rescript format -stdin: check if tmpfile exists

[Minnozz]

And use more restrictive permissions.
We should not accidentally overwrite a random file.

See discussion in 86a5568#r654858470

[cristianoc]

Would you rebase? This can probably progress now.

[Minnozz]

@cristianoc Done.

[cristianoc]

Where's the "check if tmpfile exists" part?

[Minnozz]

The wx flags to openSync:

'w': Open file for writing. The file is created (if it does not exist) or truncated (if it exists). 'wx': Like 'w' but fails if the path exists. 

[cristianoc]

How about failing with a dedicated error message if that exists?

[Minnozz]

@cristianoc I would rather depend on tmp to create the temporary file, which encasulates this logic. Is that okay?

[cristianoc]

@cristianoc I would rather depend on tmp to create the temporary file, which encasulates this logic. Is that okay?

Notice on failure one gets a nice checkout of all the files used. In the current dir, visible with git diff.

That's an experience to keep.

[cristianoc]

@cristianoc I would rather depend on tmp to create the temporary file, which encasulates this logic. Is that okay?

Notice on failure one gets a nice checkout of all the files used. In the current dir, visible with git diff.

That's an experience to keep.

Sorry wrong comment

[cristianoc]

Comment: sure go ahead

[cristianoc]

Btw how comes this does not work?

 var filename = path.join( os.tmpdir(), "rescript_" + crypto.randomBytes(8).toString("hex") + path.parse(use_stdin).base );

[Minnozz]

I created a new PR that uses the tmp package: #5486.

[cristianoc]

Back to this.

[cristianoc]

Will complete this.
Missing context of where this originated. Where is the issue where this was reported to create problems?