charset.c

/*
 * Copyright (C) 1984-2022  Mark Nudelman
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information, see the README file.
 */


/*
 * Functions to define the character set
 * and do things specific to the character set.
 */

#include "less.h"
#if HAVE_LOCALE
#include <locale.h>
#include <ctype.h>
#include <langinfo.h>
#endif

#include "charset.h"

#if MSDOS_COMPILER==WIN32C
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif

extern int bs_mode;

public int utf_mode = 0;

/*
 * Predefined character sets,
 * selected by the LESSCHARSET environment variable.
 */
struct charset {
    char *name;
    int *p_flag;
    char *desc;
} charsets[] = {
        { "ascii",              NULL,       "8bcccbcc18b95.b" },
        { "utf-8",              &utf_mode,  "8bcccbcc18b95.b126.bb" },
        { "iso8859",            NULL,       "8bcccbcc18b95.33b." },
        { "latin3",             NULL,       "8bcccbcc18b95.33b5.b8.b15.b4.b12.b18.b12.b." },
        { "arabic",             NULL,       "8bcccbcc18b95.33b.3b.7b2.13b.3b.b26.5b19.b" },
        { "greek",              NULL,       "8bcccbcc18b95.33b4.2b4.b3.b35.b44.b" },
        { "greek2005",          NULL,       "8bcccbcc18b95.33b14.b35.b44.b" },
        { "hebrew",             NULL,       "8bcccbcc18b95.33b.b29.32b28.2b2.b" },
        { "koi8-r",             NULL,       "8bcccbcc18b95.b." },
        { "KOI8-T",             NULL,       "8bcccbcc18b95.b8.b6.b8.b.b.5b7.3b4.b4.b3.b.b.3b." },
        { "georgianps",         NULL,       "8bcccbcc18b95.3b11.4b12.2b." },
        { "tcvn",               NULL,       "b..b...bcccbccbbb7.8b95.b48.5b." },
        { "TIS-620",            NULL,       "8bcccbcc18b95.b.4b.11b7.8b." },
        { "next",               NULL,       "8bcccbcc18b95.bb125.bb" },
        { "dos",                NULL,       "8bcccbcc12bc5b95.b." },
        { "windows-1251",       NULL,       "8bcccbcc12bc5b95.b24.b." },
        { "windows-1252",       NULL,       "8bcccbcc12bc5b95.b.b11.b.2b12.b." },
        { "windows-1255",       NULL,       "8bcccbcc12bc5b95.b.b8.b.5b9.b.4b." },
        { "ebcdic",             NULL,       "5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b." },
        { "IBM-1047",           NULL,       "4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc191.b" },
        { NULL, NULL, NULL }
};

/*
 * Support "locale charmap"/nl_langinfo(CODESET) values, as well as others.
 */
struct cs_alias {
    char *name;
    char *oname;
} cs_aliases[] = {
    { "UTF-8",              "utf-8" },
    { "utf8",               "utf-8" },
    { "UTF8",               "utf-8" },
    { "ANSI_X3.4-1968",     "ascii" },
    { "US-ASCII",           "ascii" },
    { "latin1",             "iso8859" },
    { "ISO-8859-1",         "iso8859" },
    { "latin9",             "iso8859" },
    { "ISO-8859-15",        "iso8859" },
    { "latin2",             "iso8859" },
    { "ISO-8859-2",         "iso8859" },
    { "ISO-8859-3",         "latin3" },
    { "latin4",             "iso8859" },
    { "ISO-8859-4",         "iso8859" },
    { "cyrillic",           "iso8859" },
    { "ISO-8859-5",         "iso8859" },
    { "ISO-8859-6",         "arabic" },
    { "ISO-8859-7",         "greek" },
    { "IBM9005",            "greek2005" },
    { "ISO-8859-8",         "hebrew" },
    { "latin5",             "iso8859" },
    { "ISO-8859-9",         "iso8859" },
    { "latin6",             "iso8859" },
    { "ISO-8859-10",        "iso8859" },
    { "latin7",             "iso8859" },
    { "ISO-8859-13",        "iso8859" },
    { "latin8",             "iso8859" },
    { "ISO-8859-14",        "iso8859" },
    { "latin10",            "iso8859" },
    { "ISO-8859-16",        "iso8859" },
    { "IBM437",             "dos" },
    { "EBCDIC-US",          "ebcdic" },
    { "IBM1047",            "IBM-1047" },
    { "KOI8-R",             "koi8-r" },
    { "KOI8-U",             "koi8-r" },
    { "GEORGIAN-PS",        "georgianps" },
    { "TCVN5712-1",         "tcvn" },
    { "NEXTSTEP",           "next" },
    { "windows",            "windows-1252" }, /* backward compatibility */
    { "CP1251",             "windows-1251" },
    { "CP1252",             "windows-1252" },
    { "CP1255",             "windows-1255" },
    { NULL, NULL }
};

