Fix bug in detecting potentially empty groups.

git-svn-id: svn://vcs.exim.org/pcre/code/trunk@170 2f5784b3-3f2a-0410-8824-cb99058d5e15

4 files changed, 24 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 3cb3820..a0a8d9c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -38,6 +38,10 @@ Version 7.2 01-May-07
         
  7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and 
     PCRE_INFO_JCHANGED. 
+    
+ 8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not 
+    terminating or by crashing. Diagnosed by Viktor Griph; it was in the code 
+    for detecting groups that can match an empty string.
 
 
 Version 7.1 24-Apr-07
diff --git a/pcre_compile.c b/pcre_compile.c
index 2002d20..c930193 100644
--- a/pcre_compile.c
+++ b/pcre_compile.c
@@ -1370,7 +1370,18 @@ for (code = first_significant_code(code + _pcre_OP_lengths[*code], NULL, 0, TRUE
   const uschar *ccode;
 
   c = *code;
+  
+  /* Groups with zero repeats can of course be empty; skip them. */
 
+  if (c == OP_BRAZERO || c == OP_BRAMINZERO)
+    {
+    do code += GET(code, 1); while (*code == OP_ALT);
+    c = *code;
+    continue;
+    }
+
+  /* For other groups, scan the branches. */
+   
   if (c == OP_BRA || c == OP_CBRA || c == OP_ONCE)
     {
     BOOL empty_branch;
@@ -1387,12 +1398,7 @@ for (code = first_significant_code(code + _pcre_OP_lengths[*code], NULL, 0, TRUE
       }
     while (*code == OP_ALT);
     if (!empty_branch) return FALSE;   /* All branches are non-empty */
-
-    /* Move past the KET and fudge things so that the increment in the "for"
-    above has no effect. */
-
-    c = OP_END;
-    code += 1 + LINK_SIZE - _pcre_OP_lengths[c];
+    c = *code;    
     continue;
     }
 
diff --git a/testdata/testinput1 b/testdata/testinput1
index d8ef12b..4d619a8 100644
--- a/testdata/testinput1
+++ b/testdata/testinput1
@@ -4018,4 +4018,7 @@
   abc
   abc\n  
 
+/(.*(.)?)*/
+    abcd
+
 / End of testinput1 /
diff --git a/testdata/testoutput1 b/testdata/testoutput1
index b513dca..0bfad1e 100644
--- a/testdata/testoutput1
+++ b/testdata/testoutput1
@@ -6571,4 +6571,9 @@ No match
   abc\n  
 No match
 
+/(.*(.)?)*/
+    abcd
+ 0: abcd
+ 1: 
+
 / End of testinput1 /