cifs: add new function to get unicode string length in bytes

Working in units of words means we do a lot of unnecessary conversion back
and forth. Standardize on bytes instead since that's more useful for
allocating buffers and such. Also, remove hostlen_fromUCS since the new
function has a similar purpose.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifs_unicode.c

@@ -25,6 +25,37 @@
 #include "cifsglob.h"
 #include "cifs_debug.h"
 
+/*
+ * cifs_ucs2_bytes - how long will a string be after conversion?
+ * @ucs - pointer to input string
+ * @maxbytes - don't go past this many bytes of input string
+ * @codepage - destination codepage
+ *
+ * Walk a ucs2le string and return the number of bytes that the string will
+ * be after being converted to the given charset, not including any null
+ * termination required. Don't walk past maxbytes in the source buffer.
+ */
+int
+cifs_ucs2_bytes(const __le16 *from, int maxbytes,
+		const struct nls_table *codepage)
+{
+	int i;
+	int charlen, outlen = 0;
+	int maxwords = maxbytes / 2;
+	char tmp[NLS_MAX_CHARSET_SIZE];
+
+	for (i = 0; from[i] && i < maxwords; i++) {
+		charlen = codepage->uni2char(le16_to_cpu(from[i]), tmp,
+					     NLS_MAX_CHARSET_SIZE);
+		if (charlen > 0)
+			outlen += charlen;
+		else
+			outlen++;
+	}
+
+	return outlen;
+}
+
 /*
  * cifs_mapchar - convert a little-endian char to proper char in codepage
  * @target - where converted character should be copied

fs/cifs/cifs_unicode.h

@@ -74,6 +74,8 @@ extern struct UniCaseRange UniLowerRange[];
 #ifdef __KERNEL__
 int cifs_from_ucs2(char *to, const __le16 *from, int tolen, int fromlen,
 		   const struct nls_table *codepage, bool mapchar);
+int cifs_ucs2_bytes(const __le16 *from, int maxbytes,
+		    const struct nls_table *codepage);
 int cifs_strfromUCS_le(char *, const __le16 *, int, const struct nls_table *);
 int cifs_strtoUCS(__le16 *, const char *, int, const struct nls_table *);
 #endif

fs/cifs/cifssmb.c

@@ -3928,27 +3928,6 @@ CIFSGetSrvInodeNumber(const int xid, struct cifsTconInfo *tcon,
 	return rc;
 }
 
-/* computes length of UCS string converted to host codepage
- * @src:	UCS string
- * @maxlen:	length of the input string in UCS characters
- * 		(not in bytes)
- *
- * return:	size of input string in host codepage
- */
-static int hostlen_fromUCS(const __le16 *src, const int maxlen,
-		const struct nls_table *nls_codepage) {
-	int i;
-	int hostlen = 0;
-	char to[4];
-	int charlen;
-	for (i = 0; (i < maxlen) && src[i]; ++i) {
-		charlen = nls_codepage->uni2char(le16_to_cpu(src[i]),
-				to, NLS_MAX_CHARSET_SIZE);
-		hostlen += charlen > 0 ? charlen : 1;
-	}
-	return hostlen;
-}
-
 /* parses DFS refferal V3 structure
  * caller is responsible for freeing target_nodes
  * returns:
@@ -4016,8 +3995,8 @@ parse_DFS_referrals(TRANSACTION2_GET_DFS_REFER_RSP *pSMBr,
 						GFP_KERNEL);
 			cifsConvertToUCS((__le16 *) tmp, searchName,
 					PATH_MAX, nls_codepage, remap);
-			node->path_consumed = hostlen_fromUCS(tmp,
-					le16_to_cpu(pSMBr->PathConsumed)/2,
+			node->path_consumed = cifs_ucs2_bytes(tmp,
+					le16_to_cpu(pSMBr->PathConsumed),
 					nls_codepage);
 			kfree(tmp);
 		} else