[libgpiod PATCH] Add cmake support

[Andreas Pokorny <andreas.pokorny@gmail.com>]

This is a wip cmake support for libgpiod. It allows to integrate
libgpiod as part of a bigger cmake project built via the new package
management feature of cmake called FetchContent or as git submodule.
This work is motivated by the fact that not all distributions offer
proper development packages with bindings enabled and for the different
kernel api versions of gpio. This change can be provided/used as an
external build script, or conveniently shipped with libgpiod if desired.
Both ways I felt the urge to share it with upstream and potential users.

It does offer various build options to control whether tests, C++
bindings, tools, python bindings or examples are built. Furthermore
you can control if the libraries are built as archives or shared
libraries. Basic install support is available.

The options are:
 * ENABLE_LIBGPIOD_TOOLS (OFF)
 * ENABLE_LIBGPIOD_TESTS (OFF)
 * ENABLE_LIBGPIOD_SHARED (OFF)
 * ENABLE_LIBGPIOD_CXX_BINDINGS (ON)
 * ENABLE_LIBGPIOD_PYTHON_BINDINGS (ON)
 * ENABLE_LIBGPIOD_EXAMPLES (OFF)

This change is still wip, not everything works well enough:
 * examples are not built
 * tests are built but not integrated properly
 * the library versioning does currently not match the libtool generated
   library names (input on how to achieve that is highly welcome)
 * install location of the python module is still incorrect
 * man page generation is missing
 * doxygen generation is missing
---
 CMakeLists.txt    | 215 ++++++++++++++++++++++++++++++++++++++++++++++
 cmake_config.h.in |   6 ++
 2 files changed, 221 insertions(+)
 create mode 100644 CMakeLists.txt
 create mode 100644 cmake_config.h.in

