Remove directory symlinks before starting upload

[konradpabjan]

Overview

Resolves #76

The root cause was that fs.lstat was used instead of fs.stat. Certain paths should have been omitted from the list of files to upload and this ensures directories correctly get identified before an upload begins.

• What is the difference between the two? https://stackoverflow.com/questions/32478698/what-is-the-different-between-stat-fstat-and-lstat-functions-in-node-js
• Some more information: fs.lstat() of a linked directory returns false from stat.isDirectory() nodejs/node#25342
• Even more info: https://github.com/actions/toolkit/blob/ccad19055eadcd85dd8bf73a487385c9c7233b4e/packages/glob/src/internal-globber.ts#L218

fs.lstat will always return false when isDirectory is called if the filePath is a symbolic link. This can cause problems down the line when fs.createReadStream is called inside @actions/artifact during upload.

Testing

https://github.com/konradpabjan/macos-eisdir/runs/914682769?check_suite_focus=true

I used a minimal repo that a user created as part of #76
In a earlier failed run, you can see that the problematic file is a symlink: https://github.com/konradpabjan/macos-eisdir/runs/914415784?check_suite_focus=true#step:5:81

With the symlink present i first tried lstat() then realPath() and then isDirectory() before that is able to correctly say if that is a directory. A single call with stat() will correctly determine if the path is a directory. In addition, even with the full real path, I tried doing fs.createReadStream and that would fail with the same EISDIR error so the symlink/directory should never be uploaded to begin with

[yacaovsnc]

Did you test with a symlink loop here? What would happen?

[konradpabjan]

Loops would not be included as part of the rawSearchResults. @actions/glob checks beforehand for broken symlinks and cycles and removes them.

We filter out directories after @actions/glob has finished searching