Bug - regular expressions

- Fixed bug where regexec was not being properly called.
- Fixed bug where multiple subexpressions were not being properly handled.
- Fixed bug that allowed regex matching to run off the end of a string.
- Fixed bug that causes regex captures to not be properly offset into the input
  string.
- Removed () from unit tests.

src/RX.cpp

@@ -96,7 +96,7 @@ void RX::compile ()
 
     int result;
     if ((result = regcomp (&_regex, _pattern.c_str (),
-                           REG_EXTENDED | /*REG_NOSUB |*/ REG_NEWLINE |
+                           REG_EXTENDED | REG_NEWLINE |
                            (_case_sensitive ? 0 : REG_ICASE))) != 0)
     {
       char message[256];
@@ -125,16 +125,21 @@ bool RX::match (
   if (!_compiled)
     compile ();
 
-  regmatch_t rm[RX_MAX_MATCHES];
-  if (regexec (&_regex, in.c_str (), RX_MAX_MATCHES, rm, 0) == 0)
+  regmatch_t rm[2];
+  int offset = 0;
+  int length = in.length ();
+  while (regexec (&_regex, in.c_str () + offset, 2, &rm[0], 0) == 0 &&
+         offset < length)
   {
-    for (unsigned int i = 1; i < 1 + _regex.re_nsub; ++i)
-      matches.push_back (in.substr (rm[i].rm_so, rm[i].rm_eo - rm[i].rm_so));
+    matches.push_back (in.substr (rm[0].rm_so + offset, rm[0].rm_eo - rm[0].rm_so));
+    offset += rm[0].rm_eo;
 
-    return true;
+    // Protection against zero-width patterns causing infinite loops.
+    if (rm[0].rm_so == rm[0].rm_eo)
+      ++offset;
   }
 
-  return false;
+  return matches.size () ? true : false;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -146,19 +151,22 @@ bool RX::match (
   if (!_compiled)
     compile ();
 
-  regmatch_t rm[RX_MAX_MATCHES];
-  if (regexec (&_regex, in.c_str (), RX_MAX_MATCHES, rm, 0) == 0)
+  regmatch_t rm[2];
+  int offset = 0;
+  int length = in.length ();
+  while (regexec (&_regex, in.c_str () + offset, 2, &rm[0], 0) == 0 &&
+         offset < length)
   {
-    for (unsigned int i = 1; i < 1 + _regex.re_nsub; ++i)
-    {
-      start.push_back (rm[i].rm_so);
-      end.push_back   (rm[i].rm_eo);
-    }
+    start.push_back (rm[0].rm_so + offset);
+    end.push_back   (rm[0].rm_eo + offset);
+    offset += rm[0].rm_eo;
 
-    return true;
+    // Protection against zero-width patterns causing infinite loops.
+    if (rm[0].rm_so == rm[0].rm_eo)
+      ++offset;
   }
 
-  return false;
+  return start.size () ? true : false;
 }
 
 ////////////////////////////////////////////////////////////////////////////////

src/RX.h

@@ -33,8 +33,6 @@
 #include <vector>
 #include <regex.h>
 
-#define RX_MAX_MATCHES 64
-
 class RX
 {
 public:

test/rx.t.cpp

@@ -32,7 +32,7 @@ Context context;
 
 int main (int argc, char** argv)
 {
-  UnitTest ut (16);
+  UnitTest ut (21);
 
   std::string text = "This is a test.";
 
@@ -40,10 +40,10 @@ int main (int argc, char** argv)
   ut.ok (r1.match (text), text + " =~ /i. /");
 
   std::vector <std::string> matches;
-  RX r2 ("(i.) ", false);
-  ut.ok (r2.match (matches, text), text + " =~ /(i.) /");
-  ut.ok (matches.size () == 1, "1 match");
-  ut.is (matches[0], "is", "$1 == is");
+  ut.ok (r1.match (matches, text), text + " =~ /i. /");
+  ut.ok (matches.size () == 2, "2 match");
+  ut.is (matches[0], "is ", "$1 == is\\s");
+  ut.is (matches[1], "is ", "$1 == is\\s");
 
   text = "abcdefghijklmnopqrstuvwxyz";
 
@@ -68,17 +68,27 @@ int main (int argc, char** argv)
   std::vector <std::string> results;
   std::vector <int> start;
   std::vector <int> end;
-  RX r8 ("(e..)", true);
-  ut.ok (r8.match (results, text), "(e..) there are matches");
-  ut.ok (r8.match (start, end, text), "(e..) there are matches");
-  ut.is (results.size (), (size_t) 1, "(e..) == 1 match");
-  ut.is (results[0], "est", "(e..)[0] == 'est'");
-  ut.is (start[0],      11, "(e..)[0] == 11->");
-  ut.is (end[0],        14, "(e..)[0] == ->14");
+  RX r8 ("e..", true);
+  ut.ok (r8.match (results, text), "e.. there are matches");
+  ut.ok (r8.match (start, end, text), "e.. there are matches");
+  ut.is (results.size (), (size_t) 4, "e.. == 4 matches");
+  ut.is (results[0], "est", "e..[0] == 'est'");
+  ut.is (start[0],      11, "e..[0] == 11->");
+  ut.is (end[0],        14, "e..[0] == ->14");
 
-  RX r9 ("\\bthe\\b");
+  results.clear ();
+  RX r9 ("e", true);
+  ut.ok (r9.match (results, text),           "e there are matches");
+  ut.is (results.size (), (size_t) 6,        "e == 6 matches");
+
+  start.clear ();
+  end.clear ();
+  ut.ok (r9.match (start, end, text),        "e there are matches");
+  ut.is (start.size (), (size_t) 6,          "e == 6 matches");
+
+  RX r10 ("\\bthe\\b");
   text = "this is the end.";
-  ut.ok (r9.match (text), text + " =~ /\\bthe\\b/");
+  ut.ok (r10.match (text), text + " =~ /\\bthe\\b/");
 
   return 0;
 }