[PATCH 06/10] regex: avoid duplicate in espilon closure

[Paul Eggert]

* lib/regcomp.c (calc_eclosure_iter): Insert NODE into epsilon
closure first rather than last.  Otherwise, the epsilon closure
might contain a duplicate of NODE.
---
 ChangeLog     | 5 +++++
 lib/regcomp.c | 8 +++-----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index f4583e0af..74304474b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2021-02-05  Paul Eggert  <egg...@cs.ucla.edu>
 
+       regex: avoid duplicate in espilon closure
+       * lib/regcomp.c (calc_eclosure_iter): Insert NODE into epsilon
+       closure first rather than last.  Otherwise, the epsilon closure
+       might contain a duplicate of NODE.
+
        regex-tests: fix typo
        * tests/test-regex.c (main): Fix typo that would have caused an
        old test case to report incorrect values on failure.
diff --git a/lib/regcomp.c b/lib/regcomp.c
index d93698ae7..887e5b506 100644
--- a/lib/regcomp.c
+++ b/lib/regcomp.c
@@ -1695,12 +1695,14 @@ calc_eclosure_iter (re_node_set *new_set, re_dfa_t 
*dfa, Idx node, bool root)
   reg_errcode_t err;
   Idx i;
   re_node_set eclosure;
-  bool ok;
   bool incomplete = false;
   err = re_node_set_alloc (&eclosure, dfa->edests[node].nelem + 1);
   if (__glibc_unlikely (err != REG_NOERROR))
     return err;
 
+  /* An epsilon closure includes itself.  */
+  eclosure.elems[eclosure.nelem++] = node;
+
   /* This indicates that we are calculating this node now.
      We reference this value to avoid infinite loop.  */
   dfa->eclosures[node].nelem = -1;
@@ -1753,10 +1755,6 @@ calc_eclosure_iter (re_node_set *new_set, re_dfa_t *dfa, 
Idx node, bool root)
          }
       }
 
-  /* An epsilon closure includes itself.  */
-  ok = re_node_set_insert (&eclosure, node);
-  if (__glibc_unlikely (! ok))
-    return REG_ESPACE;
   if (incomplete && !root)
     dfa->eclosures[node].nelem = 0;
   else
-- 
2.27.0