8/23/2023 0 Comments Xz compression format![]() Before xz took over as the default compression format on in 2013, following the 'latest' link would have gotten you a bzip2 compressed file. Public override GetCacheDependency(String virtualPath, virtualPathDependencies, DateTime utcStart)Īnd VirtualFile is defined like this: namespace . The latest 4.13.9 source release of the Linux kernel is 780MiB, but thanks to xz compression, the download is a much more managable 96 MiB (an 88 reduction). Public override string GetFileHash(string virtualPath, virtualPathDependencies) Return new ZipVirtualDirectory (virtualDir, _zipFile) Public override VirtualDirectory GetDirectory (string virtualDir) Return new ZipVirtualFile (virtualPath, _zipFile) Public override VirtualFile GetFile (string virtualPath) String zipPath = Util.ConvertVirtualPathToZipPath (virtualDir, false) Public override bool DirectoryExists (string virtualDir) String zipPath = Util.ConvertVirtualPathToZipPath (virtualPath, true) Typically, the compressed form of the archive receives a filename by appending the format-specific compressor suffix to the archive file name. Public override bool FileExists (string virtualPath) To achieve archive compression, a variety of compression programs are available, such as gzip, bzip2, xz, lzip, lzma, zstd, or compress, which compress the entire tar archive. Public ZipFileVirtualPathProvider (string zipFilename) : base () ![]() Public class ZipFileVirtualPathProvider : The important code looks like this: namespace You can also do websites with dynamic pages (ASP.NET) pages.ĪSP.NET ZIP Virtual Path Provider, based on DotNetZip With the benefit of those features, DotNetZip has been used within the implementation of a Virtual Path Provider for ASP.NET, that does exactly what you describe - it serves all the content for a particular website from a compressed ZIP file. Using DotNetZip, you can reference particular entries in the zip randomly, and can decompress them out of order, and can return a stream that decompresses as it extracts an entry. You could possibly try compressing using xz -C crc32 to compare the results, but I'm still not having success making a valid compressed file using the Python2 libraries.DotNetZip is a zip archive library for. However it seems to use CRC32 as the default checksum algorithm (others use CRC64) and there is a bug that prevents changing the checksum algorithm What module are you using that is called "lzma" in Python2 and what command did you use to compress the data?ĮDIT 2 Okay, I found the pyliblzma module for Python2. Under Python3 lzma produces the same result as xz, however under Python2 PyLZMA produces a different result that cannot be extracted using the xz command line util. This compresses a file test.txt with the xz command line utility and with the Python module and compares the results. xz, the command-line compressor and decompressor (analogous to gzip) liblzma, a software librarywith an APIsimilar to zlib. With open('test.txt', 'rb') as f, open('', 'wb') as out: xz file, the compressed data could vary without affecting the contents.ĮDIT I've been looking into this further, and wrote this script to test the PyLZMA Python2.x module and the lzma Python3.x built in module from _future_ import print_function I would not be concerned about the differences in the compressed files - depending on the container format and the checksum type used in the. I've also verified it using the regular sha256sum as well (when I wrote the data to file). If f1sum.hexdigest() = f2sum.hexdigest(): Here's my test code to confirm this: # I have created two identical text files with some random phrasesį1sum.update(f1_xzbuf) f2sum.update(f2_xzbuf) Not sure if it helps, but I made sure the LZMA Python module in my repository wasn't installed to avoid possible name conflicts. UPDATE: I found a fix for it by installing the backport (from Python 3.3) via peterjc's Git repository ( link here), and now it's showing identical checksums. Out_file = open('/home/ki2ne/Desktop/', 'wb')Īnd I noticed there were two different checksums (MD5 and SHA256) from the resulting file compared to when I used the plain xz (although I could decompress fine with either method - the checksums of the decompressed versions of both files were the same). In_file = open('/home/ki2ne/Desktop/song.wav', 'rb')Ĭompressed_data = xz.compress(input_data) My code used during the experiment was: import lzma as xz I'm experimenting with the lzma module in Python 2.7.6 to see if I could create compressed files using the XZ format for a future project that will make use of it.
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