Re: [PATCH] build-sys: fix parallel builds w/setarch links

[Karel Zak <kzak@redhat.com>]

On Sun, May 10, 2015 at 01:38:08PM -0700, Isaac Dunham wrote:
> On Tue, May 05, 2015 at 11:37:33AM +0100, Pádraig Brady wrote:
> > On 04/05/15 04:51, Mike Frysinger wrote:
> > > From: Mike Frysinger <vapier@chromium.org>
> > > 
> > > The symlink generation tries to write to the sys-utils/ subdir but does
> > > not make sure that dir exists.  This can sometimes lead to parallel build
> > > failures when building out-of-tree
> > 
> > >  $(SETARCH_MAN_LINKS):
> > > +	$(AM_V_at) test -d $(dir $@) || mkdir -p $(dir $@)
> > >  	$(AM_V_GEN)echo ".so man8/setarch.8" > $@
> > >  
> > >  install-exec-hook-setarch:
> > 
> > The `test -d ... ||` bit is racy and redundant I think
> 
> Racy, yes, but no more so than "mkdir -p $DIR && install $FILE $DIR":
> it's an inherent limitation of shell scripts.
> 
> Redundant, certainly: mkdir -p $DIR is required to succeed if $DIR is
> a preexisting directory (though it will fail if part of the path is a
> regular file).

 It seems that 'test || mkdir' is nothing unusual in makefiles. The
 problem is "mkdir -p" portability (at least from autotools point of
 view :-), it seems that the proper way is to use 

    @$(MKDIR_P) $(dir $@)

 rather than directly call mkdir.


    Karel


-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com