src/common/convert_UTF.cc - breakpad - Git at Google

 /*
  * Copyright © 1991-2015 Unicode, Inc. All rights reserved.
  * Distributed under the Terms of Use in
  * http://www.unicode.org/copyright.html.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of the Unicode data files and any associated documentation
  * (the "Data Files") or Unicode software and any associated documentation
  * (the "Software") to deal in the Data Files or Software
  * without restriction, including without limitation the rights to use,
  * copy, modify, merge, publish, distribute, and/or sell copies of
  * the Data Files or Software, and to permit persons to whom the Data Files
  * or Software are furnished to do so, provided that
  * (a) this copyright and permission notice appear with all copies
  * of the Data Files or Software,
  * (b) this copyright and permission notice appear in associated
  * documentation, and
  * (c) there is clear notice in each modified Data File or in the Software
  * as well as in the documentation associated with the Data File(s) or
  * Software that the data or software has been modified.
  *
  * THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF
  * ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
  * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  * NONINFRINGEMENT OF THIRD PARTY RIGHTS.
  * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS
  * NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL
  * DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  * PERFORMANCE OF THE DATA FILES OR SOFTWARE.
  *
  * Except as contained in this notice, the name of a copyright holder
  * shall not be used in advertising or otherwise to promote the sale,
  * use or other dealings in these Data Files or Software without prior
  * written authorization of the copyright holder.
  */

 /* ---------------------------------------------------------------------

 Conversions between UTF32, UTF-16, and UTF-8. Source code file.
 Author: Mark E. Davis, 1994.
 Rev History: Rick McGowan, fixes & updates May 2001.
 Sept 2001: fixed const & error conditions per
 mods suggested by S. Parent & A. Lillich.
 June 2002: Tim Dodd added detection and handling of incomplete
 source sequences, enhanced error detection, added casts
 to eliminate compiler warnings.
 July 2003: slight mods to back out aggressive FFFE detection.
 Jan 2004: updated switches in from-UTF8 conversions.
 Oct 2004: updated to use UNI_MAX_LEGAL_UTF32 in UTF-32 conversions.

 See the header file "ConvertUTF.h" for complete documentation.

 ------------------------------------------------------------------------ */


 #include "convert_UTF.h"
 #ifdef CVTUTF_DEBUG
 #include <stdio.h>
 #endif

 #include "common/macros.h"

 namespace google_breakpad {

 namespace {

 const int halfShift  = 10; /* used for shifting by 10 bits */

 const UTF32 halfBase = 0x0010000UL;
 const UTF32 halfMask = 0x3FFUL;

 }  // namespace

 #define UNI_SUR_HIGH_START  (UTF32)0xD800
 #define UNI_SUR_HIGH_END    (UTF32)0xDBFF
 #define UNI_SUR_LOW_START   (UTF32)0xDC00
 #define UNI_SUR_LOW_END     (UTF32)0xDFFF

 /* --------------------------------------------------------------------- */

 ConversionResult ConvertUTF32toUTF16 (const UTF32** sourceStart, const UTF32* sourceEnd,
                                       UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags) {
   ConversionResult result = conversionOK;
   const UTF32* source = *sourceStart;
   UTF16* target = *targetStart;
   while (source < sourceEnd) {
     UTF32 ch;
     if (target >= targetEnd) {
 	    result = targetExhausted; break;
     }
     ch = *source++;
     if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
 	    /* UTF-16 surrogate values are illegal in UTF-32; 0xffff or 0xfffe are both reserved values */
 	    if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
         if (flags == strictConversion) {
           --source; /* return to the illegal value itself */
           result = sourceIllegal;
           break;
         } else {
           *target++ = UNI_REPLACEMENT_CHAR;
         }
 	    } else {
         *target++ = (UTF16)ch; /* normal case */
 	    }
     } else if (ch > UNI_MAX_LEGAL_UTF32) {
 	    if (flags == strictConversion) {
         result = sourceIllegal;
 	    } else {
         *target++ = UNI_REPLACEMENT_CHAR;
 	    }
     } else {
 	    /* target is a character in range 0xFFFF - 0x10FFFF. */
 	    if (target + 1 >= targetEnd) {
         --source; /* Back up source pointer! */
         result = targetExhausted; break;
 	    }
 	    ch -= halfBase;
 	    *target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START);
 	    *target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START);
     }
   }
 *sourceStart = source;
 *targetStart = target;
 return result;
 }

