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diff --git a/utf/rune.c b/utf/rune.c
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+/*
+ * The authors of this software are Rob Pike and Ken Thompson.
+ * Copyright (c) 2002 by Lucent Technologies.
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose without fee is hereby granted, provided that this entire notice
+ * is included in all copies of any software which is or includes a copy
+ * or modification of this software and in all copies of the supporting
+ * documentation for such software.
+ * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
+ * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
+ * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
+ */
+#include <stdarg.h>
+#include <string.h>
+#include "phonenumbers/utf/utf.h"
+#include "phonenumbers/utf/utfdef.h"
+
+enum
+{
+ Bit1 = 7,
+ Bitx = 6,
+ Bit2 = 5,
+ Bit3 = 4,
+ Bit4 = 3,
+ Bit5 = 2,
+
+ T1 = ((1<<(Bit1+1))-1) ^ 0xFF, /* 0000 0000 */
+ Tx = ((1<<(Bitx+1))-1) ^ 0xFF, /* 1000 0000 */
+ T2 = ((1<<(Bit2+1))-1) ^ 0xFF, /* 1100 0000 */
+ T3 = ((1<<(Bit3+1))-1) ^ 0xFF, /* 1110 0000 */
+ T4 = ((1<<(Bit4+1))-1) ^ 0xFF, /* 1111 0000 */
+ T5 = ((1<<(Bit5+1))-1) ^ 0xFF, /* 1111 1000 */
+
+ Rune1 = (1<<(Bit1+0*Bitx))-1, /* 0000 0000 0111 1111 */
+ Rune2 = (1<<(Bit2+1*Bitx))-1, /* 0000 0111 1111 1111 */
+ Rune3 = (1<<(Bit3+2*Bitx))-1, /* 1111 1111 1111 1111 */
+ Rune4 = (1<<(Bit4+3*Bitx))-1,
+ /* 0001 1111 1111 1111 1111 1111 */
+
+ Maskx = (1<<Bitx)-1, /* 0011 1111 */
+ Testx = Maskx ^ 0xFF, /* 1100 0000 */
+
+ Bad = Runeerror,
+};
+
+/*
+ * Modified by Wei-Hwa Huang, Google Inc., on 2004-09-24
+ * This is a slower but "safe" version of the old chartorune
+ * that works on strings that are not necessarily null-terminated.
+ *
+ * If you know for sure that your string is null-terminated,
+ * chartorune will be a bit faster.
+ *
+ * It is guaranteed not to attempt to access "length"
+ * past the incoming pointer. This is to avoid
+ * possible access violations. If the string appears to be
+ * well-formed but incomplete (i.e., to get the whole Rune
+ * we'd need to read past str+length) then we'll set the Rune
+ * to Bad and return 0.
+ *
+ * Note that if we have decoding problems for other
+ * reasons, we return 1 instead of 0.
+ */
+int
+charntorune(Rune *rune, const char *str, int length)
+{
+ int c, c1, c2, c3;
+ long l;
+
+ /* When we're not allowed to read anything */
+ if(length <= 0) {
+ goto badlen;
+ }
+
+ /*
+ * one character sequence (7-bit value)
+ * 00000-0007F => T1
+ */
+ c = *(uchar*)str;
+ if(c < Tx) {
+ *rune = c;
+ return 1;
+ }
+
+ // If we can't read more than one character we must stop
+ if(length <= 1) {
+ goto badlen;
+ }
+
+ /*
+ * two character sequence (11-bit value)
+ * 0080-07FF => T2 Tx
+ */
+ c1 = *(uchar*)(str+1) ^ Tx;
+ if(c1 & Testx)
+ goto bad;
+ if(c < T3) {
+ if(c < T2)
+ goto bad;
+ l = ((c << Bitx) | c1) & Rune2;
+ if(l <= Rune1)
+ goto bad;
+ *rune = l;
+ return 2;
+ }
+
+ // If we can't read more than two characters we must stop
+ if(length <= 2) {
+ goto badlen;
+ }
+
+ /*
+ * three character sequence (16-bit value)
+ * 0800-FFFF => T3 Tx Tx
+ */
+ c2 = *(uchar*)(str+2) ^ Tx;
+ if(c2 & Testx)
+ goto bad;
+ if(c < T4) {
+ l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
+ if(l <= Rune2)
+ goto bad;
+ *rune = l;
+ return 3;
+ }
+
+ if (length <= 3)
+ goto badlen;
+
+ /*
+ * four character sequence (21-bit value)
+ * 10000-1FFFFF => T4 Tx Tx Tx
+ */
+ c3 = *(uchar*)(str+3) ^ Tx;
+ if (c3 & Testx)
+ goto bad;
+ if (c < T5) {
+ l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
+ if (l <= Rune3)
+ goto bad;
+ *rune = l;
+ return 4;
+ }
+
+ // Support for 5-byte or longer UTF-8 would go here, but
+ // since we don't have that, we'll just fall through to bad.
