The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_scanf.c

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    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  * 4. Neither the name of the University nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  * From: Id: vfscanf.c,v 1.13 1998/09/25 12:20:27 obrien Exp 
   33  * From: static char sccsid[] = "@(#)strtol.c   8.1 (Berkeley) 6/4/93";
   34  * From: static char sccsid[] = "@(#)strtoul.c  8.1 (Berkeley) 6/4/93";
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: releng/6.2/sys/kern/subr_scanf.c 164286 2006-11-14 20:42:41Z cvs2svn $");
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/ctype.h>
   43 #include <sys/limits.h>
   44 
   45 /*
   46  * Note that stdarg.h and the ANSI style va_start macro is used for both
   47  * ANSI and traditional C compilers.
   48  */
   49 #include <machine/stdarg.h>
   50 
   51 #define BUF             32      /* Maximum length of numeric string. */
   52 
   53 /*
   54  * Flags used during conversion.
   55  */
   56 #define LONG            0x01    /* l: long or double */
   57 #define SHORT           0x04    /* h: short */
   58 #define SUPPRESS        0x08    /* suppress assignment */
   59 #define POINTER         0x10    /* weird %p pointer (`fake hex') */
   60 #define NOSKIP          0x20    /* do not skip blanks */
   61 #define QUAD            0x400
   62 
   63 /*
   64  * The following are used in numeric conversions only:
   65  * SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
   66  * SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
   67  */
   68 #define SIGNOK          0x40    /* +/- is (still) legal */
   69 #define NDIGITS         0x80    /* no digits detected */
   70 
   71 #define DPTOK           0x100   /* (float) decimal point is still legal */
   72 #define EXPOK           0x200   /* (float) exponent (e+3, etc) still legal */
   73 
   74 #define PFXOK           0x100   /* 0x prefix is (still) legal */
   75 #define NZDIGITS        0x200   /* no zero digits detected */
   76 
   77 /*
   78  * Conversion types.
   79  */
   80 #define CT_CHAR         0       /* %c conversion */
   81 #define CT_CCL          1       /* %[...] conversion */
   82 #define CT_STRING       2       /* %s conversion */
   83 #define CT_INT          3       /* integer, i.e., strtoq or strtouq */
   84 typedef u_quad_t (*ccfntype)(const char *, char **, int);
   85 
   86 static const u_char *__sccl(char *, const u_char *);
   87 
   88 int
   89 sscanf(const char *ibuf, const char *fmt, ...)
   90 {
   91         va_list ap;
   92         int ret;
   93         
   94         va_start(ap, fmt);
   95         ret = vsscanf(ibuf, fmt, ap);
   96         va_end(ap);
   97         return(ret);
   98 }
   99 
  100 int
  101 vsscanf(const char *inp, char const *fmt0, va_list ap)
  102 {
  103         int inr;
  104         const u_char *fmt = (const u_char *)fmt0;
  105         int c;                  /* character from format, or conversion */
  106         size_t width;           /* field width, or 0 */
  107         char *p;                /* points into all kinds of strings */
  108         int n;                  /* handy integer */
  109         int flags;              /* flags as defined above */
  110         char *p0;               /* saves original value of p when necessary */
  111         int nassigned;          /* number of fields assigned */
  112         int nconversions;       /* number of conversions */
  113         int nread;              /* number of characters consumed from fp */
  114         int base;               /* base argument to strtoq/strtouq */
  115         ccfntype ccfn;          /* conversion function (strtoq/strtouq) */
  116         char ccltab[256];       /* character class table for %[...] */
  117         char buf[BUF];          /* buffer for numeric conversions */
  118 
  119         /* `basefix' is used to avoid `if' tests in the integer scanner */
  120         static short basefix[17] =
  121                 { 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
  122 
  123         inr = strlen(inp);
  124         
  125         nassigned = 0;
  126         nconversions = 0;
  127         nread = 0;
  128         base = 0;               /* XXX just to keep gcc happy */
  129         ccfn = NULL;            /* XXX just to keep gcc happy */
  130         for (;;) {
  131                 c = *fmt++;
  132                 if (c == 0)
  133                         return (nassigned);
  134                 if (isspace(c)) {
  135                         while (inr > 0 && isspace(*inp))
  136                                 nread++, inr--, inp++;
  137                         continue;
  138                 }
  139                 if (c != '%')
  140                         goto literal;
  141                 width = 0;
  142                 flags = 0;
  143                 /*
  144                  * switch on the format.  continue if done;
  145                  * break once format type is derived.
