[TxMt] Re: TextMate 1.5 and Ruby 2.0.0

[Matt Neuburg]

Allan Odgaard <mailinglist at textmate.org>
wrote:

> On Mar 8, 2013, at 7:02 PM, Matt Neuburg
> <matt at tidbits.com> wrote:
> 
> > following that up, I was able to discover this: system() and exec()
> and spawn() and IO.popen() in ruby 2.0 apparently close non-standard file
> descriptors by default
> 
> Woah! That would cetainly explain it, assuming you use ruby 2.0 for the
> actual RubyMate script.
> 
> We generally recommend that you use ruby 1.8.7 for all the TextMate
> commands (i.e. have /usr/bin first in your PATH) and then set TM_RUBY to
> whatever ruby you want used for user scripts.

I don't think it's reasonable to assume that people will do something so
complex. I for one have gone to great trouble to ensure that I am using
one version of Ruby globally; it is unlikely that I would deliberately
undermine that. Also it is shaky to assume that Ruby 1.8.7 will persist
into the future. We are entering an age when Ruby 2 *is* Ruby. That is
the future for which we must plan. TextMate's internal scripts must be
prepared to deal with whatever version of Ruby they encounter in the
real world that surrounds them...!

> Do you have any reference on ruby 2.0 closing non-standard file
> descriptors? I only found the ":close_other" option for spawn, but it
> doesn't say it is the default behavior.

The key location that got me started is
https://github.com/ruby/ruby/blob/v2_0_0_0/NEWS, where we read:

  * incompatible changes:
    * system() and exec() closes non-standard file descriptors
      (The default of :close_others option is changed to true by
default.)

I've seen this expressed elsewhere in a slightly different way:

"Kernel#system and #exec does not inherit non-standard file descriptor
by default."

And, as I said, take a look at http://ruby-doc.org/core-2.0/Kernel.html
- under "spawn" we are explicitly told that ":close_others is true by
default for spawn and IO.popen", and then we are told under "system" and
"exec" that their options are the same as for "spawn". Also, in
http://www.ruby-doc.org/core-2.0/IO.html, we are told this:

"Ruby sets close-on-exec flags of all file descriptors by default since
Ruby 2.0.0. So you don't need to set by yourself. Also, unsetting a
close-on-exec flag can cause file descriptor leak if another thread use
fork() and exec() (via system() method for example). If you really needs
file descriptor inheritance to child process, use spawn()'s argument
such as fd=>fd."

Hope this helps - m.




-- 
matt neuburg, phd = matt at tidbits.com, http://www.apeth.net/matt/
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