 /* --------------------------------------------------------------------- */

 ConversionResult ConvertUTF16toUTF32 (const UTF16** sourceStart, const UTF16* sourceEnd,
                                       UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags) {
   ConversionResult result = conversionOK;
   const UTF16* source = *sourceStart;
   UTF32* target = *targetStart;
   UTF32 ch, ch2;
   while (source < sourceEnd) {
     const UTF16* oldSource = source; /*  In case we have to back up because of target overflow. */
     ch = *source++;
     /* If we have a surrogate pair, convert to UTF32 first. */
     if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
 	    /* If the 16 bits following the high surrogate are in the source buffer... */
 	    if (source < sourceEnd) {
         ch2 = *source;
         /* If it's a low surrogate, convert to UTF32. */
         if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
           ch = ((ch - UNI_SUR_HIGH_START) << halfShift)
           + (ch2 - UNI_SUR_LOW_START) + halfBase;
           ++source;
         } else if (flags == strictConversion) { /* it's an unpaired high surrogate */
           --source; /* return to the illegal value itself */
           result = sourceIllegal;
           break;
         }
 	    } else { /* We don't have the 16 bits following the high surrogate. */
         --source; /* return to the high surrogate */
         result = sourceExhausted;
         break;
 	    }
     } else if (flags == strictConversion) {
 	    /* UTF-16 surrogate values are illegal in UTF-32 */
 	    if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
         --source; /* return to the illegal value itself */
         result = sourceIllegal;
         break;
 	    }
     }
     if (target >= targetEnd) {
 	    source = oldSource; /* Back up source pointer! */
 	    result = targetExhausted; break;
     }
     *target++ = ch;
   }
   *sourceStart = source;
   *targetStart = target;
 #ifdef CVTUTF_DEBUG
   if (result == sourceIllegal) {
     fprintf(stderr, "ConvertUTF16toUTF32 illegal seq 0x%04x,%04x\n", ch, ch2);
     fflush(stderr);
   }
 #endif
   return result;
 }

 /* --------------------------------------------------------------------- */

 namespace {

 /*
  * Index into the table below with the first byte of a UTF-8 sequence to
  * get the number of trailing bytes that are supposed to follow it.
  * Note that *legal* UTF-8 values can't have 4 or 5-bytes. The table is
  * left as-is for anyone who may want to do such conversion, which was
  * allowed in earlier algorithms.
  */
 const char trailingBytesForUTF8[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, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
   2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 3,3,3,3,3,3,3,3,4,4,4,4,5,5,5,5
 };

 /*
  * Magic values subtracted from a buffer value during UTF8 conversion.
  * This table contains as many values as there might be trailing bytes
  * in a UTF-8 sequence.
  */
 const UTF32 offsetsFromUTF8[6] = { 0x00000000UL, 0x00003080UL, 0x000E2080UL,
   0x03C82080UL, 0xFA082080UL, 0x82082080UL };

 /*
  * Once the bits are split out into bytes of UTF-8, this is a mask OR-ed
  * into the first byte, depending on how many bytes follow.  There are
  * as many entries in this table as there are UTF-8 sequence types.
  * (I.e., one byte sequence, two byte... etc.). Remember that sequencs
  * for *legal* UTF-8 will be 4 or fewer bytes total.
  */
 const UTF8 firstByteMark[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC };

 /* --------------------------------------------------------------------- */

 /* The interface converts a whole buffer to avoid function-call overhead.
 * Constants have been gathered. Loops & conditionals have been removed as
 * much as possible for efficiency, in favor of drop-through switches.
 * (See "Note A" at the bottom of the file for equivalent code.)
 * If your compiler supports it, the "isLegalUTF8" call can be turned
 * into an inline function.
 */

 }  // namespace

 /* --------------------------------------------------------------------- */

 ConversionResult ConvertUTF16toUTF8 (const UTF16** sourceStart, const UTF16* sourceEnd,
                                      UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags) {
   ConversionResult result = conversionOK;
   const UTF16* source = *sourceStart;
   UTF8* target = *targetStart;
   while (source < sourceEnd) {
     UTF32 ch;
     unsigned short bytesToWrite = 0;
     const UTF32 byteMask = 0xBF;
     const UTF32 byteMark = 0x80;
     const UTF16* oldSource = source; /* In case we have to back up because of target overflow. */
     ch = *source++;
     /* If we have a surrogate pair, convert to UTF32 first. */
     if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
 	    /* If the 16 bits following the high surrogate are in the source buffer... */
 	    if (source < sourceEnd) {
         UTF32 ch2 = *source;
         /* If it's a low surrogate, convert to UTF32. */
         if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
           ch = ((ch - UNI_SUR_HIGH_START) << halfShift)
           + (ch2 - UNI_SUR_LOW_START) + halfBase;
           ++source;
         } else if (flags == strictConversion) { /* it's an unpaired high surrogate */
           --source; /* return to the illegal value itself */
           result = sourceIllegal;
           break;
         }
 	    } else { /* We don't have the 16 bits following the high surrogate. */
         --source; /* return to the high surrogate */
         result = sourceExhausted;
         break;
 	    }
     } else if (flags == strictConversion) {
 	    /* UTF-16 surrogate values are illegal in UTF-32 */
 	    if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
         --source; /* return to the illegal value itself */
         result = sourceIllegal;
         break;
 	    }
     }
     /* Figure out how many bytes the result will require */
     if (ch < (UTF32)0x80) {	     bytesToWrite = 1;
     } else if (ch < (UTF32)0x800) {     bytesToWrite = 2;
     } else if (ch < (UTF32)0x10000) {   bytesToWrite = 3;
     } else if (ch < (UTF32)0x110000) {  bytesToWrite = 4;
     } else {			    bytesToWrite = 3;
       ch = UNI_REPLACEMENT_CHAR;
     }

