Re: ANN: NetworkManager (0.9.10-rc1) released

On Thu, 26 Jun 2014 15:49:20 -0500
Dan Williams <dcbw redhat com> wrote:

On Thu, 2014-06-26 at 14:58 -0500, Dan Williams wrote:
On Thu, 2014-06-26 at 12:44 -0500, Robby Workman wrote:
On Thu, 26 Jun 2014 12:27:14 -0500
Robby Workman <robby rlworkman net> wrote:

On Thu, 26 Jun 2014 10:16:41 -0500
Dan Williams <dcbw redhat com> wrote:

On Thu, 2014-06-26 at 01:19 -0500, Robby Workman wrote:
On Thu, 26 Jun 2014 07:55:58 +0200
Vincent Bernat <bernat luffy cx> wrote:

 ❦ 25 juin 2014 21:36 -0500, Robby Workman
<robby rlworkman net> :

Okay, looks like that's ncurses, so let's link ncurses

  [rworkman liberty NetworkManager-]$ gcc -o
testrl -lreadline -lncurses testrl.c [rworkman liberty
NetworkManager-]$ strings testrl | grep readline readline

Now, here's where I'm unclear.  If I add
LDFLAGS="-lnurses" to the configure environment, the
test passes and the complete build occurs successfully.
What's unclear is *why* that's needed -- is this an
omission in the NM sources (isn't nmtui a curses client
and thus ncurses should be linked?) or is something
different about how we (Slackware) build readline?

GNU readline requires linking to ncurses as well to get
termcap symbols. Here is an autoconf recipe for that:

If I'm reading that correctly, that snippet above tries to
link in curses if it encounters failure, so perhaps NM
should use it? Maybe not though - there's at least one
other project (nftables) where I've encountered the same

While digging around a bit after sending this, I found that
we add "--with-curses" to the readline configure to use it
instead of libtermcap, so it's *supposed* to be linked in
already and this would not be a problem.  However, for
whatever reason (it's not clear whether it's intentional or
not), the upstream sources don't use TERMCAP_LIBS (set to
"-lcurses" per the configure flag) when building the shared
library.  It appears that at least one distro solves that
by running 'make SHLIB_LIBS="-lcurses"' when building, but
I don't see where Fedora did that, so it's not clear at all
how they link curses (or even if they do, when means I
wonder how the configure test in OP works there). 

Assuming this is indeed a problem, it's been in Slackware
for years without causing any actual issues - the readline
library from 13.37 (released in April 2011) doesn't link
ncurses either, so I'm not convinced that we're doing
anything wrong (but I'm open to argument).

What does 'ldd' on your return?  Mine has: =>  (0x00007fff191fe000) => /lib64/
(0x0000003473400000) => /lib64/
(0x000000345ac00000) /lib64/

so at least the dynamic linker knows that libtinfo (provided
by ncurses) is required here, and should load that in for the
configure test program.

# ldd /usr/lib64/ (0x00007ffff43ff000) => /lib64/ (0x00007ffda6b37000)
        /lib64/ (0x00007ffda7179000)

I don't have any links to support this, but in talking with a
couple of folks who've "been around a while," it seems that the
lack of direct linking is intentional on the part of upstream
readlinke -- this allows the specific apps to use whichever
(termcap / ncurses) is appropriate for them.  The autoconf
stuff linked earlier seems to somewhat support that, but again,
I don't have a definitive answer on it.

...and comment #1 seems to support that (but apparently the
official RH position changed since then):

Fun.  nmcli doesn't care which one you link with, so NM would rather
just use whatever you have lying around.  Unfortunately it seems we
have to make the user specify one?

Robby, can you test the attached patch?  If it works for you we'll try
to get it into git master and 0.9.10.

Yep, configure test for readline passes, the build completes successfully,
and the nmtui binary at least runs (I've not actually running the NM daemon
version yet, so I can't really test functionality).

Thanks for the patience and help on this :-)


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