Nemo: How to Debug Nemo

Created on 27 Jan 2020 · 5Comments · Source: linuxmint/nemo

I am using Linux Mint 19.3 Tricia.

I am tinkering with the nemo source code. I need a little debugging help. I checked https://forums.linuxmint.com/viewtopic.php?t=235125
https://stackoverflow.com/questions/31282505/how-to-debug-nemo-linux-mint-file-manager

The way I am changing the code and trying to debug is -

turned on 'source code repositories'.

git clone https://github.com/linuxmint/nemo
cd nemo

Now I am editing the code. I am using printf( "key_1 %s \n", key_1); to observe different variables.

sudo apt-get build-dep nemo 
dpkg-buildpackage 
cd .. && sudo dpkg -i *.deb

ctrl+alt+backspace to restart Xorg

Then I am using

$ gdb nemo
(gdb) r

Then looking for the printf output.

I am sure there is a more elegant solution. Is there any way I can debug the code without printf, dpkg-buildpackage, ctrl+alt+backspace?

Source

blueray453

Most helpful comment

Hi sorry, I meant to respond sooner.

The way you're building is fine. One thing I'll do to save time after the initial build and install using dpkg-buildpackage, is instead run:
sudo ninja -C debian/build install
-- to recompile subsequent times - it's much much faster, and there aren't any packages to install again (the system doesn't really care, you're copying over existing files) - this is good for doing as you are - adding debug output, etc. Just understand that when you want to do another 'real' build using dpkg-buildpackage, you'll need to use sudo to clean out the build folder (I use sudo git clean -fdx - this returns it to its pristine state).

I've never tried to develop in a full ide, so I'm not even really sure how breakpoints work there. The simplest method is to insert a G_BREAKPOINT() wherever you want it to stop - then you can do whatever you need to do in gdb.

You don't need to restart the session to restart nemo, just either do:
nemo --quit
or
killall nemo

If you want to debug the desktop icons, that is run with nemo-desktop, so you'll need to kill/restart it instead. (You need to kill it twice the first time, the session manager attempts to restart it exactly once after the session starts, if it terminates).

I use print statements mostly, or gdb if I need to do something more complicated (there's plenty of documentation out there) - it depends on what you're attempting to fix or work on. Valgrind is a good tool for looking for memory leaks - check out https://wiki.gnome.org/Valgrind.

If you're getting glib/gtk/gobject warnings you can run G_DEBUG=fatal_warnings gdb to start gdb, which will break on those warnings (and you can continue past them).

This library - https://developer.gnome.org/glib/stable is what pretty much everything is based on in nemo (along with gtk3) - I usually install the 'devhelp' program, along with -doc packages for these, which I find faster than browsing the web docs.

mtwebster on 30 Jan 2020

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All 5 comments

@mtwebster I think nemo-main.c is the main entry point. If I put breakpoint in VSCode, and run this file, will it work? What command shall I give to run nemo-main.c.

blueray453 on 30 Jan 2020

Hi sorry, I meant to respond sooner.

You don't need to restart the session to restart nemo, just either do:
nemo --quit
or
killall nemo

If you're getting glib/gtk/gobject warnings you can run G_DEBUG=fatal_warnings gdb to start gdb, which will break on those warnings (and you can continue past them).

mtwebster on 30 Jan 2020

❤1 👍1

@blueray453 thank you for asking. I have been wondering the in's and out's as well for this.

@mtwebster thank you for guidance and pointing in the correct direction.