[PATCHv3 2/3] usb: gadget: u_os_desc: helper functions for accessing ext prop buffer

[Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>]

Provide helper functions to get pointers to particular locations within
a buffer holding an extended properties descriptor.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
---
 drivers/usb/gadget/u_os_desc.h | 59 ++++++++++++++++++++++++++++++++----------
 1 file changed, 46 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/gadget/u_os_desc.h b/drivers/usb/gadget/u_os_desc.h
index ea5cf8c..947b7dd 100644
--- a/drivers/usb/gadget/u_os_desc.h
+++ b/drivers/usb/gadget/u_os_desc.h
@@ -35,27 +35,63 @@
 #define USB_EXT_PROP_UNICODE_LINK		6
 #define USB_EXT_PROP_UNICODE_MULTI		7
 
+static inline u8 *__usb_ext_prop_ptr(u8 *buf, size_t offset)
+{
+	return buf + offset;
+}
+
+static inline u8 *usb_ext_prop_size_ptr(u8 *buf)
+{
+	return __usb_ext_prop_ptr(buf, USB_EXT_PROP_DW_SIZE);
+}
+
+static inline u8 *usb_ext_prop_type_ptr(u8 *buf)
+{
+	return __usb_ext_prop_ptr(buf, USB_EXT_PROP_DW_PROPERTY_DATA_TYPE);
+}
+
+static inline u8 *usb_ext_prop_name_len_ptr(u8 *buf)
+{
+	return __usb_ext_prop_ptr(buf, USB_EXT_PROP_W_PROPERTY_NAME_LENGTH);
+}
+
+static inline u8 *usb_ext_prop_name_ptr(u8 *buf)
+{
+	return __usb_ext_prop_ptr(buf, USB_EXT_PROP_B_PROPERTY_NAME);
+}
+
+static inline u8 *usb_ext_prop_data_len_ptr(u8 *buf, size_t off)
+{
+	return __usb_ext_prop_ptr(buf,
+				  USB_EXT_PROP_DW_PROPERTY_DATA_LENGTH + off);
+}
+
+static inline u8 *usb_ext_prop_data_ptr(u8 *buf, size_t off)
+{
+	return __usb_ext_prop_ptr(buf, USB_EXT_PROP_B_PROPERTY_DATA + off);
+}
+
 static inline void usb_ext_prop_put_size(u8 *buf, int dw_size)
 {
-	put_unaligned_le32(dw_size, &buf[USB_EXT_PROP_DW_SIZE]);
+	put_unaligned_le32(dw_size, usb_ext_prop_size_ptr(buf));
 }
 
 static inline void usb_ext_prop_put_type(u8 *buf, int type)
 {
-	put_unaligned_le32(type, &buf[USB_EXT_PROP_DW_PROPERTY_DATA_TYPE]);
+	put_unaligned_le32(type, usb_ext_prop_type_ptr(buf));
 }
 
 static inline int usb_ext_prop_put_name(u8 *buf, const char *name, int pnl)
 {
 	int result;
 
-	put_unaligned_le16(pnl, &buf[USB_EXT_PROP_W_PROPERTY_NAME_LENGTH]);
+	put_unaligned_le16(pnl, usb_ext_prop_name_len_ptr(buf));
 	result = utf8s_to_utf16s(name, strlen(name), UTF16_LITTLE_ENDIAN,
-		(wchar_t *) &buf[USB_EXT_PROP_B_PROPERTY_NAME], pnl - 2);
+		(wchar_t *) usb_ext_prop_name_ptr(buf), pnl - 2);
 	if (result < 0)
 		return result;
 
-	put_unaligned_le16(0, &buf[USB_EXT_PROP_B_PROPERTY_NAME + pnl]);
+	put_unaligned_le16(0, &buf[USB_EXT_PROP_B_PROPERTY_NAME + pnl - 2]);
 
 	return pnl;
 }
@@ -63,26 +99,23 @@ static inline int usb_ext_prop_put_name(u8 *buf, const char *name, int pnl)
 static inline void usb_ext_prop_put_binary(u8 *buf, int pnl, const u8 *data,
 					   int data_len)
 {
-	put_unaligned_le32(data_len,
-			   &buf[USB_EXT_PROP_DW_PROPERTY_DATA_LENGTH + pnl]);
-	memcpy(&buf[USB_EXT_PROP_B_PROPERTY_DATA + pnl], data, data_len);
+	put_unaligned_le32(data_len, usb_ext_prop_data_len_ptr(buf, pnl));
+	memcpy(usb_ext_prop_data_ptr(buf, pnl), data, data_len);
 }
 
 static inline int usb_ext_prop_put_unicode(u8 *buf, int pnl, const char *string,
 					   int data_len)
 {
 	int result;
-	put_unaligned_le32(data_len,
-			&buf[USB_EXT_PROP_DW_PROPERTY_DATA_LENGTH + pnl]);
-
+	put_unaligned_le32(data_len, usb_ext_prop_data_len_ptr(buf, pnl));
 	result = utf8s_to_utf16s(string, data_len >> 1, UTF16_LITTLE_ENDIAN,
-			(wchar_t *) &buf[USB_EXT_PROP_B_PROPERTY_DATA + pnl],
+			(wchar_t *) usb_ext_prop_data_ptr(buf, pnl),
 			data_len - 2);
 	if (result < 0)
 		return result;
 
 	put_unaligned_le16(0,
-			&buf[USB_EXT_PROP_B_PROPERTY_DATA + pnl + data_len]);
+		&buf[USB_EXT_PROP_B_PROPERTY_DATA + pnl + data_len - 2]);
 
 	return data_len;
 }
-- 
1.8.3.2

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