fix(data): reject partial and malformed map data

str.c

@@ -1,24 +1,33 @@
 #include "dat.h"
 #include "fn.h"
 
-void
+int
 sinit(Str *s, char *src, int n)
 {
+	Str tmp = {0};
+	Rune r;
 	int len;
 
+	if(s == nil)
+		return 0;
 	s->n = 0;
 	if(n < 0 || (n > 0 && src == nil))
-		return;
-	while(n > 0 && s->n < Maxrunes){
+		return 0;
+	while(n > 0){
+		if(tmp.n >= Maxrunes)
+			return 0;
 		if(!fullrune(src, n))
-			break;
-		len = chartorune(&s->r[s->n], src);
-		if(len > n)
-			break;
-		s->n++;
+			return 0;
+		len = chartorune(&r, src);
+		if(len > n || (r == Runeerror && len == 1) ||
+		   (r >= 0xd800 && r <= 0xdfff))
+			return 0;
+		tmp.r[tmp.n++] = r;
 		src += len;
 		n -= len;
 	}
+	*s = tmp;
+	return 1;
 }
 
 void