switch_utf8.c

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/*
 * FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 * Copyright (C) 2005-2014, Anthony Minessale II <anthm@freeswitch.org>
 *
 * Version: MPL 1.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 *
 * The Initial Developer of the Original Code is
 * Seven Du <dujinfang@gmail.com>
 * Portions created by the Initial Developer are Copyright (C)
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 * Anthony Minessale II <anthm@freeswitch.org>
 *
 *
 * switch_utf8.c UTf8
 *
 */

#include "switch_utf8.h"

/*
  Basic UTF-8 manipulation routines
  by Jeff Bezanson
  placed in the public domain Fall 2005

  This code is designed to provide the utilities you need to manipulate
  UTF-8 as an internal string encoding. These functions do not perform the
  error checking normally needed when handling UTF-8 data, so if you happen
  to be from the Unicode Consortium you will want to flay me alive.
  I do this because error checking can be performed at the boundaries (I/O),
  with these routines reserved for higher performance on data known to be
  valid.
*/

static const uint32_t offsetsFromUTF8[6] = {
    0x00000000UL, 0x00003080UL, 0x000E2080UL,
    0x03C82080UL, 0xFA082080UL, 0x82082080UL
};

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
};

/* returns length of next utf-8 sequence */
SWITCH_DECLARE(int) switch_u8_seqlen(char *s)
{
        return trailingBytesForUTF8[(unsigned int)(unsigned char)s[0]] + 1;
}

/* conversions without error checking
   only works for valid UTF-8, i.e. no 5- or 6-byte sequences
   srcsz = source size in bytes, or -1 if 0-terminated
   sz = dest size in # of wide characters

   returns # characters converted
   dest will always be L'\0'-terminated, even if there isn't enough room
   for all the characters.
   if sz = srcsz+1 (i.e. 4*srcsz+4 bytes), there will always be enough space.
   */
SWITCH_DECLARE(int) switch_u8_toucs(uint32_t *dest, int sz, char *src, int srcsz)
{
        uint32_t ch;
        char *src_end = src + srcsz;
        int nb;
        int i=0;

        while (i < sz-1) {
                nb = trailingBytesForUTF8[(unsigned char)*src];
                if (srcsz == -1) {
                        if (*src == 0)
                                goto done_toucs;
                }
                else {
                        if (src + nb >= src_end)
                                goto done_toucs;
                }
                ch = 0;
                switch (nb) {
                        /* these fall through deliberately */
                        case 3: ch += (unsigned char)*src++; ch <<= 6;
                        case 2: ch += (unsigned char)*src++; ch <<= 6;
                        case 1: ch += (unsigned char)*src++; ch <<= 6;
                        case 0: ch += (unsigned char)*src++;
                }
                ch -= offsetsFromUTF8[nb];
                dest[i++] = ch;
        }
done_toucs:
        dest[i] = 0;
        return i;
}

/* srcsz = number of source characters, or -1 if 0-terminated
   sz = size of dest buffer in bytes

   returns # characters converted
   dest will only be '\0'-terminated if there is enough space. this is
   for consistency; imagine there are 2 bytes of space left, but the next
   character requires 3 bytes. in this case we could NUL-terminate, but in
   general we can't when there's insufficient space. therefore this function
   only NUL-terminates if all the characters fit, and there's space for
   the NUL as well.
   the destination string will never be bigger than the source string.
   */
SWITCH_DECLARE(int) switch_u8_toutf8(char *dest, int sz, uint32_t *src, int srcsz)
{
        uint32_t ch;
        int i = 0;
        char *dest_end = dest + sz;

        while (srcsz<0 ? src[i]!=0 : i < srcsz) {
                ch = src[i];
                if (ch < 0x80) {
                        if (dest >= dest_end)
                                return i;
                        *dest++ = (char)ch;
                }
                else if (ch < 0x800) {
                        if (dest >= dest_end-1)
                                return i;
                        *dest++ = (ch>>6) | 0xC0;
                        *dest++ = (ch & 0x3F) | 0x80;
                }
                else if (ch < 0x10000) {
                        if (dest >= dest_end-2)
                                return i;
                        *dest++ = (ch>>12) | 0xE0;
                        *dest++ = ((ch>>6) & 0x3F) | 0x80;
                        *dest++ = (ch & 0x3F) | 0x80;
                }
                else if (ch < 0x110000) {
                        if (dest >= dest_end-3)
                                return i;
                        *dest++ = (ch>>18) | 0xF0;
                        *dest++ = ((ch>>12) & 0x3F) | 0x80;
                        *dest++ = ((ch>>6) & 0x3F) | 0x80;
                        *dest++ = (ch & 0x3F) | 0x80;
                }
                i++;
        }
        if (dest < dest_end)
                *dest = '\0';
        return i;
}

