Bug 40916

Created attachment 15922 [details]
Code an binaries to repro the bug

If a zip file has entries that don't have a "last write time" set, then the ZipArchiveEntry objects that are generated have a LastWriteTime of DateTime.MinValue.

While that seems like a reasonable time to use, it's different from .NET on Windows and can cause problems when the ZipArchiveEntry.LastWriteTime is used while unzipping the ZipArchive to disk. This caused a bug in NuGet: https://github.com/NuGet/Home/issues/2518

See the attached file for a project that reproduces the issue. It contains a zip file (*.nupkg) that has entries that don't have a last write time.

On .NET on Windows, for zip entries that don't have a last write time, the return value for ZipArchiveEntry.LastWriteTime is:
  1/1/1980 12:00:00 AM, Ticks=624511296000000000

On Mono on Linux, the return value for ZipArchiveEntry.LastWriteTime is:
  1/1/0001 12:00:00 AM, Ticks=0

Here is the sample code from the attachment:

namespace EntryTimeApp
{
    class Program
    {
        static void Main(string[] args)
        {
            string file = "modernhttpclient.2.4.2.nupkg";
            System.IO.Stream zipStream = System.IO.File.OpenRead(file);
            System.IO.Compression.ZipArchive zip = new System.IO.Compression.ZipArchive(zipStream, System.IO.Compression.ZipArchiveMode.Read);

            System.Console.WriteLine("Dumping entries in " + file);

            foreach (System.IO.Compression.ZipArchiveEntry entry in zip.Entries)
            {
                System.Console.WriteLine(string.Format("Name:{0}, Time:{1}, Ticks:{2}", entry.FullName, entry.LastWriteTime, entry.LastWriteTime.Ticks));
            }

            System.Console.WriteLine("Done");
        }
    }
}