I have googled without any luck.
My question is if there is a way to see when the file has been zipped? I am not asking for when the file has been created or modified rather to see when it has been zipped.
Is there a byte I can read from the zipped file somehow to find out this in code (C#)?
Best regards
As far as I can tell,that information is not stored in the zip file. The only info you can get is the last time that file inside the zip was modified. That datetime could or could not be the first time that file was included in the zip file.
If you want to get the last time the entry in the zip archive was changed, you can use the ZipArchiveEntry.LastWriteTime in the System.IO.Compression Namespace.
If you have any doubt of what info is availble in a zip file, you can check this wikipedia article : Zip File Format
Related
I am developing an application which takes the Back Up of Docx file. For the Initial Back Up I copy the entire file in the destination, but next time I want to perform an incremental Back Up i.e I want to backup only that segment of the Docx file that has undergone changes. I need to find the most efficient to do the same.
I would really be thankful if I get any help in this regard.
The DOCX file is different from the previous Microsoft Word programs, which use the file extension DOC, in the sense that whereas a DOC file uses a text or binary format for storing a document, a DOCX file is based on XML and uses ZIP compression for a smaller file size. In other words, a DOCX file is a set of XML files that have been compressed using ZIP.
It might help if you can use ZipFile to dissect and tell which file is really changed and then incrementally save only the changes in your VCS.
In my asp.net aplication I would like to give the oportunity to the user to check on its local machine zip file. Then I would like to get this file on server(without saving it on the server) unzip it proceed and save proceeded data to database.
What should I do to accomplish this task? Thank You for any hints
I would use a zip library to read in the zip file stream and process the files contained inside. I have previously used SharpZipLib for this purpose before. See SharpZipLib Examples for more information.
My application need to download multiple files in Silverlight, and because I don't want to ask user multiple times for permission to save the files, I save the files in IsolatedStorage first and then I want to zip them all to a file and ask once for saving permission.
therefore I used SharpZipLib to zip multiple files which are located in IsolatedStorage, the problem is that SharpZipLib just accept file address as ZipEntery:
ZipEntry z= new ZipEntry(name);
and as you know cause the files are located in IsolatedStorage I don't have the address of them.
I saw sample on Create a Zip from/to a memory stream or byte array but I cant use it for multiple files.
Please help me to find a way to use SharpZipLib or introduce me another way to downloading multiple files without asking multiple times for permission.
The name in ZipEntry z= new ZipEntry(name); is a logical/relative name inside your zip, you can establish it any way you want.
So as long as you can re-open you IsoStorage files as a Stream, you should be able to use SharpZip.
I am using Sharpziplib version 0.86 to extract a zip file. It is working fine but while extracting a winzip file through code,Lastwritetime is changing in seconds...
Have used this also File.SetLastWriteTime(fullPath, theEntry.DateTime);
Actual file Lastwritetime:4/8/2010 2:29:03PM
After zipping that file using winzip and while extracting that file using the code,extracted file Lastwritetime changes to 4/8/2010 2:29:04PM...Is there any fix for this???
I got this response from Sharpziplib Forum
Hi
This appears to be a WinZip bug. I have not noticed this before.
I did this test:
1) Use WinZip to add a file to a zip. In WinZip click Properties and Details. Look through the details list and find the file time stamp.
2) Use SharpZipLib to create a similar zip file with the same inputfile. Open the result in Winzip and look at the Properties > Details for the file time stamp.
My input file has a Modified timestamp (file properties) of 2010-12-14 15:51:28 and in my test, SharpZipLib stored it correctly in the zip, while WinZip stored it as 2010-12-14 15:51:30
In other words WinZip added 2 seconds when putting it into the zip.
After extracting (either with WinZip or SharpZip), the Modified is now 15:51:30 instead of the original 15:51:28.
it is amazing that such an obvious bug in WinZip can have gone unreported and unfixed for so long. If you have a paid version you should certainly raise a bug fault with them.
I just remembered something about 2 second granularity in the old 8.3 file system timestamps.
Quick google found this ...
Quote "Original DOS file system had only 32 bytes to represent a file in the directory. The very restrictive 8.3 filename and the limited granularity (2 second) in file date are corrected in the Win32 file systems (VFAT)."
from http://www.xxcopy.com/xxcopy15.htm
The Zip format only allows 2 second granularity in the standard time stamp entry.The date and time are encoded in standard MS-DOS format.
An optional NTFS Extra Data field (0x000a) can be included, which may hold last modification time, last access time and creation time. WinZip does not appear to create it. SharpZip will use it if present but as far as I can see, it is not created when using FastZip to create a zip. That might be a useful option to add to the code. You can certainly create it manually if using ZipFile.
Hope this helps,
David
I think it might just be the operating system that is causing this. I've tried what happens in Explorer. I've got a text file with a modified time stamp of 17:06:45. I right click on the file and choose Send to | Compressed (zipped) folder. Then I right click on the new zip-file and choose Extract All... followed by Next, Next, Finish. Now the extracted text file has a time stamp of 17:06:46.
The same happens when I use 7-Zip, or WinRar. But then it only happens when using a .zip file. If I let them create a .7Z or a .RAR file the time stamp isn't changed.
Found an article on Wikipedia about the zip format. If you search it for "seconds" you'll find a section describing that the ZIP file system mimics the DOS FAT file system, which only has a time resolution of two seconds.
I have a archive (I know its a game compression) and I am trying to figure out how it is compressed so I can add files to it using C#. It opens/works in 7zip, and winrar. But when I use ZipForge/ComponentAce archive reference it says Invalid File.
Any help?
Steve
Have you opened the file up in a binary editor to see if the first few bytes denote the format?
For example ZIP files have the header format given on here http://www.ta7.de/txt/computer/computer016.htm
What extension does the file have?