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USB: Clean up root hub string descriptors

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The previous code had a bug that would add a trailing null byte to
the returned descriptor.

Signed-off-by: George Spelvin <linux@horizon.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
George Spelvin 2009-08-24 22:06:41 -04:00 committed by Greg Kroah-Hartman
parent 48d316770b
commit 392ca68b40
1 changed files with 64 additions and 47 deletions
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111
drivers/usb/core/hcd.c
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@ -337,72 +337,89 @@ static const u8 ss_rh_config_descriptor[] = {
/*-------------------------------------------------------------------------*/
/*
* helper routine for returning string descriptors in UTF-16LE
* input can actually be ISO-8859-1; ASCII is its 7-bit subset
/**
* ascii2desc() - Helper routine for producing UTF-16LE string descriptors
* @s: Null-terminated ASCII (actually ISO-8859-1) string
* @buf: Buffer for USB string descriptor (header + UTF-16LE)
* @len: Length (in bytes; may be odd) of descriptor buffer.
*
* The return value is the number of bytes filled in: 2 + 2*strlen(s) or
* buflen, whichever is less.
*
* USB String descriptors can contain at most 126 characters; input
* strings longer than that are truncated.
*/
static unsigned ascii2utf(char *s, u8 *utf, int utfmax)
static unsigned
ascii2desc(char const *s, u8 *buf, unsigned len)
{
unsigned retval;
unsigned n, t = 2 + 2*strlen(s);
for (retval = 0; *s && utfmax > 1; utfmax -= 2, retval += 2) {
*utf++ = *s++;
*utf++ = 0;
if (t > 254)
t = 254; /* Longest possible UTF string descriptor */
if (len > t)
len = t;
t += USB_DT_STRING << 8; /* Now t is first 16 bits to store */
n = len;
while (n--) {
*buf++ = t;
if (!n--)
break;
*buf++ = t >> 8;
t = (unsigned char)*s++;
}
if (utfmax > 0) {
*utf = *s;
++retval;
}
return retval;
return len;
}
/*
* rh_string - provides manufacturer, product and serial strings for root hub
* @id: the string ID number (1: serial number, 2: product, 3: vendor)
/**
* rh_string() - provides string descriptors for root hub
* @id: the string ID number (0: langids, 1: serial #, 2: product, 3: vendor)
* @hcd: the host controller for this root hub
* @data: return packet in UTF-16 LE
* @len: length of the return packet
* @data: buffer for output packet
* @len: length of the provided buffer
*
* Produces either a manufacturer, product or serial number string for the
* virtual root hub device.
* Returns the number of bytes filled in: the length of the descriptor or
* of the provided buffer, whichever is less.
*/
static unsigned rh_string(int id, struct usb_hcd *hcd, u8 *data, unsigned len)
static unsigned
rh_string(int id, struct usb_hcd const *hcd, u8 *data, unsigned len)
{
char buf [100];
char buf[100];
char const *s;
static char const langids[4] = {4, USB_DT_STRING, 0x09, 0x04};
// language ids
if (id == 0) {
buf[0] = 4; buf[1] = 3; /* 4 bytes string data */
buf[2] = 0x09; buf[3] = 0x04; /* MSFT-speak for "en-us" */
len = min_t(unsigned, len, 4);
memcpy (data, buf, len);
switch (id) {
case 0:
/* Array of LANGID codes (0x0409 is MSFT-speak for "en-us") */
/* See http://www.usb.org/developers/docs/USB_LANGIDs.pdf */
if (len > 4)
len = 4;
memcpy(data, langids, len);
return len;
// serial number
} else if (id == 1) {
strlcpy (buf, hcd->self.bus_name, sizeof buf);
// product description
} else if (id == 2) {
strlcpy (buf, hcd->product_desc, sizeof buf);
// id 3 == vendor description
} else if (id == 3) {
case 1:
/* Serial number */
s = hcd->self.bus_name;
break;
case 2:
/* Product name */
s = hcd->product_desc;
break;
case 3:
/* Manufacturer */
snprintf (buf, sizeof buf, "%s %s %s", init_utsname()->sysname,
init_utsname()->release, hcd->driver->description);
s = buf;
break;
default:
/* Can't happen; caller guarantees it */
return 0;
}
switch (len) { /* All cases fall through */
default:
len = 2 + ascii2utf (buf, data + 2, len - 2);
case 2:
data [1] = 3; /* type == string */
case 1:
data [0] = 2 * (strlen (buf) + 1);
case 0:
; /* Compiler wants a statement here */
}
return len;
return ascii2desc(s, data, len);
}