Wrapped the mkdirSync with a try/catch

[henricavalcante]

Wrapped the mkdirSync with existsSync to prevent file already exists… exception

it may fix:

https://github.com/avh4/binwrap/issues/29 https://github.com/avh4/elm-format/issues/602

[harrysarson]

If may make a suggestion the node documentation (see https://nodejs.org/api/fs.html#fs_fs_exists_path_callback) does not recommend this pattern to check if a file exists before writing it as it may introduce a race condition.

They instead recommend using a try`catch` statement.

[henricavalcante]

May it introduce a race condition even with fs.existsSync()? This is not an issue only on fs.exists()?

[harrysarson]

I believe it is possible for the directory to be created between calling fs.existsSync() and fs.mkdirSync(). The OS is allowed to halt execution of a process whilst it does other things (and I think "other things" could include creating a directory). The chance of anyone getting caught by this in practice is incredibly small but concurrency bugs are a very nasty class of problems and to avoid them like the plague leads to a better quality of life for everyone involved.

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At least this is what I think. From the docs of fs.existsSync():

For detailed information, see the documentation of the asynchronous version of this API: fs.exists().

Therefore, I believe the warnings given for fs.exits() also apply for fs.existsSync().

fs.exists() is deprecated, but fs.existsSync() is not. The callback parameter to fs.exists() accepts parameters that are inconsistent with other Node.js callbacks. fs.existsSync() does not use a callback.

The fact that fs.exits() is deprecated but fs.existsSync() is not does not mean that fs.existsSync() avoids the race conditions but simply that it doesn't have unusual callback parameters.

[henricavalcante]

Yes, I got your point and did some tests and using fs.exits() to check if a file exists and doing something with that file/folder it may result in a race condition because the file is a shared resource and it can be modified by another process/thread. In this specific case, it will be almost impossible to happen but I will change the code to use try/catch instead of checking if it exists before.

[mikeastock]

Any update on if this will get merged and released?

[henricavalcante]

Anything else I need to do to get this merged?

[avh4]

Is there a way we can add a test for this to make sure it doesn't regress in the future?

[avh4]

I added a test here: https://github.com/avh4/binwrap/pull/32/commits/4384a9c32b581bb4c88daffe3fd398e2680cba63

[avh4]

Thanks! This was merged via https://github.com/avh4/binwrap/pull/32