SWITCH_DECLARE(int) switch_u8_wc_toutf8(char *dest, uint32_t ch)
{
        if (ch < 0x80) {
                dest[0] = (char)ch;
                return 1;
        }
        if (ch < 0x800) {
                dest[0] = (ch>>6) | 0xC0;
                dest[1] = (ch & 0x3F) | 0x80;
                return 2;
        }
        if (ch < 0x10000) {
                dest[0] = (ch>>12) | 0xE0;
                dest[1] = ((ch>>6) & 0x3F) | 0x80;
                dest[2] = (ch & 0x3F) | 0x80;
                return 3;
        }
        if (ch < 0x110000) {
                dest[0] = (ch>>18) | 0xF0;
                dest[1] = ((ch>>12) & 0x3F) | 0x80;
                dest[2] = ((ch>>6) & 0x3F) | 0x80;
                dest[3] = (ch & 0x3F) | 0x80;
                return 4;
        }
        return 0;
}

/* charnum => byte offset */
SWITCH_DECLARE(int) switch_u8_offset(char *str, int charnum)
{
        int offs=0;

        while (charnum > 0 && str[offs]) {
                (void)(isutf(str[++offs]) || isutf(str[++offs]) ||
                                isutf(str[++offs]) || ++offs);
                charnum--;
        }
        return offs;
}

/* byte offset => charnum */
SWITCH_DECLARE(int) switch_u8_charnum(char *s, int offset)
{
        int charnum = 0, offs=0;

        while (offs < offset && s[offs]) {
                (void)(isutf(s[++offs]) || isutf(s[++offs]) ||
                                isutf(s[++offs]) || ++offs);
                charnum++;
        }
        return charnum;
}

/* number of characters */
SWITCH_DECLARE(int) switch_u8_strlen(char *s)
{
        int count = 0;
        int i = 0;

        while (switch_u8_nextchar(s, &i) != 0)
                count++;

        return count;
}

/* reads the next utf-8 sequence out of a string, updating an index */
SWITCH_DECLARE(uint32_t) switch_u8_nextchar(char *s, int *i)
{
        uint32_t ch = 0;
        int sz = 0;

        do {
                ch <<= 6;
                ch += (unsigned char)s[(*i)++];
                sz++;
        } while (s[*i] && !isutf(s[*i]));
        ch -= offsetsFromUTF8[sz-1];

        return ch;
}

SWITCH_DECLARE(void) switch_u8_inc(char *s, int *i)
{
        (void)(isutf(s[++(*i)]) || isutf(s[++(*i)]) ||
                        isutf(s[++(*i)]) || ++(*i));
}

SWITCH_DECLARE(void) switch_u8_dec(char *s, int *i)
{
        (void)(isutf(s[--(*i)]) || isutf(s[--(*i)]) ||
                        isutf(s[--(*i)]) || --(*i));
}

SWITCH_DECLARE(int) octal_digit(char c)
{
        return (c >= '0' && c <= '7');
}

SWITCH_DECLARE(int) hex_digit(char c)
{
        return ((c >= '0' && c <= '9') ||
                        (c >= 'A' && c <= 'F') ||
                        (c >= 'a' && c <= 'f'));
}

/* assumes that src points to the character after a backslash
   returns number of input characters processed */
SWITCH_DECLARE(int) switch_u8_read_escape_sequence(char *str, uint32_t *dest)
{
        uint32_t ch;
        char digs[9]="\0\0\0\0\0\0\0\0";
        int dno=0, i=1;

        ch = (uint32_t)str[0];    /* take literal character */
        if (str[0] == 'n')
                ch = L'\n';
        else if (str[0] == 't')
                ch = L'\t';
        else if (str[0] == 'r')
                ch = L'\r';
        else if (str[0] == 'b')
                ch = L'\b';
        else if (str[0] == 'f')
                ch = L'\f';
        else if (str[0] == 'v')
                ch = L'\v';
        else if (str[0] == 'a')
                ch = L'\a';
        else if (octal_digit(str[0])) {
                i = 0;
                do {
                        digs[dno++] = str[i++];
                } while (octal_digit(str[i]) && dno < 3);
                ch = strtol(digs, NULL, 8);
        }
        else if (str[0] == 'x') {
                while (hex_digit(str[i]) && dno < 2) {
                        digs[dno++] = str[i++];
                }
                if (dno > 0)
                        ch = strtol(digs, NULL, 16);
        }
        else if (str[0] == 'u') {
                while (hex_digit(str[i]) && dno < 4) {
                        digs[dno++] = str[i++];
                }
                if (dno > 0)
                        ch = strtol(digs, NULL, 16);
        }
        else if (str[0] == 'U') {
                while (hex_digit(str[i]) && dno < 8) {
                        digs[dno++] = str[i++];
                }
                if (dno > 0)
                        ch = strtol(digs, NULL, 16);
        }
        *dest = ch;

