HPCC-12349 Updated based on review

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>

system/jlib/jstring.cpp

@@ -1474,15 +1474,7 @@ int utf8CharLen(unsigned char ch)
     return len;
 }
 
-bool checkValidUtf8Char(unsigned size, const unsigned char *ch)
-{
-    for (unsigned pos = 1; pos < size; pos++)
-        if ((ch[pos] < 128) || (ch[pos] >= 192))
-            return false;  //its not a valid utf-8 character
-    return true;
-}
-
-int utf8CharLen(const unsigned char *ch)
+int utf8CharLen(const unsigned char *ch, unsigned maxsize)
 {
     //return 1 if this is an ascii character,
     //or 0 if its not a valid utf-8 character
@@ -1490,8 +1482,11 @@ int utf8CharLen(const unsigned char *ch)
         return 1;
 
     unsigned char len = utf8CharLen(*ch);
-    if (len && !checkValidUtf8Char(len, ch))
+    if (maxsize!=(unsigned)-1 && len>maxsize)
         return 0;
+    for (unsigned pos = 1; pos < len; pos++)
+        if ((ch[pos] < 128) || (ch[pos] >= 192))
+            return 0;  //its not a valid utf-8 character after all
 
     return len;
 }
@@ -1984,7 +1979,8 @@ StringBuffer &appendJSONRealValue(StringBuffer& s, const char *name, double valu
 
 inline StringBuffer &encodeJSONChar(StringBuffer &s, const char *&ch, unsigned &remaining)
 {
-    switch (*ch)
+    byte next = *ch;
+    switch (next)
     {
         case '\b':
             s.append("\\b");
@@ -2005,26 +2001,23 @@ inline StringBuffer &encodeJSONChar(StringBuffer &s, const char *&ch, unsigned &
         case '\\':
         case '/':
             s.append('\\');
-            s.append(*ch);
+            s.append(next);
             break;
         default:
-            if (*ch >= ' ' && ((byte)*ch) < 128)
-                s.append(*ch);
-            else if (*ch < ' ' && *ch > 0)
-                s.append("\\u00").appendhex(*ch, true);
+            if (next >= ' ' && next < 128)
+                s.append(next);
+            else if (next < ' ' && next > 0)
+                s.append("\\u00").appendhex(next, true);
             else //json is always supposed to be utf8 (or other unicode formats)
             {
-                unsigned chlen = utf8CharLen((unsigned char)*ch); //check first byte
-                if (chlen==0 || chlen > remaining || !checkValidUtf8Char(chlen, (const unsigned char *) ch))
-                    s.append("\\u00").appendhex(*ch, true);
+                unsigned chlen = utf8CharLen((const unsigned char *)ch, remaining);
+                if (chlen==0)
+                    s.append("\\u00").appendhex(next, true);
                 else
                 {
-                    s.append(*ch);
-                    while(--chlen)
-                    {
-                        s.append(*(++ch));
-                        remaining--;
-                    }
+                    s.append(chlen, ch);
+                    ch += (chlen-1);
+                    remaining -= (chlen-1);
                 }
             }
             break;
@@ -2038,7 +2031,7 @@ StringBuffer &encodeJSON(StringBuffer &s, unsigned size, const char *value)
 {
     if (!value)
         return s;
-    while (size && *value)
+    while (size)
         encodeJSONChar(s, value, size);
     return s;
 }

system/jlib/jstring.hpp

@@ -371,7 +371,7 @@ extern jlib_decl const char *encodeXML(const char *x, IIOStream &out, unsigned f
 extern jlib_decl void decodeXML(ISimpleReadStream &in, StringBuffer &out, unsigned len=(unsigned)-1);
 
 extern jlib_decl int utf8CharLen(unsigned char ch);
-extern jlib_decl int utf8CharLen(const unsigned char *ch);
+extern jlib_decl int utf8CharLen(const unsigned char *ch, unsigned maxsize = (unsigned)-1);
 
 inline const char *encodeUtf8XML(const char *x, StringBuffer &ret, unsigned flags=false, unsigned len=(unsigned)-1)
 {