Makefile: Add static check for misuse of LITTLE_ENDIAN and BIG_ENDIAN.

I've pointed out two misuses of these macros in review in the last week,
by different authors.  It's time to make it difficult to screw this up.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Thomas Graf <tgraf@noironetworks.com>

diff --git a/Makefile.am b/Makefile.am
index 0cfc603..ddc7acb 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -258,6 +258,23 @@ check-assert-h-usage:
         fi
 .PHONY: check-assert-h-usage
 
+# Check that LITTLE_ENDIAN and BIG_ENDIAN are not used unless BYTE_ORDER is
+# also mentioned.  (<endian.h> always defines the former two constants.  They
+# must be compared to BYTE_ORDER to get the machine's correct endianness.  But
+# it is better to use WORDS_BIGENDIAN.)
+ALL_LOCAL += check-endian
+check-endian:
+       @if test -e $(srcdir)/.git && (git --version) >/dev/null 2>&1 && \
+           (cd $(srcdir) && git --no-pager grep -l -E \
+             -e 'BIG_ENDIAN|LITTLE_ENDIAN' --and --not -e 'BYTE_ORDER' | \
+           $(EGREP) -v '^datapath/'); \
+         then \
+           echo "See above for list of files that misuse LITTLE""_ENDIAN"; \
+           echo "or BIG""_ENDIAN.  Please use WORDS_BIGENDIAN instead."; \
+           exit 1; \
+        fi
+.PHONY: check-endian
+
 ALL_LOCAL += thread-safety-check
 thread-safety-check:
        @cd $(srcdir); \