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fish-shell/src/utf8.cpp
ridiculousfish 58d56f91f3 Tweak UTF8 decoding interface 
Previously, when decoding UTF-8, we would first run through the
array to compute the correct size, then allocate a buffer of that size,
then run through the array again to fill the buffer, and then copy it
into a std::wstring. With this fix we can copy it into the string
directly, reducing allocations and only requiring a single pass.
2016-03-02 11:24:23 -08:00

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/*
* Copyright (c) 2007 Alexey Vatchenko <av@bsdua.org>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, 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 THIS SOFTWARE.
*/
#include <sys/types.h>
#include <stdint.h>
#include "utf8.h"
#include <string>
#include <limits>
#include <algorithm>
#define _NXT 0x80
#define _SEQ2 0xc0
#define _SEQ3 0xe0
#define _SEQ4 0xf0
#define _SEQ5 0xf8
#define _SEQ6 0xfc
#define _BOM 0xfeff
/* We can tweak the following typedef to allow us to simulate Windows-style 16 bit wchar's on Unix */
typedef wchar_t utf8_wchar_t;
#define UTF8_WCHAR_MAX ((size_t)std::numeric_limits<utf8_wchar_t>::max())
typedef std::basic_string<utf8_wchar_t> utf8_wstring_t;
bool is_wchar_ucs2()
{
return UTF8_WCHAR_MAX <= 0xFFFF;
}
static size_t utf8_to_wchar_internal(const char *in, size_t insize, utf8_wstring_t *result, int flags);
static size_t wchar_to_utf8_internal(const utf8_wchar_t *in, size_t insize, char *out, size_t outsize, int flags);
static bool safe_copy_wchar_to_utf8_wchar(const wchar_t *in, utf8_wchar_t *out, size_t count)
{
bool result = true;
for (size_t i=0; i < count; i++)
{
wchar_t c = in[i];
if (c > UTF8_WCHAR_MAX)
{
result = false;
break;
}
out[i] = c;
}
return result;
}
bool wchar_to_utf8_string(const std::wstring &str, std::string *result)
{
result->clear();
const size_t inlen = str.size();
if (inlen == 0)
{
return true;
}
bool success = false;
const wchar_t *input = str.c_str();
size_t outlen = wchar_to_utf8(input, inlen, NULL, 0, 0);
if (outlen > 0)
{
char *tmp = new char[outlen];
size_t outlen2 = wchar_to_utf8(input, inlen, tmp, outlen, 0);
if (outlen2 > 0)
{
result->assign(tmp, outlen2);
success = true;
}
delete[] tmp;
}
return success;
}
size_t utf8_to_wchar(const char *in, size_t insize, std::wstring *out, int flags)
{
if (in == NULL || insize == 0)
{
return 0;
}
size_t result;
if (sizeof(wchar_t) == sizeof(utf8_wchar_t))
{
result = utf8_to_wchar_internal(in, insize, reinterpret_cast<utf8_wstring_t *>(out), flags);
}
else if (out == NULL)
{
result = utf8_to_wchar_internal(in, insize, NULL, flags);
}
else
{
// Allocate a temporary buffer to hold the output,
// invoke the conversion with the temporary,
// and then copy it back
utf8_wstring_t tmp_output;
result = utf8_to_wchar_internal(in, insize, &tmp_output, flags);
out->insert(out->end(), tmp_output.begin(), tmp_output.end());
}
return result;
}
size_t wchar_to_utf8(const wchar_t *in, size_t insize, char *out, size_t outsize, int flags)
{
if (in == NULL || insize == 0 || (outsize == 0 && out != NULL))
{
return 0;
}
size_t result;
if (sizeof(wchar_t) == sizeof(utf8_wchar_t))
{
result = wchar_to_utf8_internal(reinterpret_cast<const utf8_wchar_t *>(in), insize, out, outsize, flags);
}
else
{
// Allocate a temporary buffer to hold the input
// the std::copy performs the size conversion
// note: insize may be 0
utf8_wchar_t *tmp_input = new utf8_wchar_t[insize];
if (! safe_copy_wchar_to_utf8_wchar(in, tmp_input, insize))
{
// our utf8_wchar_t is UCS-16 and there was an astral character
result = 0;
}
else
{
// Invoke the conversion with the temporary, then clean up the input
result = wchar_to_utf8_internal(tmp_input, insize, out, outsize, flags);
}
delete[] tmp_input;
}
return result;
}
static int __wchar_forbitten(utf8_wchar_t sym);
static int __utf8_forbitten(unsigned char octet);
static int
__wchar_forbitten(utf8_wchar_t sym)
{
/* Surrogate pairs */
if (sym >= 0xd800 && sym <= 0xdfff)
return (-1);
return (0);
}
static int
__utf8_forbitten(unsigned char octet)
{
switch (octet)
{
case 0xc0:
case 0xc1:
case 0xf5:
case 0xff:
return (-1);
}
return (0);
}
/*
* DESCRIPTION
* This function translates UTF-8 string into UCS-2 or UCS-4 string (all symbols
* will be in local machine byte order).
