86 lines
2.4 KiB
C++
86 lines
2.4 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2013.
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This file is part of the Sortix C Library.
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The Sortix C Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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The Sortix C Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
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wchar/mbrlen.cpp
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Determine number of bytes in next multibyte character.
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*******************************************************************************/
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#include <errno.h>
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#include <string.h>
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#include <wchar.h>
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static size_t utf8_header_length(unsigned char uc)
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{
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if ( (uc & 0b11000000) == 0b10000000 )
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return 0;
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if ( (uc & 0b10000000) == 0b00000000 )
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return 1;
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if ( (uc & 0b11100000) == 0b11000000 )
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return 2;
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if ( (uc & 0b11110000) == 0b11100000 )
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return 3;
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if ( (uc & 0b11111000) == 0b11110000 )
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return 4;
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if ( (uc & 0b11111100) == 0b11111000 )
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return 5;
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if ( (uc & 0b11111110) == 0b11111100 )
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return 6;
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return (size_t) -1;
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}
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// TODO: Use the shift state.
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extern "C"
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size_t mbrlen(const char* restrict s, size_t n, mbstate_t* restrict ps)
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{
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size_t expected_length;
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for ( size_t i = 0; i < n; i++ )
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{
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unsigned char uc = (unsigned char) s[i];
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if ( i == 0 )
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{
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if ( !uc )
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{
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memset(ps, 0, sizeof(*ps));
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return 0;
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}
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if ( (expected_length = utf8_header_length(uc)) == (size_t) -1 )
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return errno = EILSEQ, (size_t) -1;
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// Check if we encounted an unexpected character claiming to be in
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// the middle of a UTF-8 multibyte sequence (10xxxxxx).
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if ( expected_length == 0 )
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// TODO: Should we play catch up with the partial sequence?
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return errno = EILSEQ, (size_t) -1;
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}
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// All non-header bytes should be of the form 10xxxxxx.
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if ( 0 < i && expected_length < n && (uc & 0b11000000) != 0b10000000 )
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return errno = EILSEQ, (size_t) -1;
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if ( i + 1 == expected_length )
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return i + 1;
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}
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return (size_t) -2;
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}
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