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List:       kde-frameworks-devel
Subject:    Re: Review Request 126161: OS X housekeeping
From:       René J.V. Bertin <rjvbertin () gmail ! com>
Date:       2015-11-26 16:20:26
Message-ID: 20151126162026.23104.61832 () mimi ! kde ! org
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This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/126161/
-----------------------------------------------------------

(Updated Nov. 26, 2015, 5:20 p.m.)


Review request for KDE Software on Mac OS X and KDE Frameworks.


Changes
-------

This revision moves introduces `kinit_mac.mm` in order to cut down on the number of \
#ifdefs, and merges in David's suggestion:

After looking more closely at the underlying issue, it turns out that the off-limits \
behaviour that results in a crash (possibly an abort) is the fact of calling \
non-POSIX APIs (which are non-reentrant) after a `fork()`. In `kdeinit` this happens \
during the `dlopen` call (`QLibrary::load`), when KDE and/or Qt ctors are called. \
Calling `dlopen` becomes safe again after starting a new process through `exec`. \
                Thus, my new proposition does:
- fork + exec when `launch()` is told to start executable. This is in fact the same \
                code-path also used on other Unix variants
- fork + exec(helper) when `launch()` is told to start a shared library containing \
`kdeinitmain` or `kdemain`; the helper then calls `dlopen` and finally the resolved \
`kde*main` function.

The code is now prepared to be slimmed down if the helper tool turns out to be \
redundant (`kdeinit` or `klauncher` are never used to "launch" a shared library). I'd \
really prefer to let this become apparent in time, rather than having to figure out \
at an unknown time in the future why some features fail to work (or rather, slap a \
big fat warning into the user's face).


Repository: kinit


Description
-------

This patch addresses several issues with the OS X adaptations:

-1 replaces the obsolete Q_OS_MAC with Q_OS_OSX
-2 builds the relevant applications `nongui` instead of as app bundles
-3 turns klauncher into an "agent" by setting `LSUIElement` to true programmatically
-4 ports a patch that has been in MacPorts' `port:kdelibs4` since October 14th 2009, \
which prevents a kdeinit crash that is caused by calling exec after `fork()` in an \
application that has used non-POSIX APIs and/or calling those APIs in the exec'ed \
application. This patch (originally by MacPorts developers Jeremy Lainé and Jeremy \
Lavergne) rearranges call order and uses a proxy application to do the actual exec.


Diffs (updated)
-----

  src/kdeinit/CMakeLists.txt f94db71 
  src/kdeinit/kdeinit5_proxy.mm PRE-CREATION 
  src/kdeinit/kinit.cpp a18008a 
  src/kdeinit/kinit_mac.mm PRE-CREATION 
  src/klauncher/CMakeLists.txt 746edfa 
  src/klauncher/klauncher.h e155f72 
  src/klauncher/klauncher.cpp 8b3d343 
  src/klauncher/klauncher_main.cpp f69aaa5 
  src/start_kdeinit/CMakeLists.txt 46d6cb3 
  src/wrapper.cpp 95b7ec2 

Diff: https://git.reviewboard.kde.org/r/126161/diff/


Testing
-------

On OS X 10.9.5 with Qt 5.5.1 and KF5rameworks 5.16.0 . With this patch, starting \
`kded5` will launch kdeinit5 and klauncher5 as expected, but `kdeinit5 --kded` does \
not yet launch `kded5`. This is probably acceptable for typical KF5 use on OS X \
(kded5 can be launched as a login item or as a LaunchAgent) but I will have another \
look at why the kded isn't started.

I am not yet able to perform further testing; practice will for instance have to show \
whether point 2 above needs revision (apps that need to be installed as app bundles).

Similarly it will have to be seen whether point 3 above has any drawbacks. \
Applications running as agents do not show up in the Dock or App Switcher. Thus, \
klauncher will not be able to "turn itself into" an application that does have a full \
GUI presence with my current modification. I don't know if that's supposed to be \
                possible though.
NB: I have been building the KDE4 klauncher in a way that makes it impossible to \
construct a GUI at all, so I'm not expecting issues in KF5 as long as klauncher's \
role hasn't evolved too much.


Thanks,

René J.V. Bertin


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      This is an automatically generated e-mail. To reply, visit:
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<div>Review request for KDE Software on Mac OS X and KDE Frameworks.</div>
<div>By René J.V. Bertin.</div>


<p style="color: grey;"><i>Updated Nov. 26, 2015, 5:20 p.m.</i></p>



<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Changes</h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">This revision moves introduces `kinit_mac.mm` in order to cut down on \
the number of #ifdefs, and merges in David&#39;s suggestion:

After looking more closely at the underlying issue, it turns out that the off-limits \
behaviour that results in a crash (possibly an abort) is the fact of calling \
non-POSIX APIs (which are non-reentrant) after a `fork()`. In `kdeinit` this happens \
during the `dlopen` call (`QLibrary::load`), when KDE and/or Qt ctors are called. \
Calling `dlopen` becomes safe again after starting a new process through `exec`. \
                Thus, my new proposition does:
- fork + exec when `launch()` is told to start executable. This is in fact the same \
                code-path also used on other Unix variants
- fork + exec(helper) when `launch()` is told to start a shared library containing \
`kdeinitmain` or `kdemain`; the helper then calls `dlopen` and finally the resolved \
`kde*main` function.

