On Thursday, May 28, 2015 6:01:22 PM Adam Carter wrote:
> How do you tell that the library is loaded by firefox? 

Load a page with a plugin then run htop, you may see a few plugin-container 
child processes for firefox, note it's pid and then run (as root):

cat /proc/<pid>/maps | grep libxul.so

You'll see something like this:
7ff264f9b000-7ff269e4b000 r-xp 00000000 08:06 8736977                    
/usr/lib64/firefox/libxul.so
7ff269e4b000-7ff26a04a000 ---p 04eb0000 08:06 8736977                    
/usr/lib64/firefox/libxul.so
7ff26a04a000-7ff26a4ef000 r--p 04eaf000 08:06 8736977                    
/usr/lib64/firefox/libxul.so
7ff26a4ef000-7ff26a56e000 rw-p 05354000 08:06 8736977                    
/usr/lib64/firefox/libxul.so
f

> How would it know to load libraries for other binaries?

When firefox starts the plugin-container process it may just set the 
LD_LIBRARY_PATH environment variable for it, just like the script from the 
binary packages do, or it may do something more complicated. You'll have to 
look at the code to find out.

-- 
Fernando Rodriguez