cmake: Don't try setting revision if git isn't found

diff --git a/buildsys/target/engine.cmake b/buildsys/target/engine.cmake
index bc2ee5fd75146e3fc3806c151e4282b86da9dd96..191f176a48d04519c87e18391537b71dc256316e 100644 (file)
--- a/buildsys/target/engine.cmake
+++ b/buildsys/target/engine.cmake
@@ -3,20 +3,30 @@ target_compile_definitions(common INTERFACE -D_FILE_OFFSET_BITS=64 -D__KERNEL_ST
 
 set(ENV{TZ} "UTC")
 
-# Build a version string for the engine.
-execute_process(
-       COMMAND git rev-parse --short HEAD
-       WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
-       OUTPUT_VARIABLE revision
-       OUTPUT_STRIP_TRAILING_WHITESPACE
-)
-
-execute_process(
-       COMMAND "git show -s --format=%ad --date='format-local:%a %b %d %Y %H:%M:%S UTC'"
-       OUTPUT_VARIABLE timestamp
-       OUTPUT_STRIP_TRAILING_WHITESPACE
-)
-set(DP_BUILD_REVISION "${timestamp} - ${revision}")
+find_package(Git)
+
+if(NOT GIT_FOUND AND NOT EXISTS ${CMAKE_SOURCE_DIR}/.git)
+       message(WARNING "Both the .git directory and Git itself were not found. Commit-based version strings are unavailable. Consider installing git and downloading the repository using it")
+elseif(NOT GIT_FOUND)
+       message(WARNING "Git not found. Commit-based version strings are unavailable. Consider installing git.")
+elseif(NOT EXISTS ${CMAKE_SOURCE_DIR}/.git)
+       message(WARNING ".git directory not found. Commit-based version strings are unavailable. Consider downloading the repository using git")
+else()
+       # Build a version string for the engine
+       execute_process(
+               COMMAND git rev-parse --short HEAD
+               WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+               OUTPUT_VARIABLE revision
+               OUTPUT_STRIP_TRAILING_WHITESPACE
+       )
+
+       execute_process(
+               COMMAND "git show -s --format=%ad --date='format-local:%a %b %d %Y %H:%M:%S UTC'"
+               OUTPUT_VARIABLE timestamp
+               OUTPUT_STRIP_TRAILING_WHITESPACE
+       )
+       set(DP_BUILD_REVISION "${timestamp} - ${revision}")
+endif()
 
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "(x|i[36])86|AMD64")
        option(ENGINE_CONFIG_SSE "Build with SSE support (x86 and x86_64 only)" ON)