umask-util: simplify RUN_WITH_UMASK()

Why have a struct to store the iteration bit if we actually have plenty
place in mode_t?

diff --git a/src/basic/umask-util.h b/src/basic/umask-util.h
index e964292eaf4813893ecb0f7937a5514a9dd912be..cad745170ebfb0d0eec652bb54dbfd97f215c2d1 100644 (file)
--- a/src/basic/umask-util.h
+++ b/src/basic/umask-util.h
@@ -8,21 +8,19 @@
 #include "macro.h"
 
 static inline void umaskp(mode_t *u) {
-        umask(*u);
+        umask(*u & 0777);
 }
 
 #define _cleanup_umask_ _cleanup_(umaskp)
 
-struct _umask_struct_ {
-        mode_t mask;
-        bool quit;
-};
+/* We make use of the fact here that the umask() concept is using only the lower 9 bits of mode_t, although
+ * mode_t has space for the file type in the bits further up. We simply OR in the file type mask S_IFMT to
+ * distinguish the first and the second iteration of the RUN_WITH_UMASK() loop, so that we can run the first
+ * one, and exit on the second. */
 
-static inline void _reset_umask_(struct _umask_struct_ *s) {
-        umask(s->mask);
-};
+assert_cc((S_IFMT & 0777) == 0);
 
 #define RUN_WITH_UMASK(mask)                                            \
-        for (_cleanup_(_reset_umask_) struct _umask_struct_ _saved_umask_ = { umask(mask), false }; \
-             !_saved_umask_.quit ;                                      \
-             _saved_umask_.quit = true)
+        for (_cleanup_umask_ mode_t _saved_umask_ = umask(mask) | S_IFMT; \
+             FLAGS_SET(_saved_umask_, S_IFMT);                          \
+             _saved_umask_ &= 0777)