("[content_types].xml", StringComparison.OrdinalIgnoreCase))
                             {
                                 AddContentTypes(Encoding.UTF8.GetString(b));
@@ -141,10 +145,6 @@ internal ZipPackage(Stream stream)
                                 }
                             }
                         }
-                        else
-                        {
-                        }
-                        e = zip.GetNextEntry();
                     }
 
                     foreach (var p in Parts)
@@ -169,16 +169,22 @@ internal ZipPackage(Stream stream)
                     {
                         throw (new InvalidDataException("The file is not an valid Package file. If the file is encrypted, please supply the password in the constructor."));
                     }
-                    if (!hasContentTypeXml)
-                    {
-                        throw (new InvalidDataException("The file is not an valid Package file. If the file is encrypted, please supply the password in the constructor."));
-                    }
-                    zip.Close();
-                    zip.Dispose();
                 }
             }
         }
 
+        private static ZipFile ReadZipFile(Stream stream)
+        {
+            try
+            {
+                return ZipFile.Read(stream);
+            }
+            catch (ZipException ex)
+            {
+                throw new InvalidDataException("The file is not an valid Package file. If the file is encrypted, please supply the password in the constructor.", ex);
+            }
+        }
+
         private void AddContentTypes(string xml)
         {
             var doc = new XmlDocument();

EPPlusTest/EPPlusTest.Core.csproj

@@ -33,6 +33,10 @@
     <WarningsAsErrors>$(WarningsAsErrors);CA1416</WarningsAsErrors>
   </PropertyGroup>
 
+  <ItemGroup>
+    <None Update="Workbooks\test-zip64-descriptor.xlsx" CopyToOutputDirectory="PreserveNewest" />
+  </ItemGroup>
+
   <ItemGroup>
     <None Remove="Resources\BitmapImage.gif" />
     <None Remove="Resources\Test1.jpg" />

EPPlusTest/ExcelPackageTests.cs

@@ -1,15 +1,47 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using OfficeOpenXml;
 using System;
-using System.Collections.Generic;
 using System.IO;
-using System.Text;
 
 namespace EPPlusTest
 {
     [TestClass]
     public class ExcelPackageTests
     {
-
+        [TestMethod]
+        public void ReadWorkbookWithZip64DataDescriptors()
+        {
+            var path = Path.Combine(AppContext.BaseDirectory, "Workbooks", "test-zip64-descriptor.xlsx");
+            using (var stream = File.OpenRead(path))
+            using (var package = new ExcelPackage(stream))
+            {
+                Assert.AreEqual(1, package.Workbook.Worksheets.Count);
+                var worksheet = package.Workbook.Worksheets["Sheet1"];
+                Assert.IsNotNull(worksheet);
+                Assert.AreEqual("test", worksheet.Cells["A1"].Value);
+                Assert.AreEqual("A1", worksheet.Dimension.Address);
+            }
+        }
+
+        [TestMethod]
+        public void SaveAndReloadWorkbookWithZip64DataDescriptors()
+        {
+            var path = Path.Combine(AppContext.BaseDirectory, "Workbooks", "test-zip64-descriptor.xlsx");
+            using (var input = File.OpenRead(path))
+            using (var output = new MemoryStream())
+            {
+                using (var package = new ExcelPackage(input))
+                {
+                    package.SaveAs(output);
+                }
+                output.Position = 0;
+                using (var package = new ExcelPackage(output))
+                {
+                    Assert.AreEqual(1, package.Workbook.Worksheets.Count);
+                    Assert.AreEqual("test", package.Workbook.Worksheets["Sheet1"].Cells["A1"].Value);
+                }
+                Assert.IsTrue(input.CanRead, "Loading the package must leave the caller's input stream open.");
+            }
+        }
     }
 }