#define IS_BINARY_CHAR  01
#define IS_CONTROL_CHAR 02

static char chardef[256];
static char *binfmt = NULL;
static char *utfbinfmt = NULL;
public int binattr = AT_STANDOUT|AT_COLOR_BIN;


/*
 * Define a charset, given a description string.
 * The string consists of 256 letters,
 * one for each character in the charset.
 * If the string is shorter than 256 letters, missing letters
 * are taken to be identical to the last one.
 * A decimal number followed by a letter is taken to be a
 * repetition of the letter.
 *
 * Each letter is one of:
 *      . normal character
 *      b binary character
 *      c control character
 */
    static void
ichardef(s)
    char *s;
{
    char *cp;
    int n;
    char v;

    n = 0;
    v = 0;
    cp = chardef;
    while (*s != '\0')
    {
        switch (*s++)
        {
        case '.':
            v = 0;
            break;
        case 'c':
            v = IS_CONTROL_CHAR;
            break;
        case 'b':
            v = IS_BINARY_CHAR|IS_CONTROL_CHAR;
            break;

        case '0': case '1': case '2': case '3': case '4':
        case '5': case '6': case '7': case '8': case '9':
            n = (10 * n) + (s[-1] - '0');
            continue;

        default:
            error("invalid chardef", NULL_PARG);
            quit(QUIT_ERROR);
            /*NOTREACHED*/
        }

        do
        {
            if (cp >= chardef + sizeof(chardef))
            {
                error("chardef longer than 256", NULL_PARG);
                quit(QUIT_ERROR);
                /*NOTREACHED*/
            }
            *cp++ = v;
        } while (--n > 0);
        n = 0;
    }

    while (cp < chardef + sizeof(chardef))
        *cp++ = v;
}

/*
 * Define a charset, given a charset name.
 * The valid charset names are listed in the "charsets" array.
 */
    static int
icharset(name, no_error)
    char *name;
    int no_error;
{
    struct charset *p;
    struct cs_alias *a;

    if (name == NULL || *name == '\0')
        return (0);

    /* First see if the name is an alias. */
    for (a = cs_aliases;  a->name != NULL;  a++)
    {
        if (strcmp(name, a->name) == 0)
        {
            name = a->oname;
            break;
        }
    }

    for (p = charsets;  p->name != NULL;  p++)
    {
        if (strcmp(name, p->name) == 0)
        {
            ichardef(p->desc);
            if (p->p_flag != NULL)
            {
#if MSDOS_COMPILER==WIN32C
                *(p->p_flag) = 1 + (GetConsoleOutputCP() != CP_UTF8);
#else
                *(p->p_flag) = 1;
#endif
            }
            return (1);
        }
    }

    if (!no_error) {
        error("invalid charset name", NULL_PARG);
        quit(QUIT_ERROR);
    }
    return (0);
}

#if HAVE_LOCALE
/*
 * Define a charset, given a locale name.
 */
    static void
ilocale(VOID_PARAM)
{
    int c;

    for (c = 0;  c < (int) sizeof(chardef);  c++)
    {
        if (isprint(c))
            chardef[c] = 0;
        else if (iscntrl(c))
            chardef[c] = IS_CONTROL_CHAR;
        else
            chardef[c] = IS_BINARY_CHAR|IS_CONTROL_CHAR;
    }
}
#endif

