Fix pcretest bad behaviour for callout in lookbehind.

git-svn-id: svn://vcs.exim.org/pcre/code/trunk@1625 2f5784b3-3f2a-0410-8824-cb99058d5e15

4 files changed, 33 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 4218698..2cfa87b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -49,6 +49,10 @@ Version 8.39 xx-xxxxxx-201x
 
 12. Assertion code generator in JIT has been optimized.
 
+13. A pattern such as /(?<=((?C)0))/, which has a callout inside a lookbehind
+    assertion, caused pcre2test to generate incorrect output, and also to read 
+    uninitialized memory (detected by ASAN or valgrind).
+
 
 Version 8.38 23-November-2015
 -----------------------------
diff --git a/pcretest.c b/pcretest.c
index 488e419..63869fd 100644
--- a/pcretest.c
+++ b/pcretest.c
@@ -2250,7 +2250,7 @@ data is not zero. */
 static int callout(pcre_callout_block *cb)
 {
 FILE *f = (first_callout | callout_extra)? outfile : NULL;
-int i, pre_start, post_start, subject_length;
+int i, current_position, pre_start, post_start, subject_length;
 
 if (callout_extra)
   {
@@ -2280,14 +2280,19 @@ printed lengths of the substrings. */
 
 if (f != NULL) fprintf(f, "--->");
 
+/* If a lookbehind is involved, the current position may be earlier than the
+match start. If so, use the match start instead. */
+
+current_position = (cb->current_position >= cb->start_match)?
+  cb->current_position : cb->start_match;
+
 PCHARS(pre_start, cb->subject, 0, cb->start_match, f);
 PCHARS(post_start, cb->subject, cb->start_match,
-  cb->current_position - cb->start_match, f);
+  current_position - cb->start_match, f);
 
 PCHARS(subject_length, cb->subject, 0, cb->subject_length, NULL);
 
-PCHARSV(cb->subject, cb->current_position,
-  cb->subject_length - cb->current_position, f);
+PCHARSV(cb->subject, current_position, cb->subject_length - current_position, f);
 
 if (f != NULL) fprintf(f, "\n");
 
@@ -5740,3 +5745,4 @@ return yield;
 }
 
 /* End of pcretest.c */
+
diff --git a/testdata/testinput2 b/testdata/testinput2
index 967a241..086e0f4 100644
--- a/testdata/testinput2
+++ b/testdata/testinput2
@@ -4235,4 +4235,8 @@ backtracking verbs. --/
 /(?=a\K)/ 
     ring bpattingbobnd $ 1,oern cou \rb\L
 
+/(?<=((?C)0))/
+    9010
+    abcd
+     
 /-- End of testinput2 --/
diff --git a/testdata/testoutput2 b/testdata/testoutput2
index 5fb28d5..d414a72 100644
--- a/testdata/testoutput2
+++ b/testdata/testoutput2
@@ -14650,4 +14650,19 @@ Start of matched string is beyond its end - displaying from end to start.
  0: a
  0L 
 
+/(?<=((?C)0))/
+    9010
+--->9010
+  0  ^       0
+  0   ^      0
+ 0: 
+ 1: 0
+    abcd
+--->abcd
+  0  ^       0
+  0   ^      0
+  0    ^     0
+  0     ^    0
+No match
+     
 /-- End of testinput2 --/