Merge "zip_writer.cc: update powerof2 and use it unconditionally" am: b86e248e8b

am: 0fd9adf747 Change-Id: Id31eb3c2b8ae67dbe6c8d255879a6cc0543a5abe
2019-03-28 13:52:24 -07:00 · 2019-03-28 13:52:24 -07:00 · 707d0b6da5
parent 51ca488977 0fd9adf747
commit 707d0b6da5
1 changed files with 7 additions and 3 deletions
--- a/libziparchive/zip_writer.cc
+++ b/libziparchive/zip_writer.cc
@ -30,9 +30,13 @@
 #include "entry_name_utils-inl.h"
 #include "zip_archive_common.h"

-#if !defined(powerof2)
-#define powerof2(x) ((((x)-1) & (x)) == 0)
-#endif
+#undef powerof2
+#define powerof2(x)                                               \
+  ({                                                              \
+    __typeof__(x) _x = (x);                                       \
+    __typeof__(x) _x2;                                            \
+    __builtin_add_overflow(_x, -1, &_x2) ? 1 : ((_x2 & _x) == 0); \
+  })

 /* Zip compression methods we support */
 enum {