File regex-parse-reg-exp.patch of Package glibc.14271

2015-09-19  Paul Eggert  <eggert@cs.ucla.edu>

	Diagnose ERE '()|\1'
	Problem reported by Hanno Böck in: http://bugs.gnu.org/21513
	* lib/regcomp.c (parse_reg_exp): While parsing alternatives, keep
	track of the set of previously-completed subexpressions available
	before the first alternative, and restore this set just before
	parsing each subsequent alternative.  This lets us diagnose the
	invalid back-reference in the ERE '()|\1'.

Index: glibc-2.26/posix/regcomp.c
===================================================================
--- glibc-2.26.orig/posix/regcomp.c
+++ glibc-2.26/posix/regcomp.c
@@ -2134,6 +2134,7 @@ parse_reg_exp (re_string_t *regexp, rege
 {
   re_dfa_t *dfa = (re_dfa_t *) preg->buffer;
   bin_tree_t *tree, *branch = NULL;
+  bitset_word_t initial_bkref_map = dfa->completed_bkref_map;
   tree = parse_branch (regexp, preg, token, syntax, nest, err);
   if (BE (*err != REG_NOERROR && tree == NULL, 0))
     return NULL;
@@ -2144,6 +2145,8 @@ parse_reg_exp (re_string_t *regexp, rege
       if (token->type != OP_ALT && token->type != END_OF_RE
 	  && (nest == 0 || token->type != OP_CLOSE_SUBEXP))
 	{
+	  bitset_word_t accumulated_bkref_map = dfa->completed_bkref_map;
+	  dfa->completed_bkref_map = initial_bkref_map;
 	  branch = parse_branch (regexp, preg, token, syntax, nest, err);
 	  if (BE (*err != REG_NOERROR && branch == NULL, 0))
 	    {
@@ -2151,6 +2154,7 @@ parse_reg_exp (re_string_t *regexp, rege
 		postorder (tree, free_tree, NULL);
 	      return NULL;
 	    }
+	  dfa->completed_bkref_map |= accumulated_bkref_map;
 	}
       else
 	branch = NULL;