[PATCH 1/2] fs: configfs: make qw_sign attribute symmetric

From: Stefan Agner <stefan@agner.ch>
To: balbi@kernel.org
Cc: gregkh@linuxfoundation.org, andrzej.p@samsung.com,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	Stefan Agner <stefan@agner.ch>
Subject: [PATCH 1/2] fs: configfs: make qw_sign attribute symmetric
Date: Tue, 31 Jan 2017 18:19:16 -0800	[thread overview]
Message-ID: <20170201021917.27398-1-stefan@agner.ch> (raw)

Currently qw_sign requires UTF-8 character to set, but returns UTF-16
when read. This isn't obvious when simply using cat since the null
characters are not visible, but hexdump unveils the true string:

  # echo MSFT100 > os_desc/qw_sign
  # hexdump -C os_desc/qw_sign
  00000000  4d 00 53 00 46 00 54 00  31 00 30 00 30 00        |M.S.F.T.1.0.0.|

Make qw_sign symmetric by returning an UTF-8 string too. Also follow
common convention and add a new line at the end.

Signed-off-by: Stefan Agner <stefan@agner.ch>
---
 drivers/usb/gadget/configfs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 78c44979dde3..ea1a40f5b23d 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -786,9 +786,13 @@ static ssize_t os_desc_b_vendor_code_store(struct config_item *item,
 static ssize_t os_desc_qw_sign_show(struct config_item *item, char *page)
 {
 	struct gadget_info *gi = os_desc_item_to_gadget_info(item);
+	int res;
 
-	memcpy(page, gi->qw_sign, OS_STRING_QW_SIGN_LEN);
-	return OS_STRING_QW_SIGN_LEN;
+	res = utf16s_to_utf8s((wchar_t *) gi->qw_sign, OS_STRING_QW_SIGN_LEN,
+			      UTF16_LITTLE_ENDIAN, page, PAGE_SIZE - 1);
+	page[res++] = '\n';
+
+	return res;
 }
 
 static ssize_t os_desc_qw_sign_store(struct config_item *item, const char *page,
-- 
2.11.0
