Building a Statically Linked Transmission Daemon: An Elegant Solution

In my previous post, How to Build Statically Linked Transmission Daemon 4, I demostrated the way to create a statically linked transmission-daemon. While effective, that approach involved manually linking the final binary which is not ideal in my optinion. After some trials and erros, I discovered a more elegant solution by patching the CMakeLists.txt file for transmission-daemon, which simplifies the process significantly.

The New Approach

The key improvement in this refined method is to apply a patch to the daemon/CMakeLists.txt file. This patch, available here, modifies the build process to better support static linking. Here’s a detailed look at what the patch does.

What the Patch Does

The patch makes several critical changes to the CMakeLists.txt file:

1. Sets Library Search Preferences:

   set(CMAKE_FIND_LIBRARY_SUFFIXES ".a" ".so")
   

   This line prioritizes static libraries (.a) over shared libraries (.so) during the build process.

2. Explicitly Finds Required Libraries:

   The patch adds several find_library commands to locate necessary dependencies:

   find_library(LIB_CURL NAMES curl PATHS /usr/lib REQUIRED)
   find_library(LIB_BROTLIDEC NAMES brotlidec PATHS /usr/lib REQUIRED)
   find_library(LIB_NGHTTP2 NAMES nghttp2 PATHS /usr/lib REQUIRED)
   find_library(LIB_CARES NAMES cares PATHS /usr/lib REQUIRED)
   find_library(LIB_IDN2 NAMES idn2 PATHS /usr/lib REQUIRED)
   find_library(LIB_UNISTRING NAMES unistring PATHS /usr/lib REQUIRED)
   find_library(LIB_SSL NAMES ssl PATHS /usr/lib REQUIRED)
   find_library(LIB_Z NAMES z PATHS /lib /usr/lib REQUIRED)
   find_library(LIB_CRYPTO NAMES crypto PATHS /usr/lib REQUIRED)
   find_library(LIB_BROTLICOMMON NAMES brotlicommon PATHS /usr/lib REQUIRED)
   

   These commands ensure that the necessary libraries for static linking are located during the build configuration.

3. Links Libraries Statically:

   The target_link_libraries command is updated to link these static libraries:

   target_link_libraries(${TR_NAME}-daemon
       PRIVATE
           ${TR_NAME}
           libevent::event
           fmt::fmt-header-only
           $<$<BOOL:${WITH_SYSTEMD}>:${SYSTEMD_LIBRARIES}>
       PUBLIC
           ${LIB_CURL}
           ${LIB_BROTLIDEC}
           ${LIB_NGHTTP2}
           ${LIB_CARES}
           ${LIB_IDN2}
           ${LIB_UNISTRING}
           ${LIB_SSL}
           ${LIB_Z}
           ${LIB_CRYPTO}
           ${LIB_BROTLICOMMON}
   )
   

   This ensures that the Transmission daemon binary is linked against the static versions of these libraries, creating a fully self-contained executable.