     target += bytesToWrite;
     if (target > targetEnd) {
 	    source = oldSource; /* Back up source pointer! */
 	    target -= bytesToWrite; result = targetExhausted; break;
     }
     switch (bytesToWrite) { /* note: everything falls through. */
       case 4:
         *--target = (UTF8)((ch | byteMark) & byteMask);
         ch >>= 6;
         BP_FALLTHROUGH;
       case 3:
         *--target = (UTF8)((ch | byteMark) & byteMask);
         ch >>= 6;
         BP_FALLTHROUGH;
       case 2:
         *--target = (UTF8)((ch | byteMark) & byteMask);
         ch >>= 6;
         BP_FALLTHROUGH;
       case 1:
         *--target =  (UTF8)(ch | firstByteMark[bytesToWrite]);
     }
     target += bytesToWrite;
   }
 *sourceStart = source;
 *targetStart = target;
 return result;
 }

 /* --------------------------------------------------------------------- */

 namespace {

 /*
  * Utility routine to tell whether a sequence of bytes is legal UTF-8.
  * This must be called with the length pre-determined by the first byte.
  * If not calling this from ConvertUTF8to*, then the length can be set by:
  *  length = trailingBytesForUTF8[*source]+1;
  * and the sequence is illegal right away if there aren't that many bytes
  * available.
  * If presented with a length > 4, this returns false.  The Unicode
  * definition of UTF-8 goes up to 4-byte sequences.
  */
 Boolean isLegalUTF8(const UTF8 *source, int length) {
   UTF8 a;
   const UTF8 *srcptr = source+length;
   switch (length) {
     default: return false;
       /* Everything else falls through when "true"... */
     case 4:
       if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
       BP_FALLTHROUGH;
     case 3:
       if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
       BP_FALLTHROUGH;
     case 2:
       if ((a = (*--srcptr)) > 0xBF) return false;

       switch (*source) {
         /* no fall-through in this inner switch */
         case 0xE0: if (a < 0xA0) return false; break;
         case 0xED: if (a > 0x9F) return false; break;
         case 0xF0: if (a < 0x90) return false; break;
         case 0xF4: if (a > 0x8F) return false; break;
         default:   if (a < 0x80) return false;
       }
       BP_FALLTHROUGH;
     case 1: if (*source >= 0x80 && *source < 0xC2) return false;
   }
   if (*source > 0xF4) return false;
   return true;
 }

 }  // namespace

 /* --------------------------------------------------------------------- */

 /*
  * Exported function to return whether a UTF-8 sequence is legal or not.
  * This is not used here; it's just exported.
  */
 Boolean isLegalUTF8Sequence(const UTF8 *source, const UTF8 *sourceEnd) {
   int length = trailingBytesForUTF8[*source]+1;
   if (source+length > sourceEnd) {
     return false;
   }
   return isLegalUTF8(source, length);
 }

 /* --------------------------------------------------------------------- */

 ConversionResult ConvertUTF8toUTF16 (const UTF8** sourceStart, const UTF8* sourceEnd,
                                      UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags) {
   ConversionResult result = conversionOK;
   const UTF8* source = *sourceStart;
   UTF16* target = *targetStart;
   while (source < sourceEnd) {
     UTF32 ch = 0;
     unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
     if (source + extraBytesToRead >= sourceEnd) {
 	    result = sourceExhausted; break;
     }
     /* Do this check whether lenient or strict */
     if (! isLegalUTF8(source, extraBytesToRead+1)) {
 	    result = sourceIllegal;
 	    break;
     }
     /*
      * The cases all fall through. See "Note A" below.
      */
     switch (extraBytesToRead) {
       /* remember, illegal UTF-8 */
       case 5: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       /* remember, illegal UTF-8 */
       case 4: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       case 3: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       case 2: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       case 1: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       case 0: ch += *source++;
     }
     ch -= offsetsFromUTF8[extraBytesToRead];

     if (target >= targetEnd) {
 	    source -= (extraBytesToRead+1); /* Back up source pointer! */
 	    result = targetExhausted; break;
     }
     if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
 	    /* UTF-16 surrogate values are illegal in UTF-32 */
 	    if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
         if (flags == strictConversion) {
           source -= (extraBytesToRead+1); /* return to the illegal value itself */
           result = sourceIllegal;
           break;
         } else {
           *target++ = UNI_REPLACEMENT_CHAR;
         }
 	    } else {
         *target++ = (UTF16)ch; /* normal case */
 	    }
     } else if (ch > UNI_MAX_UTF16) {
 	    if (flags == strictConversion) {
         result = sourceIllegal;
         source -= (extraBytesToRead+1); /* return to the start */
         break; /* Bail out; shouldn't continue */
 	    } else {
         *target++ = UNI_REPLACEMENT_CHAR;
 	    }
     } else {
 	    /* target is a character in range 0xFFFF - 0x10FFFF. */
 	    if (target + 1 >= targetEnd) {
         source -= (extraBytesToRead+1); /* Back up source pointer! */
         result = targetExhausted; break;
 	    }
 	    ch -= halfBase;
 	    *target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START);
 	    *target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START);
     }
   }
 *sourceStart = source;
 *targetStart = target;
 return result;
 }