+
+ /*
+ * bad decoding
+ */
+bad:
+ *rune = Bad;
+ return 1;
+badlen:
+ *rune = Bad;
+ return 0;
+
+}
+
+
+/*
+ * This is the older "unsafe" version, which works fine on
+ * null-terminated strings.
+ */
+int
+chartorune(Rune *rune, const char *str)
+{
+ int c, c1, c2, c3;
+ long l;
+
+ /*
+ * one character sequence
+ * 00000-0007F => T1
+ */
+ c = *(uchar*)str;
+ if(c < Tx) {
+ *rune = c;
+ return 1;
+ }
+
+ /*
+ * two character sequence
+ * 0080-07FF => T2 Tx
+ */
+ c1 = *(uchar*)(str+1) ^ Tx;
+ if(c1 & Testx)
+ goto bad;
+ if(c < T3) {
+ if(c < T2)
+ goto bad;
+ l = ((c << Bitx) | c1) & Rune2;
+ if(l <= Rune1)
+ goto bad;
+ *rune = l;
+ return 2;
+ }
+
+ /*
+ * three character sequence
+ * 0800-FFFF => T3 Tx Tx
+ */
+ c2 = *(uchar*)(str+2) ^ Tx;
+ if(c2 & Testx)
+ goto bad;
+ if(c < T4) {
+ l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
+ if(l <= Rune2)
+ goto bad;
+ *rune = l;
+ return 3;
+ }
+
+ /*
+ * four character sequence (21-bit value)
+ * 10000-1FFFFF => T4 Tx Tx Tx
+ */
+ c3 = *(uchar*)(str+3) ^ Tx;
+ if (c3 & Testx)
+ goto bad;
+ if (c < T5) {
+ l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
+ if (l <= Rune3)
+ goto bad;
+ *rune = l;
+ return 4;
+ }
+
+ /*
+ * Support for 5-byte or longer UTF-8 would go here, but
+ * since we don't have that, we'll just fall through to bad.
+ */
+
+ /*
+ * bad decoding
+ */
+bad:
+ *rune = Bad;
+ return 1;
+}
+
+int
+isvalidcharntorune(const char* str, int length, Rune* rune, int* consumed) {
+ *consumed = charntorune(rune, str, length);
+ return *rune != Runeerror || *consumed == 3;
+}
+
+int
+runetochar(char *str, const Rune *rune)
+{
+ /* Runes are signed, so convert to unsigned for range check. */
+ unsigned long c;
+
+ /*
+ * one character sequence
+ * 00000-0007F => 00-7F
+ */
+ c = *rune;
+ if(c <= Rune1) {
+ str[0] = c;
+ return 1;
+ }
+
+ /*
+ * two character sequence
+ * 0080-07FF => T2 Tx
+ */
+ if(c <= Rune2) {
+ str[0] = T2 | (c >> 1*Bitx);
+ str[1] = Tx | (c & Maskx);
+ return 2;
+ }
+
+ /*
+ * If the Rune is out of range, convert it to the error rune.
+ * Do this test here because the error rune encodes to three bytes.
+ * Doing it earlier would duplicate work, since an out of range
+ * Rune wouldn't have fit in one or two bytes.
+ */
+ if (c > Runemax)
+ c = Runeerror;
+
+ /*
+ * three character sequence
+ * 0800-FFFF => T3 Tx Tx
+ */
+ if (c <= Rune3) {
+ str[0] = T3 | (c >> 2*Bitx);
+ str[1] = Tx | ((c >> 1*Bitx) & Maskx);
+ str[2] = Tx | (c & Maskx);
+ return 3;
+ }
+
+ /*
+ * four character sequence (21-bit value)
+ * 10000-1FFFFF => T4 Tx Tx Tx
+ */
+ str[0] = T4 | (c >> 3*Bitx);
+ str[1] = Tx | ((c >> 2*Bitx) & Maskx);
+ str[2] = Tx | ((c >> 1*Bitx) & Maskx);
+ str[3] = Tx | (c & Maskx);
+ return 4;
+}
+
+int
+runelen(Rune rune)
+{
+ char str[10];
+
+ return runetochar(str, &rune);
+}
+
+int
+runenlen(const Rune *r, int nrune)
+{
+ int nb, c;
+
+ nb = 0;
+ while(nrune--) {
+ c = *r++;
+ if (c <= Rune1)
+ nb++;
+ else if (c <= Rune2)
+ nb += 2;
+ else if (c <= Rune3)
+ nb += 3;
+ else /* assert(c <= Rune4) */
+ nb += 4;
+ }
+ return nb;
+}
+
+int
+fullrune(const char *str, int n)
+{
+ if (n > 0) {
+ int c = *(uchar*)str;
+ if (c < Tx)
+ return 1;
+ if (n > 1) {
+ if (c < T3)
+ return 1;
+ if (n > 2) {
+ if (c < T4 || n > 3)
+ return 1;
+ }
+ }
+ }
+ return 0;
+}
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