From: robe@...
Date: 2014-07-19T10:14:37+00:00
Subject: [ruby-core:63866] [ruby-trunk - Bug #10067] File.file? misleading semantics & documentation for symbolic links

Issue #10067 has been updated by Michael Renner.


Nobuyoshi Nakada wrote:

> Citing from [POSIX manpage test(1)](http://www.unix.com/man-page/POSIX/1/test/)
> > With the exception of the `-h pathname` and `-L pathname` primaries,
> > if a `pathname` argument is a symbolic link, `test` shall evaluate the
> > expression by resolving the symbolic link and using the file
> > referenced by the link.

Oh my, just double-checked, Python and Perl have implemented the same behaviour as test(1), along with Ruby.

The big difference being the wording of the documentation. The test man page explicitly states:

> True if pathname **resolves to** an existing directory entry for a [..]

as well as the paragraph you quoted.

I guess clarifying that in the File documentation is warranted as well as pointing out that people are strongly advised to use lstat if they want consistent behaviour.

I personally would go as far and ditch the test(1) semantics and stick to querying lstat() by default, but that's just me and will probably break lots of things ;)

----------------------------------------
Bug #10067: File.file? misleading semantics & documentation for symbolic links
https://bugs.ruby-lang.org/issues/10067#change-47891

* Author: Michael Renner
* Status: Open
* Priority: Normal
* Assignee: Zachary Scott
* Category: doc
* Target version: current: 2.2.0
* ruby -v: ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
The documentation for ``File.file?`` states:

"Returns true if the named file exists and is a regular file."


When trying that out I get the following results:


~~~
% /usr/bin/stat link
  File: `link' -> `file'
  Size: 4         	Blocks: 0          IO Block: 4096   symbolic link
Device: 16h/22d	Inode: 2804357     Links: 1
Access: (0777/lrwxrwxrwx)  Uid: ( 1000/    robe)   Gid: ( 1000/    robe)
Access: 2014-07-19 01:01:51.514979670 +0200
Modify: 2014-07-19 01:01:50.799975936 +0200
Change: 2014-07-19 01:01:50.799975936 +0200
 Birth: -
% ruby -e "puts File.file?('link')"
false
% ruby -e "puts File.symlink?('link')"
true
% touch file
% ruby -e "puts File.file?('link')"
true
% ruby -e "puts File.symlink?('link')"
true
%
~~~

which is entirely not what one would expect.

You need to decide if the ``File`` ``?``-methods offer [stat](http://pubs.opengroup.org/onlinepubs/009695399/functions/stat.html) _OR_ [lstat](http://pubs.opengroup.org/onlinepubs/009695399/functions/lstat.html) semantic, change it and document it accordingly.

The current documentation and implementation behavior is especially confusing since the [POSIX standard](http://pubs.opengroup.org/onlinepubs/009695399/basedefs/sys/stat.h.html) states that the type of a file can be either a regular file _OR_ a symlink, not both at the same time.



-- 
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