[Pythonmac-SIG] python clone of "otool -Lv"

[Bob Ippolito]

I did a quick proof-of-concept utility that clones the functionality of 
otool -Lv today.  It needs ctypes, because that's how I wrote the 
structure parsing stuff... not for any other good reason.  The output 
of "python potool.py /some/executable_or_dylib" should be identical to 
the output of "otool -Lv /some/executable_or_dylib".

The idea behind this is to write a version of install_name_tool in 
Python, so that we don't have to depend on the presence of developer 
tools for that kind of installation.  It's pretty essential for 
bundlebuilder kinda stuff if you want to embed frameworks, or 
installing frameworks to semi-arbitrary locations on a user's computer 
(i.e. admin, network or user).  It doesn't do this yet, but all the 
parsing/generating code for this kind of modification is there.

There's an ld flag that you should to use to pad these headers 
(-headerpad_max_install_names) if you're going to have any luck making 
paths longer.  By default, they end up with just enough zero padding 
cstring termination and 32bit alignment.

It's available at:  http://undefined.org/python/potool-0.0.tgz

Anyone, please feel free to take this and write the install_name_tool 
code ;)  All the information I needed to write this part of the 
functionality was in /usr/include/mach-o/loader.h.  I took a look at 
the install_name_tool source code and man page.  The best it does is 
modify these dylib structures in-place.  It's not capable of expanding 
them to accommodate paths beyond the padding size of the mach-o file.  
Emulating this tool should be rather easy.

-bob