How to calculate CID of file data?

[bonedaddy]

I'm currently trying to figure out how I can calculate the content hash of a file, without adding it to IPFS. I took a look at the code for the Shell.Add function, however it forwards the request onto ipfs itself, waiting for the returned response to retrieve the hash. What I'm attempting to do is calculate the hash of a file to be able to send that to a user, followed by uploading the hash to my ipfs node. The reason I want to caluclate the hash before uploading it to IPFS, is that this will be quicker to send them a response, instead of say having to wait for an entire 10GB file to be pinned to IPFS.

[magik6k]

ipfs add has --only-hash (or -n) option which calculates the hash. Currently there isn't a function exposing the option here, but it will be done as a part of #76.

There has been some discussion on this topic in https://discuss.ipfs.io/t/how-to-calculate-file-directory-hash/777

[bonedaddy]

Amazing. Thank you.