Check that any dependency file is newer than Makefile before concatenating

On slower file systems, this makes a huge difference

Reviewed-by: Rich Salz <rsalz@openssl.org>

diff --git a/Configurations/unix-Makefile.tmpl b/Configurations/unix-Makefile.tmpl
index 47608f7d841dfeb7e3d6b2fd6d040be2c46a2247..b591c4da20529d28c46671b500c7e7eb829c8ef7 100644 (file)
--- a/Configurations/unix-Makefile.tmpl
+++ b/Configurations/unix-Makefile.tmpl
@@ -249,17 +249,39 @@ clean: libclean
        rm -f $(TARFILE)
 
 # This exists solely for those who still type 'make depend'
+#
+# We check if any depfile is newer than Makefile and decide to
+# concatenate only if that is true, or if 'test' (a.k.a [ )
+# doesn't have the option to figure it out (-nt).
+#
+# To check if test has the file age comparison operator, we
+# simply try, and rely test to exit with 0 if the comparison
+# was true, 1 if false, and most importantly, 2 if it doesn't
+# recognise the operator.
 depend:
-       @( sed -e '/^# DO NOT DELETE THIS LINE.*/,$$d' < Makefile; \
-         echo '# DO NOT DELETE THIS LINE -- make depend depends on it.'; \
-         echo; \
+       @catdepends=false; \
+       if [ Makefile -nt Makefile ] 2>/dev/null || [ $$? = 1 ]; then \
          for d in $(DEPS); do \
-           if [ -f $$d ]; then cat $$d; fi; \
-         done ) > Makefile.new
-       @if ! cmp Makefile.new Makefile >/dev/null 2>&1; then \
-               mv -f Makefile.new Makefile; \
+           if [ $$d -nt Makefile ]; then \
+             catdepends=true; \
+             break; \
+           fi; \
+         done; \
        else \
-               rm -f Makefile.new; \
+         catdepends=true; \
+       fi; \
+       if [ $$catdepends = true ]; then \
+         ( sed -e '/^# DO NOT DELETE THIS LINE.*/,$$d' < Makefile; \
+           echo '# DO NOT DELETE THIS LINE -- make depend depends on it.'; \
+           echo; \
+           for d in $(DEPS); do \
+             if [ -f $$d ]; then cat $$d; fi; \
+           done ) > Makefile.new; \
+         if ! cmp Makefile.new Makefile >/dev/null 2>&1; then \
+           mv -f Makefile.new Makefile; \
+         else \
+           rm -f Makefile.new; \
+         fi; \
        fi
 
 # Install helper targets #############################################