json: escape slash in </ sequence

* lib.c (out_json_str): When the < character is seen, if the
lookahead character is /, output the < and a backslash to
escape the /.

* txr.1: Moved description of special JSON output handling
under tojson, and described the above escaping there also.

1 files changed, 5 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index 75cbc739..aafc933a 100644
--- a/lib.c
+++ b/lib.c
@@ -12592,6 +12592,11 @@ static void out_json_str(val str, val out)
     case '\t':
       put_string(lit("\\t"), out);
       break;
+    case '<':
+      put_char(chr(ch), out);
+      if (*cstr == '/')
+        put_char(chr('\\'), out);
+      break;
     case 0xDC00:
       put_string(lit("\\u0000"), out);
       break;