lib/libcr/stdio/vfscanf.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#)vfscanf.c        8.1 (Berkeley) 6/4/93
  37  * $FreeBSD: src/lib/libc/stdio/vfscanf.c,v 1.14.2.2 2002/04/17 14:58:23 ache Exp $
  38  * $DragonFly: src/lib/libcr/stdio/Attic/vfscanf.c,v 1.2 2003/06/17 04:26:46 dillon Exp $
  39  */
  40
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <ctype.h>
  44 #if __STDC__
  45 #include <stdarg.h>
  46 #else
  47 #include <varargs.h>
  48 #endif
  49 #include <string.h>
  50
  51 #include "collate.h"
  52 #include "local.h"
  53
  54 #define FLOATING_POINT
  55
  56 #ifdef FLOATING_POINT
  57 #include <locale.h>
  58 #include "floatio.h"
  59 #endif
  60
  61 #define BUF             513     /* Maximum length of numeric string. */
  62
  63 /*
  64  * Flags used during conversion.
  65  */
  66 #define LONG            0x01    /* l: long or double */
  67 #define LONGDBL         0x02    /* L: long double */
  68 #define SHORT           0x04    /* h: short */
  69 #define SUPPRESS        0x08    /* suppress assignment */
  70 #define POINTER         0x10    /* weird %p pointer (`fake hex') */
  71 #define NOSKIP          0x20    /* do not skip blanks */
  72 #define QUAD            0x400
  73
  74 /*
  75  * The following are used in numeric conversions only:
  76  * SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
  77  * SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
  78  */
  79 #define SIGNOK          0x40    /* +/- is (still) legal */
  80 #define NDIGITS         0x80    /* no digits detected */
  81
  82 #define DPTOK           0x100   /* (float) decimal point is still legal */
  83 #define EXPOK           0x200   /* (float) exponent (e+3, etc) still legal */
  84
  85 #define PFXOK           0x100   /* 0x prefix is (still) legal */
  86 #define NZDIGITS        0x200   /* no zero digits detected */
  87
  88 /*
  89  * Conversion types.
  90  */
  91 #define CT_CHAR         0       /* %c conversion */
  92 #define CT_CCL          1       /* %[...] conversion */
  93 #define CT_STRING       2       /* %s conversion */
  94 #define CT_INT          3       /* integer, i.e., strtoq or strtouq */
  95 #define CT_FLOAT        4       /* floating, i.e., strtod */
  96
  97 #define u_char unsigned char
  98 #define u_long unsigned long
  99
 100 static u_char *__sccl(char *, u_char *);
 101
 102 /*
 103  * vfscanf
 104  */
 105 int
 106 __svfscanf(FILE *fp, char const *fmt0, va_list ap)
 107 {
 108         u_char *fmt = (u_char *)fmt0;
 109         int c;                  /* character from format, or conversion */
 110         size_t width;           /* field width, or 0 */
 111         char *p;                /* points into all kinds of strings */
 112         int n;                  /* handy integer */
 113         int flags;              /* flags as defined above */
 114         char *p0;               /* saves original value of p when necessary */
 115         int nassigned;          /* number of fields assigned */
 116         int nconversions;       /* number of conversions */
 117         int nread;              /* number of characters consumed from fp */
 118         int base;               /* base argument to strtoq/strtouq */
 119         u_quad_t(*ccfn)();      /* conversion function (strtoq/strtouq) */
 120         char ccltab[256];       /* character class table for %[...] */
 121         char buf[BUF];          /* buffer for numeric conversions */
 122
 123         /* `basefix' is used to avoid `if' tests in the integer scanner */
 124         static short basefix[17] =
 125                 { 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
 126 #ifdef FLOATING_POINT
 127         char decimal_point = localeconv()->decimal_point[0];
 128 #endif
 129
 130         nassigned = 0;
 131         nconversions = 0;
 132         nread = 0;
 133         base = 0;               /* XXX just to keep gcc happy */
 134         ccfn = NULL;            /* XXX just to keep gcc happy */
 135         for (;;) {
 136                 c = *fmt++;
 137                 if (c == 0)
 138                         return (nassigned);
 139                 if (isspace(c)) {
 140                         while ((fp->_r > 0 || __srefill(fp) == 0) && isspace(*fp->_p))
 141                                 nread++, fp->_r--, fp->_p++;
 142                         continue;
 143                 }
 144                 if (c != '%')
 145                         goto literal;
 146                 width = 0;
 147                 flags = 0;
 148                 /*
 149                  * switch on the format.  continue if done;
 150                  * break once format type is derived.