*
* It takes the following arguments:
* in - input UTF-8 string. It can be null-terminated.
* insize - size of input string in bytes.
* out_string - result buffer for UCS-2/4 string.
*
* RETURN VALUES
* The function returns size of result buffer (in wide characters).
* Zero is returned in case of error.
*
* CAVEATS
* 1. If UTF-8 string contains zero symbols, they will be translated
* as regular symbols.
* 2. If UTF8_IGNORE_ERROR or UTF8_SKIP_BOM flag is set, sizes may vary
* when `out' is NULL and not NULL. It's because of special UTF-8
* sequences which may result in forbitten (by RFC3629) UNICODE
* characters. So, the caller must check return value every time and
* not prepare buffer in advance (\0 terminate) but after calling this
* function.
*/
static size_t utf8_to_wchar_internal(const char *in, size_t insize, utf8_wstring_t *out_string, int flags)
{
unsigned char *p, *lim;
utf8_wchar_t high;
size_t n, total, i, n_bits;
if (in == NULL || insize == 0)
return (0);
if (out_string != NULL)
out_string->clear();
total = 0;
p = (unsigned char *)in;
lim = p + insize;
for (; p < lim; p += n)
{
if (__utf8_forbitten(*p) != 0 &&
(flags & UTF8_IGNORE_ERROR) == 0)
return (0);
/*
* Get number of bytes for one wide character.
*/
n = 1; /* default: 1 byte. Used when skipping bytes. */
if ((*p & 0x80) == 0)
high = (utf8_wchar_t)*p;
else if ((*p & 0xe0) == _SEQ2)
{
n = 2;
high = (utf8_wchar_t)(*p & 0x1f);
}
else if ((*p & 0xf0) == _SEQ3)
{
n = 3;
high = (utf8_wchar_t)(*p & 0x0f);
}
else if ((*p & 0xf8) == _SEQ4)
{
n = 4;
high = (utf8_wchar_t)(*p & 0x07);
}
else if ((*p & 0xfc) == _SEQ5)
{
n = 5;
high = (utf8_wchar_t)(*p & 0x03);
}
else if ((*p & 0xfe) == _SEQ6)
{
n = 6;
high = (utf8_wchar_t)(*p & 0x01);
}
else
{
if ((flags & UTF8_IGNORE_ERROR) == 0)
return (0);
continue;
}
/* does the sequence header tell us truth about length? */
if (lim - p <= n - 1)
{
if ((flags & UTF8_IGNORE_ERROR) == 0)
return (0);
n = 1;
continue; /* skip */
}
/*
* Validate sequence.
* All symbols must have higher bits set to 10xxxxxx
*/
if (n > 1)
{
for (i = 1; i < n; i++)
{
if ((p[i] & 0xc0) != _NXT)
break;
}
if (i != n)
{
if ((flags & UTF8_IGNORE_ERROR) == 0)
return (0);
n = 1;
continue; /* skip */
}
}
total++;
if (out_string == NULL)
continue;
uint32_t out_val = 0;
n_bits = 0;
for (i = 1; i < n; i++)
{
out_val |= (utf8_wchar_t)(p[n - i] & 0x3f) << n_bits;
n_bits += 6; /* 6 low bits in every byte */
}
out_val |= high << n_bits;
bool skip = false;
if (__wchar_forbitten(out_val) != 0)
{
if ((flags & UTF8_IGNORE_ERROR) == 0)
{
return 0; /* forbitten character */
}
else
{
skip = true;
}
}
else if (out_val == _BOM && (flags & UTF8_SKIP_BOM) != 0)
{
skip = true;
}
if (skip)
{
total--;
}
else if (out_val > UTF8_WCHAR_MAX)
{
// wchar_t is UCS-2, but the UTF-8 specified an astral character
return 0;
}
else
{
out_string->push_back(out_val);
}
}
return (total);
}
/*
* DESCRIPTION
* This function translates UCS-2/4 symbols (given in local machine
* byte order) into UTF-8 string.