 /* --------------------------------------------------------------------- */

 ConversionResult ConvertUTF32toUTF8 (const UTF32** sourceStart, const UTF32* sourceEnd,
                                      UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags) {
   ConversionResult result = conversionOK;
   const UTF32* source = *sourceStart;
   UTF8* target = *targetStart;
   while (source < sourceEnd) {
     UTF32 ch;
     unsigned short bytesToWrite = 0;
     const UTF32 byteMask = 0xBF;
     const UTF32 byteMark = 0x80;
     ch = *source++;
     if (flags == strictConversion ) {
 	    /* UTF-16 surrogate values are illegal in UTF-32 */
 	    if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
         --source; /* return to the illegal value itself */
         result = sourceIllegal;
         break;
 	    }
     }
     /*
      * Figure out how many bytes the result will require. Turn any
      * illegally large UTF32 things (> Plane 17) into replacement chars.
      */
     if (ch < (UTF32)0x80) {	     bytesToWrite = 1;
     } else if (ch < (UTF32)0x800) {     bytesToWrite = 2;
     } else if (ch < (UTF32)0x10000) {   bytesToWrite = 3;
     } else if (ch <= UNI_MAX_LEGAL_UTF32) {  bytesToWrite = 4;
     } else {			    bytesToWrite = 3;
       ch = UNI_REPLACEMENT_CHAR;
       result = sourceIllegal;
     }

     target += bytesToWrite;
     if (target > targetEnd) {
 	    --source; /* Back up source pointer! */
 	    target -= bytesToWrite; result = targetExhausted; break;
     }
     switch (bytesToWrite) { /* note: everything falls through. */
       case 4:
         *--target = (UTF8)((ch | byteMark) & byteMask);
         ch >>= 6;
         BP_FALLTHROUGH;
       case 3:
         *--target = (UTF8)((ch | byteMark) & byteMask);
         ch >>= 6;
         BP_FALLTHROUGH;
       case 2:
         *--target = (UTF8)((ch | byteMark) & byteMask);
         ch >>= 6;
         BP_FALLTHROUGH;
       case 1:
         *--target = (UTF8) (ch | firstByteMark[bytesToWrite]);
     }
     target += bytesToWrite;
   }
 *sourceStart = source;
 *targetStart = target;
 return result;
 }

 /* --------------------------------------------------------------------- */

 ConversionResult ConvertUTF8toUTF32 (const UTF8** sourceStart, const UTF8* sourceEnd,
                                      UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags) {
   ConversionResult result = conversionOK;
   const UTF8* source = *sourceStart;
   UTF32* target = *targetStart;
   while (source < sourceEnd) {
     UTF32 ch = 0;
     unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
     if (source + extraBytesToRead >= sourceEnd) {
 	    result = sourceExhausted; break;
     }
     /* Do this check whether lenient or strict */
     if (! isLegalUTF8(source, extraBytesToRead+1)) {
 	    result = sourceIllegal;
 	    break;
     }
     /*
      * The cases all fall through. See "Note A" below.
      */
     switch (extraBytesToRead) {
       case 5: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       case 4: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       case 3: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       case 2: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       case 1: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
       case 0: ch += *source++;
     }
     ch -= offsetsFromUTF8[extraBytesToRead];

     if (target >= targetEnd) {
 	    source -= (extraBytesToRead+1); /* Back up the source pointer! */
 	    result = targetExhausted; break;
     }
     if (ch <= UNI_MAX_LEGAL_UTF32) {
 	    /*
 	     * UTF-16 surrogate values are illegal in UTF-32, and anything
 	     * over Plane 17 (> 0x10FFFF) is illegal.
 	     */
 	    if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
         if (flags == strictConversion) {
           source -= (extraBytesToRead+1); /* return to the illegal value itself */
           result = sourceIllegal;
           break;
         } else {
           *target++ = UNI_REPLACEMENT_CHAR;
         }
 	    } else {
         *target++ = ch;
 	    }
     } else { /* i.e., ch > UNI_MAX_LEGAL_UTF32 */
 	    result = sourceIllegal;
 	    *target++ = UNI_REPLACEMENT_CHAR;
     }
   }
   *sourceStart = source;
   *targetStart = target;
   return result;
 }

 /* ---------------------------------------------------------------------

 Note A.
 The fall-through switches in UTF-8 reading code save a
 temp variable, some decrements & conditionals.  The switches
 are equivalent to the following loop:
 {
   int tmpBytesToRead = extraBytesToRead+1;
   do {
 		ch += *source++;
 		--tmpBytesToRead;
 		if (tmpBytesToRead) ch <<= 6;
   } while (tmpBytesToRead > 0);
 }
 In UTF-8 writing code, the switches on "bytesToWrite" are
 similarly unrolled loops.

