platform_bionic/libc/bionic/mbrtoc16.cpp
Elliott Hughes 9d66092bfd mbrtoc16: explain the line that has no test coverage.
We could remove this line, but it seems reasonable to leave it in for
clarification/safety, especially if it's moved after the common success
case?

Test: treehugger
Change-Id: I5f7e0da8397f80018e6d55321b26371790087f5c
2021-11-18 10:11:07 -08:00

92 lines
3.4 KiB
C++

/*
* Copyright (C) 2014 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <assert.h>
#include <errno.h>
#include <uchar.h>
#include <wchar.h>
#include "private/bionic_mbstate.h"
static inline bool mbspartialc16(const mbstate_t* state) {
return mbstate_get_byte(state, 3) != 0;
}
static size_t begin_surrogate(char32_t c32, char16_t* pc16,
size_t nconv, mbstate_t* state) {
c32 -= 0x10000;
char16_t trail = (c32 & 0x3ff) | 0xdc00;
mbstate_set_byte(state, 0, trail & 0x00ff);
mbstate_set_byte(state, 1, (trail & 0xff00) >> 8);
mbstate_set_byte(state, 3, nconv & 0xff);
*pc16 = ((c32 & 0xffc00) >> 10) | 0xd800;
// Defined by POSIX as return value for first surrogate character.
return static_cast<size_t>(-3);
}
static size_t finish_surrogate(char16_t* pc16, mbstate_t* state) {
char16_t trail = mbstate_get_byte(state, 1) << 8 |
mbstate_get_byte(state, 0);
*pc16 = trail;
return mbstate_reset_and_return(mbstate_get_byte(state, 3), state);
}
size_t mbrtoc16(char16_t* pc16, const char* s, size_t n, mbstate_t* ps) {
static mbstate_t __private_state;
mbstate_t* state = (ps == nullptr) ? &__private_state : ps;
char16_t __private_pc16;
if (pc16 == nullptr) {
pc16 = &__private_pc16;
}
if (mbspartialc16(state)) {
return finish_surrogate(pc16, state);
}
char32_t c32;
size_t nconv = mbrtoc32(&c32, s, n, state);
if (__MB_IS_ERR(nconv)) {
return nconv;
} else if (nconv == 0) {
return mbstate_reset_and_return(nconv, state);
} else if (c32 < 0x10000) {
*pc16 = static_cast<char16_t>(c32);
return mbstate_reset_and_return(nconv, state);
} else if (c32 > 0x10ffff) {
// This case is currently handled by mbrtoc32() returning an error, but
// if that function is extended to cover 5-byte sequences (which are
// illegal at the moment), we'd need to explicitly handle the case of
// codepoints that can't be represented as a surrogate pair here.
return mbstate_reset_and_return_illegal(EILSEQ, state);
} else {
return begin_surrogate(c32, pc16, nconv, state);
}
}