 151                  */
 152 again:          c = *fmt++;
 153                 switch (c) {
 154                 case '%':
 155 literal:
 156                         if (fp->_r <= 0 && __srefill(fp))
 157                                 goto input_failure;
 158                         if (*fp->_p != c)
 159                                 goto match_failure;
 160                         fp->_r--, fp->_p++;
 161                         nread++;
 162                         continue;
 163
 164                 case '*':
 165                         flags |= SUPPRESS;
 166                         goto again;
 167                 case 'l':
 168                         flags |= LONG;
 169                         goto again;
 170                 case 'q':
 171                         flags |= QUAD;
 172                         goto again;
 173                 case 'L':
 174                         flags |= LONGDBL;
 175                         goto again;
 176                 case 'h':
 177                         flags |= SHORT;
 178                         goto again;
 179
 180                 case '0': case '1': case '2': case '3': case '4':
 181                 case '5': case '6': case '7': case '8': case '9':
 182                         width = width * 10 + c - '0';
 183                         goto again;
 184
 185                 /*
 186                  * Conversions.
 187                  * Those marked `compat' are for 4.[123]BSD compatibility.
 188                  *
 189                  * (According to ANSI, E and X formats are supposed
 190                  * to the same as e and x.  Sorry about that.)
 191                  */
 192                 case 'D':       /* compat */
 193                         flags |= LONG;
 194                         /* FALLTHROUGH */
 195                 case 'd':
 196                         c = CT_INT;
 197                         ccfn = (u_quad_t (*)())strtoq;
 198                         base = 10;
 199                         break;
 200
 201                 case 'i':
 202                         c = CT_INT;
 203                         ccfn = (u_quad_t (*)())strtoq;
 204                         base = 0;
 205                         break;
 206
 207                 case 'O':       /* compat */
 208                         flags |= LONG;
 209                         /* FALLTHROUGH */
 210                 case 'o':
 211                         c = CT_INT;
 212                         ccfn = strtouq;
 213                         base = 8;
 214                         break;
 215
 216                 case 'u':
 217                         c = CT_INT;
 218                         ccfn = strtouq;
 219                         base = 10;
 220                         break;
 221
 222                 case 'X':       /* compat   XXX */
 223                         flags |= LONG;
 224                         /* FALLTHROUGH */
 225                 case 'x':
 226                         flags |= PFXOK; /* enable 0x prefixing */
 227                         c = CT_INT;
 228                         ccfn = strtouq;
 229                         base = 16;
 230                         break;
 231
 232 #ifdef FLOATING_POINT
 233                 case 'E':       /* compat   XXX */
 234                 case 'F':       /* compat */
 235                         flags |= LONG;
 236                         /* FALLTHROUGH */
 237                 case 'e': case 'f': case 'g':
 238                         c = CT_FLOAT;
 239                         break;
 240 #endif
 241
 242                 case 's':
 243                         c = CT_STRING;
 244                         break;
 245
 246                 case '[':
 247                         fmt = __sccl(ccltab, fmt);
 248                         flags |= NOSKIP;
 249                         c = CT_CCL;
 250                         break;
 251
 252                 case 'c':
 253                         flags |= NOSKIP;
 254                         c = CT_CHAR;
 255                         break;
 256
 257                 case 'p':       /* pointer format is like hex */
 258                         flags |= POINTER | PFXOK;
 259                         c = CT_INT;
 260                         ccfn = strtouq;
 261                         base = 16;
 262                         break;
 263
 264                 case 'n':
 265                         nconversions++;
 266                         if (flags & SUPPRESS)   /* ??? */
 267                                 continue;
 268                         if (flags & SHORT)
 269                                 *va_arg(ap, short *) = nread;
 270                         else if (flags & LONG)
 271                                 *va_arg(ap, long *) = nread;
 272                         else if (flags & QUAD)
 273                                 *va_arg(ap, quad_t *) = nread;
 274                         else
 275                                 *va_arg(ap, int *) = nread;
 276                         continue;
 277
 278                 /*
 279                  * Disgusting backwards compatibility hacks.    XXX
 280                  */
 281                 case '\0':      /* compat */
 282                         return (EOF);
 283
 284                 default:        /* compat */
 285                         if (isupper(c))
 286                                 flags |= LONG;
 287                         c = CT_INT;
 288                         ccfn = (u_quad_t (*)())strtoq;
 289                         base = 10;
 290                         break;
 291                 }
 292
 293                 /*
 294                  * We have a conversion that requires input.
