Issue #22340 has been updated by k0kubun (Takashi Kokubun). Backport changed from 3.3: REQUIRED, 3.4: DONE, 4.0: REQUIRED to 3.3: REQUIRED, 3.4: DONE, 4.0: DONE ruby_4_0 commit:2374bd218c8d32795cabf82e8f46ecf6e271cf87. ---------------------------------------- Bug #22340: Win32: File.stat succeeds on symbolic-link loops on Windows https://bugs.ruby-lang.org/issues/22340#change-119443 * Author: nobu (Nobuyoshi Nakada) * Status: Closed * Backport: 3.3: REQUIRED, 3.4: DONE, 4.0: DONE ---------------------------------------- On Windows, `File.stat` succeeds on a self-referential symbolic link instead of raising `Errno::ELOOP`, and `File.exist?` returns `true`. Opening the same link raises `Errno::ELOOP`. I noticed this while adding symbolic-link tests to FileUtils, whose Windows CI reported the unexpected `File.exist?` result. ## Reproduction ````ruby require 'tmpdir' Dir.mktmpdir do |dir| Dir.chdir(dir) do File.symlink('a', 'a') p File.readlink('a') # => "a" p File.exist?('a') # => true; expected false p File.stat('a') # succeeds; expected Errno::ELOOP File.open('a') # raises Errno::ELOOP ensure File.unlink('a') if File.symlink?('a') end end ```` `File.lstat('a')` should continue to succeed and identify the entry as a symbolic link. ## Cause In `winnt_stat`, failure to open the resolved path falls back to `stat_by_find` unless `open_error` matches one of the listed errors. The symbolic-link-following implementation introduced in f5b96e594c769cf309b70fd7736caaf90372a3b6 retained this fallback, which was intended to handle sharing violations for files such as `pagefile.sys`. `ERROR_CANT_RESOLVE_FILENAME` is not listed, so a symbolic-link loop also reaches the fallback, which retrieves information about the link itself and reports success. -- https://bugs.ruby-lang.org/