coreapi unixfs: change Wrap logic to make more sense

[magik6k]

Currently coreunix.Adder wrap logic is weird, which causes coreapi.Unixfs().Add to also be weird:

data	wrap	hidden	hash
(file)	❌	❌	(QmFile)
(file)	✔️	❌	(QmWrapper)/QmFile
(dir)/(file)	❌	❌	(QmFile)
(dir)/(file)	✔️	❌	(QmDir)/filename
(dir)/(.file)	✔️	❌	(QmDir)/.filename
(dir)/(.file)	✔️	✔️	(QmDir)/.filename

With this PR it does this:

data	wrap	hidden	hash
(file)	❌	❌	(QmFile)
(file)	✔️	❌	(QmWrapper)/QmFile
(dir)/(file)	❌	❌	(QmDir)/filename
(dir)/(file)	✔️	❌	(QmWrapper)/QmDir/filename
(dir)/(.file)	✔️	❌	(QmWrapper)/QmEmptyDir/
(dir)/(.file)	✔️	✔️	(QmWrapper)/(QmDir)/.filename

New behaviour IMO makes much more sense from API consumer perspective.

TODO:

• Cleanup Adder code
• Fix regressions
• Merge Unixfs.Wrap Fixes interface-go-ipfs-core#10
• Merge Handle stdin name in cli/parse go-ipfs-cmds#157

Reviews welcome

[Kubuxu]

As far as I know, --warp main use case is/was preserving the name of a file when a file is added.

I can see how it is a bit weird that it doesn't happen in case of directories but I have to highlight that it is quite a big breaking change and I would expect would break existing workflows and scripts.

[magik6k]

ipfs add --wrap won't be affected by this change, I just didn't fix it yet.

[Stebalien]

I'm having trouble understanding this.

• What's this "top level" thing and can we get rid of it? It seems like we're mixing two code paths with some shared logic.
• Why do I care if a file is a directory or not when adding it?

[Stebalien]

I'm having trouble understanding this comment. Why do we care if the file we're adding is a directory?

[magik6k]

It made sense before I rewrote this code.

[Stebalien]

Here's my attempt to simplify this: #6121. It may be totally wrong but it'll at least help me better understand how this all works.

[magik6k]

Why do I care if a file is a directory or not when adding it?

When adding a directory, we add its entries to mfs (so mfs root is the directory). When adding a file, we also add it to mfs with its hash as the name so that wrap works.

If we could drop wrap from adder/coreapi it would make this much simpler (we wouldn't use mfs at all when adding single files)

[Stebalien]

If we could drop wrap from adder/coreapi it would make this much simpler (we wouldn't use mfs at all when adding single files)

Unless you can think of a reason not to, let's just do that. It's really trivial to wrap a file anyways.

[jmank88]

Needs v0.0.4 to cover #6118

[Stebalien]

(ok, I'm not going to block this on my now massive PR)