 295                  */
 296                 if (fp->_r <= 0 && __srefill(fp))
 297                         goto input_failure;
 298
 299                 /*
 300                  * Consume leading white space, except for formats
 301                  * that suppress this.
 302                  */
 303                 if ((flags & NOSKIP) == 0) {
 304                         while (isspace(*fp->_p)) {
 305                                 nread++;
 306                                 if (--fp->_r > 0)
 307                                         fp->_p++;
 308                                 else if (__srefill(fp))
 309                                         goto input_failure;
 310                         }
 311                         /*
 312                          * Note that there is at least one character in
 313                          * the buffer, so conversions that do not set NOSKIP
 314                          * ca no longer result in an input failure.
 315                          */
 316                 }
 317
 318                 /*
 319                  * Do the conversion.
 320                  */
 321                 switch (c) {
 322
 323                 case CT_CHAR:
 324                         /* scan arbitrary characters (sets NOSKIP) */
 325                         if (width == 0)
 326                                 width = 1;
 327                         if (flags & SUPPRESS) {
 328                                 size_t sum = 0;
 329                                 for (;;) {
 330                                         if ((n = fp->_r) < width) {
 331                                                 sum += n;
 332                                                 width -= n;
 333                                                 fp->_p += n;
 334                                                 if (__srefill(fp)) {
 335                                                         if (sum == 0)
 336                                                             goto input_failure;
 337                                                         break;
 338                                                 }
 339                                         } else {
 340                                                 sum += width;
 341                                                 fp->_r -= width;
 342                                                 fp->_p += width;
 343                                                 break;
 344                                         }
 345                                 }
 346                                 nread += sum;
 347                         } else {
 348                                 size_t r = fread((void *)va_arg(ap, char *), 1,
 349                                     width, fp);
 350
 351                                 if (r == 0)
 352                                         goto input_failure;
 353                                 nread += r;
 354                                 nassigned++;
 355                         }
 356                         nconversions++;
 357                         break;
 358
 359                 case CT_CCL:
 360                         /* scan a (nonempty) character class (sets NOSKIP) */
 361                         if (width == 0)
 362                                 width = (size_t)~0;     /* `infinity' */
 363                         /* take only those things in the class */
 364                         if (flags & SUPPRESS) {
 365                                 n = 0;
 366                                 while (ccltab[*fp->_p]) {
 367                                         n++, fp->_r--, fp->_p++;
 368                                         if (--width == 0)
 369                                                 break;
 370                                         if (fp->_r <= 0 && __srefill(fp)) {
 371                                                 if (n == 0)
 372                                                         goto input_failure;
 373                                                 break;
 374                                         }
 375                                 }
 376                                 if (n == 0)
 377                                         goto match_failure;
 378                         } else {
 379                                 p0 = p = va_arg(ap, char *);
 380                                 while (ccltab[*fp->_p]) {
 381                                         fp->_r--;
 382                                         *p++ = *fp->_p++;
 383                                         if (--width == 0)
 384                                                 break;
 385                                         if (fp->_r <= 0 && __srefill(fp)) {
 386                                                 if (p == p0)
 387                                                         goto input_failure;
 388                                                 break;
 389                                         }
 390                                 }
 391                                 n = p - p0;
 392                                 if (n == 0)
 393                                         goto match_failure;
 394                                 *p = 0;
 395                                 nassigned++;
 396                         }
 397                         nread += n;
 398                         nconversions++;
 399                         break;
 400
 401                 case CT_STRING:
 402                         /* like CCL, but zero-length string OK, & no NOSKIP */
 403                         if (width == 0)
 404                                 width = (size_t)~0;
 405                         if (flags & SUPPRESS) {
 406                                 n = 0;
 407                                 while (!isspace(*fp->_p)) {
 408                                         n++, fp->_r--, fp->_p++;
 409                                         if (--width == 0)
 410                                                 break;
 411                                         if (fp->_r <= 0 && __srefill(fp))
 412                                                 break;
 413                                 }
 414                                 nread += n;
 415                         } else {
 416                                 p0 = p = va_arg(ap, char *);
 417                                 while (!isspace(*fp->_p)) {
 418                                         fp->_r--;
 419                                         *p++ = *fp->_p++;
 420                                         if (--width == 0)
 421                                                 break;
 422                                         if (fp->_r <= 0 && __srefill(fp))
 423                                                 break;
 424                                 }
 425                                 *p = 0;
 426                                 nread += p - p0;
 427                                 nassigned++;
 428                         }
 429                         nconversions++;
 430                         continue;
 431
 432                 case CT_INT:
 433                         /* scan an integer as if by strtoq/strtouq */
 434 #ifdef hardway
 435                         if (width == 0 || width > sizeof(buf) - 1)
 436                                 width = sizeof(buf) - 1;
 437 #else
 438                         /* size_t is unsigned, hence this optimisation */
 439                         if (--width > sizeof(buf) - 2)
 440                                 width = sizeof(buf) - 2;
 441                         width++;
 442 #endif
 443                         flags |= SIGNOK | NDIGITS | NZDIGITS;
 444                         for (p = buf; width; width--) {
 445                                 c = *fp->_p;
 446                                 /*
 447                                  * Switch on the character; `goto ok'
 448                                  * if we accept it as a part of number.
