contrib/less/charset.c

   1 /*
   2  * Copyright (C) 1984-2019  Mark Nudelman
   3  *
   4  * You may distribute under the terms of either the GNU General Public
   5  * License or the Less License, as specified in the README file.
   6  *
   7  * For more information, see the README file.
   8  */
   9
  10
  11 /*
  12  * Functions to define the character set
  13  * and do things specific to the character set.
  14  */
  15
  16 #include "less.h"
  17 #if HAVE_LOCALE
  18 #include <locale.h>
  19 #include <ctype.h>
  20 #include <langinfo.h>
  21 #endif
  22
  23 #include "charset.h"
  24
  25 #if MSDOS_COMPILER==WIN32C
  26 #define WIN32_LEAN_AND_MEAN
  27 #include <windows.h>
  28 #endif
  29
  30 extern int bs_mode;
  31
  32 public int utf_mode = 0;
  33
  34 /*
  35  * Predefined character sets,
  36  * selected by the LESSCHARSET environment variable.
  37  */
  38 struct charset {
  39         char *name;
  40         int *p_flag;
  41         char *desc;
  42 } charsets[] = {
  43         { "ascii",              NULL,       "8bcccbcc18b95.b" },
  44         { "utf-8",              &utf_mode,  "8bcccbcc18b95.b126.bb" },
  45         { "iso8859",            NULL,       "8bcccbcc18b95.33b." },
  46         { "latin3",             NULL,       "8bcccbcc18b95.33b5.b8.b15.b4.b12.b18.b12.b." },
  47         { "arabic",             NULL,       "8bcccbcc18b95.33b.3b.7b2.13b.3b.b26.5b19.b" },
  48         { "greek",              NULL,       "8bcccbcc18b95.33b4.2b4.b3.b35.b44.b" },
  49         { "greek2005",          NULL,       "8bcccbcc18b95.33b14.b35.b44.b" },
  50         { "hebrew",             NULL,       "8bcccbcc18b95.33b.b29.32b28.2b2.b" },
  51         { "koi8-r",             NULL,       "8bcccbcc18b95.b." },
  52         { "KOI8-T",             NULL,       "8bcccbcc18b95.b8.b6.b8.b.b.5b7.3b4.b4.b3.b.b.3b." },
  53         { "georgianps",         NULL,       "8bcccbcc18b95.3b11.4b12.2b." },
  54         { "tcvn",               NULL,       "b..b...bcccbccbbb7.8b95.b48.5b." },
  55         { "TIS-620",            NULL,       "8bcccbcc18b95.b.4b.11b7.8b." },
  56         { "next",               NULL,       "8bcccbcc18b95.bb125.bb" },
  57         { "dos",                NULL,       "8bcccbcc12bc5b95.b." },
  58         { "windows-1251",       NULL,       "8bcccbcc12bc5b95.b24.b." },
  59         { "windows-1252",       NULL,       "8bcccbcc12bc5b95.b.b11.b.2b12.b." },
  60         { "windows-1255",       NULL,       "8bcccbcc12bc5b95.b.b8.b.5b9.b.4b." },
  61         { "ebcdic",             NULL,       "5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b." },
  62         { "IBM-1047",           NULL,       "4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc191.b" },
  63         { NULL, NULL, NULL }
  64 };
  65
  66 /*
  67  * Support "locale charmap"/nl_langinfo(CODESET) values, as well as others.
