How do I modify the install name of a .dylib at build time

Question

I am building the google-gflags commandline flags library for C++ on Mac OS X (10.7.1). The build process is as such:

$ ./configure --prefix=output
$ make
$ make install 

I'd like to change the install name of the generated shared library at build time and not use install_name_tool afterwards.

By default, the install name of the generated shared library, libgflags.dylib, is the output path:

$ otool -L ./output/libgflags.dylib
$ ./output/libgflags.dylib:
    /tmp/gflags-1.5/output/lib/libgflags.0.dylib (compatibility version 2.0.0, current version 2.0.0)
    /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 52.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 159.0.0) 

The man page for ld(1) has a -install_name option which can be used to change the install name of a dynamic library at link-time.

For example, with a dummy program:

$ g++ -dynamiclib temp.cc -install_name /tmp/temp.dylib -o temp.dylib
$ otool -L temp.dylib 
temp.dylib:
    /tmp/temp.dylib (compatibility version 0.0.0, current version 0.0.0)
    /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 52.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 159.0.0)

But, I am unable to use this command line option with the ./configure script. I've tried manually setting the CFLAGS variable, but that results in a error:

$ CFLAGS="-install_name /tmp/desired/location/libgflags.dylib" ./configure
checking for a BSD-compatible install... /opt/local/bin/ginstall -c
checking whether build environment is sane... yes
checking for gawk... no
checking for mawk... no
checking for nawk... no
checking for awk... awk
checking whether make sets $(MAKE)... yes
checking for gcc... gcc
checking whether the C compiler works... no
configure: error: in `/Users/vibhav/Code/install_name_test/gflags-1.5':
configure: error: C compiler cannot create executables

So, is it possible for me to change the install name of .dylib generated by configure and make without using install_name_tool?

Hannelorehanner

I do not understand what you are trying to do. Why can't you simply run ./configure --prefix /tmp/desired/location? – Com

That's a valid question. I cannot to set --prefix to that location for various reasons, including that my build location is different from my application's "install" location. I simply want to pass the appropriate linker flag while using configure. – Hannelorehanner

Your scenario is still not clear to me. Could you explain how the standard ./configure --prefix /somewhere && make && make install is wrong for your setup? Why would your build location matter? (You should use an absolute prefix, of course.) Are you trying to link to libglflags without installing it? (In that case you should use libtool to link your application with libflag.la and let libtool do its magic to link with a non-installed library.) Do you want to install the library to a temporary location before it is copied to its final location? (It's a job for the DESTDIR variable.) – Com

The Apple folks recommend using -headerpad_max_install_names to compile and link. Then, when you make install, you use install_name_tool to update the record so its points to the fully qualified pathname (i.e., /usr/local/lib/libfoo.dylib). Nick X basically answered the same, but he did not mention the Apple's recommendation or -headerpad_max_install_names. – Ballonet

Answer 1

Generally, passing linker arguments through g++ must be prefaced with -Wl and spaces must be replaced with commas. So, if you want to pass "-install_name /tmp/temp.dylib" to the linker you will need to call this:

g++ -Wl,-install_name,/tmp/temp.dylib ...

Amery

Answer 2

one possible approach would be editing the config.status manually. but before I try to do that, install_name_tool -id saved my life.

Lawsuit