git: bmake - Always pass the jobs pipe descriptor

[Matthew Dillon]

commit 7fafe32491764cd82be639892c65d4b3c798efc8
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Sat Apr 5 12:48:59 2014 -0700

    bmake - Always pass the jobs pipe descriptor
    
    * bmake currently requires a .MAKE target dependency to induce the passing
      of the jobs pipe descriptor to sub-jobs (aka sub-makes).  This requirement
      was lost due to a bug in bmake where it's F_SETFD fcntl was being run on
      the wrong descriptor.  This was recently fixed in bmake and exposed this
      new problem.
    
    * bmake might be run with the MAKEFLAGS environment intact but not be passed
      the jobs descriptor.  While bmake creates a new fresh jobs descriptor in
      this case, it would remain an issue if some other parent program happened
      to use a pipe descriptor with the same fd number.
    
    * bmake or intermediate build programs might not be run with a .MAKE target
      dependency, causing sub-bmakes to run an excessive number of concurrent
      jobs.
    
    * The question is whether we can really safely require this new behavior
      or whether we should revert to the prior behavior.
    
      FreeBSD modified the default to be the prior behavior of always passing
      the jobs pipe descriptor and added a new .MAKE* directive to override it,
      but I don't see how this helps matters when the default really needs to be
      the always-pass behavior anyway.
    
      The only other solution is to use a filesystem-visible pipe (filesystem fifo
      in /tmp), which the old make used.  But this often results in a lot of cruft
      building up in /tmp from ^C's and/or system crashes.  This solution is the
      most compatible with expectations, frankly.
    
    * For now revert to the prior behavior of always passing the jobs pipe
      descriptor.  This does a better job of guarenteeing that the descriptor
      number remains intact through multiple fork/execs.

Summary of changes:
 contrib/bmake/job.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/7fafe32491764cd82be639892c65d4b3c798efc8


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