commit 1fe4356f6867f0be8995b19f95d4809a8174021c
author Nick Kralevich <nnk@google.com> Thu Mar 28 13:38:44 2019 -0700
committer android-build-merger <android-build-merger@google.com> Thu Mar 28 13:38:44 2019 -0700
tree 2557be51b5b04e77c74fa02ca1d01b54fe89fe28
parent 44a0f41d55c5a2fd1ed0d3ae689e68cd87f84900
parent ea58388c4d8baa6cdc725fe0b20e7f5bdb15019a

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

Change-Id: I182bab95eb26b06d8d7a8f173519edae270660b2

libziparchive/zip_writer.cc

diff --git a/libziparchive/zip_writer.cc b/libziparchive/zip_writer.cc
index 981df3a..0df0fa5 100644
--- 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 {