/*
 * Define the printing format for control (or binary utf) chars.
 */
    public void
setfmt(s, fmtvarptr, attrptr, default_fmt)
    char *s;
    char **fmtvarptr;
    int *attrptr;
    char *default_fmt;
{
    if (s && utf_mode)
    {
        /* It would be too hard to account for width otherwise.  */
        char constant *t = s;
        while (*t)
        {
            if (*t < ' ' || *t > '~')
            {
                s = default_fmt;
                goto attr;
            }
            t++;
        }
    }

    /* %n is evil */
    if (s == NULL || *s == '\0' ||
        (*s == '*' && (s[1] == '\0' || s[2] == '\0' || strchr(s + 2, 'n'))) ||
        (*s != '*' && strchr(s, 'n')))
        s = default_fmt;

    /*
     * Select the attributes if it starts with "*".
     */
 attr:
    if (*s == '*' && s[1] != '\0')
    {
        switch (s[1])
        {
        case 'd':  *attrptr = AT_BOLD;      break;
        case 'k':  *attrptr = AT_BLINK;     break;
        case 's':  *attrptr = AT_STANDOUT;  break;
        case 'u':  *attrptr = AT_UNDERLINE; break;
        default:   *attrptr = AT_NORMAL;    break;
        }
        s += 2;
    }
    *fmtvarptr = s;
}

/*
 *
 */
    static void
set_charset(VOID_PARAM)
{
    char *s;

#if MSDOS_COMPILER==WIN32C
    /*
     * If the Windows console is using UTF-8, we'll use it too.
     */
    if (GetConsoleOutputCP() == CP_UTF8)
        if (icharset("utf-8", 1))
            return;
#endif
    /*
     * See if environment variable LESSCHARSET is defined.
     */
    s = lgetenv("LESSCHARSET");
    if (icharset(s, 0))
        return;

    /*
     * LESSCHARSET is not defined: try LESSCHARDEF.
     */
    s = lgetenv("LESSCHARDEF");
    if (!isnullenv(s))
    {
        ichardef(s);
        return;
    }

#if HAVE_LOCALE
#ifdef CODESET
    /*
     * Try using the codeset name as the charset name.
     */
    s = nl_langinfo(CODESET);
    if (icharset(s, 1))
        return;
#endif
#endif

#if HAVE_STRSTR
    /*
     * Check whether LC_ALL, LC_CTYPE or LANG look like UTF-8 is used.
     */
    if ((s = lgetenv("LC_ALL")) != NULL ||
        (s = lgetenv("LC_CTYPE")) != NULL ||
        (s = lgetenv("LANG")) != NULL)
    {
        if (   strstr(s, "UTF-8") != NULL || strstr(s, "utf-8") != NULL
            || strstr(s, "UTF8")  != NULL || strstr(s, "utf8")  != NULL)
            if (icharset("utf-8", 1))
                return;
    }
#endif

#if HAVE_LOCALE
    /*
     * Get character definitions from locale functions,
     * rather than from predefined charset entry.
     */
    ilocale();
#else
#if MSDOS_COMPILER
    /*
     * Default to "dos".
     */
    (void) icharset("dos", 1);
#else
    /*
     * Default to "latin1".
     */
    (void) icharset("latin1", 1);
#endif
#endif
}

/*
 * Initialize charset data structures.
 */
    public void
init_charset(VOID_PARAM)
{
    char *s;

#if HAVE_LOCALE
    setlocale(LC_ALL, "");
#endif

    set_charset();

    s = lgetenv("LESSBINFMT");
    setfmt(s, &binfmt, &binattr, "*s<%02X>");

    s = lgetenv("LESSUTFBINFMT");
    setfmt(s, &utfbinfmt, &binattr, "<U+%04lX>");
}

/*
 * Is a given character a "binary" character?
 */
    public int
binary_char(c)
    LWCHAR c;
{
    if (utf_mode)
        return (is_ubin_char(c));
    c &= 0377;
    return (chardef[c] & IS_BINARY_CHAR);
}

/*
 * Is a given character a "control" character?
 */
    public int
control_char(c)
    LWCHAR c;
{
    c &= 0377;
    return (chardef[c] & IS_CONTROL_CHAR);
}