*
* It takes the following arguments:
* in - input unicode string. It can be null-terminated.
* insize - size of input string in wide characters.
* out - result buffer for utf8 string. If out is NULL,
* function returns size of result buffer.
* outsize - size of result buffer.
*
* RETURN VALUES
* The function returns size of result buffer (in bytes). Zero is returned
* in case of error.
*
* CAVEATS
* If UCS-4 string contains zero symbols, they will be translated
* as regular symbols.
*/
static size_t wchar_to_utf8_internal(const utf8_wchar_t *in, size_t insize, char *out, size_t outsize, int flags)
{
const utf8_wchar_t *w, *wlim;
unsigned char *p, *lim;
size_t total, n;
if (in == NULL || insize == 0 || (outsize == 0 && out != NULL))
return (0);
w = in;
wlim = w + insize;
p = (unsigned char *)out;
lim = p + outsize;
total = 0;
for (; w < wlim; w++)
{
if (__wchar_forbitten(*w) != 0)
{
if ((flags & UTF8_IGNORE_ERROR) == 0)
return (0);
else
continue;
}
if (*w == _BOM && (flags & UTF8_SKIP_BOM) != 0)
continue;
const int32_t w_wide = *w;
if (w_wide < 0)
{
if ((flags & UTF8_IGNORE_ERROR) == 0)
return (0);
continue;
}
else if (w_wide <= 0x0000007f)
n = 1;
else if (w_wide <= 0x000007ff)
n = 2;
else if (w_wide <= 0x0000ffff)
n = 3;
else if (w_wide <= 0x001fffff)
n = 4;
else if (w_wide <= 0x03ffffff)
n = 5;
else /* if (w_wide <= 0x7fffffff) */
n = 6;
total += n;
if (out == NULL)
continue;
if (lim - p <= n - 1)
return (0); /* no space left */
/* extract the wchar_t as big-endian. If wchar_t is UCS-16, the first two bytes will be 0 */
unsigned char oc[4];
uint32_t w_tmp = *w;
oc[3] = w_tmp & 0xFF;
w_tmp >>= 8;
oc[2] = w_tmp & 0xFF;
w_tmp >>= 8;
oc[1] = w_tmp & 0xFF;
w_tmp >>= 8;
oc[0] = w_tmp & 0xFF;
switch (n)
{
case 1:
p[0] = oc[3];
break;
case 2:
p[1] = _NXT | (oc[3] & 0x3f);
p[0] = _SEQ2 | (oc[3] >> 6) | ((oc[2] & 0x07) << 2);
break;
case 3:
p[2] = _NXT | (oc[3] & 0x3f);
p[1] = _NXT | (oc[3] >> 6) | ((oc[2] & 0x0f) << 2);
p[0] = _SEQ3 | ((oc[2] & 0xf0) >> 4);
break;
case 4:
p[3] = _NXT | (oc[3] & 0x3f);
p[2] = _NXT | (oc[3] >> 6) | ((oc[2] & 0x0f) << 2);
p[1] = _NXT | ((oc[2] & 0xf0) >> 4) |
((oc[1] & 0x03) << 4);
p[0] = _SEQ4 | ((oc[1] & 0x1f) >> 2);
break;
case 5:
p[4] = _NXT | (oc[3] & 0x3f);
p[3] = _NXT | (oc[3] >> 6) | ((oc[2] & 0x0f) << 2);
p[2] = _NXT | ((oc[2] & 0xf0) >> 4) |
((oc[1] & 0x03) << 4);
p[1] = _NXT | (oc[1] >> 2);
p[0] = _SEQ5 | (oc[0] & 0x03);
break;
case 6:
p[5] = _NXT | (oc[3] & 0x3f);
p[4] = _NXT | (oc[3] >> 6) | ((oc[2] & 0x0f) << 2);
p[3] = _NXT | (oc[2] >> 4) | ((oc[1] & 0x03) << 4);
p[2] = _NXT | (oc[1] >> 2);
p[1] = _NXT | (oc[0] & 0x3f);
p[0] = _SEQ6 | ((oc[0] & 0x40) >> 6);
break;
}
/*
* NOTE: do not check here for forbitten UTF-8 characters.
* They cannot appear here because we do proper convertion.
*/
p += n;
}
return (total);
}
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