path_open all flags support

[pmp-p]

it seems path_open does not allocate fd when passed OFLAGS_CREAT, does not handle OFLAGS_EXCL
and maybe does not return all possible values in all posible cases ( ERRNO_EXIST / ERRNO_NOTDIR )

[konsumer]

Notes from discord:

• the fd is not allocated when creating
• it should test for file, then if file is not there, test for valid parent and rights to create in it
• leads to fopen with mode w/w+ failing right now
• needs logic here

[konsumer]

Coming back to this issue, what actionable changes are needed? Is this an actual feature you need for something, or is it a "it would be better if it followed the spec" sort of thing?

[pmp-p]

it would be for full support of underlying emscripten FS / browserFS / zenfs in case a user wasip1 program / plugin extension requires complete fs functions. Did not happen yet in my use case but i expect it will happen.

[konsumer]

Did the 4b892dc commit resolve it (with your PR?)

[pmp-p]

No i'm quite sure it is very incomplete for all the combinations possible with OFLAGS_CREAT/OFLAGS_DIRECTORY/OFLAGS_EXCL/OFLAGS_TRUNC from oflags against fsRightsBase/fsRightsInheriting

[konsumer]

Ah, ok. I will leave the issue until someone needs it. I am not totally sure I understand what is missing, but so far I have been ok without it.