udf: udf_CS0toNLS cleanup

- fix error handling - always zero output variable
- don't zero explicitely fields zeroed by memset
- mark "in" paramater as const

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/unicode.c

@@ -249,35 +249,32 @@ error_out:
 }
 
 static int udf_CS0toNLS(struct nls_table *nls, struct ustr *utf_o,
-			struct ustr *ocu_i)
+			const struct ustr *ocu_i)
 {
-	uint8_t *ocu;
-	uint32_t c;
+	const uint8_t *ocu;
 	uint8_t cmp_id, ocu_len;
 	int i;
 
-	ocu = ocu_i->u_name;
 
 	ocu_len = ocu_i->u_len;
-	cmp_id = ocu_i->u_cmpID;
-	utf_o->u_len = 0;
-
 	if (ocu_len == 0) {
 		memset(utf_o, 0, sizeof(struct ustr));
-		utf_o->u_cmpID = 0;
-		utf_o->u_len = 0;
 		return 0;
 	}
 
-	if ((cmp_id != 8) && (cmp_id != 16)) {
+	cmp_id = ocu_i->u_cmpID;
+	if (cmp_id != 8 && cmp_id != 16) {
+		memset(utf_o, 0, sizeof(struct ustr));
 		printk(KERN_ERR "udf: unknown compression code (%d) stri=%s\n",
 		       cmp_id, ocu_i->u_name);
 		return 0;
 	}
 
+	ocu = ocu_i->u_name;
+	utf_o->u_len = 0;
 	for (i = 0; (i < ocu_len) && (utf_o->u_len <= (UDF_NAME_LEN - 3));) {
 		/* Expand OSTA compressed Unicode to Unicode */
-		c = ocu[i++];
+		uint32_t c = ocu[i++];
 		if (cmp_id == 16)
 			c = (c << 8) | ocu[i++];