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USB: remove homegrown UTF conversion routine for gadgets

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This patch (as1502) removes the UTF8-to-UTF16 conversion routine in
the USB gadget library and replaces it with a call to the equivalent
function in the NLS library.

The only downside worth noting is that the NLS library routine
requires the output buffer to be 16-bit aligned.  This is always true
in the gadget code, because the output buffer is always a
usb_request buffer being used to send a string descriptor.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2011-11-17 16:42:24 -05:00 committed by Greg Kroah-Hartman
parent 0720a06a75
commit 86dc243cb2
2 changed files with 5 additions and 69 deletions
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1
drivers/usb/gadget/Kconfig
View file

@ -15,6 +15,7 @@
menuconfig USB_GADGET menuconfig USB_GADGET
tristate "USB Gadget Support" tristate "USB Gadget Support"
select NLS
help help
USB is a master/slave protocol, organized with one master USB is a master/slave protocol, organized with one master
host (such as a PC) controlling up to 127 peripheral devices. host (such as a PC) controlling up to 127 peripheral devices.

73
drivers/usb/gadget/usbstring.c
View file

@ -13,82 +13,17 @@
#include <linux/string.h> #include <linux/string.h>
#include <linux/device.h> #include <linux/device.h>
#include <linux/init.h> #include <linux/init.h>
#include <linux/nls.h>
#include <linux/usb/ch9.h> #include <linux/usb/ch9.h>
#include <linux/usb/gadget.h> #include <linux/usb/gadget.h>
#include <asm/unaligned.h>
static int utf8_to_utf16le(const char *s, __le16 *cp, unsigned len)
{
int count = 0;
u8 c;
u16 uchar;
/* this insists on correct encodings, though not minimal ones.
* BUT it currently rejects legit 4-byte UTF-8 code points,
* which need surrogate pairs. (Unicode 3.1 can use them.)
*/
while (len != 0 && (c = (u8) *s++) != 0) {
if (unlikely(c & 0x80)) {
// 2-byte sequence:
// 00000yyyyyxxxxxx = 110yyyyy 10xxxxxx
if ((c & 0xe0) == 0xc0) {
uchar = (c & 0x1f) << 6;
c = (u8) *s++;
if ((c & 0xc0) != 0x80)
goto fail;
c &= 0x3f;
uchar |= c;
// 3-byte sequence (most CJKV characters):
// zzzzyyyyyyxxxxxx = 1110zzzz 10yyyyyy 10xxxxxx
} else if ((c & 0xf0) == 0xe0) {
uchar = (c & 0x0f) << 12;
c = (u8) *s++;
if ((c & 0xc0) != 0x80)
goto fail;
c &= 0x3f;
uchar |= c << 6;
c = (u8) *s++;
if ((c & 0xc0) != 0x80)
goto fail;
c &= 0x3f;
uchar |= c;
/* no bogus surrogates */
if (0xd800 <= uchar && uchar <= 0xdfff)
goto fail;
// 4-byte sequence (surrogate pairs, currently rare):
// 11101110wwwwzzzzyy + 110111yyyyxxxxxx
// = 11110uuu 10uuzzzz 10yyyyyy 10xxxxxx
// (uuuuu = wwww + 1)
// FIXME accept the surrogate code points (only)
} else
goto fail;
} else
uchar = c;
put_unaligned_le16(uchar, cp++);
count++;
len--;
}
return count;
fail:
return -1;
}
/** /**
* usb_gadget_get_string - fill out a string descriptor * usb_gadget_get_string - fill out a string descriptor
* @table: of c strings encoded using UTF-8 * @table: of c strings encoded using UTF-8
* @id: string id, from low byte of wValue in get string descriptor * @id: string id, from low byte of wValue in get string descriptor
* @buf: at least 256 bytes * @buf: at least 256 bytes, must be 16-bit aligned
* *
* Finds the UTF-8 string matching the ID, and converts it into a * Finds the UTF-8 string matching the ID, and converts it into a
* string descriptor in utf16-le. * string descriptor in utf16-le.
@ -125,8 +60,8 @@ usb_gadget_get_string (struct usb_gadget_strings *table, int id, u8 *buf)
/* string descriptors have length, tag, then UTF16-LE text */ /* string descriptors have length, tag, then UTF16-LE text */
len = min ((size_t) 126, strlen (s->s)); len = min ((size_t) 126, strlen (s->s));
memset (buf + 2, 0, 2 * len); /* zero all the bytes */ len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
len = utf8_to_utf16le(s->s, (__le16 *)&buf[2], len); (wchar_t *) &buf[2], 126);
if (len < 0) if (len < 0)
return -EINVAL; return -EINVAL;
buf [0] = (len + 1) * 2; buf [0] = (len + 1) * 2;