/* * Copyright 2001-2004 Unicode, Inc. * * Disclaimer * * This source code is provided as is by Unicode, Inc. No claims are * made as to fitness for any particular purpose. No warranties of any * kind are expressed or implied. The recipient agrees to determine * applicability of information provided. If this file has been * purchased on magnetic or optical media from Unicode, Inc., the * sole remedy for any claim will be exchange of defective media * within 90 days of receipt. * * Limitations on Rights to Redistribute This Code * * Unicode, Inc. hereby grants the right to freely use the information * supplied in this file in the creation of products supporting the * Unicode Standard, and to make copies of this file in any form * for internal or external distribution as long as this notice * remains attached. */ /* --------------------------------------------------------------------- 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 TSK_UNI_MAX_LEGAL_UTF32 in UTF-32 conversions. See the header file "ConvertUTF.h" for complete documentation. ------------------------------------------------------------------------ */ #ifdef CVTUTF_DEBUG #include #endif #include "aux_tools.h" static const int halfShift = 10; /* used for shifting by 10 bits */ static const UTF32 halfBase = 0x0010000UL; static const UTF32 halfMask = 0x3FFUL; #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 #define false 0 #define true 1 /* --------------------------------------------------------------------- */ /* --------------------------------------------------------------------- */ /* * 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. */ static 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. */ static 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. */ static 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. */ /* --------------------------------------------------------------------- */ TSKConversionResult tsk_UTF16toUTF8(uint16_t endian, const UTF16 ** sourceStart, const UTF16 * sourceEnd, UTF8 ** targetStart, UTF8 * targetEnd, TSKConversionFlags flags) { TSKConversionResult result = TSKconversionOK; 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 = tsk_getu16(endian, (uint8_t *) source); 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 = tsk_getu16(endian, (uint8_t *) 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 == TSKstrictConversion) { /* it's an unpaired high surrogate */ --source; /* return to the illegal value itself */ result = TSKsourceIllegal; break; } } else { /* We don't have the 16 bits following the high surrogate. */ --source; /* return to the high surrogate */ result = TSKsourceExhausted; break; } } else if (flags == TSKstrictConversion) { /* 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 = TSKsourceIllegal; 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 = TSK_UNI_REPLACEMENT_CHAR; } target += bytesToWrite; if (target > targetEnd) { source = oldSource; /* Back up source pointer! */ target -= bytesToWrite; result = TSKtargetExhausted; break; } switch (bytesToWrite) { /* note: everything falls through. */ case 4: *--target = (UTF8) ((ch | byteMark) & byteMask); ch >>= 6; case 3: *--target = (UTF8) ((ch | byteMark) & byteMask); ch >>= 6; case 2: *--target = (UTF8) ((ch | byteMark) & byteMask); ch >>= 6; case 1: *--target = (UTF8) (ch | firstByteMark[bytesToWrite]); } target += bytesToWrite; } *sourceStart = source; *targetStart = target; return result; } /* --------------------------------------------------------------------- */ /* * 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. */ static 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; case 3: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false; 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; } case 1: if (*source >= 0x80 && *source < 0xC2) return false; } if (*source > 0xF4) return false; return true; } /* --------------------------------------------------------------------- */ /* * Exported function to return whether a UTF-8 sequence is legal or not. * This is not used here; it's just exported. */ Boolean tsk_isLegalUTF8Sequence(const UTF8 * source, const UTF8 * sourceEnd) { int length = trailingBytesForUTF8[*source] + 1; if (source + length > sourceEnd) { return false; } return isLegalUTF8(source, length); } /* --------------------------------------------------------------------- */ // The result of this is in the local endian ordering TSKConversionResult tsk_UTF8toUTF16(const UTF8 ** sourceStart, const UTF8 * sourceEnd, UTF16 ** targetStart, UTF16 * targetEnd, TSKConversionFlags flags) { TSKConversionResult result = TSKconversionOK; const UTF8 *source = *sourceStart; UTF16 *target = *targetStart; while (source < sourceEnd) { UTF32 ch = 0; unsigned short extraBytesToRead = trailingBytesForUTF8[*source]; if (source + extraBytesToRead >= sourceEnd) { result = TSKsourceExhausted; break; } /* Do this check whether lenient or strict */ if (!isLegalUTF8(source, extraBytesToRead + 1)) { result = TSKsourceIllegal; break; } /* * The cases all fall through. See "Note A" below. */ switch (extraBytesToRead) { case 5: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */ case 4: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */ case 3: ch += *source++; ch <<= 6; case 2: ch += *source++; ch <<= 6; case 1: ch += *source++; ch <<= 6; case 0: ch += *source++; } ch -= offsetsFromUTF8[extraBytesToRead]; if (target >= targetEnd) { source -= (extraBytesToRead + 1); /* Back up source pointer! */ result = TSKtargetExhausted; break; } if (ch <= TSK_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 == TSKstrictConversion) { source -= (extraBytesToRead + 1); /* return to the illegal value itself */ result = TSKsourceIllegal; break; } else { *target++ = TSK_UNI_REPLACEMENT_CHAR; } } else { *target++ = (UTF16) ch; /* normal case */ } } else if (ch > TSK_UNI_MAX_UTF16) { if (flags == TSKstrictConversion) { result = TSKsourceIllegal; source -= (extraBytesToRead + 1); /* return to the start */ break; /* Bail out; shouldn't continue */ } else { *target++ = TSK_UNI_REPLACEMENT_CHAR; } } else { /* target is a character in range 0xFFFF - 0x10FFFF. */ if (target + 1 >= targetEnd) { source -= (extraBytesToRead + 1); /* Back up source pointer! */ result = TSKtargetExhausted; 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; }