 --------------------------------------------------------------------- */

 }  // namespace google_breakpad
	/*
	* Copyright © 1991-2015 Unicode, Inc. All rights reserved.
	* Distributed under the Terms of Use in
	* http://www.unicode.org/copyright.html.
	*
	* Permission is hereby granted, free of charge, to any person obtaining
	* a copy of the Unicode data files and any associated documentation
	* (the "Data Files") or Unicode software and any associated documentation
	* (the "Software") to deal in the Data Files or Software
	* without restriction, including without limitation the rights to use,
	* copy, modify, merge, publish, distribute, and/or sell copies of
	* the Data Files or Software, and to permit persons to whom the Data Files
	* or Software are furnished to do so, provided that
	* (a) this copyright and permission notice appear with all copies
	* of the Data Files or Software,
	* (b) this copyright and permission notice appear in associated
	* documentation, and
	* (c) there is clear notice in each modified Data File or in the Software
	* as well as in the documentation associated with the Data File(s) or
	* Software that the data or software has been modified.
	*
	* THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF
	* ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
	* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	* NONINFRINGEMENT OF THIRD PARTY RIGHTS.
	* IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS
	* NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL
	* DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
	* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
	* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
	* PERFORMANCE OF THE DATA FILES OR SOFTWARE.
	*
	* Except as contained in this notice, the name of a copyright holder
	* shall not be used in advertising or otherwise to promote the sale,
	* use or other dealings in these Data Files or Software without prior
	* written authorization of the copyright holder.
	*/

	/* ---------------------------------------------------------------------

	Conversions between UTF32, UTF-16, and UTF-8. Source code file.
	Author: Mark E. Davis, 1994.
	Rev History: Rick McGowan, fixes & updates May 2001.
	Sept 2001: fixed const & error conditions per
	mods suggested by S. Parent & A. Lillich.
	June 2002: Tim Dodd added detection and handling of incomplete
	source sequences, enhanced error detection, added casts
	to eliminate compiler warnings.
	July 2003: slight mods to back out aggressive FFFE detection.
	Jan 2004: updated switches in from-UTF8 conversions.
	Oct 2004: updated to use UNI_MAX_LEGAL_UTF32 in UTF-32 conversions.

	See the header file "ConvertUTF.h" for complete documentation.

	------------------------------------------------------------------------ */


	#include "convert_UTF.h"
	#ifdef CVTUTF_DEBUG
	#include <stdio.h>
	#endif

	#include "common/macros.h"

	namespace google_breakpad {

	namespace {

	const int halfShift = 10; /* used for shifting by 10 bits */

	const UTF32 halfBase = 0x0010000UL;
	const UTF32 halfMask = 0x3FFUL;

	} // namespace

	#define UNI_SUR_HIGH_START (UTF32)0xD800
	#define UNI_SUR_HIGH_END (UTF32)0xDBFF
	#define UNI_SUR_LOW_START (UTF32)0xDC00
	#define UNI_SUR_LOW_END (UTF32)0xDFFF

	/* --------------------------------------------------------------------- */

	ConversionResult ConvertUTF32toUTF16 (const UTF32** sourceStart, const UTF32* sourceEnd,
	UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags) {
	ConversionResult result = conversionOK;
	const UTF32* source = *sourceStart;
	UTF16* target = *targetStart;
	while (source < sourceEnd) {
	UTF32 ch;
	if (target >= targetEnd) {
	result = targetExhausted; break;
	}
	ch = *source++;
	if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
	/* UTF-16 surrogate values are illegal in UTF-32; 0xffff or 0xfffe are both reserved values */
	if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
	if (flags == strictConversion) {
	--source; /* return to the illegal value itself */
	result = sourceIllegal;
	break;
	} else {
	*target++ = UNI_REPLACEMENT_CHAR;
	}
	} else {
	target++ = (UTF16)ch; / normal case */
	}
	} else if (ch > UNI_MAX_LEGAL_UTF32) {
	if (flags == strictConversion) {
	result = sourceIllegal;
	} else {
	*target++ = UNI_REPLACEMENT_CHAR;
	}
	} else {
	/* target is a character in range 0xFFFF - 0x10FFFF. */
	if (target + 1 >= targetEnd) {
	--source; /* Back up source pointer! */
	result = targetExhausted; break;
	}
	ch -= halfBase;
	*target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START);
	*target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START);
	}
	}
	*sourceStart = source;
	*targetStart = target;
	return result;
	}