        return i;
}

/* convert a string with literal \uxxxx or \Uxxxxxxxx characters to UTF-8
example: u8_unescape(mybuf, 256, "hello\\u220e")
note the double backslash is needed if called on a C string literal */
SWITCH_DECLARE(int) switch_u8_unescape(char *buf, int sz, char *src)
{
        int c=0, amt;
        uint32_t ch;
        char temp[4];

        while (*src && c < sz) {
                if (*src == '\\') {
                        src++;
                        amt = switch_u8_read_escape_sequence(src, &ch);
                }
                else {
                        ch = (uint32_t)*src;
                        amt = 1;
                }
                src += amt;
                amt = switch_u8_wc_toutf8(temp, ch);
                if (amt > sz-c)
                        break;
                memcpy(&buf[c], temp, amt);
                c += amt;
        }
        if (c < sz)
                buf[c] = '\0';
        return c;
}

SWITCH_DECLARE(int) switch_u8_escape_wchar(char *buf, int sz, uint32_t ch)
{
        if (ch == L'\n')
                return snprintf(buf, sz, "\\n");
        else if (ch == L'\t')
                return snprintf(buf, sz, "\\t");
        else if (ch == L'\r')
                return snprintf(buf, sz, "\\r");
        else if (ch == L'\b')
                return snprintf(buf, sz, "\\b");
        else if (ch == L'\f')
                return snprintf(buf, sz, "\\f");
        else if (ch == L'\v')
                return snprintf(buf, sz, "\\v");
        else if (ch == L'\a')
                return snprintf(buf, sz, "\\a");
        else if (ch == L'\\')
                return snprintf(buf, sz, "\\\\");
        else if (ch < 32 || ch == 0x7f)
                return snprintf(buf, sz, "\\x%hhX", (unsigned char)ch);
        else if (ch > 0xFFFF)
                return snprintf(buf, sz, "\\U%.8X", (uint32_t)ch);
        else if (ch >= 0x80 && ch <= 0xFFFF)
                return snprintf(buf, sz, "\\u%.4hX", (unsigned short)ch);

        return snprintf(buf, sz, "%c", (char)ch);
}

SWITCH_DECLARE(int) switch_u8_escape(char *buf, int sz, char *src, int escape_quotes)
{
        int c=0, i=0, amt;

        while (src[i] && c < sz) {
                if (escape_quotes && src[i] == '"') {
                        amt = snprintf(buf, sz - c, "\\\"");
                        i++;
                }
                else {
                        amt = switch_u8_escape_wchar(buf, sz - c, switch_u8_nextchar(src, &i));
                }
                c += amt;
                buf += amt;
        }
        if (c < sz)
                *buf = '\0';
        return c;
}

SWITCH_DECLARE(char *) switch_u8_strchr(char *s, uint32_t ch, int *charn)
{
        int i = 0, lasti=0;
        uint32_t c;

        *charn = 0;
        while (s[i]) {
                c = switch_u8_nextchar(s, &i);
                if (c == ch) {
                        return &s[lasti];
                }
                lasti = i;
                (*charn)++;
        }
        return NULL;
}

SWITCH_DECLARE(char *) switch_u8_memchr(char *s, uint32_t ch, size_t sz, int *charn)
{
        int i = 0, lasti=0;
        uint32_t c;
        int csz;

        *charn = 0;
        while (i < sz) {
                c = csz = 0;
                do {
                        c <<= 6;
                        c += (unsigned char)s[i++];
                        csz++;
                } while (i < sz && !isutf(s[i]));
                c -= offsetsFromUTF8[csz-1];

                if (c == ch) {
                        return &s[lasti];
                }
                lasti = i;
                (*charn)++;
        }
        return NULL;
}

SWITCH_DECLARE(int) switch_u8_is_locale_utf8(char *locale)
{
        /* this code based on libutf8 */
        const char* cp = locale;

        for (; *cp != '\0' && *cp != '@' && *cp != '+' && *cp != ','; cp++) {
                if (*cp == '.') {
                        const char* encoding = ++cp;
                        for (; *cp != '\0' && *cp != '@' && *cp != '+' && *cp != ','; cp++)
                                ;
                        if ((cp-encoding == 5 && !strncmp(encoding, "UTF-8", 5))
                                        || (cp-encoding == 4 && !strncmp(encoding, "utf8", 4)))
                                return 1; /* it's UTF-8 */
                        break;
                }
        }
        return 0;
}



/* reads the next utf-8 sequence out of a string, updating an index */
SWITCH_DECLARE(uint32_t) switch_u8_get_char(char *s, int *i)
{
        uint32_t ch = 0;
        int sz = 0;

        do {
                ch <<= 6;
                ch += (unsigned char)s[(*i)++];
                sz++;
        } while (s[*i] && !isutf(s[*i]));

        ch -= offsetsFromUTF8[sz-1];

        return ch;
}