The Tor Browser: intl/icu/source/common/utf_impl.c@fc2d59ddac77 (annotated)

intl/icu/source/common/utf_impl.c@fc2d59ddac77 (annotated)

intl/icu/source/common/utf_impl.c

Wed, 31 Dec 2014 07:22:50 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 07:22:50 +0100
branch: TOR_BUG_3246
changeset 4: fc2d59ddac77
permissions: -rw-r--r--

Correct previous dual key logic pending first delivery installment.

 /*
 ******************************************************************************
 *
 *   Copyright (C) 1999-2012, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 ******************************************************************************
 *   file name:  utf_impl.c
 *   encoding:   US-ASCII
 *   tab size:   8 (not used)
 *   indentation:4
 *
 *   created on: 1999sep13
 *   created by: Markus W. Scherer
 *
 *   This file provides implementation functions for macros in the utfXX.h
 *   that would otherwise be too long as macros.
 */
 /* set import/export definitions */
 #ifndef U_UTF8_IMPL
 #   define U_UTF8_IMPL
 #endif
 #include "unicode/utypes.h"
 #include "unicode/utf.h"
 #include "unicode/utf8.h"
 #include "unicode/utf_old.h"
 #include "uassert.h"
 /*
  * This table could be replaced on many machines by
  * a few lines of assembler code using an
  * "index of first 0-bit from msb" instruction and
  * one or two more integer instructions.
  *
  * For example, on an i386, do something like
  * - MOV AL, leadByte
  * - NOT AL         (8-bit, leave b15..b8==0..0, reverse only b7..b0)
  * - MOV AH, 0
  * - BSR BX, AX     (16-bit)
  * - MOV AX, 6      (result)
  * - JZ finish      (ZF==1 if leadByte==0xff)
  * - SUB AX, BX (result)
  * -finish:
  * (BSR: Bit Scan Reverse, scans for a 1-bit, starting from the MSB)
  *
  * In Unicode, all UTF-8 byte sequences with more than 4 bytes are illegal;
  * lead bytes above 0xf4 are illegal.
  * We keep them in this table for skipping long ISO 10646-UTF-8 sequences.
  */
 U_EXPORT const uint8_t
 utf8_countTrailBytes[256]={
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 , 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 , 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 , 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
 , 3, 3, 3, 3,
 , 3, 3,    /* illegal in Unicode */
 , 4, 4, 4, /* illegal in Unicode */
 , 5,       /* illegal in Unicode */
 , 0        /* illegal bytes 0xfe and 0xff */
 };
 static const UChar32
 utf8_minLegal[4]={ 0, 0x80, 0x800, 0x10000 };
 static const UChar32
 utf8_errorValue[6]={
     UTF8_ERROR_VALUE_1, UTF8_ERROR_VALUE_2, UTF_ERROR_VALUE, 0x10ffff,
 x3ffffff, 0x7fffffff
 };
 static UChar32
 errorValue(int32_t count, int8_t strict) {
     if(strict>=0) {
         return utf8_errorValue[count];
     } else if(strict==-3) {
         return 0xfffd;
     } else {
         return U_SENTINEL;
     }
 }
 /*
  * Handle the non-inline part of the U8_NEXT() and U8_NEXT_FFFD() macros
  * and their obsolete sibling UTF8_NEXT_CHAR_SAFE().
  *
  * U8_NEXT() supports NUL-terminated strings indicated via length<0.
  *
  * The "strict" parameter controls the error behavior:
  * <0  "Safe" behavior of U8_NEXT():
  *     -1: All illegal byte sequences yield U_SENTINEL=-1.
  *     -2: Same as -1, except for lenient treatment of surrogate code points as legal.
  *         Some implementations use this for roundtripping of
  *         Unicode 16-bit strings that are not well-formed UTF-16, that is, they
  *         contain unpaired surrogates.
  *     -3: All illegal byte sequences yield U+FFFD.
  *  0  Obsolete "safe" behavior of UTF8_NEXT_CHAR_SAFE(..., FALSE):
  *     All illegal byte sequences yield a positive code point such that this
  *     result code point would be encoded with the same number of bytes as
  *     the illegal sequence.
  * >0  Obsolete "strict" behavior of UTF8_NEXT_CHAR_SAFE(..., TRUE):
  *     Same as the obsolete "safe" behavior, but non-characters are also treated
  *     like illegal sequences.
  *
  * Note that a UBool is the same as an int8_t.
  */
 U_CAPI UChar32 U_EXPORT2
 utf8_nextCharSafeBody(const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict) {
     int32_t i=*pi;
     uint8_t count=U8_COUNT_TRAIL_BYTES(c);
     U_ASSERT(count <= 5); /* U8_COUNT_TRAIL_BYTES returns value 0...5 */
     if(i+count<=length || length<0) {
         uint8_t trail;
         U8_MASK_LEAD_BYTE(c, count);
         /* support NUL-terminated strings: do not read beyond the first non-trail byte */
         switch(count) {
         /* each branch falls through to the next one */
         case 0:
             /* count==0 for illegally leading trail bytes and the illegal bytes 0xfe and 0xff */
         case 5:
         case 4:
             /* count>=4 is always illegal: no more than 3 trail bytes in Unicode's UTF-8 */
             break;
         case 3:
             trail=s[i++]-0x80;
             c=(c<<6)|trail;
             /* c>=0x110 would result in code point>0x10ffff, outside Unicode */
             if(c>=0x110 || trail>0x3f) { break; }
         case 2:
             trail=s[i++]-0x80;
             c=(c<<6)|trail;
             /*
              * test for a surrogate d800..dfff unless we are lenient:
              * before the last (c<<6), a surrogate is c=360..37f
              */
             if(((c&0xffe0)==0x360 && strict!=-2) || trail>0x3f) { break; }
         case 1:
             trail=s[i++]-0x80;
             c=(c<<6)|trail;
             if(trail>0x3f) { break; }
             /* correct sequence - all trail bytes have (b7..b6)==(10) */
