Bug 40916 - [System.IO.Compression] ZipArchive can create an ZipArchiveEntry that has a modified time of DateTime.MinValue
Summary: [System.IO.Compression] ZipArchive can create an ZipArchiveEntry that has a m...
Alias: None
Product: Class Libraries
Classification: Mono
Component: General ()
Version: 4.2.0 (C6)
Hardware: PC Linux
: Normal normal
Target Milestone: (C7SR1)
Assignee: João Matos
: 37970 ()
Depends on:
Reported: 2016-05-05 19:01 UTC by Peter Spada
Modified: 2016-07-13 22:04 UTC (History)
5 users (show)

Is this bug a regression?: ---
Last known good build:

Code an binaries to repro the bug (2.65 MB, application/x-zip-compressed)
2016-05-05 19:01 UTC, Peter Spada

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.

Please create a new report on GitHub or Developer Community with your current version information, steps to reproduce, and relevant error messages or log files if you are hitting an issue that looks similar to this resolved bug and you do not yet see a matching new report.

Related Links:

Description Peter Spada 2016-05-05 19:01:01 UTC
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));

Comment 1 João Matos 2016-06-17 17:31:11 UTC
Comment 2 Matt Ward 2016-06-22 13:49:34 UTC
*** Bug 37970 has been marked as a duplicate of this bug. ***
Comment 5 João Matos 2016-07-08 13:40:11 UTC
The build you tested does not contain the relevant commit, please test a more recent build.