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List:       kde-core-devel
Subject:    KCrash API
From:       "Hummel, Timo" <timo.hummel () sap ! com>
Date:       2000-04-13 9:36:26
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Hi kde-core-devel and kde-devel,

today I'll write a few lines about the API for KCrash so developers can
already start implementing the crash functions. Thanks to Tom Braun, David
Faure and Waldo Bastian (and others) who improved the code which I wrote so
poorly :)

Introduction
-----------------

KCrash are a few functions to set crash handlers for different signals.
Technically, they are only wrappers for signal(3), but also include support
for an emergency save function. The signal handlers are automatically
replaced whenever you refer to KApplication, except if you specified
"--nocrashhandler" as argument for the application or set an environment
variable called KDE_DEBUG to something. By default, the new KDE crash
handler will be called (with support for the emergency save function,
recursion handling and displaying Dr. Konqi), unless the user configured
something else in the control panel (a module and implementation follows
later). If the user configured KCrash not to handle signals, the emergency
save function won't be called at all.

The KCrash handler sits in KApplication and collects important data which
will be displayed in Dr. Konqi later. Currently, only the application name,
application path and the signal number will be displayed, plus an additional
i18n'ed description in Dr. Konqi.

Functions
-----------------

There are a few functions you need to use if you want to:
- Define your own crash handler
- Define your own emergency save function
- Extent the KCrash interface with new informations displayed


KCrash::setEmergencySaveFunction (void (*saveFunction) (int));

Pass your user-defined function to this one, and it will be called whenever
a crash occurs. If you don't want an emergency save function, just pass NULL
to it. You can also change this during run-time, if you want to have several
emergency save functions in different parts of your application. If your
emergency save function crashes, the KDE default crash handler recognizes
this and does a normal shutdown (no infinite loop).

KCrash::setCrashHandler (void (*crashHandler) (int));

Pass your user-defined crash-handler function to this one, and it will be
used as crash handler. Make sure that your function does not crash itself,
or this might crash your whole machine (always implement a recursion
counter). You can additionally specify NULL to use the system's crash
handler or KCrash::defaultCrashHandler to use the KDE crash handler
(default).

If you want everything being handled automatically, you don't need to do
anything, since everything is made in the KApplication class. The default
behaviour is: Catch SIGSEGV, launch Dr. Konqi and display the informations.
If there are other suitable signals which should be handled, please tell me.

Yours
Timo

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