  146                  */
  147 again:          c = *fmt++;
  148                 switch (c) {
  149                 case '%':
  150 literal:
  151                         if (inr <= 0)
  152                                 goto input_failure;
  153                         if (*inp != c)
  154                                 goto match_failure;
  155                         inr--, inp++;
  156                         nread++;
  157                         continue;
  158 
  159                 case '*':
  160                         flags |= SUPPRESS;
  161                         goto again;
  162                 case 'l':
  163                         flags |= LONG;
  164                         goto again;
  165                 case 'q':
  166                         flags |= QUAD;
  167                         goto again;
  168                 case 'h':
  169                         flags |= SHORT;
  170                         goto again;
  171 
  172                 case '': case '1': case '2': case '3': case '4':
  173                 case '5': case '6': case '7': case '8': case '9':
  174                         width = width * 10 + c - '';
  175                         goto again;
  176 
  177                 /*
  178                  * Conversions.
  179                  *
  180                  */
  181                 case 'd':
  182                         c = CT_INT;
  183                         ccfn = (ccfntype)strtoq;
  184                         base = 10;
  185                         break;
  186 
  187                 case 'i':
  188                         c = CT_INT;
  189                         ccfn = (ccfntype)strtoq;
  190                         base = 0;
  191                         break;
  192 
  193                 case 'o':
  194                         c = CT_INT;
  195                         ccfn = strtouq;
  196                         base = 8;
  197                         break;
  198 
  199                 case 'u':
  200                         c = CT_INT;
  201                         ccfn = strtouq;
  202                         base = 10;
  203                         break;
  204 
  205                 case 'x':
  206                         flags |= PFXOK; /* enable 0x prefixing */
  207                         c = CT_INT;
  208                         ccfn = strtouq;
  209                         base = 16;
  210                         break;
  211 
  212                 case 's':
  213                         c = CT_STRING;
  214                         break;
  215 
  216                 case '[':
  217                         fmt = __sccl(ccltab, fmt);
  218                         flags |= NOSKIP;
  219                         c = CT_CCL;
  220                         break;
  221 
  222                 case 'c':
  223                         flags |= NOSKIP;
  224                         c = CT_CHAR;
  225                         break;
  226 
  227                 case 'p':       /* pointer format is like hex */
  228                         flags |= POINTER | PFXOK;
  229                         c = CT_INT;
  230                         ccfn = strtouq;
  231                         base = 16;
  232                         break;
  233 
  234                 case 'n':
  235                         nconversions++;
  236                         if (flags & SUPPRESS)   /* ??? */
  237                                 continue;
  238                         if (flags & SHORT)
  239                                 *va_arg(ap, short *) = nread;
  240                         else if (flags & LONG)
  241                                 *va_arg(ap, long *) = nread;
  242                         else if (flags & QUAD)
  243                                 *va_arg(ap, quad_t *) = nread;
  244                         else
  245                                 *va_arg(ap, int *) = nread;
  246                         continue;
  247                 }
  248 
  249                 /*
  250                  * We have a conversion that requires input.
  251                  */
  252                 if (inr <= 0)
  253                         goto input_failure;
  254 
  255                 /*
  256                  * Consume leading white space, except for formats
  257                  * that suppress this.
  258                  */
  259                 if ((flags & NOSKIP) == 0) {
  260                         while (isspace(*inp)) {
  261                                 nread++;
  262                                 if (--inr > 0)
  263                                         inp++;
  264                                 else 
  265                                         goto input_failure;
  266                         }
  267                         /*
  268                          * Note that there is at least one character in
  269                          * the buffer, so conversions that do not set NOSKIP
  270                          * can no longer result in an input failure.
