2 files changed, 99 insertions, 0 deletions
diff --git a/cmake/CheckGit.cmake b/cmake/CheckGit.cmake
new file mode 100644
index 0000000..bd17447
--- /dev/null
+++ b/cmake/CheckGit.cmake
@@ -0,0 +1,84 @@
+set(CURRENT_LIST_DIR ${CMAKE_CURRENT_LIST_DIR})
+if (NOT DEFINED pre_configure_dir)
+    set(pre_configure_dir ${CMAKE_CURRENT_LIST_DIR})
+endif ()
+
+if (NOT DEFINED post_configure_dir)
+    set(post_configure_dir ${CMAKE_BINARY_DIR}/include)
+endif ()
+
+set(pre_configure_file ${pre_configure_dir}/git_version.hpp.in)
+set(post_configure_file ${post_configure_dir}/git_version.hpp)
+
+function(CheckGitWrite git_hash)
+    file(WRITE ${CMAKE_BINARY_DIR}/git-state.txt ${git_hash})
+endfunction()
+
+function(CheckGitRead git_hash)
+    if (EXISTS ${CMAKE_BINARY_DIR}/git-state.txt)
+        file(STRINGS ${CMAKE_BINARY_DIR}/git-state.txt CONTENT)
+        LIST(GET CONTENT 0 var)
+
+        set(${git_hash} ${var} PARENT_SCOPE)
+    endif ()
+endfunction()
+
+function(CheckGitVersion git_hash)
+    # Get the latest abbreviated commit hash of the working branch
+    execute_process(
+        COMMAND git log -1 --format=%H
+        WORKING_DIRECTORY ${CMAKE_CURRENT_LIST_DIR}
+        OUTPUT_VARIABLE GIT_HASH
+        OUTPUT_STRIP_TRAILING_WHITESPACE
+        )
+
+    CheckGitRead(GIT_HASH_CACHE)
+    if (NOT EXISTS ${post_configure_dir})
+        file(MAKE_DIRECTORY ${post_configure_dir})
+    endif ()
+
+    # if (NOT EXISTS ${post_configure_dir}/git_version.h)
+    #     file(COPY ${pre_configure_dir}/git_version.h DESTINATION ${post_configure_dir})
+    # endif()
+
+    if (NOT DEFINED GIT_HASH_CACHE)
+        set(GIT_HASH_CACHE "INVALID")
+    endif ()
+
+    # Only update the git_version.cpp if the hash has changed. This will
+    # prevent us from rebuilding the project more than we need to.
+    if (NOT ${GIT_HASH} STREQUAL ${GIT_HASH_CACHE} OR NOT EXISTS ${post_configure_file})
+        # Set che GIT_HASH_CACHE variable the next build won't have
+        # to regenerate the source file.
+        CheckGitWrite(${GIT_HASH})
+
+        configure_file(${pre_configure_file} ${post_configure_file} @ONLY)
+    endif ()
+    set(${git_hash} ${GIT_HASH} PARENT_SCOPE)
+
+
+endfunction()
+
+function(CheckGitSetup top_git_hash)
+
+    add_custom_target(AlwaysCheckGit COMMAND ${CMAKE_COMMAND}
+        -DRUN_CHECK_GIT_VERSION=1
+        -Dpre_configure_dir=${pre_configure_dir}
+        -Dpost_configure_file=${post_configure_dir}
+        -DGIT_HASH_CACHE=${GIT_HASH_CACHE}
+        -P ${CURRENT_LIST_DIR}/CheckGit.cmake
+        BYPRODUCTS ${post_configure_file}
+        )
+
+    add_library(git_version INTERFACE ${CMAKE_BINARY_DIR}/include/git_version.hpp)
+    add_dependencies(git_version AlwaysCheckGit)
+
+    CheckGitVersion(git_hash)
+    set(${top_git_hash} ${git_hash} PARENT_SCOPE)
+endfunction()
+
+# This is used to run this function from an external cmake process.
+if (RUN_CHECK_GIT_VERSION)
+    CheckGitVersion(git_hash)
+    set(${GIT_HASH} ${git_hash})
+endif ()
diff --git a/cmake/git_version.hpp.in b/cmake/git_version.hpp.in
new file mode 100644
index 0000000..ede9623
--- /dev/null
+++ b/cmake/git_version.hpp.in
@@ -0,0 +1,15 @@
+#ifndef GIT_VERSION_HPP
+#define GIT_VERSION_HPP
+
+#include <cstdint>
+
+namespace fud {
+
+constexpr uint8_t FudVersionMajor = @PROJECT_VERSION_MAJOR@;
+constexpr uint8_t FudVersionMinor = @PROJECT_VERSION_MINOR@;
+constexpr uint8_t FudVersionPatch = @PROJECT_VERSION_PATCH@;
+constexpr const char GitHash[] = "@GIT_HASH@";
+
+} // namespace fud
+
+#endif