  68  */
  69 struct cs_alias {
  70         char *name;
  71         char *oname;
  72 } cs_aliases[] = {
  73         { "UTF-8",              "utf-8" },
  74         { "utf8",               "utf-8" },
  75         { "UTF8",               "utf-8" },
  76         { "ANSI_X3.4-1968",     "ascii" },
  77         { "US-ASCII",           "ascii" },
  78         { "latin1",             "iso8859" },
  79         { "ISO-8859-1",         "iso8859" },
  80         { "latin9",             "iso8859" },
  81         { "ISO-8859-15",        "iso8859" },
  82         { "latin2",             "iso8859" },
  83         { "ISO-8859-2",         "iso8859" },
  84         { "ISO-8859-3",         "latin3" },
  85         { "latin4",             "iso8859" },
  86         { "ISO-8859-4",         "iso8859" },
  87         { "cyrillic",           "iso8859" },
  88         { "ISO-8859-5",         "iso8859" },
  89         { "ISO-8859-6",         "arabic" },
  90         { "ISO-8859-7",         "greek" },
  91         { "IBM9005",            "greek2005" },
  92         { "ISO-8859-8",         "hebrew" },
  93         { "latin5",             "iso8859" },
  94         { "ISO-8859-9",         "iso8859" },
  95         { "latin6",             "iso8859" },
  96         { "ISO-8859-10",        "iso8859" },
  97         { "latin7",             "iso8859" },
  98         { "ISO-8859-13",        "iso8859" },
  99         { "latin8",             "iso8859" },
 100         { "ISO-8859-14",        "iso8859" },
 101         { "latin10",            "iso8859" },
 102         { "ISO-8859-16",        "iso8859" },
 103         { "IBM437",             "dos" },
 104         { "EBCDIC-US",          "ebcdic" },
 105         { "IBM1047",            "IBM-1047" },
 106         { "KOI8-R",             "koi8-r" },
 107         { "KOI8-U",             "koi8-r" },
 108         { "GEORGIAN-PS",        "georgianps" },
 109         { "TCVN5712-1",         "tcvn" },
 110         { "NEXTSTEP",           "next" },
 111         { "windows",            "windows-1252" }, /* backward compatibility */
 112         { "CP1251",             "windows-1251" },
 113         { "CP1252",             "windows-1252" },
 114         { "CP1255",             "windows-1255" },
 115         { NULL, NULL }
 116 };
 117
 118 #define IS_BINARY_CHAR  01
 119 #define IS_CONTROL_CHAR 02
 120
 121 static char chardef[256];
 122 static char *binfmt = NULL;
 123 static char *utfbinfmt = NULL;
 124 public int binattr = AT_STANDOUT;
 125
 126
 127 /*
 128  * Define a charset, given a description string.
 129  * The string consists of 256 letters,
 130  * one for each character in the charset.
 131  * If the string is shorter than 256 letters, missing letters
 132  * are taken to be identical to the last one.
 133  * A decimal number followed by a letter is taken to be a
 134  * repetition of the letter.
 135  *
 136  * Each letter is one of:
 137  *      . normal character
 138  *      b binary character
 139  *      c control character
 140  */
 141         static void
 142 ichardef(s)
 143         char *s;
 144 {
 145         char *cp;
 146         int n;
 147         char v;
 148
 149         n = 0;
 150         v = 0;
 151         cp = chardef;
 152         while (*s != '\0')
 153         {
 154                 switch (*s++)
 155                 {
 156                 case '.':
 157                         v = 0;
 158                         break;
 159                 case 'c':
 160                         v = IS_CONTROL_CHAR;
 161                         break;
 162                 case 'b':
 163                         v = IS_BINARY_CHAR|IS_CONTROL_CHAR;
 164                         break;
 165
 166                 case '0': case '1': case '2': case '3': case '4':
 167                 case '5': case '6': case '7': case '8': case '9':
 168                         n = (10 * n) + (s[-1] - '0');
 169                         continue;
 170
 171                 default:
 172                         error("invalid chardef", NULL_PARG);
 173                         quit(QUIT_ERROR);
 174                         /*NOTREACHED*/
 175                 }
 176
 177                 do
 178                 {
 179                         if (cp >= chardef + sizeof(chardef))
 180                         {
 181                                 error("chardef longer than 256", NULL_PARG);
 182                                 quit(QUIT_ERROR);
 183                                 /*NOTREACHED*/
 184                         }
 185                         *cp++ = v;
 186                 } while (--n > 0);
 187                 n = 0;
 188         }
 189
 190         while (cp < chardef + sizeof(chardef))
 191                 *cp++ = v;
 192 }
 193
 194 /*
 195  * Define a charset, given a charset name.
 196  * The valid charset names are listed in the "charsets" array.
