diff options
| -rw-r--r-- | drivers/usb/core/message.c | 63 |
1 files changed, 45 insertions, 18 deletions
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index 2bed83caacb..9720e699f47 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -806,6 +806,48 @@ static int usb_string_sub(struct usb_device *dev, unsigned int langid, return rc; } +static int usb_get_langid(struct usb_device *dev, unsigned char *tbuf) +{ + int err; + + if (dev->have_langid) + return 0; + + if (dev->string_langid < 0) + return -EPIPE; + + err = usb_string_sub(dev, 0, 0, tbuf); + + /* If the string was reported but is malformed, default to english + * (0x0409) */ + if (err == -ENODATA || (err > 0 && err < 4)) { + dev->string_langid = 0x0409; + dev->have_langid = 1; + dev_err(&dev->dev, + "string descriptor 0 malformed (err = %d), " + "defaulting to 0x%04x\n", + err, dev->string_langid); + return 0; + } + + /* In case of all other errors, we assume the device is not able to + * deal with strings at all. Set string_langid to -1 in order to + * prevent any string to be retrieved from the device */ + if (err < 0) { + dev_err(&dev->dev, "string descriptor 0 read error: %d\n", + err); + dev->string_langid = -1; + return -EPIPE; + } + + /* always use the first langid listed */ + dev->string_langid = tbuf[2] | (tbuf[3] << 8); + dev->have_langid = 1; + dev_dbg(&dev->dev, "default language 0x%04x\n", + dev->string_langid); + return 0; +} + /** * usb_string - returns UTF-8 version of a string descriptor * @dev: the device whose string descriptor is being retrieved @@ -837,24 +879,9 @@ int usb_string(struct usb_device *dev, int index, char *buf, size_t size) if (!tbuf) return -ENOMEM; - /* get langid for strings if it's not yet known */ - if (!dev->have_langid) { - err = usb_string_sub(dev, 0, 0, tbuf); - if (err < 0) { - dev_err(&dev->dev, - "string descriptor 0 read error: %d\n", - err); - } else if (err < 4) { - dev_err(&dev->dev, "string descriptor 0 too short\n"); - } else { - dev->string_langid = tbuf[2] | (tbuf[3] << 8); - /* always use the first langid listed */ - dev_dbg(&dev->dev, "default language 0x%04x\n", - dev->string_langid); - } - - dev->have_langid = 1; - } + err = usb_get_langid(dev, tbuf); + if (err < 0) + goto errout; err = usb_string_sub(dev, dev->string_langid, index, tbuf); if (err < 0) |