From: Thomas Weißschuh <thomas@t-8ch.de>
Date: Fri, 14 Oct 2022 19:54:47 +0000 (+0200)
Subject: autotools: stop using AC_C_BIGENDIAN / WORDS_BIGENDIAN
X-Git-Tag: v2.39-rc1~479^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=83b418c19c3959b2f23bba6c7cf1316ee6e404ed;p=thirdparty%2Futil-linux.git

autotools: stop using AC_C_BIGENDIAN / WORDS_BIGENDIAN

This define is specific to autotools. Not defining the macro will lead
to silently miscompiled code as has happened with the meson build.

Instead use macros provided by the compiler itself. It does not need any
support from the buildsystem and is supported by both gcc and clang.

If a compiler does not support this feature we will get a loud error
instead of silent miscompilation.

Furthermore it probably better supports universal binaries on macOS
which compiles multiple architectures in a single build.
---

diff --git a/configure.ac b/configure.ac
index e760889ccf..6c0720c143 100644
--- a/configure.ac
+++ b/configure.ac
@@ -127,7 +127,6 @@ AC_PROG_YACC
 AC_CANONICAL_HOST
 AC_C_CONST
 AC_C_VOLATILE
-AC_C_BIGENDIAN
 
 dnl Compiler warnings
 UL_WARN_ADD([-fno-common])
diff --git a/disk-utils/cramfs.h b/disk-utils/cramfs.h
index e0ddbda1c8..43bbf52649 100644
--- a/disk-utils/cramfs.h
+++ b/disk-utils/cramfs.h
@@ -36,11 +36,7 @@
 #define CRAMFS_OFFSET_WIDTH 26
 
 #ifndef HOST_IS_BIG_ENDIAN
-#ifdef WORDS_BIGENDIAN
-#define HOST_IS_BIG_ENDIAN 1
-#else
-#define HOST_IS_BIG_ENDIAN 0
-#endif
+#define HOST_IS_BIG_ENDIAN (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
 #endif
 
 /*
diff --git a/include/bitops.h b/include/bitops.h
index 72274de0b5..16ba2abd61 100644
--- a/include/bitops.h
+++ b/include/bitops.h
@@ -87,7 +87,7 @@
 #endif
 
 #ifndef htobe16
-# if !defined(WORDS_BIGENDIAN)
+# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 #  define htobe16(x) bswap_16 (x)
 #  define htole16(x) (x)
 #  define be16toh(x) bswap_16 (x)
diff --git a/lib/md5.c b/lib/md5.c
index 3765ab93ed..eedc71b075 100644
--- a/lib/md5.c
+++ b/lib/md5.c
@@ -18,7 +18,7 @@
 
 #include "md5.h"
 
-#if !defined(WORDS_BIGENDIAN)
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 # define byteReverse(buf, len)	/* Nothing */
 #else
 static void byteReverse(unsigned char *buf, unsigned longs);
@@ -38,7 +38,7 @@ static void byteReverse(unsigned char *buf, unsigned longs)
     } while (--longs);
 }
 #endif /* !ASM_MD5 */
-#endif /* !WORDS_BIGENDIAN */
+#endif /* __ORDER_LITTLE_ENDIAN__ */
 
 /*
  * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
diff --git a/lib/sha1.c b/lib/sha1.c
index 22d33b3151..eedeaa84ae 100644
--- a/lib/sha1.c
+++ b/lib/sha1.c
@@ -19,7 +19,7 @@
 #define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))
 
 /* blk0() and blk() perform the initial expand. */
-#ifdef WORDS_BIGENDIAN
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 # define blk0(i) block->l[i]
 #else
 # define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xFF00FF00) \
diff --git a/libblkid/src/superblocks/minix.c b/libblkid/src/superblocks/minix.c
index 6011842f7f..8447814f45 100644
--- a/libblkid/src/superblocks/minix.c
+++ b/libblkid/src/superblocks/minix.c
@@ -61,7 +61,7 @@ static int get_minix_version(const unsigned char *data, int *other_endian)
 	if (!version)
 		return -1;
 
-#if defined(WORDS_BIGENDIAN)
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 	endian = *other_endian ? "LE" : "BE";
 #else
 	endian = *other_endian ? "BE" : "LE";
diff --git a/sys-utils/lscpu.c b/sys-utils/lscpu.c
index 7c9e4505eb..f613515873 100644
--- a/sys-utils/lscpu.c
+++ b/sys-utils/lscpu.c
@@ -999,7 +999,7 @@ static void print_summary(struct lscpu_cxt *cxt)
 	}
 	if (ct && ct->addrsz)
 		add_summary_s(tb, sec, _("Address sizes:"), ct->addrsz);
-#if !defined(WORDS_BIGENDIAN)
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 	add_summary_s(tb, sec, _("Byte Order:"), "Little Endian");
 #else
 	add_summary_s(tb, sec, _("Byte Order:"), "Big Endian");
diff --git a/tests/helpers/test_sysinfo.c b/tests/helpers/test_sysinfo.c
index e13931d04b..aea019276b 100644
--- a/tests/helpers/test_sysinfo.c
+++ b/tests/helpers/test_sysinfo.c
@@ -35,7 +35,7 @@ static int hlp_wordsize(void)
 
 static int hlp_endianness(void)
 {
-#if !defined(WORDS_BIGENDIAN)
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 	printf("LE\n");
 #else
 	printf("BE\n");