 197  */
 198         static int
 199 icharset(name, no_error)
 200         char *name;
 201         int no_error;
 202 {
 203         struct charset *p;
 204         struct cs_alias *a;
 205
 206         if (name == NULL || *name == '\0')
 207                 return (0);
 208
 209         /* First see if the name is an alias. */
 210         for (a = cs_aliases;  a->name != NULL;  a++)
 211         {
 212                 if (strcmp(name, a->name) == 0)
 213                 {
 214                         name = a->oname;
 215                         break;
 216                 }
 217         }
 218
 219         for (p = charsets;  p->name != NULL;  p++)
 220         {
 221                 if (strcmp(name, p->name) == 0)
 222                 {
 223                         ichardef(p->desc);
 224                         if (p->p_flag != NULL)
 225                         {
 226 #if MSDOS_COMPILER==WIN32C
 227                                 *(p->p_flag) = 1 + (GetConsoleOutputCP() != CP_UTF8);
 228 #else
 229                                 *(p->p_flag) = 1;
 230 #endif
 231                         }
 232                         return (1);
 233                 }
 234         }
 235
 236         if (!no_error) {
 237                 error("invalid charset name", NULL_PARG);
 238                 quit(QUIT_ERROR);
 239         }
 240         return (0);
 241 }
 242
 243 #if HAVE_LOCALE
 244 /*
 245  * Define a charset, given a locale name.
 246  */
 247         static void
 248 ilocale(VOID_PARAM)
 249 {
 250         int c;
 251
 252         for (c = 0;  c < (int) sizeof(chardef);  c++)
 253         {
 254                 if (isprint(c))
 255                         chardef[c] = 0;
 256                 else if (iscntrl(c))
 257                         chardef[c] = IS_CONTROL_CHAR;
 258                 else
 259                         chardef[c] = IS_BINARY_CHAR|IS_CONTROL_CHAR;
 260         }
 261 }
 262 #endif
 263
 264 /*
 265  * Define the printing format for control (or binary utf) chars.
 266  */
 267         public void
 268 setfmt(s, fmtvarptr, attrptr, default_fmt)
 269         char *s;
 270         char **fmtvarptr;
 271         int *attrptr;
 272         char *default_fmt;
 273 {
 274         if (s && utf_mode)
 275         {
 276                 /* It would be too hard to account for width otherwise.  */
 277                 char constant *t = s;
 278                 while (*t)
 279                 {
 280                         if (*t < ' ' || *t > '~')
 281                         {
 282                                 s = default_fmt;
 283                                 goto attr;
 284                         }
 285                         t++;
 286                 }
 287         }
 288
 289         /* %n is evil */
 290         if (s == NULL || *s == '\0' ||
 291             (*s == '*' && (s[1] == '\0' || s[2] == '\0' || strchr(s + 2, 'n'))) ||
 292             (*s != '*' && strchr(s, 'n')))
 293                 s = default_fmt;
 294
 295         /*
 296          * Select the attributes if it starts with "*".
 297          */
 298  attr:
 299         if (*s == '*' && s[1] != '\0')
 300         {
 301                 switch (s[1])
 302                 {
 303                 case 'd':  *attrptr = AT_BOLD;      break;
 304                 case 'k':  *attrptr = AT_BLINK;     break;
 305                 case 's':  *attrptr = AT_STANDOUT;  break;
 306                 case 'u':  *attrptr = AT_UNDERLINE; break;
 307                 default:   *attrptr = AT_NORMAL;    break;
 308                 }
 309                 s += 2;
 310         }
 311         *fmtvarptr = s;
 312 }
 313
 314 /*
 315  *
 316  */
 317         static void
 318 set_charset(VOID_PARAM)
 319 {
 320         char *s;
 321
 322 #if MSDOS_COMPILER==WIN32C
 323         /*
 324          * If the Windows console is using UTF-8, we'll use it too.
 325          */
 326         if (GetConsoleOutputCP() == CP_UTF8)
 327                 if (icharset("utf-8", 1))
 328                         return;
 329 #endif
 330         /*
 331          * See if environment variable LESSCHARSET is defined.
 332          */
 333         s = lgetenv("LESSCHARSET");
 334         if (icharset(s, 0))
 335                 return;
 336
 337         /*
 338          * LESSCHARSET is not defined: try LESSCHARDEF.
 339          */
 340         s = lgetenv("LESSCHARDEF");
 341         if (!isnullenv(s))
 342         {
 343                 ichardef(s);
 344                 return;
 345         }
 346
 347 #if HAVE_LOCALE
 348 #ifdef CODESET
 349         /*
 350          * Try using the codeset name as the charset name.
 351          */
 352         s = nl_langinfo(CODESET);
 353         if (icharset(s, 1))
 354                 return;
 355 #endif
 356 #endif
 357
 358 #if HAVE_STRSTR
 359         /*
 360          * Check whether LC_ALL, LC_CTYPE or LANG look like UTF-8 is used.
