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tidy-html5/src/utf8.c

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/* utf8.c -- convert characters to/from UTF-8
(c) 1998-2007 (W3C) MIT, ERCIM, Keio University
See tidy.h for the copyright notice.
Uses public interfaces to abstract input source and output
sink, which may be user supplied or either FILE* or memory
based Tidy implementations. Encoding support is uniform
regardless of I/O mechanism.
Note, UTF-8 encoding, by itself, does not affect the actual
"codepoints" of the underlying character encoding. In the
cases of ASCII, Latin1, Unicode (16-bit, BMP), these all
refer to ISO-10646 "codepoints". For anything else, they
refer to some other "codepoint" set.
Put another way, UTF-8 is a variable length method to
represent any non-negative integer value. The glyph
that a integer value represents is unchanged and defined
externally (e.g. by ISO-10646, Big5, Win1252, MacRoman,
Latin2-9, and so on).
Put still another way, UTF-8 is more of a _transfer_ encoding
than a _character_ encoding, per se.
*/
#include "tidy.h"
#include "forward.h"
#include "utf8.h"
/*
UTF-8 encoding/decoding functions
Return # of bytes in UTF-8 sequence; result < 0 if illegal sequence
Also see below for UTF-16 encoding/decoding functions
References :
1) UCS Transformation Format 8 (UTF-8):
ISO/IEC 10646-1:1996 Amendment 2 or ISO/IEC 10646-1:2000 Annex D
<http://anubis.dkuug.dk/JTC1/SC2/WG2/docs/n1335>
<http://www.cl.cam.ac.uk/~mgk25/ucs/ISO-10646-UTF-8.html>
Table 4 - Mapping from UCS-4 to UTF-8
2) Unicode standards:
<http://www.unicode.org/unicode/standard/standard.html>
3) Legal UTF-8 byte sequences:
<http://www.unicode.org/unicode/uni2errata/UTF-8_Corrigendum.html>
Code point 1st byte 2nd byte 3rd byte 4th byte
---------- -------- -------- -------- --------
U+0000..U+007F 00..7F
U+0080..U+07FF C2..DF 80..BF
U+0800..U+0FFF E0 A0..BF 80..BF
U+1000..U+FFFF E1..EF 80..BF 80..BF
U+10000..U+3FFFF F0 90..BF 80..BF 80..BF
U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF
U+100000..U+10FFFF F4 80..8F 80..BF 80..BF
The definition of UTF-8 in Annex D of ISO/IEC 10646-1:2000 also
allows for the use of five- and six-byte sequences to encode
characters that are outside the range of the Unicode character
set; those five- and six-byte sequences are illegal for the use
of UTF-8 as a transformation of Unicode characters. ISO/IEC 10646
does not allow mapping of unpaired surrogates, nor U+FFFE and U+FFFF
(but it does allow other noncharacters).
4) RFC 2279: UTF-8, a transformation format of ISO 10646:
<http://www.ietf.org/rfc/rfc2279.txt>
5) UTF-8 and Unicode FAQ:
<http://www.cl.cam.ac.uk/~mgk25/unicode.html>
6) Markus Kuhn's UTF-8 decoder stress test file:
<http://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-test.txt>
7) UTF-8 Demo:
<http://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-demo.txt>
8) UTF-8 Sampler:
<http://www.columbia.edu/kermit/utf8.html>
9) Transformation Format for 16 Planes of Group 00 (UTF-16):
ISO/IEC 10646-1:1996 Amendment 1 or ISO/IEC 10646-1:2000 Annex C
<http://anubis.dkuug.dk/JTC1/SC2/WG2/docs/n2005/n2005.pdf>
<http://www.cl.cam.ac.uk/~mgk25/ucs/ISO-10646-UTF-16.html>
10) RFC 2781: UTF-16, an encoding of ISO 10646:
<http://www.ietf.org/rfc/rfc2781.txt>
11) UTF-16 invalid surrogate pairs:
<http://www.unicode.org/unicode/faq/utf_bom.html#16>
UTF-16 UTF-8 UCS-4
D83F DFF* F0 9F BF B* 0001FFF*
D87F DFF* F0 AF BF B* 0002FFF*
D8BF DFF* F0 BF BF B* 0003FFF*
D8FF DFF* F1 8F BF B* 0004FFF*
D93F DFF* F1 9F BF B* 0005FFF*
D97F DFF* F1 AF BF B* 0006FFF*
...
