[CMake] Setting RPATH lookup on macOS

[Juan Sanchez]

I never suggested copying files into the build tree.  The original
question was about how to locate libraries at runtime.  You don't
necessarily have to use @rpath, @executable_path is also a valid
option.  Another valid option one is to strip out @rpath and use
DYLD_LIBRARY_PATH or DYLD_FALLBACK_LIBRARY_PATH.

If you want to set an rpath from cmake, you can also use target properties like:
INSTALL_RPATH
BUILD_WITH_INSTALL_RPATH

where BUILD_WITH_INSTALL_RPATH is useful if you don't want to use
CMake's install system.

Regards,

Juan

On Thu, Sep 12, 2019 at 10:56 AM Michael Jackson
<mike.jackson at bluequartz.net> wrote:
>
> On macOS you really should _not_ have to copy the libraries into the build tree. I have never had to do that in 10 years of our product (Windows is a different story). The trick is setting the correct options to add in the paths to the libraries into the RPATH of the executable/library. (at least on macOS & Linux systems).
>
>
>
> --
>
> Mike Jackson
>
>
>
>
>
> From: Juan Sanchez <juan.e.sanchez at gmail.com>
> Date: Thursday, September 12, 2019 at 11:35 AM
> To: Michael Jackson <mike.jackson at bluequartz.net>
> Cc: CMake <cmake at cmake.org>
> Subject: Re: [CMake] Setting RPATH lookup on macOS
>
>
>
> The macOS install_name_tool can be used to change the RPATH of your binaries.  It can also be used to set the path for each of the libraries to be loaded.  For a python module I compile, I copy each of its dylib into the appropriate directory relative to my shared library.  I then use the install_name_tool to change from an absolute path to a path relative to @loader_path.
>
>
>
> install_name_tool -change $j "@loader_path/../gcc/`basename $j`" $i
>
> where $j is the full path output from "otool -L" and "@loader_path/../gcc" would point to a directory "gcc" relative to the directory containing my python module.
>
> For a binary executable, I would explore placing required dylib files into a directory relative to @executable_path.
>
> Regards,
>
>
>
> Juan
>
>
>
> On Wed, Sep 11, 2019 at 4:33 PM Michael Jackson <mike.jackson at bluequartz.net> wrote:
>
> Already looked on google and at the CMake documentation but everything listed does not seem to work so here is the setup.
>
> I am using MKL and I have a home grown FindMKL since there isn’t an official one. Inside that is the typical find_library() calls which will find the libraries just fine. One of those libraries is a dynamic library (.dylib). Using otool -L on that library the install_name is encoded as @rpath.
>
> Now I have my add_executable(foo…) and target_link_libraries (Foo ${MKL_LIBRARIES} ).
>
> Everything compiles and links fine. The issue is at runtime. The app will not launch because libmkl_rt.dylib is not loaded because the path to that library is not encoded into the executable.
>
> 639:[mjackson at ferb:ifort-release]$ otool -l Bin/EMsoftWorkbench.app/Contents/MacOS/EMsoftWorkbench | grep "path"
>          name @rpath/libEbsdLib.dylib (offset 24)
>          name @rpath/libmkl_rt.dylib (offset 24)
>          name @rpath/QtOpenGL.framework/Versions/5/QtOpenGL (offset 24)
>          name @rpath/QtNetwork.framework/Versions/5/QtNetwork (offset 24)
>          name @rpath/QtConcurrent.framework/Versions/5/QtConcurrent (offset 24)
>          name @rpath/QtWidgets.framework/Versions/5/QtWidgets (offset 24)
>          name @rpath/QtGui.framework/Versions/5/QtGui (offset 24)
>          name @rpath/QtCore.framework/Versions/5/QtCore (offset 24)
>          path /Users/Shared/EMsoft_SDK-ifort/EbsdLib-0.1-Release/lib (offset 12)
>          path /Users/Shared/EMsoft_SDK-ifort/Qt5.12.3/5.12.3/clang_64/lib (offset 12)
>
>
> Oddly the Qt libraries and one of my own libraries do get their rpaths encoded. I feel like I need to append to the RPATH that gets encoded into the executable but I am not really figuring out how to do that.
>
> Help....
>
> --
> Michael Jackson | Owner, President
>       BlueQuartz Software
> [e] mike.jackson at bluequartz.net
> [w] www.bluequartz.net <http://www.bluequartz.net>
>
>
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