Re: mkfs.xfs protofile and paths with spaces

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Jan 23, 2023 at 10:13:12PM +0100, Daan De Meyer wrote:
> Hi,
> 
> We're trying to use mkfs.xfs's "-p" protofile option for unprivileged
> population of XFS filesystems. However, the man page does not specify
> how to encode filenames with spaces in them. Spaces are used as the
> token delimiter so I was wondering if there's some way to escape
> filenames with spaces in them?

Spaces in filenames apparently weren't common when protofiles were
introduced in the Fourth Edition Unix in November 1973[1], so that
wasn't part of the specification for them:

    "The prototype file contains tokens separated by spaces or new
     lines."

The file format seems to have spread to other filesystems (minix, xenix,
afs, jfs, aix, etc.) without anybody adding support for spaces in
filenames.

One could make the argument that the protofile parsing code should
implicitly 's/\// /g' in the filename token since no Unix supports
slashes in directory entries, but that's not what people have been
doing for the past several decades.

At this point, 50 years later, it probably would make more sense to
clone the mke2fs -d functionality ("slurp up this directory tree") if
there's interest?  Admittedly, at this point it's so old that we ought
to rev the entire format.

[1] https://dspinellis.github.io/unix-v4man/v4man.pdf (page 274)
or https://man.cat-v.org/unix-6th/8/mkfs 

--D

> Cheers,
> 
> Daan De Meyer