DBBF DFF* F3 BF BF B* 000FFFF*
DBFF DFF* F4 8F BF B* 0010FFF*
* = E or F
1010 A
1011 B
1100 C
1101 D
1110 E
1111 F
*/
#define kNumUTF8Sequences 7
#define kMaxUTF8Bytes 4
#define kUTF8ByteSwapNotAChar 0xFFFE
#define kUTF8NotAChar 0xFFFF
#define kMaxUTF8FromUCS4 0x10FFFF
#define kUTF16SurrogatesBegin 0x10000
#define kMaxUTF16FromUCS4 0x10FFFF
/* UTF-16 surrogate pair areas */
#define kUTF16LowSurrogateBegin 0xD800
#define kUTF16LowSurrogateEnd 0xDBFF
#define kUTF16HighSurrogateBegin 0xDC00
#define kUTF16HighSurrogateEnd 0xDFFF
/* offsets into validUTF8 table below */
static const int offsetUTF8Sequences[kMaxUTF8Bytes + 1] =
{
0, /* 1 byte */
1, /* 2 bytes */
2, /* 3 bytes */
4, /* 4 bytes */
kNumUTF8Sequences /* must be last */
};
static const struct validUTF8Sequence
{
uint lowChar;
uint highChar;
int numBytes;
byte validBytes[8];
} validUTF8[kNumUTF8Sequences] =
{
/* low high #bytes byte 1 byte 2 byte 3 byte 4 */
{0x0000, 0x007F, 1, {0x00, 0x7F, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}},
{0x0080, 0x07FF, 2, {0xC2, 0xDF, 0x80, 0xBF, 0x00, 0x00, 0x00, 0x00}},
{0x0800, 0x0FFF, 3, {0xE0, 0xE0, 0xA0, 0xBF, 0x80, 0xBF, 0x00, 0x00}},
{0x1000, 0xFFFF, 3, {0xE1, 0xEF, 0x80, 0xBF, 0x80, 0xBF, 0x00, 0x00}},
{0x10000, 0x3FFFF, 4, {0xF0, 0xF0, 0x90, 0xBF, 0x80, 0xBF, 0x80, 0xBF}},
{0x40000, 0xFFFFF, 4, {0xF1, 0xF3, 0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF}},
{0x100000, 0x10FFFF, 4, {0xF4, 0xF4, 0x80, 0x8F, 0x80, 0xBF, 0x80, 0xBF}}
};
int TY_(DecodeUTF8BytesToChar)( uint* c, uint firstByte, ctmbstr successorBytes,
TidyInputSource* inp, int* count )
{
byte tempbuf[10];
byte *buf = &tempbuf[0];
uint ch = 0, n = 0;
int i, bytes = 0;
Bool hasError = no;
if ( successorBytes )
buf = (byte*) successorBytes;
/* special check if we have been passed an EOF char */
if ( firstByte == EndOfStream )
{
/* at present */
*c = firstByte;
*count = 1;
return 0;
}
ch = firstByte; /* first byte is passed in separately */
if (ch <= 0x7F) /* 0XXX XXXX one byte */
{
n = ch;
bytes = 1;
}
else if ((ch & 0xE0) == 0xC0) /* 110X XXXX two bytes */
{
n = ch & 31;
bytes = 2;
}
else if ((ch & 0xF0) == 0xE0) /* 1110 XXXX three bytes */
{
n = ch & 15;
bytes = 3;
}
else if ((ch & 0xF8) == 0xF0) /* 1111 0XXX four bytes */
{
n = ch & 7;
bytes = 4;
}
else if ((ch & 0xFC) == 0xF8) /* 1111 10XX five bytes */
{
n = ch & 3;
bytes = 5;
hasError = yes;
}
else if ((ch & 0xFE) == 0xFC) /* 1111 110X six bytes */
{
n = ch & 1;
bytes = 6;
hasError = yes;
}
else
{
/* not a valid first byte of a UTF-8 sequence */
n = ch;
bytes = 1;
hasError = yes;
