resolved problem with proprietary KOBIL windoze driver

src/pcsc.hxx

@@ -368,14 +368,14 @@ namespace pcsc {
         Strings res;
         std::string grp(join(groups));
         DWORD num(0);
-        if (!check(SCardListReaders(_id, grp.size()?strconv(grp).data():0, 0,
+        if (!check(SCardListReaders(_id, groups.size()?strconv(grp).data():0, 0,
                                     &num),
-                   "(1) smartcard list readers of groups "+grp))
+                   "smartcard get size of readers of groups "+grp))
           return res;
         std::auto_ptr<char_t> nm(new char_t[num]);
-        if (!check(SCardListReaders(_id, grp.size()?strconv(grp).data():0,
+        if (!check(SCardListReaders(_id, groups.size()?strconv(grp).data():0,
                                     nm.get(), &num),
-                   "(2) smartcard list readers of groups "+grp))
+                   "smartcard list reader names of groups "+grp))
           return res;
         return res = split(strconv(string(nm.get(), num-1)));
       }
@@ -667,7 +667,7 @@ namespace pcsc {
       //! Splits a buffer with 0 separators into a vector of strings.
       Strings split(const std::string& in) {
         Strings res;
-        for (std::string::size_type pos(0); pos<in.size();
+        for (std::string::size_type pos(0); pos<in.size() && in[pos]!=0;
              pos+=res.rbegin()->size()+1)
           res.push_back(in.substr(pos).c_str());
         return res;
@@ -676,9 +676,12 @@ namespace pcsc {
       //!  Joins a vector of strings into a  buffer with 0 separators.
       std::string join(const Strings& in) {
         std::string res;
-        for (Strings::const_iterator it(in.begin());
-             it!=in.end(); ++it)
-          res+=*it+'\0';
+        if (in.size()) {
+          for (Strings::const_iterator it(in.begin());
+               it!=in.end(); ++it)
+            res+=*it+'\0';
+          res+='\0';
+        }
         return res;
       }