[CMake] how to debug CPack creation

[Craig Scott]

On Sun, Oct 21, 2018 at 3:41 AM Илья Шипицин <chipitsine at gmail.com> wrote:

>
>
> сб, 20 окт. 2018 г. в 18:31, Eric Noulard <eric.noulard at gmail.com>:
>
>>
>>> And the content is:
>>> $ rpm -qpl softether-vpnserver-5.1.9660-1.x86_64.rpm
>>> /lib
>>> /lib/systemd
>>> /lib/systemd/system
>>> /lib/systemd/system/softether-vpnserver.service
>>> /usr/libexec
>>> /usr/libexec/softether
>>> /usr/libexec/softether/vpnserver
>>> /usr/libexec/softether/vpnserver/hamcore.se2
>>> /usr/libexec/softether/vpnserver/vpnserver
>>> /usr/local
>>> /usr/local/bin
>>> /usr/local/bin/vpnserver
>>>
>>> the content of the .deb is similar:
>>> $ dpkg-deb -c softether-vpnserver_5.1.9660_amd64.deb
>>> drwxr-xr-x root/root         0 2018-10-20 14:45 ./lib/
>>> drwxr-xr-x root/root         0 2018-10-20 14:45 ./lib/systemd/
>>> drwxr-xr-x root/root         0 2018-10-20 14:45 ./lib/systemd/system/
>>> -rw-r--r-- root/root       700 2018-10-20 14:45
>>> ./lib/systemd/system/softether-vpnserver.service
>>> drwxr-xr-x root/root         0 2018-10-20 14:45 ./usr/
>>> drwxr-xr-x root/root         0 2018-10-20 14:45 ./usr/libexec/
>>> drwxr-xr-x root/root         0 2018-10-20 14:45 ./usr/libexec/softether/
>>> drwxr-xr-x root/root         0 2018-10-20 14:45
>>> ./usr/libexec/softether/vpnserver/
>>> -rw-r--r-- root/root   1770716 2018-10-20 14:45
>>> ./usr/libexec/softether/vpnserver/hamcore.se2
>>> -rwxr-xr-x root/root   2088960 2018-10-20 14:45
>>> ./usr/libexec/softether/vpnserver/vpnserver
>>> drwxr-xr-x root/root         0 2018-10-20 14:45 ./usr/local/
>>> drwxr-xr-x root/root         0 2018-10-20 14:45 ./usr/local/bin/
>>> -rwxr-xr-x root/root        72 2018-10-20 14:45 ./usr/local/bin/vpnserver
>>>
>>> The main question is, what filesystem layout do you expect for those
>>> files?
>>>
>>>
>> Now I think I get it.
>> IN vpnserver CMakeLists.txt you do:
>>
>> install_systemd_service("vpnserver"
>> "${CMAKE_SOURCE_DIR}/systemd/softether-vpnserver.service"
>> "${CMAKE_INSTALL_FULL_LIBEXECDIR}/softether/vpnserver/vpnserver")
>>
>> So at this point (during CMake config step)
>> "${CMAKE_INSTALL_FULL_LIBEXECDIR}/softether/vpnserver/vpnserver"
>> is /usr/local/softether/vpnserver/vpnserver
>>
>> In your install_systemd_service CMake macro wrapper you do:
>>
>> macro(install_systemd_service component file_path binary_path)
>>     get_filename_component(file_name ${file_path} NAME)
>>     get_filename_component(binary_directory ${binary_path} DIRECTORY)
>>
>>     file(READ ${file_path} FILE_CONTENT)
>>     string(REPLACE "[DIRECTORY]" ${binary_directory} FILE_CONTENT
>> ${FILE_CONTENT})
>>     string(REPLACE "[BINARY]" ${binary_path} FILE_CONTENT ${FILE_CONTENT})
>>     file(WRITE ${CMAKE_SOURCE_DIR}/tmp/systemd/${file_name}
>> ${FILE_CONTENT})
>> ...
>>
>> So you generate a systemd service file which contains /usr/local prefix
>> because this is the one which
>> is know during "CMake configuration step".
>>
>> You cannot do that this way with .deb or .rpm because you don't know the
>> "actual" prefix that will be in the package
>> because it is controlby CPACK_PACKAGING_INSTALL_PREFIX  "at CPack time",
>> i.e. when CPack runs.
>>
>> It's even worse because .deb or .rpm may be relocated see e.g.:
>>
>> https://www.cyberciti.biz/faq/howto-install-rpm-package-into-another-directory/
>>
>> When you want to install script that should know where things get
>> installed you have 3 options:
>>
>> 1) Assume the binary executable is installed in the path
>>     thus call the executable as-is "vpnserver" without absolute path
>>
>> 2) Put a pre- or post- install script that will compute the appropriate
>> path
>>    **during package installation** when you are sure what the real path
>> will be.
>>    Have a look at CPACK_DEBIAN_PACKAGE_CONTROL_EXTRA in
>> https://cmake.org/cmake/help/latest/cpack_gen/deb.html
>> or
>> https://cmake.org/cmake/help/latest/cpack_gen/rpm.html#variable:CPACK_RPM_SPEC_MORE_DEFINE
>>
>> 3) Ensure that you generate package with
>>    CMAKE_INSTALL_PREFIX == CPACK_PACKAGING_INSTALL_PREFIX
>>    This is ok but will break if the installation of the package is
>> relocated.
>>
>
> this is good.
> is there a way to install shared libs to system location ? (in order to
> avoid ld manipulation)
>

If your app isn't part of the Linux distribution itself, you shouldn't
install it to /usr. You should be looking to install to somewhere like /opt
instead (or maybe /usr/local, but /opt is generally better). You should be
able to use RPATH to avoid needing to mess with the library search path -
search the CMake docs for INSTALL_RPATH, it has pretty good support for
RPATH these days. Just be sure to use relative RPATHs (i.e. start each path
with $ORIGIN for Linux) to ensure your package remains relocatable.


-- 
Craig Scott
Melbourne, Australia
https://crascit.com

New book released: Professional CMake: A Practical Guide
<https://crascit.com/professional-cmake/>
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