	/* --------------------------------------------------------------------- */

	ConversionResult ConvertUTF16toUTF32 (const UTF16** sourceStart, const UTF16* sourceEnd,
	UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags) {
	ConversionResult result = conversionOK;
	const UTF16* source = *sourceStart;
	UTF32* target = *targetStart;
	UTF32 ch, ch2;
	while (source < sourceEnd) {
	const UTF16* oldSource = source; /* In case we have to back up because of target overflow. */
	ch = *source++;
	/* If we have a surrogate pair, convert to UTF32 first. */
	if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
	/* If the 16 bits following the high surrogate are in the source buffer... */
	if (source < sourceEnd) {
	ch2 = *source;
	/* If it's a low surrogate, convert to UTF32. */
	if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
	ch = ((ch - UNI_SUR_HIGH_START) << halfShift)
	+ (ch2 - UNI_SUR_LOW_START) + halfBase;
	++source;
	} else if (flags == strictConversion) { /* it's an unpaired high surrogate */
	--source; /* return to the illegal value itself */
	result = sourceIllegal;
	break;
	}
	} else { /* We don't have the 16 bits following the high surrogate. */
	--source; /* return to the high surrogate */
	result = sourceExhausted;
	break;
	}
	} else if (flags == strictConversion) {
	/* UTF-16 surrogate values are illegal in UTF-32 */
	if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
	--source; /* return to the illegal value itself */
	result = sourceIllegal;
	break;
	}
	}
	if (target >= targetEnd) {
	source = oldSource; /* Back up source pointer! */
	result = targetExhausted; break;
	}
	*target++ = ch;
	}
	*sourceStart = source;
	*targetStart = target;
	#ifdef CVTUTF_DEBUG
	if (result == sourceIllegal) {
	fprintf(stderr, "ConvertUTF16toUTF32 illegal seq 0x%04x,%04x\n", ch, ch2);
	fflush(stderr);
	}
	#endif
	return result;
	}

	/* --------------------------------------------------------------------- */

	namespace {

	/*
	* Index into the table below with the first byte of a UTF-8 sequence to
	* get the number of trailing bytes that are supposed to follow it.
	* Note that legal UTF-8 values can't have 4 or 5-bytes. The table is
	* left as-is for anyone who may want to do such conversion, which was
	* allowed in earlier algorithms.
	*/
	const char trailingBytesForUTF8[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, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
	1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
	2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 3,3,3,3,3,3,3,3,4,4,4,4,5,5,5,5
	};

	/*
	* Magic values subtracted from a buffer value during UTF8 conversion.
	* This table contains as many values as there might be trailing bytes
	* in a UTF-8 sequence.
	*/
	const UTF32 offsetsFromUTF8[6] = { 0x00000000UL, 0x00003080UL, 0x000E2080UL,
	0x03C82080UL, 0xFA082080UL, 0x82082080UL };

	/*
	* Once the bits are split out into bytes of UTF-8, this is a mask OR-ed
	* into the first byte, depending on how many bytes follow. There are
	* as many entries in this table as there are UTF-8 sequence types.
	* (I.e., one byte sequence, two byte... etc.). Remember that sequencs
	* for legal UTF-8 will be 4 or fewer bytes total.
	*/
	const UTF8 firstByteMark[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC };

	/* --------------------------------------------------------------------- */

	/* The interface converts a whole buffer to avoid function-call overhead.
	* Constants have been gathered. Loops & conditionals have been removed as
	* much as possible for efficiency, in favor of drop-through switches.
	* (See "Note A" at the bottom of the file for equivalent code.)
	* If your compiler supports it, the "isLegalUTF8" call can be turned
	* into an inline function.
	*/

	} // namespace

	/* --------------------------------------------------------------------- */

	ConversionResult ConvertUTF16toUTF8 (const UTF16** sourceStart, const UTF16* sourceEnd,
	UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags) {
	ConversionResult result = conversionOK;
	const UTF16* source = *sourceStart;
	UTF8* target = *targetStart;
	while (source < sourceEnd) {
	UTF32 ch;
	unsigned short bytesToWrite = 0;
	const UTF32 byteMask = 0xBF;
	const UTF32 byteMark = 0x80;
	const UTF16* oldSource = source; /* In case we have to back up because of target overflow. */
	ch = *source++;
	/* If we have a surrogate pair, convert to UTF32 first. */
	if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
	/* If the 16 bits following the high surrogate are in the source buffer... */
	if (source < sourceEnd) {
	UTF32 ch2 = *source;
	/* If it's a low surrogate, convert to UTF32. */
	if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
	ch = ((ch - UNI_SUR_HIGH_START) << halfShift)
	+ (ch2 - UNI_SUR_LOW_START) + halfBase;
	++source;
	} else if (flags == strictConversion) { /* it's an unpaired high surrogate */
	--source; /* return to the illegal value itself */
	result = sourceIllegal;
	break;
	}
	} else { /* We don't have the 16 bits following the high surrogate. */
	--source; /* return to the high surrogate */
	result = sourceExhausted;
	break;
	}
	} else if (flags == strictConversion) {
	/* UTF-16 surrogate values are illegal in UTF-32 */
	if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
	--source; /* return to the illegal value itself */
	result = sourceIllegal;
	break;
	}
	}
	/* Figure out how many bytes the result will require */
	if (ch < (UTF32)0x80) { bytesToWrite = 1;
	} else if (ch < (UTF32)0x800) { bytesToWrite = 2;
	} else if (ch < (UTF32)0x10000) { bytesToWrite = 3;
	} else if (ch < (UTF32)0x110000) { bytesToWrite = 4;
	} else { bytesToWrite = 3;
	ch = UNI_REPLACEMENT_CHAR;
	}

