Scorpio: some improvement required

[yyk808]

In the past few days I tested scorpio for integrating zed with mega and here are my suggestions for it.

• Gracefully start and quit: When scorpio receives a signal to quit, it won't umount the mountpoint. Causing it cannot correctly start in the next time.

• Confusing meanings for mount: mountpoint and mount doesn't share the same meaning
  https://github.com/web3infra-foundation/mega/blob/c64b9e938f80d8ceffb249dd5ca05cc792b1f60d/scorpio/src/main.rs#L30
  https://github.com/web3infra-foundation/mega/blob/c64b9e938f80d8ceffb249dd5ca05cc792b1f60d/scorpio/src/deamon/mod.rs#L84

• mountpoint should not be hard-coded: request it from /api/config would be nice.

• Duplicated mount paths: Simply call /api/mount on the same path twice and you'll got:
  

• Let's use absolute path: Just a suggestion.

• IO Error on reading non-exist files: Using cat command for a non-exsiting file in the fuse would get a IO Error message.
  

[yyk808]

@Ivanbeethoven

[Ivanbeethoven]

Got it !

[Ivanbeethoven]

PRs #688 and #687 has solved the problems :

• Gracefully start and quit
• Confusing meanings for mount
• mountpoint should not be hard-coded
• Duplicated mount paths： Now you can't mount twice

TODO:

• IO Error on reading non-exist files : need some error check with libc function .
• Let's use absolute path