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..386b239
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,215 @@
+cmake_policy(SET CMP0057 NEW)
+cmake_policy(SET CMP0048 NEW)
+cmake_policy(SET CMP0077 NEW)
+cmake_minimum_required(VERSION 3.14)
+
+project(libgpiod VERSION 2.0.0 LANGUAGES C CXX)
+set(EXTRA_VERSION "devel")
+set(GPIOD_SOVERSION 4.1.2)
+set(GPIOD_MOCK_SOVERSION 0.1.0)
+set(GPIOD_CXX_BINDING_SOVERSION 2.1.1)
+
+include(FetchContent)
+include(CheckSymbolExists)
+include(CheckIncludeFile)
+include(GNUInstallDirs)
+FetchContent_Declare(
+  Catch2
+  GIT_REPOSITORY https://github.com/catchorg/Catch2.git
+  GIT_TAG v2.13.7
+  )
+check_symbol_exists(ioctl "sys/ioctl.h" HAVE_IOCTL)
+set(CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
+check_symbol_exists(asprintf "stdio.h" HAVE_ASPRINTF)
+check_symbol_exists(scandir "dirent.h" HAVE_SCANDIR)
+check_symbol_exists(alphasort "dirent.h" HAVE_ALPHASORT)
+check_symbol_exists(ppoll "signal.h;poll.h"  HAVE_PPOLL)
+check_symbol_exists(realpath "limits.h;stdlib.h"  HAVE_REALPATH)
+check_include_file(getopt.h HAVE_GETOPT_H)
+check_include_file(sys/sysmacros.h  HAVE_SYS_MACROS_H)
+check_include_file(linux/version.h  HAVE_LINUX_VERSION_H)
+check_include_file(linux/const.h  HAVE_LINUX_CONST_H)
+check_include_file(linux/ioctl.h  HAVE_LINUX_IOCTL_H)
+check_include_file(linux/types.h  HAVE_LINUX_TYPES_H)
+if(HAVE_IOCTL AND HAVE_ASPRINTF AND HAVE_SCANDIR AND HAVE_ALPHASORT
AND HAVE_PPOLL AND HAVE_REALPATH AND HAVE_GETOPT_H
+  AND HAVE_LINUX_CONST_H AND HAVE_LINUX_IOCTL_H AND HAVE_LINUX_TYPES_H)
+  message(STATUS "Header and function check successfull")
+else()
+  message(SEND_ERROR "Missing headers or symbols - libgpiod will not compile")
+endif()
+
+option(ENABLE_LIBGPIOD_TOOLS OFF "enable libgpiod tools")
+option(ENABLE_LIBGPIOD_TESTS OFF "enable libgpiod tests")
+option(ENABLE_LIBGPIOD_SHARED OFF "enable shared libgpiod libraries")
+option(ENABLE_LIBGPIOD_CXX_BINDINGS ON "enable libgpiod C++ bindings")
+option(ENABLE_LIBGPIOD_PYTHON_BINDINGS ON "enable libgpiod C++ bindings")
+option(ENABLE_LIBGPIOD_EXAMPLES OFF "enable libgpiod examples")
+
+set(LIB_TYPE STATIC)
+if(ENABLE_LIBGPIOD_SHARED)
+  set(LIB_TYPE SHARED)
+endif()
+
+if(ENABLE_LIBGPIOD_TESTS)
+  find_package(PkgConfig)
+  find_package(Threads)
+  pkg_check_modules(KMOD REQUIRED libkmod>=18)
+  pkg_check_modules(UDEV REQUIRED libudev>=215)
+  pkg_check_modules(GLIB REQUIRED glib-2.0>=2.50)
+  check_symbol_exists(qsort "stdlib.h" HAVE_QSORT)
+
+  add_library(gpiomockup SHARED
+        tests/mockup/gpio-mockup.c
+        tests/mockup/gpio-mockup.h)
+  set_target_properties(gpiomockup PROPERTIES
+    VERSION ${PROJECT_VERSION}
+    SOVERSION ${GPIOD_MOCK_SOVERSION}
+    PUBLIC_HEADER tests/mockup/gpio-mockup.h
+    )
+  target_compile_options(gpiomockup PRIVATE -Wall -Wextra
-fvisibility=hidden -include ${CMAKE_BINARY_DIR}/config.h)
+  target_link_libraries(gpiomockup PRIVATE ${KMOD_LDFLAGS}
${UDEV_LDFLAGS} Threads::Threads)
+  target_include_directories(gpiomockup PUBLIC
$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/tests/mockup/>)
+
+  enable_testing()
+  add_executable(gpiod_tests
+        tests/gpiod-test.c
+        tests/gpiod-test.h
+        tests/tests-chip.c
+        tests/tests-event.c
+        tests/tests-line.c
+        tests/tests-misc.c)
+  target_compile_options(gpiod_tests PRIVATE ${GLIB_CFLAGS} -Wall
-Wextra -include ${CMAKE_BINARY_DIR}/config.h)
+  target_compile_definitions(gpiod_tests PRIVATE G_LOG_DOMAIN="gpiod-test")
+  target_link_libraries(gpiod_tests PRIVATE gpiod ${GLIB_LDFLAGS}
Threads::Threads gpiomockup)
+
+  find_program(BATS bats)
+     #REQUIRED)
+  if(BATS_FOUND)
+    # TODO
+  endif()
+endif()
+
+set(GPIOD_VERSION_STR "${PROJECT_VERSION}-${EXTRA_VERSION}")
+configure_file(cmake_config.h.in config.h)
+add_library(gpiod ${LIB_TYPE} lib/core.c lib/helpers.c lib/internal.h
lib/misc.c lib/uapi/gpio.h)
+target_compile_options(gpiod PRIVATE -Wall -Wextra
-fvisibility=hidden -include ${CMAKE_BINARY_DIR}/config.h)
+add_library(gpiod::gpiod ALIAS gpiod)
+set_target_properties(gpiod PROPERTIES
+  VERSION ${PROJECT_VERSION}
+  SOVERSION ${GPIOD_SOVERSION}
+  PUBLIC_HEADER include/gpiod.h
+  )
+target_include_directories(gpiod PUBLIC
$<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/include/>)
+install(TARGETS gpiod
+  PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+  LIBRARY DESTINATION lib
+  ARCHIVE DESTINATION lib/static)
+
+if(ENABLE_LIBGPIOD_TOOLS)
+  check_symbol_exists(basename "libgen.h" HAVE_BASENAME)