 449                                  */
 450                                 switch (c) {
 451
 452                                 /*
 453                                  * The digit 0 is always legal, but is
 454                                  * special.  For %i conversions, if no
 455                                  * digits (zero or nonzero) have been
 456                                  * scanned (only signs), we will have
 457                                  * base==0.  In that case, we should set
 458                                  * it to 8 and enable 0x prefixing.
 459                                  * Also, if we have not scanned zero digits
 460                                  * before this, do not turn off prefixing
 461                                  * (someone else will turn it off if we
 462                                  * have scanned any nonzero digits).
 463                                  */
 464                                 case '0':
 465                                         if (base == 0) {
 466                                                 base = 8;
 467                                                 flags |= PFXOK;
 468                                         }
 469                                         if (flags & NZDIGITS)
 470                                             flags &= ~(SIGNOK|NZDIGITS|NDIGITS);
 471                                         else
 472                                             flags &= ~(SIGNOK|PFXOK|NDIGITS);
 473                                         goto ok;
 474
 475                                 /* 1 through 7 always legal */
 476                                 case '1': case '2': case '3':
 477                                 case '4': case '5': case '6': case '7':
 478                                         base = basefix[base];
 479                                         flags &= ~(SIGNOK | PFXOK | NDIGITS);
 480                                         goto ok;
 481
 482                                 /* digits 8 and 9 ok iff decimal or hex */
 483                                 case '8': case '9':
 484                                         base = basefix[base];
 485                                         if (base <= 8)
 486                                                 break;  /* not legal here */
 487                                         flags &= ~(SIGNOK | PFXOK | NDIGITS);
 488                                         goto ok;
 489
 490                                 /* letters ok iff hex */
 491                                 case 'A': case 'B': case 'C':
 492                                 case 'D': case 'E': case 'F':
 493                                 case 'a': case 'b': case 'c':
 494                                 case 'd': case 'e': case 'f':
 495                                         /* no need to fix base here */
 496                                         if (base <= 10)
 497                                                 break;  /* not legal here */
 498                                         flags &= ~(SIGNOK | PFXOK | NDIGITS);
 499                                         goto ok;
 500
 501                                 /* sign ok only as first character */
 502                                 case '+': case '-':
 503                                         if (flags & SIGNOK) {
 504                                                 flags &= ~SIGNOK;
 505                                                 goto ok;
 506                                         }
 507                                         break;
 508
 509                                 /* x ok iff flag still set & 2nd char */
 510                                 case 'x': case 'X':
 511                                         if (flags & PFXOK && p == buf + 1) {
 512                                                 base = 16;      /* if %i */
 513                                                 flags &= ~PFXOK;
 514                                                 goto ok;
 515                                         }
 516                                         break;
 517                                 }
 518
 519                                 /*
 520                                  * If we got here, c is not a legal character
 521                                  * for a number.  Stop accumulating digits.
 522                                  */
 523                                 break;
 524                 ok:
 525                                 /*
 526                                  * c is legal: store it and look at the next.
 527                                  */
 528                                 *p++ = c;
 529                                 if (--fp->_r > 0)
 530                                         fp->_p++;
 531                                 else if (__srefill(fp))
 532                                         break;          /* EOF */
 533                         }
 534                         /*
 535                          * If we had only a sign, it is no good; push
 536                          * back the sign.  If the number ends in `x',
 537                          * it was [sign] '0' 'x', so push back the x
 538                          * and treat it as [sign] '0'.
