Parse hexadecimal escapes in strings (from Lua 5.2).

2 files changed, 29 insertions, 13 deletions

diff --git a/src/lj_errmsg.h b/src/lj_errmsg.h
index b06a7798..d9fc615b 100644
--- a/src/lj_errmsg.h
+++ b/src/lj_errmsg.h
@@ -117,7 +117,7 @@ ERRDEF(XNUMBER,	"malformed number")
 ERRDEF(XLSTR,   "unfinished long string")
 ERRDEF(XLCOM,   "unfinished long comment")
 ERRDEF(XSTR,    "unfinished string")
-ERRDEF(XESC,    "escape sequence too large")
+ERRDEF(XESC,    "invalid escape sequence")
 ERRDEF(XLDELIM, "invalid long string delimiter")
 ERRDEF(XBCLOAD, "cannot load Lua bytecode")
 ERRDEF(XTOKEN,  LUA_QS " expected")
diff --git a/src/lj_lex.c b/src/lj_lex.c
index d3544e8e..fde7d9ca 100644
--- a/src/lj_lex.c
+++ b/src/lj_lex.c
@@ -154,7 +154,7 @@ static void read_string(LexState *ls, int delim, TValue *tv)
       continue;
     case '\\': {
       int c;
-      next(ls);  /* do not save the `\' */
+      next(ls);  /* Skip the '\\'. */
       switch (ls->current) {
       case 'a': c = '\a'; break;
       case 'b': c = '\b'; break;
@@ -163,20 +163,36 @@ static void read_string(LexState *ls, int delim, TValue *tv)
       case 'r': c = '\r'; break;
       case 't': c = '\t'; break;
       case 'v': c = '\v'; break;
+      case 'x':  /* Hexadecimal escape '\xXX'. */
+        c = (next(ls) & 15u) << 4;
+        if (!lj_char_isdigit(ls->current)) {
+          if (!lj_char_isxdigit(ls->current)) goto err_xesc;
+          c += 9 << 4;
+        }
+        c += (next(ls) & 15u);
+        if (!lj_char_isdigit(ls->current)) {
+          if (!lj_char_isxdigit(ls->current)) goto err_xesc;
+          c += 9;
+        }
+        break;
       case '\n': case '\r': save(ls, '\n'); inclinenumber(ls); continue;
-      case END_OF_STREAM: continue;  /* will raise an error next loop */
+      case END_OF_STREAM: continue;
       default:
         if (!lj_char_isdigit(ls->current)) {
-          save_and_next(ls);  /* handles \\, \", \', and \? */
-        } else {  /* \xxx */
-          int i = 0;
-          c = 0;
-          do {
-            c = 10*c + (ls->current-'0');
-            next(ls);
-          } while (++i<3 && lj_char_isdigit(ls->current));
-          if (c > 255)
-            lj_lex_error(ls, TK_string, LJ_ERR_XESC);
+          save_and_next(ls);  /* Handles '\\', '\"' and "\'". */
+        } else {  /* Decimal escape '\ddd'. */
+          c = (ls->current - '0');
+          if (lj_char_isdigit(next(ls))) {
+            c = c*10 + (ls->current - '0');
+            if (lj_char_isdigit(next(ls))) {
+              c = c*10 + (ls->current - '0');
+              if (c > 255) {
+              err_xesc:
+                lj_lex_error(ls, TK_string, LJ_ERR_XESC);
+              }
+              next(ls);
+            }
+          }
           save(ls, c);
         }
         continue;