< Development | Tutorials | Debugging Revision as of 20:03, 4 February 2008 (view source)18.104.22.168 (talk | contribs) (fixme dbus)← Older edit Revision as of 22:27, 26 February 2009 (view source) TMG (talk | contribs) (→Debugging io-slaves with valgrind: kdeinit -> kdeinit4)Newer edit → Line 48: Line 48: command can be used to let klauncher run all https io-slaves via valgrind: command can be used to let klauncher run all https io-slaves via valgrind: − KDE_SLAVE_VALGRIND=https kdeinit+ KDE_SLAVE_VALGRIND=https kdeinit4 The valgrind output will appear as the stderr output of the kdeinit process. The valgrind output will appear as the stderr output of the kdeinit process. Line 55: Line 55: KDE_SLAVE_VALGRIND_SKIN=calltree ( for example ) KDE_SLAVE_VALGRIND_SKIN=calltree ( for example ) − ==How to get debug output== ==How to get debug output== Revision as of 22:27, 26 February 2009 This page describes how you can debug an ioslave with gdb. Contents 1 How does an io-slave get started? 2 Attaching gdb to a io-slave 3 Debugging io-slaves with valgrind 4 How to get debug output How does an io-slave get started? Your application request 'klauncher' via DCOP [FIXME: Isn't that dbus now?] for a slave. If 'klauncher' does not have an idle slave ready, it will ask kdeinit to start a new one. kdeinit forks and dlopens the library that contains the io-slave. Then it calls kdemain() or, if that is not present, main() in the library. Attaching gdb to a io-slave Due to the above sequence it is rather hard to get an io-slave in your debugger. But wait there is hope. You can start klauncher in such a way that slaves for a certain protocol (the first parameter of KIO::SlaveBase() constructor of the slave class) are started in debug mode. E.g. to start all 'http' slaves in debug mode, you type: in KDE 3: KDE_SLAVE_DEBUG_WAIT=http kdeinit in KDE 4: KDE_SLAVE_DEBUG_WAIT=http kdeinit4 This will restart 'kdeinit' and 'klauncher'. When your application now requests a http slave, the slave will be started by kdeinit, but before it calls kdemain() (cq. main()) it will suspend the slave by sending it a SIGSTOP signal. In the terminal from which you started kdeinit you will get the following message: kdeinit: Suspending process kdeinit: 'gdb kdeinit 16779' to debug kdeinit: 'kill -SIGCONT 16779' to continue You can now debug your slave by typing (or pasting) 'gdb kdeinit 16779' in a terminal. If you don't want to debug a slave you can let it continue by sending it a SIGCONT by typing 'kill -SIGCONT 16779'. Be aware that slaves will not be killed while they are suspended. Once you have started gdb, you can set e.g. breakpoints and then resume the slave by typing 'continue'. The debugger will return immediate with a message that a SIGSTOP has been received so you will have to type 'continue' a second time. See also Windows-specific notes on debugging io-slaves. Debugging io-slaves with valgrind KLauncher can be told to run certain io-slaves through valgrind. The following command can be used to let klauncher run all https io-slaves via valgrind: KDE_SLAVE_VALGRIND=https kdeinit4 The valgrind output will appear as the stderr output of the kdeinit process. The $VALGRIND_OPTS environment variable can be used to pass options to valgrind. If you want to use a different skin: KDE_SLAVE_VALGRIND_SKIN=calltree ( for example ) How to get debug output It is useful to redirect the debug output of your particular slave to a file instead of stderr. E.g. I myself use the following lines in $KDEDIR/share/config/kdebugrc.  InfoOutput=0 InfoFilename=/tmp/http  InfoOutput=0 InfoFilename=/tmp/http This redirects all debug info for areas 7103 and 7113 (as used by kio_http) to the file /tmp/http. To get debug information from the SMB slave you can add the following to kioslaverc: [SMB] DebugLevel=100 This will print additional debug info to the stderr of your kdeinit process, which typically ends up in ~/.X.err or ~/.xsession-errors Retrieved from "https://techbase.kde.org/index.php?title=Development/Tutorials/Debugging/Debugging_IOSlaves&oldid=39028" Content is available under Creative Commons License SA 4.0 unless otherwise noted.