Create directory in database root fails with "Directory is read-only" about datakit HOT 7 CLOSED

BTW, this is the best documentation I could find for the 9p protocol's errors:

http://lxr.free-electrons.com/source/net/9p/error.c

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Isn't this correct? The root is read-only, and /branch already exists. Is the bug that we should return File exists rather than Directory is read-only?

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Maybe? It wasn't clear to me that the root was RO, but now I know! Thanks!
It didn't help matters that from the filesystem, ls didin't show a branch directory and that mkdir branch would also complete without error.

As for the error message, yes I'd expect File Exists before Directory is read-only.
What I'd like is a safe way for a client to handle certain types of error.
In the mkdir -p example. it's okay if part of the path exists and I can safely ignore the error.
It is however, not ok to ignore other errors e.g No space left on device for example.

It seems the documentation is scare for error strings... I'm not really fond of pattern matching error strings to determine the "kind" of error either 😭 but I think it's the best we can do with the protocol as it stands. Open to other ideas though...

from datakit.

Why didn't ls show it? It does with the Linux and OCaml clients, at least:

/Database # ls
branch     remotes    snapshots  trees
/Database # mkdir branch
mkdir: can't create directory 'branch': File exists

I guess Linux is adding the File exists here because ocaml9p shows the protocol message:

tal@Thomass-MacBook-Pro ~> ocaml9p shell 
9P > ls
drwxrwxr-x ? root root 0 Jan 1 1970 branch    
drwxrwxr-x ? root root 0 Jan 1 1970 trees     
drwxrwxr-x ? root root 0 Jan 1 1970 snapshots 
drwxrwxr-x ? root root 0 Jan 1 1970 remotes   
9P > mkdir branch
Directory is read-only

strace shows:

mkdir("/Database/branch", 0777)         = -1 EEXIST (File exists)

from datakit.

Closing, as I don't think there's anything to fix here. Linux reports "file exists" rather than "read only" because it checks whether the directory exists before calling mkdir, and you can do that too if you want. Please reopen if you disagree.

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Nope, I think this was probably user error ;)
The mkdir thing I mentioned was user error - I was using the host filesystem.
Happy to help adding some docs :D

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More docs are always welcome :-)

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