 361          */
 362         if ((s = lgetenv("LC_ALL")) != NULL ||
 363             (s = lgetenv("LC_CTYPE")) != NULL ||
 364             (s = lgetenv("LANG")) != NULL)
 365         {
 366                 if (   strstr(s, "UTF-8") != NULL || strstr(s, "utf-8") != NULL
 367                     || strstr(s, "UTF8")  != NULL || strstr(s, "utf8")  != NULL)
 368                         if (icharset("utf-8", 1))
 369                                 return;
 370         }
 371 #endif
 372
 373 #if HAVE_LOCALE
 374         /*
 375          * Get character definitions from locale functions,
 376          * rather than from predefined charset entry.
 377          */
 378         ilocale();
 379 #else
 380 #if MSDOS_COMPILER
 381         /*
 382          * Default to "dos".
 383          */
 384         (void) icharset("dos", 1);
 385 #else
 386         /*
 387          * Default to "latin1".
 388          */
 389         (void) icharset("latin1", 1);
 390 #endif
 391 #endif
 392 }
 393
 394 /*
 395  * Initialize charset data structures.
 396  */
 397         public void
 398 init_charset(VOID_PARAM)
 399 {
 400         char *s;
 401
 402 #if HAVE_LOCALE
 403         setlocale(LC_ALL, "");
 404 #endif
 405
 406         set_charset();
 407
 408         s = lgetenv("LESSBINFMT");
 409         setfmt(s, &binfmt, &binattr, "*s<%02X>");
 410
 411         s = lgetenv("LESSUTFBINFMT");
 412         setfmt(s, &utfbinfmt, &binattr, "<U+%04lX>");
 413 }
 414
 415 /*
 416  * Is a given character a "binary" character?
 417  */
 418         public int
 419 binary_char(c)
 420         LWCHAR c;
 421 {
 422         if (utf_mode)
 423                 return (is_ubin_char(c));
 424         c &= 0377;
 425         return (chardef[c] & IS_BINARY_CHAR);
 426 }
 427
 428 /*
 429  * Is a given character a "control" character?
 430  */
 431         public int
 432 control_char(c)
 433         LWCHAR c;
 434 {
 435         c &= 0377;
 436         return (chardef[c] & IS_CONTROL_CHAR);
 437 }
 438
 439 /*
 440  * Return the printable form of a character.
 441  * For example, in the "ascii" charset '\3' is printed as "^C".
 442  */
 443         public char *
 444 prchar(c)
 445         LWCHAR c;
 446 {
 447         /* {{ This buffer can be overrun if LESSBINFMT is a long string. }} */
 448         static char buf[32];
 449
 450         c &= 0377;
 451         if ((c < 128 || !utf_mode) && !control_char(c))
 452                 SNPRINTF1(buf, sizeof(buf), "%c", (int) c);
 453         else if (c == ESC)
 454                 strcpy(buf, "ESC");
 455 #if IS_EBCDIC_HOST
 456         else if (!binary_char(c) && c < 64)
 457                 SNPRINTF1(buf, sizeof(buf), "^%c",
 458                 /*
 459                  * This array roughly inverts CONTROL() #defined in less.h,
 460                  * and should be kept in sync with CONTROL() and IBM-1047.
 461                  */
 462                 "@ABC.I.?...KLMNO"
 463                 "PQRS.JH.XY.."
 464                 "\\]^_"
 465                 "......W[.....EFG"
 466                 "..V....D....TU.Z"[c]);
 467 #else
 468         else if (c < 128 && !control_char(c ^ 0100))
 469                 SNPRINTF1(buf, sizeof(buf), "^%c", (int) (c ^ 0100));
 470 #endif
 471         else
 472                 SNPRINTF1(buf, sizeof(buf), binfmt, c);
 473         return (buf);
 474 }
 475
 476 /*
 477  * Return the printable form of a UTF-8 character.
 478  */
 479         public char *
 480 prutfchar(ch)
 481         LWCHAR ch;
 482 {
 483         static char buf[32];
 484
 485         if (ch == ESC)
 486                 strcpy(buf, "ESC");
 487         else if (ch < 128 && control_char(ch))
 488         {
 489                 if (!control_char(ch ^ 0100))
 490                         SNPRINTF1(buf, sizeof(buf), "^%c", ((char) ch) ^ 0100);
 491                 else
 492                         SNPRINTF1(buf, sizeof(buf), binfmt, (char) ch);
 493         } else if (is_ubin_char(ch))
 494         {
 495                 SNPRINTF1(buf, sizeof(buf), utfbinfmt, ch);
 496         } else
 497         {
 498                 char *p = buf;
 499                 if (ch >= 0x80000000)
 500                         ch = 0xFFFD; /* REPLACEMENT CHARACTER */
 501                 put_wchar(&p, ch);
 502                 *p = '\0';
 503         }
 504         return (buf);
 505 }
 506
 507 /*
 508  * Get the length of a UTF-8 character in bytes.