The code is now prepared to be slimmed down if the helper tool turns out to be \
redundant (`kdeinit` or `klauncher` are never used to &quot;launch&quot; a shared \
library). I&#39;d really prefer to let this become apparent in time, rather than \
having to figure out at an unknown time in the future why some features fail to work \
(or rather, slap a big fat warning into the user&#39;s face).</pre>  </td>
 </tr>
</table>







<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt;">Repository: </b>
kinit
</div>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
 <table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">This patch addresses several issues with the OS X \
adaptations:</p> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
                inherit;white-space: inherit;">-1 replaces the obsolete Q_OS_MAC with \
                Q_OS_OSX
-2 builds the relevant applications <code style="text-rendering: inherit;color: \
#4444cc;padding: 0;white-space: normal;margin: 0;line-height: inherit;">nongui</code> \
                instead of as app bundles
-3 turns klauncher into an "agent" by setting <code style="text-rendering: \
inherit;color: #4444cc;padding: 0;white-space: normal;margin: 0;line-height: \
                inherit;">LSUIElement</code> to true programmatically
-4 ports a patch that has been in MacPorts' <code style="text-rendering: \
inherit;color: #4444cc;padding: 0;white-space: normal;margin: 0;line-height: \
inherit;">port:kdelibs4</code> since October 14th 2009, which prevents a kdeinit \
crash that is caused by calling exec after <code style="text-rendering: \
inherit;color: #4444cc;padding: 0;white-space: normal;margin: 0;line-height: \
inherit;">fork()</code> in an application that has used non-POSIX APIs and/or calling \
those APIs in the exec'ed application. This patch (originally by MacPorts developers \
Jeremy Lainé and Jeremy Lavergne) rearranges call order and uses a proxy application \
to do the actual exec.</p></pre>  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">On OS X 10.9.5 with Qt 5.5.1 and KF5rameworks 5.16.0 . \
With this patch, starting <code style="text-rendering: inherit;color: \
#4444cc;padding: 0;white-space: normal;margin: 0;line-height: inherit;">kded5</code> \
will launch kdeinit5 and klauncher5 as expected, but <code style="text-rendering: \
inherit;color: #4444cc;padding: 0;white-space: normal;margin: 0;line-height: \
inherit;">kdeinit5 --kded</code> does not yet launch <code style="text-rendering: \
inherit;color: #4444cc;padding: 0;white-space: normal;margin: 0;line-height: \
inherit;">kded5</code>. This is probably acceptable for typical KF5 use on OS X \
(kded5 can be launched as a login item or as a LaunchAgent) but I will have another \
look at why the kded isn't started.</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">I am not yet able to \
perform further testing; practice will for instance have to show whether point 2 \
above needs revision (apps that need to be installed as app bundles).</p> <p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">Similarly it will have to be seen whether point 3 above has any drawbacks. \
Applications running as agents do not show up in the Dock or App Switcher. Thus, \
klauncher will not be able to "turn itself into" an application that does have a full \
GUI presence with my current modification. I don't know if that's supposed to be \
                possible though.
NB: I have been building the KDE4 klauncher in a way that makes it impossible to \
construct a GUI at all, so I'm not expecting issues in KF5 as long as klauncher's \
role hasn't evolved too much.</p></pre>  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> \
(updated)</h1> <ul style="margin-left: 3em; padding-left: 0;">

 <li>src/kdeinit/CMakeLists.txt <span style="color: grey">(f94db71)</span></li>

 <li>src/kdeinit/kdeinit5_proxy.mm <span style="color: \
grey">(PRE-CREATION)</span></li>

 <li>src/kdeinit/kinit.cpp <span style="color: grey">(a18008a)</span></li>

 <li>src/kdeinit/kinit_mac.mm <span style="color: grey">(PRE-CREATION)</span></li>

 <li>src/klauncher/CMakeLists.txt <span style="color: grey">(746edfa)</span></li>

 <li>src/klauncher/klauncher.h <span style="color: grey">(e155f72)</span></li>

 <li>src/klauncher/klauncher.cpp <span style="color: grey">(8b3d343)</span></li>

 <li>src/klauncher/klauncher_main.cpp <span style="color: grey">(f69aaa5)</span></li>

 <li>src/start_kdeinit/CMakeLists.txt <span style="color: grey">(46d6cb3)</span></li>

 <li>src/wrapper.cpp <span style="color: grey">(95b7ec2)</span></li>

</ul>

<p><a href="https://git.reviewboard.kde.org/r/126161/diff/" style="margin-left: \
3em;">View Diff</a></p>






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