+  check_symbol_exists(daemon "unistd.h" HAVE_DAEMON)
+  check_symbol_exists(signalfd "sys/signalfd.h" HAVE_SIGNALFD)
+  check_symbol_exists(setlinebuf "stdio.h"   HAVE_SETLINEBUF)
+  if(HAVE_BASENAME AND HAVE_DAEMON AND HAVE_SIGNALFD AND HAVE_SETLINEBUF)
+    message(STATUS "Header and function check for tools successfull")
+  else()
+    message(SEND_ERROR "Missing headers or symbols - libgpiod tools
will not compile")
+  endif()
+
+  add_library(tools-common STATIC tools/tools-common.c tools/tools-common.h)
+  target_compile_options(tools-common PRIVATE -include
${CMAKE_BINARY_DIR}/config.h)
+  target_link_libraries(tools-common PUBLIC gpiod)
+  add_executable(gpiodetect tools/gpiodetect.c)
+  add_executable(gpioinfo tools/gpioinfo.c)
+  add_executable(gpioget tools/gpioget.c)
+  add_executable(gpioset tools/gpioset.c)
+  add_executable(gpiomon tools/gpiomon.c)
+  add_executable(gpiofind tools/gpiofind.c)
+  target_link_libraries(gpiodetect tools-common)
+  target_link_libraries(gpioinfo tools-common)
+  target_link_libraries(gpioget tools-common)
+  target_link_libraries(gpioset tools-common)
+  target_link_libraries(gpiomon tools-common)
+  target_link_libraries(gpiofind tools-common)
+endif()
+
+if(ENABLE_LIBGPIOD_CXX_BINDINGS)
+  add_library(gpiodcxx ${LIB_TYPE}
+    bindings/cxx/gpiod.hpp
+    bindings/cxx/chip.cpp
+    bindings/cxx/internal.hpp
+    bindings/cxx/iter.cpp
+    bindings/cxx/line.cpp
+    bindings/cxx/line_bulk.cpp
+    )
+  add_library(gpiod::gpiodcxx ALIAS gpiodcxx)
+  target_compile_options(gpiodcxx PRIVATE -Wall -Wextra -fvisibility=hidden)
+  target_include_directories(gpiodcxx PUBLIC
$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/bindings/cxx>)
+  target_link_libraries(gpiodcxx PUBLIC gpiod)
+  set_target_properties(gpiodcxx PROPERTIES
+    VERSION ${PROJECT_VERSION}
+    SOVERSION ${GPIOD_CXX_BINDING_SOVERSION}
+    PUBLIC_HEADER bindings/cxx/gpiod.hpp
+    )
+
+  install(TARGETS gpiodcxx
+    PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+    LIBRARY DESTINATION lib
+    ARCHIVE DESTINATION lib)
+
+  target_compile_features(gpiodcxx PUBLIC cxx_std_11)
+  if(ENABLE_LIBGPIOD_TESTS)
+    FetchContent_MakeAvailable(Catch2)
+    add_executable(gpiod_cxx_test
+      bindings/cxx/tests/gpio-mockup.cpp
+      bindings/cxx/tests/gpio-mockup.hpp
+      bindings/cxx/tests/gpiod-cxx-test-main.cpp
+      bindings/cxx/tests/gpiod-cxx-test.cpp
+      bindings/cxx/tests/tests-chip.cpp
+      bindings/cxx/tests/tests-event.cpp
+      bindings/cxx/tests/tests-iter.cpp
+      bindings/cxx/tests/tests-line.cpp
+      )
+    target_link_libraries(gpiod_cxx_test PUBLIC Threads::Threads
gpiomockup gpiodcxx Catch2::Catch2)
+  endif()
+  if(ENABLE_LIBGPIOD_EXAMPLES)
+    # target_compile_features(libgpiodcxx-examples PUBLIC cxx_std_17)
+  endif()
+endif()
+
+if(ENABLE_LIBGPIOD_PYTHON_BINDINGS)
+  find_program(PYTHON_CONFIG python3-config REQUIRED)
+  execute_process(COMMAND ${PYTHON_CONFIG} --includes OUTPUT_VARIABLE
PYTHON_CPPFLAGS)
+  execute_process(COMMAND ${PYTHON_CONFIG} --libs OUTPUT_VARIABLE PYTHON_LIBS)
+  string(STRIP ${PYTHON_CPPFLAGS} PYTHON_CPPFLAGS)
+  string(REGEX REPLACE " " ";" PYTHON_CPPFLAGS ${PYTHON_CPPFLAGS})
+  string(STRIP ${PYTHON_LIBS} PYTHON_LIBS)
+  string(REGEX REPLACE " " ";" PYTHON_LIBS ${PYTHON_LIBS})
+  add_library(gpiod_module MODULE
+    bindings/python/gpiodmodule.c
+    )
+  add_library(gpiod::gpiod_module ALIAS gpiod_module)
+  target_link_libraries(gpiod_module gpiod ${PYTHON_LIBS})
+  target_compile_options(gpiod_module PRIVATE -Wall -Wextra ${PYTHON_CPPFLAGS})
+  set_target_properties(gpiod_module PROPERTIES OUTPUT_NAME gpiod PREFIX "")
+  install(TARGETS gpiod_module
+    PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+    RUNTIME DESTINATION bin
+    LIBRARY DESTINATION lib
+    ARCHIVE DESTINATION lib)
+endif()
+
+find_program(DOXYGEN doxygen)
+if(DOXYGEN_FOUND)
+  configure_file(DoxyFile.in DoxyFile)
+  set(VERSION_STR ${PROJECT_VERSION})
+  set(top_srcdir ${PROJECT_SOURCE_DIR})
+endif()
+
+if(NOT CMAKE_CROSSCOMPILING)
+  find_program(HELP2MAN help2man)
+endif()
+
+if(NOT HELP2MAN_FOUND)
+  message(STATUS "help2man not found - man pages annot be generated
automatically")
+endif()
diff --git a/cmake_config.h.in b/cmake_config.h.in
new file mode 100644
index 0000000..484e62f
--- /dev/null
+++ b/cmake_config.h.in
@@ -0,0 +1,6 @@
+/* config.h.  Generated from cmake_config.h.in by cmake.  */
+
+
+#cmakedefine GPIOD_VERSION_STR "@GPIOD_VERSION_STR@"
+
+#define _GNU_SOURCE 1
-- 
2.30.2