 509  */
 510         public int
 511 utf_len(ch)
 512         unsigned char ch;
 513 {
 514         if ((ch & 0x80) == 0)
 515                 return 1;
 516         if ((ch & 0xE0) == 0xC0)
 517                 return 2;
 518         if ((ch & 0xF0) == 0xE0)
 519                 return 3;
 520         if ((ch & 0xF8) == 0xF0)
 521                 return 4;
 522         if ((ch & 0xFC) == 0xF8)
 523                 return 5;
 524         if ((ch & 0xFE) == 0xFC)
 525                 return 6;
 526         /* Invalid UTF-8 encoding. */
 527         return 1;
 528 }
 529
 530 /*
 531  * Does the parameter point to the lead byte of a well-formed UTF-8 character?
 532  */
 533         public int
 534 is_utf8_well_formed(ss, slen)
 535         char *ss;
 536         int slen;
 537 {
 538         int i;
 539         int len;
 540         unsigned char *s = (unsigned char *) ss;
 541
 542         if (IS_UTF8_INVALID(s[0]))
 543                 return (0);
 544
 545         len = utf_len(s[0]);
 546         if (len > slen)
 547                 return (0);
 548         if (len == 1)
 549                 return (1);
 550         if (len == 2)
 551         {
 552                 if (s[0] < 0xC2)
 553                     return (0);
 554         } else
 555         {
 556                 unsigned char mask;
 557                 mask = (~((1 << (8-len)) - 1)) & 0xFF;
 558                 if (s[0] == mask && (s[1] & mask) == 0x80)
 559                         return (0);
 560         }
 561
 562         for (i = 1;  i < len;  i++)
 563                 if (!IS_UTF8_TRAIL(s[i]))
 564                         return (0);
 565         return (1);
 566 }
 567
 568 /*
 569  * Skip bytes until a UTF-8 lead byte (11xxxxxx) or ASCII byte (0xxxxxxx) is found.
 570  */
 571         public void
 572 utf_skip_to_lead(pp, limit)
 573         char **pp;
 574         char *limit;
 575 {
 576         do {
 577                 ++(*pp);
 578         } while (*pp < limit && !IS_UTF8_LEAD((*pp)[0] & 0377) && !IS_ASCII_OCTET((*pp)[0]));
 579 }
 580
 581
 582 /*
 583  * Get the value of a UTF-8 character.
 584  */
 585         public LWCHAR
 586 get_wchar(p)
 587         constant char *p;
 588 {
 589         switch (utf_len(p[0]))
 590         {
 591         case 1:
 592         default:
 593                 /* 0xxxxxxx */
 594                 return (LWCHAR)
 595                         (p[0] & 0xFF);
 596         case 2:
 597                 /* 110xxxxx 10xxxxxx */
 598                 return (LWCHAR) (
 599                         ((p[0] & 0x1F) << 6) |
 600                         (p[1] & 0x3F));
 601         case 3:
 602                 /* 1110xxxx 10xxxxxx 10xxxxxx */
 603                 return (LWCHAR) (
 604                         ((p[0] & 0x0F) << 12) |
 605                         ((p[1] & 0x3F) << 6) |
 606                         (p[2] & 0x3F));
 607         case 4:
 608                 /* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
 609                 return (LWCHAR) (
 610                         ((p[0] & 0x07) << 18) |
 611                         ((p[1] & 0x3F) << 12) |
 612                         ((p[2] & 0x3F) << 6) |
 613                         (p[3] & 0x3F));
 614         case 5:
 615                 /* 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx */
 616                 return (LWCHAR) (
 617                         ((p[0] & 0x03) << 24) |
 618                         ((p[1] & 0x3F) << 18) |
 619                         ((p[2] & 0x3F) << 12) |
 620                         ((p[3] & 0x3F) << 6) |
 621                         (p[4] & 0x3F));
 622         case 6:
 623                 /* 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx */
 624                 return (LWCHAR) (
 625                         ((p[0] & 0x01) << 30) |
 626                         ((p[1] & 0x3F) << 24) |
 627                         ((p[2] & 0x3F) << 18) |
 628                         ((p[3] & 0x3F) << 12) |
 629                         ((p[4] & 0x3F) << 6) |
 630                         (p[5] & 0x3F));
 631         }
 632 }
 633
 634 /*
 635  * Store a character into a UTF-8 string.