 539                          */
 540                         if (flags & NDIGITS) {
 541                                 if (p > buf)
 542                                         (void) ungetc(*(u_char *)--p, fp);
 543                                 goto match_failure;
 544                         }
 545                         c = ((u_char *)p)[-1];
 546                         if (c == 'x' || c == 'X') {
 547                                 --p;
 548                                 (void) ungetc(c, fp);
 549                         }
 550                         if ((flags & SUPPRESS) == 0) {
 551                                 u_quad_t res;
 552
 553                                 *p = 0;
 554                                 res = (*ccfn)(buf, (char **)NULL, base);
 555                                 if (flags & POINTER)
 556                                         *va_arg(ap, void **) =
 557                                                 (void *)(u_long)res;
 558                                 else if (flags & SHORT)
 559                                         *va_arg(ap, short *) = res;
 560                                 else if (flags & LONG)
 561                                         *va_arg(ap, long *) = res;
 562                                 else if (flags & QUAD)
 563                                         *va_arg(ap, quad_t *) = res;
 564                                 else
 565                                         *va_arg(ap, int *) = res;
 566                                 nassigned++;
 567                         }
 568                         nread += p - buf;
 569                         nconversions++;
 570                         break;
 571
 572 #ifdef FLOATING_POINT
 573                 case CT_FLOAT:
 574                         /* scan a floating point number as if by strtod */
 575 #ifdef hardway
 576                         if (width == 0 || width > sizeof(buf) - 1)
 577                                 width = sizeof(buf) - 1;
 578 #else
 579                         /* size_t is unsigned, hence this optimisation */
 580                         if (--width > sizeof(buf) - 2)
 581                                 width = sizeof(buf) - 2;
 582                         width++;
 583 #endif
 584                         flags |= SIGNOK | NDIGITS | DPTOK | EXPOK;
 585                         for (p = buf; width; width--) {
 586                                 c = *fp->_p;
 587                                 /*
 588                                  * This code mimicks the integer conversion
 589                                  * code, but is much simpler.
 590                                  */
 591                                 switch (c) {
 592
 593                                 case '0': case '1': case '2': case '3':
 594                                 case '4': case '5': case '6': case '7':
 595                                 case '8': case '9':
 596                                         flags &= ~(SIGNOK | NDIGITS);
 597                                         goto fok;
 598
 599                                 case '+': case '-':
 600                                         if (flags & SIGNOK) {
 601                                                 flags &= ~SIGNOK;
 602                                                 goto fok;
 603                                         }
 604                                         break;
 605                                 case 'e': case 'E':
 606                                         /* no exponent without some digits */
 607                                         if ((flags&(NDIGITS|EXPOK)) == EXPOK) {
 608                                                 flags =
 609                                                     (flags & ~(EXPOK|DPTOK)) |
 610                                                     SIGNOK | NDIGITS;
 611                                                 goto fok;
 612                                         }
 613                                         break;
 614                                 default:
 615                                         if ((char)c == decimal_point &&
 616                                             (flags & DPTOK)) {
 617                                                 flags &= ~(SIGNOK | DPTOK);
 618                                                 goto fok;
 619                                         }
 620                                         break;
 621                                 }
 622                                 break;
 623                 fok:
 624                                 *p++ = c;
 625                                 if (--fp->_r > 0)
 626                                         fp->_p++;
 627                                 else if (__srefill(fp))
 628                                         break;  /* EOF */
 629                         }
 630                         /*
 631                          * If no digits, might be missing exponent digits
 632                          * (just give back the exponent) or might be missing
 633                          * regular digits, but had sign and/or decimal point.