}
/* successor bytes should have the form 10XX XXXX */
/* If caller supplied buffer, use it. Else see if caller
** supplied an input source, use that.
*/
if ( successorBytes )
{
for ( i=0; i < bytes-1; ++i )
{
if ( !buf[i] || (buf[i] & 0xC0) != 0x80 )
{
hasError = yes;
bytes = i+1;
break;
}
n = (n << 6) | (buf[i] & 0x3F);
}
}
else if ( inp )
{
for ( i=0; i < bytes-1 && !inp->eof(inp->sourceData); ++i )
{
int b = inp->getByte( inp->sourceData );
buf[i] = (tmbchar) b;
/* End of data or illegal successor byte value */
if ( b == EOF || (buf[i] & 0xC0) != 0x80 )
{
hasError = yes;
bytes = i+1;
if ( b != EOF )
inp->ungetByte( inp->sourceData, buf[i] );
break;
}
n = (n << 6) | (buf[i] & 0x3F);
}
}
else if ( bytes > 1 )
{
hasError = yes;
bytes = 1;
}
if (!hasError && ((n == kUTF8ByteSwapNotAChar) || (n == kUTF8NotAChar)))
hasError = yes;
if (!hasError && (n > kMaxUTF8FromUCS4))
hasError = yes;
if (!hasError)
{
int lo, hi;
lo = offsetUTF8Sequences[bytes - 1];
hi = offsetUTF8Sequences[bytes] - 1;
/* check for overlong sequences */
if ((n < validUTF8[lo].lowChar) || (n > validUTF8[hi].highChar))
hasError = yes;
else
{
hasError = yes; /* assume error until proven otherwise */
for (i = lo; i <= hi; i++)
{
int tempCount;
byte theByte;
for (tempCount = 0; tempCount < bytes; tempCount++)
{
if (!tempCount)
theByte = (tmbchar) firstByte;
else
theByte = buf[tempCount - 1];
if ( theByte >= validUTF8[i].validBytes[(tempCount * 2)] &&
theByte <= validUTF8[i].validBytes[(tempCount * 2) + 1] )
hasError = no;
if (hasError)
break;
}
}
}
}
#if 1 && defined(_DEBUG)
if ( hasError )
{
/* debug */
fprintf( stderr, "UTF-8 decoding error of %d bytes : ", bytes );
fprintf( stderr, "0x%02x ", firstByte );
for (i = 1; i < bytes; i++)
fprintf( stderr, "0x%02x ", buf[i - 1] );
fprintf( stderr, " = U+%04ulx\n", n );
}
#endif
*count = bytes;
*c = n;
if ( hasError )
return -1;
return 0;
}
int TY_(EncodeCharToUTF8Bytes)( uint c, tmbstr encodebuf,
TidyOutputSink* outp, int* count )
{
byte tempbuf[10] = {0};
byte* buf = &tempbuf[0];
int bytes = 0;
Bool hasError = no;
if ( encodebuf )
buf = (byte*) encodebuf;
if (c <= 0x7F) /* 0XXX XXXX one byte */
{
buf[0] = (tmbchar) c;
bytes = 1;
}
else if (c <= 0x7FF) /* 110X XXXX two bytes */
{
buf[0] = (tmbchar) ( 0xC0 | (c >> 6) );
buf[1] = (tmbchar) ( 0x80 | (c & 0x3F) );
bytes = 2;
}
else if (c <= 0xFFFF) /* 1110 XXXX three bytes */
{
buf[0] = (tmbchar) (0xE0 | (c >> 12));
buf[1] = (tmbchar) (0x80 | ((c >> 6) & 0x3F));
buf[2] = (tmbchar) (0x80 | (c & 0x3F));
bytes = 3;
if ( c == kUTF8ByteSwapNotAChar || c == kUTF8NotAChar )
hasError = yes;
}
else if (c <= 0x1FFFFF) /* 1111 0XXX four bytes */
{
buf[0] = (tmbchar) (0xF0 | (c >> 18));
buf[1] = (tmbchar) (0x80 | ((c >> 12) & 0x3F));
buf[2] = (tmbchar) (0x80 | ((c >> 6) & 0x3F));
buf[3] = (tmbchar) (0x80 | (c & 0x3F));
bytes = 4;
if (c > kMaxUTF8FromUCS4)
hasError = yes;
}
else if (c <= 0x3FFFFFF) /* 1111 10XX five bytes */
{
buf[0] = (tmbchar) (0xF8 | (c >> 24));
buf[1] = (tmbchar) (0x80 | (c >> 18));
buf[2] = (tmbchar) (0x80 | ((c >> 12) & 0x3F));
buf[3] = (tmbchar) (0x80 | ((c >> 6) & 0x3F));
buf[4] = (tmbchar) (0x80 | (c & 0x3F));
bytes = 5;
