100% cpu with 177.3 MiB zip

[thisconnect]

I accidentally passed a bigger buffer to fileType,
i.e. this file https://imagemagick.org/download/windows/releases/ImageMagick-6.9.10-33.zip

Seems to hang iterating through the whole buffer here:

file-type/index.js

Line 275 in a1da90b

zipHeaderIndex = findNextZipHeaderIndex(buffer, offset);

Is that expected?

It doesn't hang of corse if I pass just a subarray
filetype(body.subarray(0, filetype.minimumBytes)) then everything works and { ext: 'zip', mime: 'application/zip' } is returned

[sindresorhus]

// @jacor84

[thisconnect]

I am currently only passing a subarray length of minimumBytes, but wonder if there would be any benefit if I pass more than that, especially with application/zip data

[jacor84]

I agree that this algorithm could be optimized for larger files. Expecially the findNextZipHeaderIndex function, which is using Array.findIndex(function). I will try to find a good solution and test for performance during the next few days. One idea is to use Buffer. indexOf() since we are looking for consecutive bytes.