 634                          */
 635                         if (flags & NDIGITS) {
 636                                 if (flags & EXPOK) {
 637                                         /* no digits at all */
 638                                         while (p > buf)
 639                                                 ungetc(*(u_char *)--p, fp);
 640                                         goto match_failure;
 641                                 }
 642                                 /* just a bad exponent (e and maybe sign) */
 643                                 c = *(u_char *)--p;
 644                                 if (c != 'e' && c != 'E') {
 645                                         (void) ungetc(c, fp);/* sign */
 646                                         c = *(u_char *)--p;
 647                                 }
 648                                 (void) ungetc(c, fp);
 649                         }
 650                         if ((flags & SUPPRESS) == 0) {
 651                                 double res;
 652
 653                                 *p = 0;
 654                                 /* XXX this loses precision for long doubles. */
 655                                 res = strtod(buf, (char **) NULL);
 656                                 if (flags & LONGDBL)
 657                                         *va_arg(ap, long double *) = res;
 658                                 else if (flags & LONG)
 659                                         *va_arg(ap, double *) = res;
 660                                 else
 661                                         *va_arg(ap, float *) = res;
 662                                 nassigned++;
 663                         }
 664                         nread += p - buf;
 665                         nconversions++;
 666                         break;
 667 #endif /* FLOATING_POINT */
 668                 }
 669         }
 670 input_failure:
 671         return (nconversions != 0 ? nassigned : EOF);
 672 match_failure:
 673         return (nassigned);
 674 }
 675
 676 /*
 677  * Fill in the given table from the scanset at the given format
 678  * (just after `[').  Return a pointer to the character past the
 679  * closing `]'.  The table has a 1 wherever characters should be
 680  * considered part of the scanset.
 681  */
 682 static u_char *
 683 __sccl(tab, fmt)
 684         char *tab;
 685         u_char *fmt;
 686 {
 687         int c, n, v, i;
 688
 689         /* first `clear' the whole table */
 690         c = *fmt++;             /* first char hat => negated scanset */
 691         if (c == '^') {
 692                 v = 1;          /* default => accept */
 693                 c = *fmt++;     /* get new first char */
 694         } else
 695                 v = 0;          /* default => reject */
 696
 697         /* XXX: Will not work if sizeof(tab*) > sizeof(char) */
 698         (void) memset(tab, v, 256);
 699
 700         if (c == 0)
 701                 return (fmt - 1);/* format ended before closing ] */
 702
 703         /*
 704          * Now set the entries corresponding to the actual scanset
 705          * to the opposite of the above.
 706          *
 707          * The first character may be ']' (or '-') without being special;
 708          * the last character may be '-'.
 709          */
 710         v = 1 - v;
 711         for (;;) {
 712                 tab[c] = v;             /* take character c */
 713 doswitch:
 714                 n = *fmt++;             /* and examine the next */
 715                 switch (n) {
 716
 717                 case 0:                 /* format ended too soon */
 718                         return (fmt - 1);
 719
 720                 case '-':
 721                         /*
 722                          * A scanset of the form
 723                          *      [01+-]
 724                          * is defined as `the digit 0, the digit 1,
 725                          * the character +, the character -', but
 726                          * the effect of a scanset such as
 727                          *      [a-zA-Z0-9]
 728                          * is implementation defined.  The V7 Unix
 729                          * scanf treats `a-z' as `the letters a through
 730                          * z', but treats `a-a' as `the letter a, the
 731                          * character -, and the letter a'.
 732                          *
 733                          * For compatibility, the `-' is not considerd
 734                          * to define a range if the character following
 735                          * it is either a close bracket (required by ANSI)
 736                          * or is not numerically greater than the character
 737                          * we just stored in the table (c).
 738                          */
 739                         n = *fmt;
 740                         if (n == ']'
 741                             || (__collate_load_error ? n < c :
 742                                 __collate_range_cmp (n, c) < 0
 743                                )
 744                            ) {
 745                                 c = '-';
 746                                 break;  /* resume the for(;;) */
 747                         }
 748                         fmt++;
 749                         /* fill in the range */
 750                         if (__collate_load_error) {
 751                                 do {
 752                                         tab[++c] = v;
 753                                 } while (c < n);
 754                         } else {
 755                                 for (i = 0; i < 256; i ++)
 756                                         if (   __collate_range_cmp (c, i) < 0
 757                                             && __collate_range_cmp (i, n) <= 0
 758                                            )
 759                                                 tab[i] = v;
 760                         }
 761 #if 1   /* XXX another disgusting compatibility hack */
 762                         c = n;
 763                         /*
 764                          * Alas, the V7 Unix scanf also treats formats
 765                          * such as [a-c-e] as `the letters a through e'.
 766                          * This too is permitted by the standard....
 767                          */
 768                         goto doswitch;
 769 #else
 770                         c = *fmt++;
 771                         if (c == 0)
 772                                 return (fmt - 1);
 773                         if (c == ']')
 774                                 return (fmt);
 775 #endif
 776                         break;
 777
 778                 case ']':               /* end of scanset */
 779                         return (fmt);
 780
 781                 default:                /* just another character */
 782                         c = n;
 783                         break;
 784                 }
 785         }
 786         /* NOTREACHED */
 787 }