 636  */
 637         public void
 638 put_wchar(pp, ch)
 639         char **pp;
 640         LWCHAR ch;
 641 {
 642         if (!utf_mode || ch < 0x80)
 643         {
 644                 /* 0xxxxxxx */
 645                 *(*pp)++ = (char) ch;
 646         } else if (ch < 0x800)
 647         {
 648                 /* 110xxxxx 10xxxxxx */
 649                 *(*pp)++ = (char) (0xC0 | ((ch >> 6) & 0x1F));
 650                 *(*pp)++ = (char) (0x80 | (ch & 0x3F));
 651         } else if (ch < 0x10000)
 652         {
 653                 /* 1110xxxx 10xxxxxx 10xxxxxx */
 654                 *(*pp)++ = (char) (0xE0 | ((ch >> 12) & 0x0F));
 655                 *(*pp)++ = (char) (0x80 | ((ch >> 6) & 0x3F));
 656                 *(*pp)++ = (char) (0x80 | (ch & 0x3F));
 657         } else if (ch < 0x200000)
 658         {
 659                 /* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
 660                 *(*pp)++ = (char) (0xF0 | ((ch >> 18) & 0x07));
 661                 *(*pp)++ = (char) (0x80 | ((ch >> 12) & 0x3F));
 662                 *(*pp)++ = (char) (0x80 | ((ch >> 6) & 0x3F));
 663                 *(*pp)++ = (char) (0x80 | (ch & 0x3F));
 664         } else if (ch < 0x4000000)
 665         {
 666                 /* 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx */
 667                 *(*pp)++ = (char) (0xF0 | ((ch >> 24) & 0x03));
 668                 *(*pp)++ = (char) (0x80 | ((ch >> 18) & 0x3F));
 669                 *(*pp)++ = (char) (0x80 | ((ch >> 12) & 0x3F));
 670                 *(*pp)++ = (char) (0x80 | ((ch >> 6) & 0x3F));
 671                 *(*pp)++ = (char) (0x80 | (ch & 0x3F));
 672         } else
 673         {
 674                 /* 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx */
 675                 *(*pp)++ = (char) (0xF0 | ((ch >> 30) & 0x01));
 676                 *(*pp)++ = (char) (0x80 | ((ch >> 24) & 0x3F));
 677                 *(*pp)++ = (char) (0x80 | ((ch >> 18) & 0x3F));
 678                 *(*pp)++ = (char) (0x80 | ((ch >> 12) & 0x3F));
 679                 *(*pp)++ = (char) (0x80 | ((ch >> 6) & 0x3F));
 680                 *(*pp)++ = (char) (0x80 | (ch & 0x3F));
 681         }
 682 }
 683
 684 /*
 685  * Step forward or backward one character in a string.
 686  */
 687         public LWCHAR
 688 step_char(pp, dir, limit)
 689         char **pp;
 690         signed int dir;
 691         constant char *limit;
 692 {
 693         LWCHAR ch;
 694         int len;
 695         char *p = *pp;
 696
 697         if (!utf_mode)
 698         {
 699                 /* It's easy if chars are one byte. */
 700                 if (dir > 0)
 701                         ch = (LWCHAR) (unsigned char) ((p < limit) ? *p++ : 0);
 702                 else
 703                         ch = (LWCHAR) (unsigned char) ((p > limit) ? *--p : 0);
 704         } else if (dir > 0)
 705         {
 706                 len = utf_len(*p);
 707                 if (p + len > limit)
 708                 {
 709                         ch = 0;
 710                         p = (char *) limit;
 711                 } else
 712                 {
 713                         ch = get_wchar(p);
 714                         p += len;
 715                 }
 716         } else
 717         {
 718                 while (p > limit && IS_UTF8_TRAIL(p[-1]))
 719                         p--;
 720                 if (p > limit)
 721                         ch = get_wchar(--p);
 722                 else
 723                         ch = 0;
 724         }
 725         *pp = p;
 726         return ch;
 727 }
 728
 729 /*
 730  * Unicode characters data
 731  * Actual data is in the generated *.uni files.