hasError = yes;
}
else if (c <= 0x7FFFFFFF) /* 1111 110X six bytes */
{
buf[0] = (tmbchar) (0xFC | (c >> 30));
buf[1] = (tmbchar) (0x80 | ((c >> 24) & 0x3F));
buf[2] = (tmbchar) (0x80 | ((c >> 18) & 0x3F));
buf[3] = (tmbchar) (0x80 | ((c >> 12) & 0x3F));
buf[4] = (tmbchar) (0x80 | ((c >> 6) & 0x3F));
buf[5] = (tmbchar) (0x80 | (c & 0x3F));
bytes = 6;
hasError = yes;
}
else
hasError = yes;
/* don't output invalid UTF-8 byte sequence to a stream */
if ( !hasError && outp != NULL )
{
int ix;
for ( ix=0; ix < bytes; ++ix )
outp->putByte( outp->sinkData, buf[ix] );
}
#if 1 && defined(_DEBUG)
if ( hasError )
{
int i;
fprintf( stderr, "UTF-8 encoding error for U+%x : ", c );
for (i = 0; i < bytes; i++)
fprintf( stderr, "0x%02x ", buf[i] );
fprintf( stderr, "\n" );
}
#endif
*count = bytes;
if (hasError)
return -1;
return 0;
}
/* return one less than the number of bytes used by the UTF-8 byte sequence */
/* str points to the UTF-8 byte sequence */
/* the Unicode char is returned in *ch */
uint TY_(GetUTF8)( ctmbstr str, uint *ch )
{
uint n;
int bytes;
int err;
bytes = 0;
/* first byte "str[0]" is passed in separately from the */
/* rest of the UTF-8 byte sequence starting at "str[1]" */
err = TY_(DecodeUTF8BytesToChar)( &n, str[0], str+1, NULL, &bytes );
if (err)
{
#if 1 && defined(_DEBUG)
fprintf(stderr, "pprint UTF-8 decoding error for U+%x : ", n);
#endif
n = 0xFFFD; /* replacement char */
}
*ch = n;
return bytes - 1;
}
/* store char c as UTF-8 encoded byte stream */
tmbstr TY_(PutUTF8)( tmbstr buf, uint c )
{
int err, count = 0;
err = TY_(EncodeCharToUTF8Bytes)( c, buf, NULL, &count );
if (err)
{
#if 1 && defined(_DEBUG)
fprintf(stderr, "pprint UTF-8 encoding error for U+%x : ", c);
#endif
/* replacement char 0xFFFD encoded as UTF-8 */
buf[0] = (byte) 0xEF;
buf[1] = (byte) 0xBF;
buf[2] = (byte) 0xBD;
count = 3;
}
buf += count;
return buf;
}
Bool TY_(IsValidUTF16FromUCS4)( tchar ucs4 )
{
return ( ucs4 <= kMaxUTF16FromUCS4 );
}
Bool TY_(IsHighSurrogate)( tchar ch )
{
return ( ch >= kUTF16HighSurrogateBegin && ch <= kUTF16HighSurrogateEnd );
}
Bool TY_(IsLowSurrogate)( tchar ch )
{
return ( ch >= kUTF16LowSurrogateBegin && ch <= kUTF16LowSurrogateEnd );
}
tchar TY_(CombineSurrogatePair)( tchar high, tchar low )
{
assert( TY_(IsHighSurrogate)(high) && TY_(IsLowSurrogate)(low) );
return ( ((low - kUTF16LowSurrogateBegin) * 0x400) +
high - kUTF16HighSurrogateBegin + 0x10000 );
}
Bool TY_(SplitSurrogatePair)( tchar utf16, tchar* low, tchar* high )
{
Bool status = ( TY_(IsValidCombinedChar)( utf16 ) && high && low );
if ( status )
{
*low = (utf16 - kUTF16SurrogatesBegin) / 0x400 + kUTF16LowSurrogateBegin;
*high = (utf16 - kUTF16SurrogatesBegin) % 0x400 + kUTF16HighSurrogateBegin;
}
return status;
}
Bool TY_(IsValidCombinedChar)( tchar ch )
{
return ( ch >= kUTF16SurrogatesBegin &&
(ch & 0x0000FFFE) != 0x0000FFFE &&
(ch & 0x0000FFFF) != 0x0000FFFF );
}
Bool TY_(IsCombinedChar)( tchar ch )
{
return ( ch >= kUTF16SurrogatesBegin );
}
/*
* local variables:
* mode: c
* indent-tabs-mode: nil
* c-basic-offset: 4
* eval: (c-set-offset 'substatement-open 0)
* end:
*/
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