fs.watch file matching is one character off in windows

[jsheely]

var fs = require('fs');

fs.watch('test/file.jsx', {}, (event, filename) => {
    console.log('Changed file', filename);
});

• Changes to a file file.js will yield change events for file.jsx
• Changes to file file.j will yield changes events file.js

Note: Tested on Windows 10

[mdolbin]

@jsheely Seems like it matches any file if its name starts the same as the one we're watching for.
For example, each of the following actions was reported as Changed file file.jsx:
(Assume we have file.jsx, file.js, file.j, bad-name.txt at the same folder)

• Create empty file file or f or ...
• Rename file to f or file.j to fil or bad-name.txt to fi or ...
• Edit f or fil or file.j or file.js or ...
• Remove f or fil or ...

Editing and renaming triggers callback twice, unless 'matching' filename was renamed to something that doesn't match file.jsx anymore or 'matching' file was deleted - these are reported once.

Reproduced on (Virtualbox)

• Windows x64 7 Ultimate SP 1
• Node v4.2.3 & v5.3.0 - one at a time

Not reproduced on

• OSX Yosemite 10.10.5 (14F1021) (macbook)
• Node v4.1.1(homebrew) & v5.3.0 (homebrew) - one at a time

[GenuineRex]

The watching functions in Windows watch directories not files. I do not see anything inside node or uv that checks for the specified file to be the file that triggered the change. Node documentation says that fs.watch relies on ReadDirectoryChangesW which is watching a directory not a specific file. Try fs.watchFIle instead.

[jsheely]

@GenuineRex True it does watch directories but it also knows what file was changed. The problem is that the libuv abstraction returns the closest file that matches the pattern being watched currently and not the actual full path to the file that was changed.

However the real file name is available that was modified and can be sent out to the event loop. I have tracked down the bug to here. #4429

Note: That this still fires a change event for a file in the directory but libraries will now be capable of filtering them out as the pattern won't match a file they are watching.

[GenuineRex]

I see it now.

[jasnell]

@saghul @bnoordhuis

[bnoordhuis]

Libuv 1.9 has a number of Windows file watcher fixes. I don't know when you plan on releasing the next v5, but there's a good chance it fixes this issue.

[wc-matteo]

Another issue probably related: nodejs/node-v0.x-archive#25689

[jasongin]

This is fixed by libuv/libuv#682. There has not yet been a libuv release containing the fix: it came after the last libuv release, v1.9.1.