 732  */
 733
 734 #define DECLARE_RANGE_TABLE_START(name) \
 735     static struct wchar_range name##_array[] = {
 736 #define DECLARE_RANGE_TABLE_END(name) \
 737     }; struct wchar_range_table name##_table = { name##_array, sizeof(name##_array)/sizeof(*name##_array) };
 738
 739 DECLARE_RANGE_TABLE_START(compose)
 740 #include "compose.uni"
 741 DECLARE_RANGE_TABLE_END(compose)
 742
 743 DECLARE_RANGE_TABLE_START(ubin)
 744 #include "ubin.uni"
 745 DECLARE_RANGE_TABLE_END(ubin)
 746
 747 DECLARE_RANGE_TABLE_START(wide)
 748 #include "wide.uni"
 749 DECLARE_RANGE_TABLE_END(wide)
 750
 751 DECLARE_RANGE_TABLE_START(fmt)
 752 #include "fmt.uni"
 753 DECLARE_RANGE_TABLE_END(fmt)
 754
 755 /* comb_table is special pairs, not ranges. */
 756 static struct wchar_range comb_table[] = {
 757         {0x0644,0x0622}, {0x0644,0x0623}, {0x0644,0x0625}, {0x0644,0x0627},
 758 };
 759
 760
 761         static int
 762 is_in_table(ch, table)
 763         LWCHAR ch;
 764         struct wchar_range_table *table;
 765 {
 766         int hi;
 767         int lo;
 768
 769         /* Binary search in the table. */
 770         if (ch < table->table[0].first)
 771                 return 0;
 772         lo = 0;
 773         hi = table->count - 1;
 774         while (lo <= hi)
 775         {
 776                 int mid = (lo + hi) / 2;
 777                 if (ch > table->table[mid].last)
 778                         lo = mid + 1;
 779                 else if (ch < table->table[mid].first)
 780                         hi = mid - 1;
 781                 else
 782                         return 1;
 783         }
 784         return 0;
 785 }
 786
 787 /*
 788  * Is a character a UTF-8 composing character?
 789  * If a composing character follows any char, the two combine into one glyph.
 790  */
 791         public int
 792 is_composing_char(ch)
 793         LWCHAR ch;
 794 {
 795         return is_in_table(ch, &compose_table) ||
 796                (bs_mode != BS_CONTROL && is_in_table(ch, &fmt_table));
 797 }
 798
 799 /*
 800  * Should this UTF-8 character be treated as binary?
 801  */
 802         public int
 803 is_ubin_char(ch)
 804         LWCHAR ch;
 805 {
 806         int ubin = is_in_table(ch, &ubin_table) ||
 807                    (bs_mode == BS_CONTROL && is_in_table(ch, &fmt_table));
 808 #if MSDOS_COMPILER==WIN32C
 809         if (!ubin && utf_mode == 2 && ch < 0x10000)
 810         {
 811                 /*
 812                  * Consider it binary if it can't be converted.
 813                  */
 814                 BOOL used_default = TRUE;
 815                 WideCharToMultiByte(GetConsoleOutputCP(), WC_NO_BEST_FIT_CHARS, (LPCWSTR) &ch, 1, NULL, 0, NULL, &used_default);
 816                 if (used_default)
 817                         ubin = 1;
 818         }
 819 #endif
 820         return ubin;
 821 }
 822
 823 /*
 824  * Is this a double width UTF-8 character?
 825  */
 826         public int
 827 is_wide_char(ch)
 828         LWCHAR ch;
 829 {
 830         return is_in_table(ch, &wide_table);
 831 }
 832
 833 /*
 834  * Is a character a UTF-8 combining character?
 835  * A combining char acts like an ordinary char, but if it follows
 836  * a specific char (not any char), the two combine into one glyph.
 837  */
 838         public int
 839 is_combining_char(ch1, ch2)
 840         LWCHAR ch1;
 841         LWCHAR ch2;
 842 {
 843         /* The table is small; use linear search. */
 844         int i;
 845         for (i = 0;  i < sizeof(comb_table)/sizeof(*comb_table);  i++)
 846         {
 847                 if (ch1 == comb_table[i].first &&
 848                     ch2 == comb_table[i].last)
 849                         return 1;
 850         }
 851         return 0;
 852 }
 853