[ { "Id": "225135", "ThreadId": "66280", "Html": "

I am using the latest DotNetZipLib and am wondering when I zip to a disk file and use:   zip.AddFile(FileName, PathName);

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I get the correct modified time stamps of the files in the zip file.

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However when I zip to a memory stream and use:  zip.AddEntry(FileName, PathName, File.ReadAllBytes(FileName));

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I do not get correct modified time stamps in the zip file but the timestamps are all the same.  (I get the time of the zip operation).

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thanks

", "PostedDate": "2009-08-18T13:52:36.003-07:00", "UserRole": null, "MarkedAsAnswerDate": null }, { "Id": "225146", "ThreadId": "66280", "Html": "

The behavior you are observing is expected.

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If you call ZipFile.AddFile(), you pass in the name of a file on the disk.  The DotNetZip library can then open the file and retrieve its timestamps, and embed those timestamps into the zip archive, once it is saved.

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If you call ZipFile.AddEntry(), there is no way for DotNetZip to know where you got the content for the entry (in this case a byte array).  You called File.ReadAllBytes(), but DotNetZip doesn't know that.  To DotNetZip, it is just a byte array, and there is no way for DotNetZip to relate that byte array back to the source filesystem file.  The bytes could just as easily have been randomly generated - there is no way for DotNetZip to know where you got them.  Therefore there is no way for DotNetZip to intelligently set the timestamps on an entry added this way.

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You seem to be mixing up 2 things:  you said "when I zip to a disk file" and "when I zip to a memory stream".    I think when you say "zip to a disk file" you mean, savve the zip archive to a file in the filesystem.  And when you say "zip to a memory stream" you mean "save the zip archive to a MemoryStream."   But the timestamps for the entries in a zipfile will not vary depending on how you save the ZipFile.  The timestamps vary (as I described above) depending on how you add the entries.

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code example #1:

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using (var zip = new ZipFile())\r\n{\r\n    zip.AddFile("MyFile.txt");\r\n    zip.Save("MyArchive.zip");\r\n}\r\n
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The above code will save the zip archive into a filesystem file, and timestamps for the single entry will be intact.

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example 2:

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using (var ms = new MemoryStream())\r\n{\r\n  using (var zip = new ZipFile())\r\n  {\r\n      zip.AddFile("MyFile.txt");\r\n      zip.Save(ms);\r\n  }\r\n}\r\n\r\n
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The above code will save the zip archive into a memory stream, and timestamps for the single entry will be intact.

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On the other hand, example 3:

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using (var zip = new ZipFile())\r\n{\r\n    zip.AddEntry("MyFile.txt","",File.ReadAllBytes("MyFile.txt"));\r\n    zip.Save("MyArchive.zip");\r\n}\r\n
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The above code will save the zip archive into a filesystem file, but timestamps for the single entry will all show "the current time".

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Likewise, example 4:

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using (var ms = new MemoryStream())\r\n{\r\n  using (var zip = new ZipFile())\r\n  {\r\n      zip.AddEntry("MyFile.txt","",File.ReadAllBytes("MyFile.txt"));\r\n      zip.Save(ms);\r\n  }\r\n}\r\n\r\n
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The above code will save the zip archive into a MemoryStream, but timestamps for the single entry will all show "the current time".

", "PostedDate": "2009-08-18T14:24:02.43-07:00", "UserRole": null, "MarkedAsAnswerDate": null }, { "Id": "225934", "ThreadId": "66280", "Html": "

Thanks for the clear explanation.  Now I can zip in memory successfully with correct file timestamps and copy the files using a different set of credentials and then write to the zip file using default credentials!

", "PostedDate": "2009-08-20T09:15:58.473-07:00", "UserRole": null, "MarkedAsAnswerDate": null } ]