Develop Reference

How to read data from inner archives without extracting zip file?

I have a zip file which contains inner zip file (Ex:ZipFile1.zip->ZipFile2.zip->file.txt). I want to read the data of inner archive file content (file.txt) using ICSharpCode.SharpZipLib library without extracting to disk. Is it possible? If it is possible, Let me know how to get this.

Based on this answer, you can open a file within the zip as a Stream. You can also open a ZipFile from a Stream. I'm sure you can see where this is heading.
using (var zip = new ZipFile("ZipFile1.zip"))
{
var nestedZipEntry = zip.GetEntry("ZipFile2.zip");
using (var nestedZipStream = zip.GetInputStream(nestedZipEntry))
using (var nestedZip = new ZipFile(nestedZipStream))
{
var fileEntry = nestedZip.GetEntry("file.txt");
using (var fileStream = nestedZip.GetInputStream(fileEntry))
using (var reader = new StreamReader(fileStream))
{
Console.WriteLine(reader.ReadToEnd());
}
}
}
What we're doing here:
Open ZipFile1.zip
Find the entry for ZipFile2.zip
Open ZipFile2.zip as a Stream
Create a new ZipFile object around nestedZipStream.
Find the entry for file.txt
Create a StreamReader around fileStream to read the text file.
Read the contents of file.txt and output it to the console.
Try it online - in this sample, the base64 data is the binary data of a zip file which contains "test.zip", which in turn contains "file.txt". The contents of that text file is "hello".
P.S. If an entry isn't found then GetEntry will return null. You'll want to check for that in any code you write. It works here because I'm sure that these entries exist in their respective archives.

System.IO: Convert zip file to byte[] without saving file

I'm having trouble using the System.IO.Compression library to create a zip file and then return the byte[] for that zip file. So I want the method to take an input string--the path for the file to be zipped--and return the corresponding byte array for the file once it's been zipped. Currently, I can save the zip file to some known path and then use System.IO.File.ReadAllBytes(path) to get the byte[].
But how can I do this if I don't know beforehand where that zip file should end up (if anywhere at all)? My attempt at the solution is below. It doesn't seem to be working because when I try to reconstruct the zip file from the byte array it says that the archive is in an unknown format or damaged. Note: I've been able to do this using the Ionic DotNetZip library; however, I'm trying to do the same with only the use of System.IO libraries.
Any ideas on how to go about this?
private static byte[] CreateZipAndFindBytes(string importfile)
{
byte[] retVal = null;
using (System.IO.MemoryStream memStream = new System.IO.MemoryStream())
{
//ZipArchive(Stream, ZipArchiveMode, Boolean) //true means leave stream open
using (System.IO.Compression.ZipArchive archive = new System.IO.Compression.ZipArchive(memStream, System.IO.Compression.ZipArchiveMode.Create, true))
{
archive.CreateEntryFromFile(importfile, "test.zip"); //adds the file to the zip
}
retVal = memStream.ToArray();
}
return retVal;
}

entryName, the second parameter of CreateEntryFromFile is supposed to be "The name of the entry to create in the zip archive." It's not the name of your zip file.
you're zipping the import file, but also renaming it with a .zip extension, and I'm assuming that the import file is not actually a zip.
do this instead
archive.CreateEntryFromFile(importfile, importfile); //adds the file to the zip

Create ZipArchive from XML with base64 encoded content

I am creating an XML file on the fly.
One of it's nodes contains a ZIP file encoded as a BASE64 string.
I then create another ZIP file.
I add this XML file and a few other JPEG files.
I output the file to the browser.
I am unable to open the FINAL ZIP file.
I get: "Windows cannot open the folder. The Compressed(zipped) Folder'c:\path\file.zip' is invalid."
I am able to save my original XML file to the file system.
I can open that XML file, decode the ZIP node and save to the file system.
I am then able to open that Zip file with no problems.
I can create the final ZIP file, OMIT my XML file, and the ZIP file opens no problem.
I seem to only have an issue with I attempt to ZIP an XML file that has a node with ZIP content encoded as a BASE64 string.
Any ideas? Code snipets are below. Heavily edited.
XDocument xDoc = new XDocument();
XDocument xDocReport = new XDocument();
XElement xNodeReport;
using (FileStream fsData = new FileStream(strFullFilePath, FileMode.Open, FileAccess.Read)) {
xDoc = XDocument.Load(fsData);
xNodeReport = xDoc.Element("Data").Element("Reports").Element("Report");
//SNIP
//create XDocument xDocReport
//SNIO
using (MemoryStream zipInMemoryReport = new MemoryStream()) {
using (ZipArchive zipFile = new ZipArchive(zipInMemoryReport, ZipArchiveMode.Update)) {
//Add REPORT to ZIP file
ZipArchiveEntry entryReport = zipFile.CreateEntry("data.xml");
using (StreamWriter writer = new StreamWriter(entryReport.Open())) {
writer.Write(xDocReport.ToString());
} //END USING report entry
}
xNodeReport.Value = System.Convert.ToBase64String(zipInMemoryReport.GetBuffer());
//I am able to write this file to disk and manipulate it no problem.
//File.WriteAllText("c:\\users\\snip\\desktop\\Report.xml",xDoc.ToString());
}
//create ZIP for response
using (MemoryStream zipInMemory = new MemoryStream()) {
using (ZipArchive zipFile = new ZipArchive(zipInMemory, ZipArchiveMode.Update)) {
//Add REPORT to ZIP file
ZipArchiveEntry entryReportWrapper = zipFile.CreateEntry("Report.xml");
//THIS IS THE STEP THAT makes the Zip "invalid". Although i can open and manipulate this source file no problem.
//********
using (StreamWriter writer = new StreamWriter(entryReportWrapper.Open())) {
xDoc.Save(writer);
}
//Add JPEG(s) to report
//Create Charts
if (chkDLSalesPrice.Checked) {chartDownloadSP.SaveImage(entryChartSP.Open(), ChartImageFormat.Jpeg);}
if (chkDLSalesDOM.Checked) {chartDownloadDOM.SaveImage(entryChartDOM.Open(), ChartImageFormat.Jpeg);}
if (chkDLSPLP.Checked) {chartDownloadSPLP.SaveImage(entryChartSPLP.Open(), ChartImageFormat.Jpeg);}
if (chkDLSPLP.Checked) {chartDownloadLP.SaveImage(entryChartLP.Open(), ChartImageFormat.Jpeg);}
} // END USING ziparchive
Response.Clear();
Response.AppendHeader("content-disposition", "attachment; filename=file.zip");
Response.ContentType = "application/zip";
Response.BinaryWrite(zipInMemory.GetBuffer());
Response.End();