/*
 * Return the printable form of a character.
 * For example, in the "ascii" charset '\3' is printed as "^C".
 */
    public char *
prchar(c)
    LWCHAR c;
{
    /* {{ This buffer can be overrun if LESSBINFMT is a long string. }} */
    static char buf[MAX_PRCHAR_LEN+1];

    c &= 0377;
    if ((c < 128 || !utf_mode) && !control_char(c))
        SNPRINTF1(buf, sizeof(buf), "%c", (int) c);
    else if (c == ESC)
        strcpy(buf, "ESC");
#if IS_EBCDIC_HOST
    else if (!binary_char(c) && c < 64)
        SNPRINTF1(buf, sizeof(buf), "^%c",
        /*
         * This array roughly inverts CONTROL() #defined in less.h,
         * and should be kept in sync with CONTROL() and IBM-1047.
         */
        "@ABC.I.?...KLMNO"
        "PQRS.JH.XY.."
        "\\]^_"
        "......W[.....EFG"
        "..V....D....TU.Z"[c]);
#else
    else if (c < 128 && !control_char(c ^ 0100))
        SNPRINTF1(buf, sizeof(buf), "^%c", (int) (c ^ 0100));
#endif
    else
        SNPRINTF1(buf, sizeof(buf), binfmt, c);
    return (buf);
}

/*
 * Return the printable form of a UTF-8 character.
 */
    public char *
prutfchar(ch)
    LWCHAR ch;
{
    static char buf[MAX_PRCHAR_LEN+1];

    if (ch == ESC)
        strcpy(buf, "ESC");
    else if (ch < 128 && control_char(ch))
    {
        if (!control_char(ch ^ 0100))
            SNPRINTF1(buf, sizeof(buf), "^%c", ((char) ch) ^ 0100);
        else
            SNPRINTF1(buf, sizeof(buf), binfmt, (char) ch);
    } else if (is_ubin_char(ch))
    {
        SNPRINTF1(buf, sizeof(buf), utfbinfmt, ch);
    } else
    {
        char *p = buf;
        if (ch >= 0x80000000)
            ch = 0xFFFD; /* REPLACEMENT CHARACTER */
        put_wchar(&p, ch);
        *p = '\0';
    }
    return (buf);
}

/*
 * Get the length of a UTF-8 character in bytes.
 */
    public int
utf_len(ch)
    int ch;
{
    if ((ch & 0x80) == 0)
        return 1;
    if ((ch & 0xE0) == 0xC0)
        return 2;
    if ((ch & 0xF0) == 0xE0)
        return 3;
    if ((ch & 0xF8) == 0xF0)
        return 4;
    if ((ch & 0xFC) == 0xF8)
        return 5;
    if ((ch & 0xFE) == 0xFC)
        return 6;
    /* Invalid UTF-8 encoding. */
    return 1;
}

/*
 * Does the parameter point to the lead byte of a well-formed UTF-8 character?
 */
    public int
is_utf8_well_formed(ss, slen)
    char *ss;
    size_t slen;
{
    size_t i;
    size_t len;
    unsigned char *s = (unsigned char *) ss;

    if (IS_UTF8_INVALID(s[0]))
        return (0);

    len = (size_t)utf_len(s[0]);
    if (len > slen)
        return (0);
    if (len == 1)
        return (1);
    if (len == 2)
    {
        if (s[0] < 0xC2)
            return (0);
    } else
    {
        unsigned char mask;
        mask = (~((1 << (8-len)) - 1)) & 0xFF;
        if (s[0] == mask && (s[1] & mask) == 0x80)
            return (0);
    }

    for (i = 1;  i < len;  i++)
        if (!IS_UTF8_TRAIL(s[i]))
            return (0);
    return (1);
}

/*
 * Skip bytes until a UTF-8 lead byte (11xxxxxx) or ASCII byte (0xxxxxxx) is found.
 */
    public void
utf_skip_to_lead(pp, limit)
    char **pp;
    char *limit;
{
    do {
        ++(*pp);
    } while (*pp < limit && !IS_UTF8_LEAD((*pp)[0] & 0377) && !IS_ASCII_OCTET((*pp)[0]));
}


