Bug #18947
open
Unexpected Errno::ENAMETOOLONG on Windows
Description
On Windows 10, I am working on a script to copy a complex folder structure.
Pathname and FileUtils work fine for me until there is a folder with a very long path (>260 chars).
Normally you cannot access such a folder with Ruby.
The next operations will raise Errno::ENOENT
Pathname.new(300_chars_path).children
FileUtils.mkpath(300_chars_path)
But there is a way in Windows to remove the MAX_PATH limitation.
You can find a small .reg file in this article:
https://docs.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=registry
After changing this system option, things start to work strangely in Ruby.
This will now raise Errno::ENAMETOOLONG:
Pathname.new(300_chars_path).children
But at the same time, you can create a folder with such a long path and write-read a file in it
FileUtils.mkpath(300_chars_path)
file = Pathname.new(300_chars_path+'/file.txt')
file.write 'oooooooooo'
puts Pathname.new(300_chars_path+'/file.txt').read
So you can work with individual items but attempts to list such folders' content fail (.children, .glob, .copy, etc).
In my case, deep .glob is broken for all the parent folders of that deep long-path folder ((
The only way I found for listing is
require 'win32ole'
fso = WIN32OLE.new 'Scripting.FileSystemObject'
for file in fso.GetFolder(300_chars_path).files
file.name
file.path.length
end
But using this workaround breaks all my code workflow built on top of Pathname and FileUtils ((.
So for me, it looks like some operations with long-path folders are not working just because in Ruby there is a check for the path length and not a real operation problem. And in some places (see .mkpath) there is no such check and all works fine.
Also notice that other applications on Windows have no problems with long-path folders (like Total Commander).
Please consider reviewing if we really need to raise Errno::ENAMETOOLONG if the LongPathsEnabled option is enabled in the Windows registry.
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