  271                          */
  272                 }
  273 
  274                 /*
  275                  * Do the conversion.
  276                  */
  277                 switch (c) {
  278 
  279                 case CT_CHAR:
  280                         /* scan arbitrary characters (sets NOSKIP) */
  281                         if (width == 0)
  282                                 width = 1;
  283                         if (flags & SUPPRESS) {
  284                                 size_t sum = 0;
  285                                 for (;;) {
  286                                         if ((n = inr) < width) {
  287                                                 sum += n;
  288                                                 width -= n;
  289                                                 inp += n;
  290                                                 if (sum == 0)
  291                                                         goto input_failure;
  292                                                 break;
  293                                         } else {
  294                                                 sum += width;
  295                                                 inr -= width;
  296                                                 inp += width;
  297                                                 break;
  298                                         }
  299                                 }
  300                                 nread += sum;
  301                         } else {
  302                                 bcopy(inp, va_arg(ap, char *), width);
  303                                 inr -= width;
  304                                 inp += width;
  305                                 nread += width;
  306                                 nassigned++;
  307                         }
  308                         nconversions++;
  309                         break;
  310 
  311                 case CT_CCL:
  312                         /* scan a (nonempty) character class (sets NOSKIP) */
  313                         if (width == 0)
  314                                 width = (size_t)~0;     /* `infinity' */
  315                         /* take only those things in the class */
  316                         if (flags & SUPPRESS) {
  317                                 n = 0;
  318                                 while (ccltab[(unsigned char)*inp]) {
  319                                         n++, inr--, inp++;
  320                                         if (--width == 0)
  321                                                 break;
  322                                         if (inr <= 0) {
  323                                                 if (n == 0)
  324                                                         goto input_failure;
  325                                                 break;
  326                                         }
  327                                 }
  328                                 if (n == 0)
  329                                         goto match_failure;
  330                         } else {
  331                                 p0 = p = va_arg(ap, char *);
  332                                 while (ccltab[(unsigned char)*inp]) {
  333                                         inr--;
  334                                         *p++ = *inp++;
  335                                         if (--width == 0)
  336                                                 break;
  337                                         if (inr <= 0) {
  338                                                 if (p == p0)
  339                                                         goto input_failure;
  340                                                 break;
  341                                         }
  342                                 }
  343                                 n = p - p0;
  344                                 if (n == 0)
  345                                         goto match_failure;
  346                                 *p = 0;
  347                                 nassigned++;
  348                         }
  349                         nread += n;
  350                         nconversions++;
  351                         break;
  352 
  353                 case CT_STRING:
  354                         /* like CCL, but zero-length string OK, & no NOSKIP */
  355                         if (width == 0)
  356                                 width = (size_t)~0;
  357                         if (flags & SUPPRESS) {
  358                                 n = 0;
  359                                 while (!isspace(*inp)) {
  360                                         n++, inr--, inp++;
  361                                         if (--width == 0)
  362                                                 break;
  363                                         if (inr <= 0)
  364                                                 break;
  365                                 }
  366                                 nread += n;
  367                         } else {
  368                                 p0 = p = va_arg(ap, char *);
  369                                 while (!isspace(*inp)) {
  370                                         inr--;
  371                                         *p++ = *inp++;
  372                                         if (--width == 0)
  373                                                 break;
  374                                         if (inr <= 0)
  375                                                 break;
  376                                 }
  377                                 *p = 0;
  378                                 nread += p - p0;
  379                                 nassigned++;
  380                         }
  381                         nconversions++;
  382                         continue;
  383 
  384                 case CT_INT:
  385                         /* scan an integer as if by strtoq/strtouq */
  386 #ifdef hardway
  387                         if (width == 0 || width > sizeof(buf) - 1)
  388                                 width = sizeof(buf) - 1;
  389 #else
  390                         /* size_t is unsigned, hence this optimisation */
  391                         if (--width > sizeof(buf) - 2)
  392                                 width = sizeof(buf) - 2;
  393                         width++;
  394 #endif
  395                         flags |= SIGNOK | NDIGITS | NZDIGITS;
  396                         for (p = buf; width; width--) {
  397                                 c = *inp;
  398                                 /*
  399                                  * Switch on the character; `goto ok'
  400                                  * if we accept it as a part of number.
