[FUSE API] invalid command line options are ignored instead of causing an error

[mhx]

Bug Report

Running a FUSE driver on Linux with an invalid option:

$ ./dwarfs boost.dwarfs mnt -oasdfasdf
fuse: unknown option(s): `-o asdfasdf'

The same on Windows using WinFsp:

C:\Users\mhx\git\dwarfs\build-vcpkg>.\dwarfs.exe boost.dwarfs mnt -oasdfasdf
The service dwarfs has been started.

In particular, even valid options with invalid values just seem to be ignored (it's hard to tell due to the lack of feedback):

C:\Users\mhx\git\dwarfs\build-vcpkg>.\dwarfs.exe boost.dwarfs mnt -oumask=foobar
The service dwarfs has been started.

For options internal to my FUSE driver, invalid values are actually handled:

C:\Users\mhx\git\dwarfs\build-vcpkg>.\dwarfs.exe boost.dwarfs mnt -odebuglevel=foo
error: invalid logger level: foo

How to Reproduce

See above.

Behaviors

I'd expect both invalid options as well as invalid values for valid options to cause an error to be reported.

Environment

• OS version and build: 10.0.22621
• WinFsp version and build: 2.0.23075

[billziss-gh]

I believe this was done on purpose. I do not recall the exact reason why, but I believe this was to match the behavior of OSXFUSE at the time the WinFsp-FUSE layer was written.

(I seem to recall that I was porting an OSXFUSE file system to Windows at the time, which relied on the OSXFUSE libfuse command line parser ignoring unknown options. I may also be completely hallucinating this as it has been 7+ years since this work was done.)

[mhx]

Thanks for getting back!

Interesting. If failing is not a option for whatever reason, maybe as least a warning could be added in case an invalid option is being ignored?

[billziss-gh]

A warning might make sense.

BTW, are you using fuse_main/fuse_main_real? Because if you are not, you have control of the options you accept via fuse_opt_parse.

[mhx]

BTW, are you using fuse_main/fuse_main_real? Because if you are not, you have control of the options you accept via fuse_opt_parse.

I am using all of fuse_opt_parse, fuse_parse_cmdline and fuse_main.

However, I can't decide if an option like umask that is internal to the FUSE layer is valid or not. That's for the FUSE layer to decide.