From 5468f6034610bb108d89e13dc24c833202ee7388 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering@redhat.com>
Date: Thu, 28 Apr 2011 10:20:43 +0200
Subject: maint: add the tight_scope syntax-checking rule

This ensures that the only externally scoped symbols are ones
that are explicitly marked as "extern" or white-listed like "main".
* src/Makefile.am (sc_tight_scope): New rule, copied from coreutils.
* cfg.mk (sc_tight_scope): Define, to hook to it from the top level.
---
 src/Makefile.am | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

(limited to 'src')

diff --git a/src/Makefile.am b/src/Makefile.am
index 257472be..ec3e1769 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -45,3 +45,43 @@ localedir = $(datadir)/locale
 AM_CPPFLAGS = -I$(top_builddir)/lib -I$(top_srcdir)/lib
 
 EXTRA_DIST = dosbuf.c
+
+# The following rule is not designed to be portable,
+# and relies on tools that not everyone has.
+
+# Most functions in src/*.c should have static scope.
+# Any that don't must be marked with `extern', but `main'
+# and `usage' are exceptions: they're always extern, but
+# do not need to be marked.  Also functions starting with __
+# are exempted due to possibly being added by the compiler
+# (when compiled as a shared library for example).
+#
+# The second nm|grep checks for file-scope variables with `extern' scope.
+.PHONY: sc_tight_scope
+sc_tight_scope: $(bin_PROGRAMS)
+	@t=exceptions-$$$$;						\
+	trap 's=$$?; rm -f $$t; exit $$s' 0;				\
+	for sig in 1 2 3 13 15; do					\
+	  eval "trap 'v=`expr $$sig + 128`; (exit $$v); exit $$v' $$sig"; \
+	done;								\
+	src=`for f in $(SOURCES); do					\
+	       test -f $$f && d= || d=$(srcdir)/; echo $$d$$f; done`;	\
+	hdr=`for f in $(noinst_HEADERS); do				\
+	       test -f $$f && d= || d=$(srcdir)/; echo $$d$$f; done`;	\
+	( printf 'main\nusage\n_.*\n';					\
+	  grep -h -A1 '^extern .*[^;]$$' $$src				\
+	    | grep -vE '^(extern |--)' | sed 's/ .*//';			\
+	  perl -lne '/^extern (?:struct |const |enum )?\S+ \**(\S*) \(/'\
+                 -e 'and print $$1' $$hdr;				\
+	) | sort -u | sed 's/^/^/;s/$$/$$/' > $$t;			\
+	nm -e *.$(OBJEXT) | sed -n 's/.* T //p'				\
+	    | sed 's/^_//' | grep -Ev -f $$t				\
+	  && { echo the above functions should have static scope >&2;	\
+	       exit 1; } || : ;						\
+	( printf '^program_name$$\n';					\
+	  perl -lne '/^extern .*?\**(\w+);/ and print "^$$1\$$"'	\
+	    $$hdr *.h ) | sort -u > $$t;				\
+	nm -e *.$(OBJEXT) | sed -n 's/.* [BD] //p'			\
+	    | sed 's/^_//' | grep -Ev -f $$t				\
+	  && { echo the above variables should have static scope >&2;	\
+	       exit 1; } || :
-- 
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