Fix back references with zero minimum repeat when the reference is unset.

git-svn-id: svn://vcs.exim.org/pcre/code/branches/pcre16@832 2f5784b3-3f2a-0410-8824-cb99058d5e15

4 files changed, 27 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 883078d..84217d1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,7 @@
 ChangeLog for PCRE
 ------------------
 
-Version 8.22
+Version 8.30
 ------------
 
 1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
@@ -17,6 +17,11 @@ Version 8.22
     match a (*MARK), and the match failed at the start of the subject, a 
     reference to memory before the start of the subject could occur. This bug 
     was introduced by fix 17 of release 8.21.
+    
+5.  A reference to an unset group with zero minimum repetition was giving
+    totally wrong answers (in non-JavaScript-compatibility mode). For example,
+    /(another)?(\1?)test/ matched against "hello world test". This bug was 
+    introduced in release 8.13.
       
 
 Version 8.21 12-Dec-2011
diff --git a/pcre_exec.c b/pcre_exec.c
index 768b7dc..d89f36c 100644
--- a/pcre_exec.c
+++ b/pcre_exec.c
@@ -2630,9 +2630,13 @@ for (;;)
       }
 
     /* Handle repeated back references. If the length of the reference is
-    zero, just continue with the main loop. */
+    zero, just continue with the main loop. If the length is negative, it
+    means the reference is unset in non-Java-compatible mode. If the minimum is 
+    zero, we can continue at the same level without recursion. For any other 
+    minimum, carrying on will result in NOMATCH. */
 
     if (length == 0) continue;
+    if (length < 0 && min == 0) continue;
 
     /* First, ensure the minimum number of matches are present. We get back
     the length of the reference string explicitly rather than passing the
diff --git a/testdata/testinput1 b/testdata/testinput1
index 9bc9b51..e0529e3 100644
--- a/testdata/testinput1
+++ b/testdata/testinput1
@@ -5244,4 +5244,10 @@ name were given. ---/
     ** Failers
     abpq  
 
+/(another)?(\1?)test/
+    hello world test
+
+/(another)?(\1+)test/
+    hello world test
+
 /-- End of testinput1 --/
diff --git a/testdata/testoutput1 b/testdata/testoutput1
index 49b4a18..4893e69 100644
--- a/testdata/testoutput1
+++ b/testdata/testoutput1
@@ -8705,4 +8705,14 @@ No match
     abpq  
 No match
 
+/(another)?(\1?)test/
+    hello world test
+ 0: test
+ 1: <unset>
+ 2: 
+
+/(another)?(\1+)test/
+    hello world test
+No match
+
 /-- End of testinput1 --/