Without a good, minimal, complete code example, it's impossible to know for sure what bugs are in the code. But there are at least two apparent errors in the code snippet you posted, one of which could easily be responsible for the "invalid .zip" error:
In the statement writer.Write(xDocReport.ToString());, the variable xDocReport has not been initialized to anything useful, at least not in the code you posted. So you'll get an empty XML document in the archive.
Since the code example is incomplete, it's possible you just omitted from the code example in your question the initialization of that variable to something else. In any case, even if you didn't that would just lead to an empty XML document in the archive, not an invalid archive.
More problematic though…
You are calling GetBuffer() on your MemoryStream objects, instead of ToArray(). You want the latter. The former gets the entire backing buffer for the MemoryStream object, including the uninitialized bytes past the end of the valid stream. Since a valid .zip file includes a CRC value at the end of the file, adding extra data beyond that causes anything trying to read the file as a .zip archive to miss the correct CRC, reading the uninitialized data instead.
Replace your calls to GetBuffer() with calls to ToArray() instead.
If the above does not lead to a solution for your problem, you should edit your post, to provide a better code example.
One last comment: there is no point in initializing a variable like xDoc to an empty XDocument object when you're going to just replace that object with a different one (e.g. by calling XDocument.Load()).

Creating a zipped Document that containing files from memory stream / byte array in C#

I'm needing to create a zipped document containing files that exist on the server. I am using the Ionic.Zip to do so, and to create a new Package (which is the zip file) I have to have either a path to a physical file or a stream. I am trying to not create an actual file that would be the zip file, instead just create a stream that would exist in memory or something. how can i do this?

Create the package using a MemoryStream then.

You can try the save method in the ZipFile Class. It can save to a stream
try this.
using (MemoryStream ms = new MemoryStream())
{
using (Ionic.Zip.ZipFile zipFile = new Ionic.Zip.ZipFile())
{
zipFile.AddFiles(filesToBeZipped, false, "NewFolder");//filesTobeZipped is a List<string>
zipFile.Save(ms);
}
}

You'll want to use the .AddEntry method on the ZipFile you've created specifying a name and the byte[] containing the actual file data.
ex.
ZipFile zipFile = new ZipFile();
zipFile.AddEntry(file.FileName, file.FileData);
where file.FileName will be the entry name (in the zip file) and file.FileData is the byte array.

How to create a zip file using encoded string in C#

I'm new to C# and using C#.Net 2.0 with Visual Studio 2005.
How can I create a zip file from a string using GZipStream. (I don't want to use any third party libraries and doing this purely using C#.)
FYI: Scenario is this. Already there is a zip file in a folder. I need to encode this zip file stream in Base64 and again zip the Base 64 encoded string. (Creating a new zip file from Base64 encoded original zip file).
Appreciate your help.
Thanks,
Chatura

Thanks Bueller for the reply. But without using any external libraries I could do it. Here is the code snippet. This is not the final code with all try/ catch etc. May be useful for others.
private static void CreateZipFromText(string text)
{
byte[] byteArray = ASCIIEncoding.ASCII.GetBytes(text);
string encodedText = Convert.ToBase64String(byteArray);
FileStream destFile = File.Create("C:\\temp\\testCreated.zip");
byte[] buffer = Encoding.UTF8.GetBytes(encodedText);
MemoryStream memoryStream = new MemoryStream();
using (System.IO.Compression.GZipStream gZipStream = new System.IO.Compression.GZipStream(destFile, System.IO.Compression.CompressionMode.Compress, true))
{
gZipStream.Write(buffer, 0, buffer.Length);
}
}

I am assuming you actually mean using the .zip archive format versus another format such as .gz. The .Net 2.0 compression libraries do not out of the box support zip format archives. The GZipStream and such compress to and from gzip format. There is an article here that shows how to support zip in C# without external libraries but I have not tried or tested it. You can find similar articles around but you have to dig to find the pure C# .NET no external library articles.
http://www.codeproject.com/KB/recipes/ZipStorer.aspx