CODEWITHSUNDEEP
zipcompressiontararchive7zip
littlecircle
littlecircle

Reputation: 1

How can I combine many files into single file without compression, keeping the same behavior across platforms?

I have a folder which includes a lot of subfolders and files. I want to combine all those files into one single large file. That file should be able to get expanded rendering back the original folder and files.

Another requirement is that the method to do it should render exactly the same output (single large file) across different platforms (Node.js, Android, iOS). I've tried ZIP utility's store mode, it indeed renders one file combining all input files and it doesn't compress them, which is good. However, when I try it on Node.js and Windows 7Zip software (ZIP format Store mode), I find that the outputs are not exactly the same. The two large files' sizes are slightly different and of course with different md5. Though they can both be expanded and return back identical files, the single files doesn't meet my requirement.

Another option I tried is Tar file format. Node.js and 7Zip renders different output as well.

Do you know anything I miss using ZIP store mode and Tar file? e.g. using specific versions or customized ZIP util?

Or, could you provide another method to realize my tasks?

I need a method to combine files which shares exactly the same protocol across Node.js, android, and iOS platforms. Thank you.

Upvotes: 0

Views: 1127

Answers (1)

Mark Adler
Mark Adler

Reputation: 112442

The problem is your requirement. You should only require that the files and directory structure be exactly reconstructed after extraction. Not that the archive itself be exactly the same. Instead of running your MD5 on the archive, instead run it on the reconstructed files.

There is no way to assure the same zip result using different compressors, or different versions of the same compressor, or the same version of the same code with different settings. If you do not have complete control of the code creating and compressing the data, e.g., by virtue of having written it yourself and assuring portability across platforms, then you cannot guarantee that the archive files will be the same.

More importantly, there is no need to have that guarantee. If you want to assure the integrity of the transfer, check the result of extraction, not the intermediate archive file. Then your check is even better than checking the archive, since you are then also verifying that there were no bugs in the construction and extraction processes.

Upvotes: 1

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