	target += bytesToWrite;
	if (target > targetEnd) {
	source = oldSource; /* Back up source pointer! */
	target -= bytesToWrite; result = targetExhausted; break;
	}
	switch (bytesToWrite) { /* note: everything falls through. */
	case 4:
	*--target = (UTF8)((ch \| byteMark) & byteMask);
	ch >>= 6;
	BP_FALLTHROUGH;
	case 3:
	*--target = (UTF8)((ch \| byteMark) & byteMask);
	ch >>= 6;
	BP_FALLTHROUGH;
	case 2:
	*--target = (UTF8)((ch \| byteMark) & byteMask);
	ch >>= 6;
	BP_FALLTHROUGH;
	case 1:
	*--target = (UTF8)(ch \| firstByteMark[bytesToWrite]);
	}
	target += bytesToWrite;
	}
	*sourceStart = source;
	*targetStart = target;
	return result;
	}

	/* --------------------------------------------------------------------- */

	namespace {

	/*
	* Utility routine to tell whether a sequence of bytes is legal UTF-8.
	* This must be called with the length pre-determined by the first byte.
	* If not calling this from ConvertUTF8to*, then the length can be set by:
	* length = trailingBytesForUTF8[*source]+1;
	* and the sequence is illegal right away if there aren't that many bytes
	* available.
	* If presented with a length > 4, this returns false. The Unicode
	* definition of UTF-8 goes up to 4-byte sequences.
	*/
	Boolean isLegalUTF8(const UTF8 *source, int length) {
	UTF8 a;
	const UTF8 *srcptr = source+length;
	switch (length) {
	default: return false;
	/* Everything else falls through when "true"... */
	case 4:
	if ((a = (*--srcptr)) < 0x80 \|\| a > 0xBF) return false;
	BP_FALLTHROUGH;
	case 3:
	if ((a = (*--srcptr)) < 0x80 \|\| a > 0xBF) return false;
	BP_FALLTHROUGH;
	case 2:
	if ((a = (*--srcptr)) > 0xBF) return false;

	switch (*source) {
	/* no fall-through in this inner switch */
	case 0xE0: if (a < 0xA0) return false; break;
	case 0xED: if (a > 0x9F) return false; break;
	case 0xF0: if (a < 0x90) return false; break;
	case 0xF4: if (a > 0x8F) return false; break;
	default: if (a < 0x80) return false;
	}
	BP_FALLTHROUGH;
	case 1: if (source >= 0x80 && source < 0xC2) return false;
	}
	if (*source > 0xF4) return false;
	return true;
	}

	} // namespace

	/* --------------------------------------------------------------------- */

	/*
	* Exported function to return whether a UTF-8 sequence is legal or not.
	* This is not used here; it's just exported.
	*/
	Boolean isLegalUTF8Sequence(const UTF8 source, const UTF8 sourceEnd) {
	int length = trailingBytesForUTF8[*source]+1;
	if (source+length > sourceEnd) {
	return false;
	}
	return isLegalUTF8(source, length);
	}

	/* --------------------------------------------------------------------- */

	ConversionResult ConvertUTF8toUTF16 (const UTF8** sourceStart, const UTF8* sourceEnd,
	UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags) {
	ConversionResult result = conversionOK;
	const UTF8* source = *sourceStart;
	UTF16* target = *targetStart;
	while (source < sourceEnd) {
	UTF32 ch = 0;
	unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
	if (source + extraBytesToRead >= sourceEnd) {
	result = sourceExhausted; break;
	}
	/* Do this check whether lenient or strict */
	if (! isLegalUTF8(source, extraBytesToRead+1)) {
	result = sourceIllegal;
	break;
	}
	/*
	* The cases all fall through. See "Note A" below.
	*/
	switch (extraBytesToRead) {
	/* remember, illegal UTF-8 */
	case 5: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	/* remember, illegal UTF-8 */
	case 4: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	case 3: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	case 2: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	case 1: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	case 0: ch += *source++;
	}
	ch -= offsetsFromUTF8[extraBytesToRead];

	if (target >= targetEnd) {
	source -= (extraBytesToRead+1); /* Back up source pointer! */
	result = targetExhausted; break;
	}
	if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
	/* UTF-16 surrogate values are illegal in UTF-32 */
	if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
	if (flags == strictConversion) {
	source -= (extraBytesToRead+1); /* return to the illegal value itself */
	result = sourceIllegal;
	break;
	} else {
	*target++ = UNI_REPLACEMENT_CHAR;
	}
	} else {
	target++ = (UTF16)ch; / normal case */
	}
	} else if (ch > UNI_MAX_UTF16) {
	if (flags == strictConversion) {
	result = sourceIllegal;
	source -= (extraBytesToRead+1); /* return to the start */
	break; /* Bail out; shouldn't continue */
	} else {
	*target++ = UNI_REPLACEMENT_CHAR;
	}
	} else {
	/* target is a character in range 0xFFFF - 0x10FFFF. */
	if (target + 1 >= targetEnd) {
	source -= (extraBytesToRead+1); /* Back up source pointer! */
	result = targetExhausted; break;
	}
	ch -= halfBase;
	*target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START);
	*target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START);
	}
	}
	*sourceStart = source;
	*targetStart = target;
	return result;
	}

