USB: remove homegrown UTF conversion routine for gadgets
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>
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@ -15,6 +15,7 @@
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menuconfig USB_GADGET
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tristate "USB Gadget Support"
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select NLS
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help
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USB is a master/slave protocol, organized with one master
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host (such as a PC) controlling up to 127 peripheral devices.
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@ -13,82 +13,17 @@
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#include <linux/string.h>
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#include <linux/device.h>
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#include <linux/init.h>
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#include <linux/nls.h>
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#include <linux/usb/ch9.h>
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#include <linux/usb/gadget.h>
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#include <asm/unaligned.h>
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static int utf8_to_utf16le(const char *s, __le16 *cp, unsigned len)
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{
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int count = 0;
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u8 c;
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u16 uchar;
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/* this insists on correct encodings, though not minimal ones.
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* BUT it currently rejects legit 4-byte UTF-8 code points,
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* which need surrogate pairs. (Unicode 3.1 can use them.)
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*/
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while (len != 0 && (c = (u8) *s++) != 0) {
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if (unlikely(c & 0x80)) {
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// 2-byte sequence:
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// 00000yyyyyxxxxxx = 110yyyyy 10xxxxxx
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if ((c & 0xe0) == 0xc0) {
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uchar = (c & 0x1f) << 6;
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c = (u8) *s++;
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if ((c & 0xc0) != 0x80)
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goto fail;
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c &= 0x3f;
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uchar |= c;
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// 3-byte sequence (most CJKV characters):
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// zzzzyyyyyyxxxxxx = 1110zzzz 10yyyyyy 10xxxxxx
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} else if ((c & 0xf0) == 0xe0) {
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uchar = (c & 0x0f) << 12;
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c = (u8) *s++;
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if ((c & 0xc0) != 0x80)
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goto fail;
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c &= 0x3f;
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uchar |= c << 6;
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c = (u8) *s++;
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if ((c & 0xc0) != 0x80)
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goto fail;
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c &= 0x3f;
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uchar |= c;
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/* no bogus surrogates */
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if (0xd800 <= uchar && uchar <= 0xdfff)
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goto fail;
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// 4-byte sequence (surrogate pairs, currently rare):
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// 11101110wwwwzzzzyy + 110111yyyyxxxxxx
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// = 11110uuu 10uuzzzz 10yyyyyy 10xxxxxx
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// (uuuuu = wwww + 1)
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// FIXME accept the surrogate code points (only)
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} else
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goto fail;
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} else
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uchar = c;
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put_unaligned_le16(uchar, cp++);
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count++;
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len--;
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}
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return count;
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fail:
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return -1;
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}
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/**
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* usb_gadget_get_string - fill out a string descriptor
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* @table: of c strings encoded using UTF-8
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* @id: string id, from low byte of wValue in get string descriptor
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* @buf: at least 256 bytes
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* @buf: at least 256 bytes, must be 16-bit aligned
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*
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* Finds the UTF-8 string matching the ID, and converts it into a
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* string descriptor in utf16-le.
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@ -125,8 +60,8 @@ usb_gadget_get_string (struct usb_gadget_strings *table, int id, u8 *buf)
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/* string descriptors have length, tag, then UTF16-LE text */
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len = min ((size_t) 126, strlen (s->s));
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memset (buf + 2, 0, 2 * len); /* zero all the bytes */
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len = utf8_to_utf16le(s->s, (__le16 *)&buf[2], len);
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len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
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(wchar_t *) &buf[2], 126);
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if (len < 0)
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return -EINVAL;
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buf [0] = (len + 1) * 2;
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