More robust git version checking

- Check the exit code from git log to check if we have a version.
- Add a "-dirty" suffix if the repo is dirty when the build is made.

CMakeLists.txt

@@ -5,7 +5,29 @@ project (tini C)
 set (tini_VERSION_MAJOR 0)
 set (tini_VERSION_MINOR 6)
 set (tini_VERSION_PATCH 0)
-execute_process (COMMAND git log -n 1 --date=local --pretty=format:"%h" WORKING_DIRECTORY "${PROJECT_SOURCE_DIR}" OUTPUT_VARIABLE tini_VERSION_GIT)
+
+# Extract git version and dirty-ness
+execute_process (
+  COMMAND git log -n 1 --date=local --pretty=format:%h
+  WORKING_DIRECTORY "${PROJECT_SOURCE_DIR}"
+  RESULT_VARIABLE git_version_check_ret
+  OUTPUT_VARIABLE tini_VERSION_GIT
+)
+
+execute_process(
+  COMMAND git status --porcelain --untracked-files=no
+  WORKING_DIRECTORY "${PROJECT_SOURCE_DIR}"
+  OUTPUT_VARIABLE git_dirty_check_out
+)
+
+if("${git_version_check_ret}" EQUAL 0)
+  set(tini_VERSION_GIT " - git.${tini_VERSION_GIT}")
+  if(NOT "${git_dirty_check_out}" STREQUAL "")
+    set(tini_VERSION_GIT "${tini_VERSION_GIT}-dirty")
+  endif()
+else()
+  set(tini_VERSION_GIT "")
+endif()
 
 # Flags
 add_definitions (-D_FORTIFY_SOURCE=2)

src/tini.c

@@ -81,7 +81,7 @@ int spawn(const sigset_t* const child_sigset_ptr, char* const argv[], int* const
 
 
 void print_usage(char* const name, FILE* const file) {
-	fprintf(file, "%s (version %s - %s)\n", basename(name), TINI_VERSION, TINI_GIT);
+	fprintf(file, "%s (version %s%s)\n", basename(name), TINI_VERSION, TINI_GIT);
 	fprintf(file, "Usage: %s [OPTIONS] PROGRAM -- [ARGS]\n\n", basename(name));
 	fprintf(file, "Execute a program under the supervision of a valid init process (%s)\n\n", basename(name));
 	fprintf(file, "  -h: Show this help message and exit.\n");

src/tiniConfig.h.in

@@ -1,2 +1,2 @@
 #define TINI_VERSION "@tini_VERSION_MAJOR@.@tini_VERSION_MINOR@.@tini_VERSION_PATCH@"
-#define TINI_GIT     @tini_VERSION_GIT@
+#define TINI_GIT     "@tini_VERSION_GIT@"