Mesa (master): util: unbreak endian detection on OpenBSD

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Module: Mesa
Branch: master
Commit: 7eab6845e9dd49f0ef0bf9a7d986aaf685e77981
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=7eab6845e9dd49f0ef0bf9a7d986aaf685e77981

Author: Jonathan Gray <jsg at jsg.id.au>
Date:   Wed Mar 28 14:06:14 2018 +1100

util: unbreak endian detection on OpenBSD

Since cbee1bfb34274668a05995b9d4c78ddec9e5ea4c endian.h is unconditionally
used if available.

glibc has byte order defines with two leading underscores.  OpenBSD
has private defines with a single leading underscore in machine/endian.h
and public defines in endian.h with no underscore.

The code under the endian.h block did not check if symbols were
defined before equating them so '#if __BYTE_ORDER == __LITTLE_ENDIAN'
would turn into '#if 0 == 0' which is always true.

Fixes: cbee1bfb342 ("meson/configure: detect endian.h instead of trying to guess when it's available")
Signed-off-by: Jonathan Gray <jsg at jsg.id.au>
Reviewed-by: Eric Engestrom <eric at engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5630>

---

 src/util/u_endian.h | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/util/u_endian.h b/src/util/u_endian.h
index 6bbae3c444c..d9ead69a4a4 100644
--- a/src/util/u_endian.h
+++ b/src/util/u_endian.h
@@ -30,10 +30,19 @@
 #ifdef HAVE_ENDIAN_H
 #include <endian.h>
 
-#if __BYTE_ORDER == __LITTLE_ENDIAN
+/* glibc */
+#if defined(__BYTE_ORDER) && (__BYTE_ORDER == __LITTLE_ENDIAN)
 # define UTIL_ARCH_LITTLE_ENDIAN 1
 # define UTIL_ARCH_BIG_ENDIAN 0
-#elif __BYTE_ORDER == __BIG_ENDIAN
+#elif defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)
+# define UTIL_ARCH_LITTLE_ENDIAN 0
+# define UTIL_ARCH_BIG_ENDIAN 1
+#endif
+
+#if defined(BYTE_ORDER) && (BYTE_ORDER == LITTLE_ENDIAN)
+# define UTIL_ARCH_LITTLE_ENDIAN 1
+# define UTIL_ARCH_BIG_ENDIAN 0
+#elif defined(BYTE_ORDER) && (BYTE_ORDER == BIG_ENDIAN)
 # define UTIL_ARCH_LITTLE_ENDIAN 0
 # define UTIL_ARCH_BIG_ENDIAN 1
 #endif
@@ -60,8 +69,8 @@
 # define UTIL_ARCH_BIG_ENDIAN 1
 #endif
 
-#elif defined(__OpenBSD__) || defined(__NetBSD__) || \
-      defined(__FreeBSD__) || defined(__DragonFly__)
+#elif defined(__NetBSD__) || defined(__FreeBSD__) || \
+      defined(__DragonFly__)
 #include <sys/types.h>
 #include <machine/endian.h>