	/* --------------------------------------------------------------------- */

	ConversionResult ConvertUTF32toUTF8 (const UTF32** sourceStart, const UTF32* sourceEnd,
	UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags) {
	ConversionResult result = conversionOK;
	const UTF32* source = *sourceStart;
	UTF8* target = *targetStart;
	while (source < sourceEnd) {
	UTF32 ch;
	unsigned short bytesToWrite = 0;
	const UTF32 byteMask = 0xBF;
	const UTF32 byteMark = 0x80;
	ch = *source++;
	if (flags == strictConversion ) {
	/* UTF-16 surrogate values are illegal in UTF-32 */
	if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
	--source; /* return to the illegal value itself */
	result = sourceIllegal;
	break;
	}
	}
	/*
	* Figure out how many bytes the result will require. Turn any
	* illegally large UTF32 things (> Plane 17) into replacement chars.
	*/
	if (ch < (UTF32)0x80) { bytesToWrite = 1;
	} else if (ch < (UTF32)0x800) { bytesToWrite = 2;
	} else if (ch < (UTF32)0x10000) { bytesToWrite = 3;
	} else if (ch <= UNI_MAX_LEGAL_UTF32) { bytesToWrite = 4;
	} else { bytesToWrite = 3;
	ch = UNI_REPLACEMENT_CHAR;
	result = sourceIllegal;
	}

	target += bytesToWrite;
	if (target > targetEnd) {
	--source; /* Back up source pointer! */
	target -= bytesToWrite; result = targetExhausted; break;
	}
	switch (bytesToWrite) { /* note: everything falls through. */
	case 4:
	*--target = (UTF8)((ch \| byteMark) & byteMask);
	ch >>= 6;
	BP_FALLTHROUGH;
	case 3:
	*--target = (UTF8)((ch \| byteMark) & byteMask);
	ch >>= 6;
	BP_FALLTHROUGH;
	case 2:
	*--target = (UTF8)((ch \| byteMark) & byteMask);
	ch >>= 6;
	BP_FALLTHROUGH;
	case 1:
	*--target = (UTF8) (ch \| firstByteMark[bytesToWrite]);
	}
	target += bytesToWrite;
	}
	*sourceStart = source;
	*targetStart = target;
	return result;
	}

	/* --------------------------------------------------------------------- */

	ConversionResult ConvertUTF8toUTF32 (const UTF8** sourceStart, const UTF8* sourceEnd,
	UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags) {
	ConversionResult result = conversionOK;
	const UTF8* source = *sourceStart;
	UTF32* target = *targetStart;
	while (source < sourceEnd) {
	UTF32 ch = 0;
	unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
	if (source + extraBytesToRead >= sourceEnd) {
	result = sourceExhausted; break;
	}
	/* Do this check whether lenient or strict */
	if (! isLegalUTF8(source, extraBytesToRead+1)) {
	result = sourceIllegal;
	break;
	}
	/*
	* The cases all fall through. See "Note A" below.
	*/
	switch (extraBytesToRead) {
	case 5: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	case 4: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	case 3: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	case 2: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	case 1: ch += *source++; ch <<= 6; BP_FALLTHROUGH;
	case 0: ch += *source++;
	}
	ch -= offsetsFromUTF8[extraBytesToRead];

	if (target >= targetEnd) {
	source -= (extraBytesToRead+1); /* Back up the source pointer! */
	result = targetExhausted; break;
	}
	if (ch <= UNI_MAX_LEGAL_UTF32) {
	/*
	* UTF-16 surrogate values are illegal in UTF-32, and anything
	* over Plane 17 (> 0x10FFFF) is illegal.
	*/
	if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
	if (flags == strictConversion) {
	source -= (extraBytesToRead+1); /* return to the illegal value itself */
	result = sourceIllegal;
	break;
	} else {
	*target++ = UNI_REPLACEMENT_CHAR;
	}
	} else {
	*target++ = ch;
	}
	} else { /* i.e., ch > UNI_MAX_LEGAL_UTF32 */
	result = sourceIllegal;
	*target++ = UNI_REPLACEMENT_CHAR;
	}
	}
	*sourceStart = source;
	*targetStart = target;
	return result;
	}

	/* ---------------------------------------------------------------------

	Note A.
	The fall-through switches in UTF-8 reading code save a
	temp variable, some decrements & conditionals. The switches
	are equivalent to the following loop:
	{
	int tmpBytesToRead = extraBytesToRead+1;
	do {
	ch += *source++;
	--tmpBytesToRead;
	if (tmpBytesToRead) ch <<= 6;
	} while (tmpBytesToRead > 0);
	}
	In UTF-8 writing code, the switches on "bytesToWrite" are
	similarly unrolled loops.

	--------------------------------------------------------------------- */

	} // namespace google_breakpad