Re: [9front] libjson can print invalid json

["Dave MacFarlane" <driusan@driusan.net>]

I was curious about keys and it looks like there's also a bug
where they're not being properly escaped. Here's a diff that
fixes that as well.

cpu% git/diff .
diff 30c5296f32b87d83529d772732726891e1261c9c uncommitted
--- a/sys/src/libjson/printjson.c
+++ b/sys/src/libjson/printjson.c
@@ -7,6 +7,32 @@
 static int printobject(Fmt*, JSON*, int);
 
 static int
+printstring(Fmt *f, char *s)
+{
+	int n;
+	
+	n = fmtrune(f, '"');
+	for(; *s; s++){
+		switch(*s){
+		case '\\':	n += fmtstrcpy(f, "\\\\");	break;
+		case '\f':	n += fmtstrcpy(f, "\\f");	break;
+		case '\b':	n += fmtstrcpy(f, "\\b");	break;
+		case '\n':	n += fmtstrcpy(f, "\\n");	break;
+		case '\r':	n += fmtstrcpy(f, "\\r");	break;
+		case '\"':	n += fmtstrcpy(f, "\\\"");	break;
+		default:
+
+			if(*s < 0x20)
+				n += fmtprint(f, "\\u%04x", *s);
+			else
+				n += fmtrune(f, *s);
+		}
+	}
+	n = fmtrune(f, '"');
+	return n;
+}
+
+static int
 printarray(Fmt *f, JSON *j, int indent)
 {
 	JSONEl *jl;
@@ -41,7 +67,8 @@
 	for(jl = j->first; jl != nil; jl = jl->next){
 		for(i = 0; i < indent; i++)
 			fmtprint(f, "\t");
-		r += fmtprint(f, "\"%s\": ", jl->name);
+		r += printstring(f, jl->name);
+		r += fmtprint(f, ": ");
 		r += printjson(f, jl->val, indent);
 		r += fmtprint(f, "%s\n", jl->next != nil ? "," : "");
 	}
@@ -65,7 +92,7 @@
 		return fmtprint(f, "%f", j->n);
 		break;
 	case JSONString:
-		return fmtprint(f, "\"%s\"", j->s);
+		return printstring(f, j->s);
 		break;
 	case JSONArray:
 		return printarray(f, j, indent+1);