/*
 * Get the value of a UTF-8 character.
 */
    public LWCHAR
get_wchar(p)
    constant char *p;
{
    switch (utf_len(p[0]))
    {
    case 1:
    default:
        /* 0xxxxxxx */
        return (LWCHAR)
            (p[0] & 0xFF);
    case 2:
        /* 110xxxxx 10xxxxxx */
        return (LWCHAR) (
            ((p[0] & 0x1F) << 6) |
            (p[1] & 0x3F));
    case 3:
        /* 1110xxxx 10xxxxxx 10xxxxxx */
        return (LWCHAR) (
            ((p[0] & 0x0F) << 12) |
            ((p[1] & 0x3F) << 6) |
            (p[2] & 0x3F));
    case 4:
        /* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
        return (LWCHAR) (
            ((p[0] & 0x07) << 18) |
            ((p[1] & 0x3F) << 12) |
            ((p[2] & 0x3F) << 6) |
            (p[3] & 0x3F));
    case 5:
        /* 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx */
        return (LWCHAR) (
            ((p[0] & 0x03) << 24) |
            ((p[1] & 0x3F) << 18) |
            ((p[2] & 0x3F) << 12) |
            ((p[3] & 0x3F) << 6) |
            (p[4] & 0x3F));
    case 6:
        /* 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx */
        return (LWCHAR) (
            ((p[0] & 0x01) << 30) |
            ((p[1] & 0x3F) << 24) |
            ((p[2] & 0x3F) << 18) |
            ((p[3] & 0x3F) << 12) |
            ((p[4] & 0x3F) << 6) |
            (p[5] & 0x3F));
    }
}

/*
 * Store a character into a UTF-8 string.
 */
    public void
put_wchar(pp, ch)
    char **pp;
    LWCHAR ch;
{
    if (!utf_mode || ch < 0x80)
    {
        /* 0xxxxxxx */
        *(*pp)++ = (char) ch;
    } else if (ch < 0x800)
    {
        /* 110xxxxx 10xxxxxx */
        *(*pp)++ = (char) (0xC0 | ((ch >> 6) & 0x1F));
        *(*pp)++ = (char) (0x80 | (ch & 0x3F));
    } else if (ch < 0x10000)
    {
        /* 1110xxxx 10xxxxxx 10xxxxxx */
        *(*pp)++ = (char) (0xE0 | ((ch >> 12) & 0x0F));
        *(*pp)++ = (char) (0x80 | ((ch >> 6) & 0x3F));
        *(*pp)++ = (char) (0x80 | (ch & 0x3F));
    } else if (ch < 0x200000)
    {
        /* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
        *(*pp)++ = (char) (0xF0 | ((ch >> 18) & 0x07));
        *(*pp)++ = (char) (0x80 | ((ch >> 12) & 0x3F));
        *(*pp)++ = (char) (0x80 | ((ch >> 6) & 0x3F));
        *(*pp)++ = (char) (0x80 | (ch & 0x3F));
    } else if (ch < 0x4000000)
    {
        /* 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx */
        *(*pp)++ = (char) (0xF0 | ((ch >> 24) & 0x03));
        *(*pp)++ = (char) (0x80 | ((ch >> 18) & 0x3F));
        *(*pp)++ = (char) (0x80 | ((ch >> 12) & 0x3F));
        *(*pp)++ = (char) (0x80 | ((ch >> 6) & 0x3F));
        *(*pp)++ = (char) (0x80 | (ch & 0x3F));
    } else
    {
        /* 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx */
        *(*pp)++ = (char) (0xF0 | ((ch >> 30) & 0x01));
        *(*pp)++ = (char) (0x80 | ((ch >> 24) & 0x3F));
        *(*pp)++ = (char) (0x80 | ((ch >> 18) & 0x3F));
        *(*pp)++ = (char) (0x80 | ((ch >> 12) & 0x3F));
        *(*pp)++ = (char) (0x80 | ((ch >> 6) & 0x3F));
        *(*pp)++ = (char) (0x80 | (ch & 0x3F));
    }
}

/*
 * Step forward or backward one character in a string.
 */
    public LWCHAR
step_char(pp, dir, limit)
    char **pp;
    signed int dir;
    constant char *limit;
{
    LWCHAR ch;
    int len;
    char *p = *pp;

    if (!utf_mode)
    {
        /* It's easy if chars are one byte. */
        if (dir > 0)
            ch = (LWCHAR) (unsigned char) ((p < limit) ? *p++ : 0);
        else
            ch = (LWCHAR) (unsigned char) ((p > limit) ? *--p : 0);
    } else if (dir > 0)
    {
        len = utf_len(*p);
        if (p + len > limit)
        {
            ch = 0;
            p = (char *) limit;
        } else
        {
            ch = get_wchar(p);
            p += len;
        }
    } else
    {
        while (p > limit && IS_UTF8_TRAIL(p[-1]))
            p--;
        if (p > limit)
            ch = get_wchar(--p);
        else
            ch = 0;
    }
    *pp = p;
    return ch;
}

