ceph/cmake/modules/MergeStaticLibraries.cmake
Bassam Tabbara c6067f48ec embedded: Add a skeleton libcephd library
libcephd is a library that contains ceph daemon code
that can be statically linked in other applications.

Added MergeStaticLibraries.cmake that can merge static libraries
to form a bigger one. This approach avoids the need to mess with
STATIC libraries all over the code base.

Signed-off-by: Bassam Tabbara <bassam.tabbara@quantum.com>
2016-11-28 23:48:02 -08:00

86 lines
3.0 KiB
CMake

# This function is a helper that will merge static libraries.
# For example,
#
# merge_static_libraries(mylib staticlibX staticlibY)
#
# mylib.a will generate a new static library mylib that is
# a combination of staticlibX and staticlibY
#
function(merge_static_libraries target)
set(dummy_source ${CMAKE_CURRENT_BINARY_DIR}/${target}_dummy.c)
add_library(${target} STATIC ${dummy_source})
# remove duplicates
set(libs ${ARGN})
list(REMOVE_DUPLICATES libs)
# validate that all libs are static
foreach(lib ${libs})
if (NOT TARGET ${lib})
message(FATAL_ERROR "${lib} not a valid target")
endif()
get_target_property(libtype ${lib} TYPE)
if(NOT libtype STREQUAL "STATIC_LIBRARY")
message(FATAL_ERROR "${lib} not a static library")
endif()
# add a dependency on the lib
add_dependencies(${target} ${lib})
endforeach()
# Force the merged Make the generated dummy source file depended on all static input
# libs. If input lib changes,the source file is touched
# which causes the desired effect (relink).
add_custom_command(
OUTPUT ${dummy_source}
COMMAND ${CMAKE_COMMAND} -E touch ${dummy_source}
DEPENDS ${libs})
# only LINUX is currently supported. OSX's libtool and windows lib.exe
# have native support for merging static libraries, and support for them
# can be easily added if required.
if(LINUX)
# generate a script to merge the static libraries in to the target
# library. see https://sourceware.org/binutils/docs/binutils/ar-scripts.html
set(mri_script "open $<TARGET_FILE:${target}>=")
foreach(lib ${libs})
# we use the generator expression TARGET_FILE to get the location
# of the library. this will not be expanded until the script file
# is written below
set(mri_script "${mri_script} addlib $<TARGET_FILE:${lib}>=")
endforeach()
set(mri_script "${mri_script} save=end")
add_custom_command(
TARGET ${target} POST_BUILD
COMMAND echo ${mri_script} | tr = \\\\n | ${CMAKE_AR} -M)
endif(LINUX)
message("-- MergeStaticLibraries: ${target}: merged ${libs}")
# we want to set the target_link_libraries correctly for the new merged
# static library. First we get the list of link libraries for each
# of the libs we are merging
set(link_libs)
foreach(lib ${libs})
get_property(trans TARGET ${lib} PROPERTY LINK_LIBRARIES)
list(APPEND link_libs ${trans})
endforeach()
if (link_libs)
# now remove the duplicates and any of the libraries we already merged
list(REMOVE_DUPLICATES link_libs)
foreach(lib ${libs})
list(REMOVE_ITEM link_libs ${lib})
endforeach()
# set the target link libraries
target_link_libraries(${target} ${link_libs})
message("-- MergeStaticLibraries: ${target}: remaining ${link_libs}")
endif()
endfunction()