From 15f22648cd99f392ac5cab6afeec2a0e97b85c6d Mon Sep 17 00:00:00 2001
From: Dmitry Mikhirev
Date: Sat, 24 Jan 2015 14:31:23 +0300
Subject: fixed global search hang when zero-length matching found

---
 pcre.c   | 31 +++++++++++++++++++++++++++++--
 tests.mk |  6 +++++-
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/pcre.c b/pcre.c
index 9da5387..3245d79 100644
--- a/pcre.c
+++ b/pcre.c
@@ -389,7 +389,17 @@ static char *match(const char *name, int argc, char **argv)
 			retstr[retlen] = '\0';
 
 			/* where to start next search */
-			offset = ovec[1];
+			if (offset == ovec[1]) { //zero-length match
+				if (offset < len) {
+					// continue with one character shift
+					offset++;
+				} else {
+					// stop global search
+					global = 0;
+				}
+			} else {
+				offset = ovec[1];
+			}
 
 			/* set named make vars to captured substrings */
 			set_named_vars(re, str, ovec, ncap);
@@ -513,7 +523,24 @@ static char *subst(const char *name, int argc, char **argv)
 			rep = NULL;
 
 			/* where to start next search */
-			offset = ovec[1];
+			if (offset == ovec[1]) { //zero-length match
+				if (offset < subjlen) {
+					// continue with one character shift
+					s = str_extend(retstr, retlen + 1);
+					if (s == NULL) {
+						goto end_subst;
+					}
+					retstr = s;
+					strncpy(retstr + retlen, str + offset, 1);
+					retlen++;
+					offset++;
+				} else {
+					// stop global search
+					global = 0;
+				}
+			} else {
+				offset = ovec[1];
+			}
 		}
 	} while (global && (ncap != PCRE_ERROR_NOMATCH));
 
diff --git a/tests.mk b/tests.mk
index 47031c1..ce00b89 100644
--- a/tests.mk
+++ b/tests.mk
@@ -2,7 +2,7 @@ ifneq ($(findstring 4.,$(MAKE_VERSION)),4.)
     $(error you need GNU make 4.x to run tests)
 endif
 
-NUMTESTS = 30
+NUMTESTS = 32
 tests := $(foreach num,$(shell seq -f%03g $(NUMTESTS)),test$(num))
 
 load pcre.so
@@ -113,6 +113,10 @@ test029 = -z "$(m ^test$,$(subj029))" -a "$(m ^test$,$(subj029),m)" = test
 test030 = -z "$(m test.test,$(subj029))" -a \
 	  "$(s test.test,passed,$(subj029),s)" = passed
 
+# test zero-length matching
+test031 = "$(m x?,aaa,g)" = ""
+test032 = "$(s x?,!,abcd,g)" = "!a!b!c!d!"
+
 ### END OF TEST EXPRESSIONS ###
 
 test%:
-- 
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