             if(c>=utf8_minLegal[count] &&
                     /* strict: forbid non-characters like U+fffe */
                     (strict<=0 || !U_IS_UNICODE_NONCHAR(c))) {
                 *pi=i;
                 return c;
             }
         /* no default branch to optimize switch()  - all values are covered */
         }
     } else {
         /* too few bytes left */
         count=length-i;
     }
     /* error handling */
     i=*pi;
     while(count>0 && U8_IS_TRAIL(s[i])) {
         ++i;
         --count;
     }
     c=errorValue(i-*pi, strict);
     *pi=i;
     return c;
 }
 U_CAPI int32_t U_EXPORT2
 utf8_appendCharSafeBody(uint8_t *s, int32_t i, int32_t length, UChar32 c, UBool *pIsError) {
     if((uint32_t)(c)<=0x7ff) {
         if((i)+1<(length)) {
             (s)[(i)++]=(uint8_t)(((c)>>6)|0xc0);
             (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80);
             return i;
         }
     } else if((uint32_t)(c)<=0xffff) {
         /* Starting with Unicode 3.2, surrogate code points must not be encoded in UTF-8. */
         if((i)+2<(length) && !U_IS_SURROGATE(c)) {
             (s)[(i)++]=(uint8_t)(((c)>>12)|0xe0);
             (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80);
             (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80);
             return i;
         }
     } else if((uint32_t)(c)<=0x10ffff) {
         if((i)+3<(length)) {
             (s)[(i)++]=(uint8_t)(((c)>>18)|0xf0);
             (s)[(i)++]=(uint8_t)((((c)>>12)&0x3f)|0x80);
             (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80);
             (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80);
             return i;
         }
     }
     /* c>0x10ffff or not enough space, write an error value */
     if(pIsError!=NULL) {
         *pIsError=TRUE;
     } else {
         length-=i;
         if(length>0) {
             int32_t offset;
             if(length>3) {
                 length=3;
             }
             s+=i;
             offset=0;
             c=utf8_errorValue[length-1];
             UTF8_APPEND_CHAR_UNSAFE(s, offset, c);
             i=i+offset;
         }
     }
     return i;
 }
 U_CAPI UChar32 U_EXPORT2
 utf8_prevCharSafeBody(const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict) {
     int32_t i=*pi;
     uint8_t b, count=1, shift=6;
     if(!U8_IS_TRAIL(c)) { return errorValue(0, strict); }
     /* extract value bits from the last trail byte */
     c&=0x3f;
     for(;;) {
         if(i<=start) {
             /* no lead byte at all */
             return errorValue(0, strict);
         }
         /* read another previous byte */
         b=s[--i];
         if((uint8_t)(b-0x80)<0x7e) { /* 0x80<=b<0xfe */
             if(b&0x40) {
                 /* lead byte, this will always end the loop */
                 uint8_t shouldCount=U8_COUNT_TRAIL_BYTES(b);
                 if(count==shouldCount) {
                     /* set the new position */
                     *pi=i;
                     U8_MASK_LEAD_BYTE(b, count);
                     c|=(UChar32)b<<shift;
                     if(count>=4 || c>0x10ffff || c<utf8_minLegal[count] || (U_IS_SURROGATE(c) && strict!=-2) || (strict>0 && U_IS_UNICODE_NONCHAR(c))) {
                         /* illegal sequence or (strict and non-character) */
                         if(count>=4) {
                             count=3;
                         }
                         c=errorValue(count, strict);
                     } else {
                         /* exit with correct c */
                     }
                 } else {
                     /* the lead byte does not match the number of trail bytes */
                     /* only set the position to the lead byte if it would
                        include the trail byte that we started with */
                     if(count<shouldCount) {
                         *pi=i;
                         c=errorValue(count, strict);
                     } else {
                         c=errorValue(0, strict);
                     }
                 }
                 break;
             } else if(count<5) {
                 /* trail byte */
                 c|=(UChar32)(b&0x3f)<<shift;
                 ++count;
                 shift+=6;
             } else {
                 /* more than 5 trail bytes is illegal */
                 c=errorValue(0, strict);
                 break;
             }
         } else {
             /* single-byte character precedes trailing bytes */
             c=errorValue(0, strict);
             break;
         }
     }
     return c;
 }
 U_CAPI int32_t U_EXPORT2
 utf8_back1SafeBody(const uint8_t *s, int32_t start, int32_t i) {
     /* i had been decremented once before the function call */
     int32_t I=i, Z;
     uint8_t b;
     /* read at most the 6 bytes s[Z] to s[i], inclusively */
     if(I-5>start) {
         Z=I-5;
     } else {
         Z=start;
     }
     /* return I if the sequence starting there is long enough to include i */
     do {
         b=s[I];
         if((uint8_t)(b-0x80)>=0x7e) { /* not 0x80<=b<0xfe */
             break;
         } else if(b>=0xc0) {
             if(U8_COUNT_TRAIL_BYTES(b)>=(i-I)) {
                 return I;
             } else {
                 break;
             }
         }
     } while(Z<=--I);
     /* return i itself to be consistent with the FWD_1 macro */
     return i;
 }

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intl/icu/source/common/utf_impl.c@fc2d59ddac77 (annotated)

intl/icu/source/common/utf_impl.c