Allow \/ in a json string

ChangeLog

@@ -1,3 +1,8 @@
+2022-02-25  Jay Berkenbilt  <ejb@ql.org>
+
+	* Bug fix in JSON parser: accept \/ in a string as valid input per
+	JSON spec even though we don't translate / to \/ on output.
+
 2022-02-22  Jay Berkenbilt  <ejb@ql.org>
 
 	* Recognize PDF strings explicitly marked as UTF-8 as allowed by

libqpdf/JSON.cc

@@ -629,6 +629,9 @@ JSONParser::decode_string(std::string const& str)
             {
               case '\\':
               case '\"':
+              case '/':
+                // \/ is allowed in json input, but so is /, so we
+                // don't map / to \/ in output.
                 result.append(1, ch);
                 break;
               case 'b':
@@ -875,7 +878,7 @@ void JSONParser::getToken()
 
           case ls_backslash:
             /* cSpell: ignore bfnrt */
-            if (strchr("\\\"bfnrt", *p))
+            if (strchr("\\\"/bfnrt", *p))
             {
                 lex_state = ls_string;
             }

libtests/qtest/json_parse/good-01.json

@@ -1,3 +1,3 @@
 {"a": "bcd", "e": [1,
                    2, 3,4,"five", {"six": 7, "8": 9}, null, true,
-                   false]}
+                   false, "a\b\f\n\r\t\\\"\/z"]}

libtests/qtest/json_parse/save-01.json

@@ -12,6 +12,7 @@
     },
     null,
     true,
-    false
+    false,
+    "a\b\f\n\r\t\\\"/z"
   ]
 }