  401                                  */
  402                                 switch (c) {
  403 
  404                                 /*
  405                                  * The digit 0 is always legal, but is
  406                                  * special.  For %i conversions, if no
  407                                  * digits (zero or nonzero) have been
  408                                  * scanned (only signs), we will have
  409                                  * base==0.  In that case, we should set
  410                                  * it to 8 and enable 0x prefixing.
  411                                  * Also, if we have not scanned zero digits
  412                                  * before this, do not turn off prefixing
  413                                  * (someone else will turn it off if we
  414                                  * have scanned any nonzero digits).
  415                                  */
  416                                 case '':
  417                                         if (base == 0) {
  418                                                 base = 8;
  419                                                 flags |= PFXOK;
  420                                         }
  421                                         if (flags & NZDIGITS)
  422                                             flags &= ~(SIGNOK|NZDIGITS|NDIGITS);
  423                                         else
  424                                             flags &= ~(SIGNOK|PFXOK|NDIGITS);
  425                                         goto ok;
  426 
  427                                 /* 1 through 7 always legal */
  428                                 case '1': case '2': case '3':
  429                                 case '4': case '5': case '6': case '7':
  430                                         base = basefix[base];
  431                                         flags &= ~(SIGNOK | PFXOK | NDIGITS);
  432                                         goto ok;
  433 
  434                                 /* digits 8 and 9 ok iff decimal or hex */
  435                                 case '8': case '9':
  436                                         base = basefix[base];
  437                                         if (base <= 8)
  438                                                 break;  /* not legal here */
  439                                         flags &= ~(SIGNOK | PFXOK | NDIGITS);
  440                                         goto ok;
  441 
  442                                 /* letters ok iff hex */
  443                                 case 'A': case 'B': case 'C':
  444                                 case 'D': case 'E': case 'F':
  445                                 case 'a': case 'b': case 'c':
  446                                 case 'd': case 'e': case 'f':
  447                                         /* no need to fix base here */
  448                                         if (base <= 10)
  449                                                 break;  /* not legal here */
  450                                         flags &= ~(SIGNOK | PFXOK | NDIGITS);
  451                                         goto ok;
  452 
  453                                 /* sign ok only as first character */
  454                                 case '+': case '-':
  455                                         if (flags & SIGNOK) {
  456                                                 flags &= ~SIGNOK;
  457                                                 goto ok;
  458                                         }
  459                                         break;
  460 
  461                                 /* x ok iff flag still set & 2nd char */
  462                                 case 'x': case 'X':
  463                                         if (flags & PFXOK && p == buf + 1) {
  464                                                 base = 16;      /* if %i */
  465                                                 flags &= ~PFXOK;
  466                                                 goto ok;
  467                                         }
  468                                         break;
  469                                 }
  470 
  471                                 /*
  472                                  * If we got here, c is not a legal character
  473                                  * for a number.  Stop accumulating digits.
  474                                  */
  475                                 break;
  476                 ok:
  477                                 /*
  478                                  * c is legal: store it and look at the next.
  479                                  */
  480                                 *p++ = c;
  481                                 if (--inr > 0)
  482                                         inp++;
  483                                 else 
  484                                         break;          /* end of input */
  485                         }
  486                         /*
  487                          * If we had only a sign, it is no good; push
  488                          * back the sign.  If the number ends in `x',
  489                          * it was [sign] '' 'x', so push back the x
  490                          * and treat it as [sign] ''.
