[KDE/Mac] Cross-platform with kdeinit5, klauncher5, kded5 and friends

[Jeremy Whiting]

Ian,

I took a look at kdelibs4 in macports and
https://trac.macports.org/browser/trunk/dports/kde/kdelibs4/files/workaround-kdeinit4-crash.patch
looks particularly interesting to what we are trying to fix here.
Especially it's use of a separate executable (helperExe) to launch
klauncher with. If you think this could be a possible solution I can look
into reworking this patch to work with what's in kf5's kinit, with proper
#ifdef Q_OS_OSX and such (or once you get qt5 to build you can take a crack
at it if you like). What do you think?

BR,
Jeremy

On Wed, Feb 11, 2015 at 5:29 PM, Ian Wadham <iandw.au at gmail.com> wrote:

> On 12/02/2015, at 10:34 AM, Brandon Allbery wrote:
> > On Wed, Feb 11, 2015 at 6:31 PM, René J.V. <rjvbertin at gmail.com> wrote:
> > I take that to mean that doing fork() doesn't oblige you to do an exec()
> afterwards, it's that you cannot do a fork() from a process that's not been
> started through exec.
> >
> > I will guess that this is related to the fact that such processes are
> actually started by launchd, and must play by launchd's rules (including
> not using fork()) so launchd can keep track of them. This would also imply
> that fork() is actually acceptable as long as the forked processes don't
> try to use the UI, but are merely background worker processes that
> communicate with the foreground process if they need UI interaction or etc.
>
> FWIW, there is some special code in the main() program of kdeinit5 that
> causes it to fork and re-exec *itself* on Apple OS X (the second time with
> a
> --no-fork arg) --- before it goes on to do its main work.
>
> For more detail, in frameworks/kinit/src/kdeinit/kinit.cpp code, see lines
> 1705 and 1576ff.  The comments at the head of the second reference say:
>
> /**
>  Calling CoreFoundation APIs (which is unavoidable in Qt/Mac) has always
> had issues
>  on Mac OS X, but as of 10.5 is explicitly disallowed with an exception.
> As a
>  result, in the case where we would normally fork and then dlopen code, or
> continue
>  to run other code, we must now fork-and-exec.
>
>  See "CoreFoundation and fork()" at
> http://developer.apple.com/releasenotes/CoreFoundation/CoreFoundation.html
> */
>
> When I can get Qt 5 to build and then Frameworks and some KF5 apps, I
> propose
> to start tracking down what is happening on Apple OS X in some of the
> paths that
> kdeinit5 and friends are following, starting with what KToolInvocation is
> doing in a
> few major cases.
>
> For a rough but obviously now-out-of-date guide see:
>
> https://techbase.kde.org/Development/Architecture/KDE4/Starting_Other_Programs
>
> Cheers, Ian W.
>
> _______________________________________________
> kde-mac at kde.org
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> KDE/Mac Information: http://community.kde.org/Mac
>
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