Error "Source and destination must not be the same" in move-sync on unicode normalization difference

• Operating System: macOs 10.15.7 (latest Catalina)
• Node.js version: v14.15.3
• fs-extra version: 9.0.1

First I’d like to thank you for fs-extra which is really great!

I’m fighting with an error when trying to move files: “Source and destination must not be the same.”

I filtered the src and destination with === and they are NOT the same -> so why is fs-extra rejecting me?

Digging deeper, they look the same. When comparing their normalized unicode representation, they are indeed the same. So I’m suspecting (but don’t really know) that fs-extra is doing a unicode normalization before validating src vs dest. (maybe Object.checkPathsSync (xxx/node_modules/fs-extra/lib/util/stat.js:51:11) [EDIT] the file system is doing unicode normalization.

If true, I believe this is incorrect. There are discussions for ex. in https://news.ycombinator.com/item?id=13953800 that states that for ex. APFS is treating pathes are “bags of bytes” and intentionally not normalizing (cf. linked https://mjtsai.com/blog/2017/03/24/apfss-bag-of-bytes-filenames/)

Hence I believe that fs-extra should not normalize. (not an expert, happy to be explained wrong)

~~somehow related to https://github.com/jprichardson/node-fs-extra/issues/759~~

[RyanZim]

My apologies for the radio silence here; I’ve been super-busy, and put open-source on hold for a few days. Glad you managed to figure it out; filesystems in general tend to do weird things, which is why we abandoned comparing actual paths for inode checks.

[Offirmo]

@manidlou sure. On a file system doing automatic unicode normalization:

const path = `voyage à Paris.jpg`.normalize('NFD') // user input = force normalization to an exotic one for demo purpose
const target_path = path.normalize('NFC') // systematic normalization of user input
assert(a !== b) // same visual appearance but not same binary reprensentation
fs_extra.moveSync(path, target_path) // error "same inode"

This is not a cosmetic fix, I read in a blog post recently someone having trouble storing then retrieving their file on S3 due to this kind of normalization being done by safari on file upload, then the database storing a different representation.

interesting reads:

• https://withblue.ink/2019/03/11/why-you-need-to-normalize-unicode-strings.html
• https://www.win.tue.nl/~aeb/linux/uc/nfc_vs_nfd.html