/*
 * Unicode characters data
 * Actual data is in the generated *.uni files.
 */

#define DECLARE_RANGE_TABLE_START(name) \
    static struct wchar_range name##_array[] = {
#define DECLARE_RANGE_TABLE_END(name) \
    }; struct wchar_range_table name##_table = { name##_array, sizeof(name##_array)/sizeof(*name##_array) };

DECLARE_RANGE_TABLE_START(compose)
#include "compose.uni"
DECLARE_RANGE_TABLE_END(compose)

DECLARE_RANGE_TABLE_START(ubin)
#include "ubin.uni"
DECLARE_RANGE_TABLE_END(ubin)

DECLARE_RANGE_TABLE_START(wide)
#include "wide.uni"
DECLARE_RANGE_TABLE_END(wide)

DECLARE_RANGE_TABLE_START(fmt)
#include "fmt.uni"
DECLARE_RANGE_TABLE_END(fmt)

/* comb_table is special pairs, not ranges. */
static struct wchar_range comb_table[] = {
    {0x0644,0x0622}, {0x0644,0x0623}, {0x0644,0x0625}, {0x0644,0x0627},
};


    static int
is_in_table(ch, table)
    LWCHAR ch;
    struct wchar_range_table *table;
{
    int hi;
    int lo;

    /* Binary search in the table. */
    if (ch < table->table[0].first)
        return 0;
    lo = 0;
    hi = table->count - 1;
    while (lo <= hi)
    {
        int mid = (lo + hi) / 2;
        if (ch > table->table[mid].last)
            lo = mid + 1;
        else if (ch < table->table[mid].first)
            hi = mid - 1;
        else
            return 1;
    }
    return 0;
}

/*
 * Is a character a UTF-8 composing character?
 * If a composing character follows any char, the two combine into one glyph.
 */
    public int
is_composing_char(ch)
    LWCHAR ch;
{
    return is_in_table(ch, &compose_table) ||
           (bs_mode != BS_CONTROL && is_in_table(ch, &fmt_table));
}

/*
 * Should this UTF-8 character be treated as binary?
 */
    public int
is_ubin_char(ch)
    LWCHAR ch;
{
    int ubin = is_in_table(ch, &ubin_table) ||
               (bs_mode == BS_CONTROL && is_in_table(ch, &fmt_table));
#if MSDOS_COMPILER==WIN32C
    if (!ubin && utf_mode == 2 && ch < 0x10000)
    {
        /*
         * Consider it binary if it can't be converted.
         */
        BOOL used_default = TRUE;
        // NOTE: avoid use of WC_NO_BEST_FIT_CHARS as it is incompatible with various code page settings and unavailable earlier that Windows 2000
        WideCharToMultiByte(GetConsoleOutputCP(), 0 /* *not* WC_NO_BEST_FIT_CHARS */, (LPCWSTR) &ch, 1, NULL, 0, NULL, &used_default);
        if (used_default)
            ubin = 1;
    }
#endif
    return ubin;
}

/*
 * Is this a double width UTF-8 character?
 */
    public int
is_wide_char(ch)
    LWCHAR ch;
{
    return is_in_table(ch, &wide_table);
}

/*
 * Is a character a UTF-8 combining character?
 * A combining char acts like an ordinary char, but if it follows
 * a specific char (not any char), the two combine into one glyph.
 */
    public int
is_combining_char(ch1, ch2)
    LWCHAR ch1;
    LWCHAR ch2;
{
    /* The table is small; use linear search. */
    size_t i;
    for (i = 0;  i < sizeof(comb_table)/sizeof(*comb_table);  i++)
    {
        if (ch1 == comb_table[i].first &&
            ch2 == comb_table[i].last)
            return 1;
    }
    return 0;
}