  491                          */
  492                         if (flags & NDIGITS) {
  493                                 if (p > buf) {
  494                                         inp--;
  495                                         inr++;
  496                                 }
  497                                 goto match_failure;
  498                         }
  499                         c = ((u_char *)p)[-1];
  500                         if (c == 'x' || c == 'X') {
  501                                 --p;
  502                                 inp--;
  503                                 inr++;
  504                         }
  505                         if ((flags & SUPPRESS) == 0) {
  506                                 u_quad_t res;
  507 
  508                                 *p = 0;
  509                                 res = (*ccfn)(buf, (char **)NULL, base);
  510                                 if (flags & POINTER)
  511                                         *va_arg(ap, void **) =
  512                                                 (void *)(uintptr_t)res;
  513                                 else if (flags & SHORT)
  514                                         *va_arg(ap, short *) = res;
  515                                 else if (flags & LONG)
  516                                         *va_arg(ap, long *) = res;
  517                                 else if (flags & QUAD)
  518                                         *va_arg(ap, quad_t *) = res;
  519                                 else
  520                                         *va_arg(ap, int *) = res;
  521                                 nassigned++;
  522                         }
  523                         nread += p - buf;
  524                         nconversions++;
  525                         break;
  526 
  527                 }
  528         }
  529 input_failure:
  530         return (nconversions != 0 ? nassigned : -1);
  531 match_failure:
  532         return (nassigned);
  533 }
  534 
  535 /*
  536  * Fill in the given table from the scanset at the given format
  537  * (just after `[').  Return a pointer to the character past the
  538  * closing `]'.  The table has a 1 wherever characters should be
  539  * considered part of the scanset.
  540  */
  541 static const u_char *
  542 __sccl(char *tab, const u_char *fmt)
  543 {
  544         int c, n, v;
  545 
  546         /* first `clear' the whole table */
  547         c = *fmt++;             /* first char hat => negated scanset */
  548         if (c == '^') {
  549                 v = 1;          /* default => accept */
  550                 c = *fmt++;     /* get new first char */
  551         } else
  552                 v = 0;          /* default => reject */
  553 
  554         /* XXX: Will not work if sizeof(tab*) > sizeof(char) */
  555         for (n = 0; n < 256; n++)
  556                      tab[n] = v;        /* memset(tab, v, 256) */
  557 
  558         if (c == 0)
  559                 return (fmt - 1);/* format ended before closing ] */
  560 
  561         /*
  562          * Now set the entries corresponding to the actual scanset
  563          * to the opposite of the above.
  564          *
  565          * The first character may be ']' (or '-') without being special;
  566          * the last character may be '-'.
  567          */
  568         v = 1 - v;
  569         for (;;) {
  570                 tab[c] = v;             /* take character c */
  571 doswitch:
  572                 n = *fmt++;             /* and examine the next */
  573                 switch (n) {
  574 
  575                 case 0:                 /* format ended too soon */
  576                         return (fmt - 1);
  577 
  578                 case '-':
  579                         /*
  580                          * A scanset of the form
  581                          *      [01+-]
  582                          * is defined as `the digit 0, the digit 1,
  583                          * the character +, the character -', but
  584                          * the effect of a scanset such as
  585                          *      [a-zA-Z0-9]
  586                          * is implementation defined.  The V7 Unix
  587                          * scanf treats `a-z' as `the letters a through
  588                          * z', but treats `a-a' as `the letter a, the
  589                          * character -, and the letter a'.
  590                          *
  591                          * For compatibility, the `-' is not considerd
  592                          * to define a range if the character following
  593                          * it is either a close bracket (required by ANSI)
  594                          * or is not numerically greater than the character
  595                          * we just stored in the table (c).
  596                          */
  597                         n = *fmt;
  598                         if (n == ']' || n < c) {
  599                                 c = '-';
  600                                 break;  /* resume the for(;;) */
  601                         }
  602                         fmt++;
  603                         /* fill in the range */
  604                         do {
  605                             tab[++c] = v;
  606                         } while (c < n);
  607                         c = n;
  608                         /*
  609                          * Alas, the V7 Unix scanf also treats formats
  610                          * such as [a-c-e] as `the letters a through e'.
  611                          * This too is permitted by the standard....
  612                          */
  613                         goto doswitch;
  614                         break;
  615 
  616                 case ']':               /* end of scanset */
  617                         return (fmt);
  618 
  619                 default:                /* just another character */
  620                         c = n;
  621                         break;
  622                 }
  623         }
  624         /* NOTREACHED */
  625 }
  626 

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