an argument of make(1)

[Giorgos Keramidas]

On Wed, 27 Aug 2008 13:00:54 -0400, Chuck Robey <chuckr at telenix.org> wrote:
> I am posting this to our arch list; if I'm wrong, we can move this.  I
> want to argue for some changes to our great make(1) tool.
>
> I've long been a fan of make, and in particular, FreeBSD's make.  In
> my own career, I've often had to do more custom creation of Makefiles,
> and while there are some folks here who definitely DO know our make
> better, I think I can honestly say I know it pretty well.  In creating
> tools for customers, I've often been forced, unwillingly, to go to the
> GNU make tool.  The reason is just one of compatibility.  There are
> several different reasons for this, which I want to list:

I can certainly feel the `pain' of reluctantly choosing GNU make, or
even of going the automake/autoconf/libtool way.   I have written a fair
amount of build glue myself too, and I know that I'd love to have BSD
make in other systems too.

Since the topic of (re)using FreeBSD make on non-BSD platforms seems to
pop up more or less every 4-6 months the last year, I've started at
least two attempts at porting 'FreeBSD make' to non BSD systems.  The
last attempt was aiming for a 'clean' set of minimal changes to the
source of make.  And it's done.  At least the *binary* of make builds
and tries to pull bsd.*.mk files on Linux and Solaris 10 here.

The actual *source* code changes needed to build a BSD-make executable
on Linux are pretty 'small':

  keramida at mithra:/home/keramida/tools$ uname -a
  Linux mithra 2.6.24-19-generic #1 SMP Fri Jul 11 23:41:49 UTC 2008 i686 GNU/Linux
  keramida at mithra:/home/keramida/tools$ hg short -r1
  1:664527963082 | 2008-07-25 16:47 +0300 | keramida: Import FreeBSD make-20080724 snapshot (svn 180782)

The diff from the first snapshot import of FreeBSD make touches only a
few files:

  keramida at mithra:/home/keramida/tools$ hg diff -r 1:tip bin/make | diffstat -p1
   bin/make/Makefile    |    8 +++++-
   bin/make/compat.c    |   67 +++++++++++++++++++++++++++++++++++++++++++++++++++
   bin/make/compat.h    |   36 +++++++++++++++++++++++++++
   bin/make/job.c       |    8 +++++-
   bin/make/main.c      |   17 ++++++++++++
   bin/make/pathnames.h |    2 -
   6 files changed, 135 insertions(+), 3 deletions(-)
  keramida at mithra:/home/keramida/tools$

Now I'm looking for some spare time to clean-up the changes a bit and
integrate them in `http://hg.hellug.gr/bmake/gker/'.

The tricky part is, however, that a lot of the functionality of make(1)
depends on the `share/mk/bsd.*.mk' files.  I have finished writing the
automake glue that installs these in `$prefix/share/mk' but now I am
kind of stuck while thinking about a good way to make the bsd.*.mk files
actually usable on, say, FreeBSD, Linux and Solaris.

> 1) while the GNU make has the -v to allow one to both identify the
> tool and the version, FreeBSD's make has no such facility, that I'm
> aware of.  You can't test & capture the type of make here, except by
> the rather inadequate trapping of getting no response at all.

Both -v and -V are taken, and I don't really like the idea of adding
long options to make(1).  Maybe we can partially ``hijack'' the -v
option to also display a verbose version string, i.e.:

    % make -v
    FreeBSD make (version 5200408120)
    make: no target to make.
    %

It's probably ok to print a version number when 'being extra verbose' :)

> OK, that'st the major argument.  I'm going to ask for one thing here,
> but it's truly extra, just my own bias's showing thru.  I wish that a
> fair number of the changes that have gone into make be taken back.
> I'm not talking about those that enhanced it's operation, I'm talking
> about all of the changes that, while trying to increase the elegance
> of the code, have really destroyed it's porrting portability, in a
> major way.  Make used to depend on a smaller set of libraries, and
> those libraries were largely those available on other systems, so the
> task for a programmer, to port our make(1) to a different platform
> wasn't all that hard to do.  Nowadays, with a great number of the
> changes having been crafted to change dependencies to FreeBSD-only
> tools, it's a real bear to port it.

make(1) is actually pretty 'easy' to compile on, say, Linux, as I wrote
above.  The only bits that are missing on Linux are:

    * An errc() function.  I added one in compat.c of my diffstat output
      above, and this accounts for most of the lines in the patches.

    * Our make(1) uses arc4random().  #ifdef HAVE_ARC4RANDOM and a few
      lines to call srandom() or srandomdev() and random() when it's
      unavailable are probably `ok' for this.

    * FreeBSD make uses getprogname(), but saving argv[0] and re-using
      that is trivial to add when HAVE_GETPROGNAME if undefined.

    * On FreeBSD/pc98 systems make tries to get the value of the
      "machdep.ispc98" by calling sysctlbyname("machdep.ispc98", ...).
      Since this part of the code is to be able to build make on pre-7.0
      FreeBSD/pc98 systems, it may be ok to #ifdef HAVE_SYSCTLBYNAME and
      ignore this compatibility code on non-FreeBSD systems.

This pretty much sums all the source code changes I had to make to build
on Linux and Solaris.  I'll see how much of the changes I can clean up
and post online at `http://hg.hellug.gr/bmake/gker/'.  It should be
pretty easy, so please ping me in a couple of days if I haven't followed
up with an "ACK, all done now".

The 'porting' of share/mk/bsd.*.mk files may be a bit trickier, and it
may even turn out to be much more difficult.  I can certainly use all
the help I can get there...

- Giorgos