Packing and unpacking files using Zip archives in .NET

We’ve looked at a couple of (de)compression techniques available in .NET in previous posts, see link below. Here we’ll look at how to compress multiple files into well-known ZIP files using .NET.

.NET4.5 has added native support for ZIP files, though you need to add the following library to reach the new functions:

New system compression dll

Say you’d like to compress all files within a folder:

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Compressing and decompressing files with BZip2 in .NET C#

BZip2 is yet another data compression algorithm, similar to GZip and Deflate. There’s no native support for BZip2 (de)compression in .NET but there’s a NuGet package provided by icsharpcode.net.

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5 ways to write to a file with C# .NET

It’s a common scenario that you need to write some content to a file. Here you see 5 ways to achieve that.

1. Using a FileStream:

private void WriteToAFileWithFileStream()
{
	using (FileStream target = File.Create(@"c:\mydirectory\target.txt"))
	{
		using (StreamWriter writer = new StreamWriter(target))
		{
			writer.WriteLine("Hello world");
		}
	}
}

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Setting the file access rule of a file with C# .NET

When creating a new file you can set the access control rule for it in code. There are a couple of objects to build the puzzle.

The FileInfo class, which describes a file in a directory, has a SetAccessControl method which accepts a FileSecurity object. The FileSecurity object has an AddAccessRule method where you can pass in a FileSystemAccessRule object. The FileSystemAccessRule object has 4 overloads, 2 of which accept an IdentityReference abstract class. One of the implementations of IdentityReference is SecurityIdentifier. SecurityIdentifier in turn has 4 overloads where the last one is probably the most straightforward to use.

  • WellKnownSidType: an enumeration listing the commonly used security identifiers
  • A domainSid of type SecurityIdentifier: this can most often be ignored. Check out the MSDN link above to see which WellKnownSidType enumeration values require this

The following method will set the access control to “Everyone”, which is represented by WellKnownSidType.WorldSid. “Everyone” will have full control over the file indicated by FileSystemRights.FullControl and AccessControlType.Allow in the FileSystemAccessRule constructor:

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Packing and unpacking files using Tar archives in .NET

You must have come across files that were archives using the tar file format. Tar files are most often used on Unix systems like Linux but it happens that you need to deal with them in a .NET project.

You can find examples of .tar files throughout the Apache download pages, such this one. You’ll notice that .tar files are often also compressed using the GZip compression algorithm which together give the “.tar.gz” extension: they are files that were packed into a tar archive and then zipped using GZip. You can find an example of using GZip in .NET on this blog here. I have only little experience with Linux but I haven’t seen standalone “.tar” files yet, only ones that were compressed in some way. This is also the approach we’ll take in the example: pack and compress a group of files.

Read more of this post

Compressing and decompressing files with BZip2 in .NET C#

BZip2 is yet another data compression algorithm, similar to GZip and Deflate. There’s no native support for BZip2 (de)compression in .NET but there’s a NuGet package provided by icsharpcode.net.

Read more of this post

Packing and unpacking files using Tar archives in .NET

You must have come across files that were archives using the tar file format. Tar files are most often used on Unix systems like Linux but it happens that you need to deal with them in a .NET project.

You can find examples of .tar files throughout the Apache download pages, such this one. You’ll notice that .tar files are often also compressed using the GZip compression algorithm which together give the “.tar.gz” extension: they are files that were packed into a tar archive and then zipped using GZip. You can find an example of using GZip in .NET on this blog here. I have only little experience with Linux but I haven’t seen standalone “.tar” files yet, only ones that were compressed in some way. This is also the approach we’ll take in the example: pack and compress a group of files.

Read more of this post

5 ways to write to a file with C# .NET

It’s a common scenario that you need to write some content to a file. Here you see 5 ways to achieve that.

1. Using a FileStream:

private void WriteToAFileWithFileStream()
{
	using (FileStream target = File.Create(@"c:\mydirectory\target.txt"))
	{
		using (StreamWriter writer = new StreamWriter(target))
		{
			writer.WriteLine("Hello world");
		}
	}
}

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Reading from a memory-mapped file in C# .NET

In this post we saw how to write to a memory-mapped file in .NET. We wrote a short string – “Here comes some log message.” – to a 10KB file. Here we’ll quickly look at how to read from the same file by mapping it into memory first.

The way to read from a file is very similar to writing to it. We’ll still need the MemoryMappedFile and MemoryMappedViewAccessor objects:

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Writing to a file using a MemoryMappedFile in C# .NET

You can use memory-mapped files to map a file to a place in memory that multiple processes can access. The necessary objects reside in the System.IO.MemoryMappedFiles namespace.

The following example will create a MemoryMappedFile object using the following ingredients:

  • The file path
  • The file mode which in this example is CreateNew, i.e. a new file will be created if it doesn’t exist
  • A map name that other processes can refer to
  • An initial size of the file. This is mandatory for files that don’t exist otherwise you’ll get an exception. The file will be given this initial size with a lot of string-termination characters. If you try to open the file in a text editor then you may get a warning that the file is full of NULL characters. This depends on the type of editor you’re using

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