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  * 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  * $FreeBSD: releng/5.0/sys/kern/subr_scanf.c 104363 2002-10-02 09:09:25Z phk $
   37  * From: Id: vfscanf.c,v 1.13 1998/09/25 12:20:27 obrien Exp 
   38  * From: static char sccsid[] = "@(#)strtol.c   8.1 (Berkeley) 6/4/93";
   39  * From: static char sccsid[] = "@(#)strtoul.c  8.1 (Berkeley) 6/4/93";
   40  */
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/ctype.h>
   45 #include <machine/limits.h>
   46 
   47 /*
   48  * Note that stdarg.h and the ANSI style va_start macro is used for both
   49  * ANSI and traditional C compilers.
   50  */
   51 #include <machine/stdarg.h>
   52 
   53 #define BUF             32      /* Maximum length of numeric string. */
   54 
   55 /*
   56  * Flags used during conversion.
   57  */
   58 #define LONG            0x01    /* l: long or double */
   59 #define SHORT           0x04    /* h: short */
   60 #define SUPPRESS        0x08    /* suppress assignment */
   61 #define POINTER         0x10    /* weird %p pointer (`fake hex') */
   62 #define NOSKIP          0x20    /* do not skip blanks */
   63 #define QUAD            0x400
   64 
   65 /*
   66  * The following are used in numeric conversions only:
   67  * SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
   68  * SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
   69  */
   70 #define SIGNOK          0x40    /* +/- is (still) legal */
   71 #define NDIGITS         0x80    /* no digits detected */
   72 
   73 #define DPTOK           0x100   /* (float) decimal point is still legal */
   74 #define EXPOK           0x200   /* (float) exponent (e+3, etc) still legal */
   75 
   76 #define PFXOK           0x100   /* 0x prefix is (still) legal */
   77 #define NZDIGITS        0x200   /* no zero digits detected */
   78 
   79 /*
   80  * Conversion types.
   81  */
   82 #define CT_CHAR         0       /* %c conversion */
   83 #define CT_CCL          1       /* %[...] conversion */
   84 #define CT_STRING       2       /* %s conversion */
   85 #define CT_INT          3       /* integer, i.e., strtoq or strtouq */
   86 typedef u_quad_t (*ccfntype)(const char *, char **, int);
   87 
   88 static const u_char *__sccl(char *, const u_char *);
   89 
   90 int
   91 sscanf(const char *ibuf, const char *fmt, ...)
   92 {
   93         va_list ap;
   94         int ret;
   95         
   96         va_start(ap, fmt);
   97         ret = vsscanf(ibuf, fmt, ap);
   98         va_end(ap);
   99         return(ret);
  100 }
  101 
  102 int
  103 vsscanf(const char *inp, char const *fmt0, va_list ap)
  104 {
  105         int inr;
  106         const u_char *fmt = (const u_char *)fmt0;
  107         int c;                  /* character from format, or conversion */
  108         size_t width;           /* field width, or 0 */
  109         char *p;                /* points into all kinds of strings */
  110         int n;                  /* handy integer */
  111         int flags;              /* flags as defined above */
  112         char *p0;               /* saves original value of p when necessary */
  113         int nassigned;          /* number of fields assigned */
  114         int nconversions;       /* number of conversions */
  115         int nread;              /* number of characters consumed from fp */
  116         int base;               /* base argument to strtoq/strtouq */
  117         ccfntype ccfn;          /* conversion function (strtoq/strtouq) */
  118         char ccltab[256];       /* character class table for %[...] */
  119         char buf[BUF];          /* buffer for numeric conversions */
  120 
  121         /* `basefix' is used to avoid `if' tests in the integer scanner */
  122         static short basefix[17] =
  123                 { 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
  124 
  125         inr = strlen(inp);
  126         
  127         nassigned = 0;
  128         nconversions = 0;
  129         nread = 0;
  130         base = 0;               /* XXX just to keep gcc happy */
  131         ccfn = NULL;            /* XXX just to keep gcc happy */
  132         for (;;) {
  133                 c = *fmt++;
  134                 if (c == 0)
  135                         return (nassigned);
  136                 if (isspace(c)) {
  137                         while (inr > 0 && isspace(*inp))
  138                                 nread++, inr--, inp++;
  139                         continue;
  140                 }
  141                 if (c != '%')
  142                         goto literal;
  143                 width = 0;
  144                 flags = 0;
  145                 /*
  146                  * switch on the format.  continue if done;
  147                  * break once format type is derived.
  148                  */
  149 again:          c = *fmt++;
  150                 switch (c) {
  151                 case '%':
  152 literal:
  153                         if (inr <= 0)
  154                                 goto input_failure;
  155                         if (*inp != c)
  156                                 goto match_failure;
  157                         inr--, inp++;
  158                         nread++;
  159                         continue;
  160 
  161                 case '*':
  162                         flags |= SUPPRESS;
  163                         goto again;
  164                 case 'l':
  165                         flags |= LONG;
  166                         goto again;
  167                 case 'q':
  168                         flags |= QUAD;
  169                         goto again;
  170                 case 'h':
  171                         flags |= SHORT;
  172                         goto again;
  173 
  174                 case '': case '1': case '2': case '3': case '4':
  175                 case '5': case '6': case '7': case '8': case '9':
  176                         width = width * 10 + c - '';
  177                         goto again;
  178 
  179                 /*
  180                  * Conversions.
  181                  *
  182                  */
  183                 case 'd':
  184                         c = CT_INT;
  185                         ccfn = (ccfntype)strtoq;
  186                         base = 10;
  187                         break;
  188 
  189                 case 'i':
  190                         c = CT_INT;
  191                         ccfn = (ccfntype)strtoq;
  192                         base = 0;
  193                         break;
  194 
  195                 case 'o':
  196                         c = CT_INT;
  197                         ccfn = strtouq;
  198                         base = 8;
  199                         break;
  200 
  201                 case 'u':
  202                         c = CT_INT;
  203                         ccfn = strtouq;
  204                         base = 10;
  205                         break;
  206 
  207                 case 'x':
  208                         flags |= PFXOK; /* enable 0x prefixing */
  209                         c = CT_INT;
  210                         ccfn = strtouq;
  211                         base = 16;
  212                         break;
  213 
  214                 case 's':
  215                         c = CT_STRING;
  216                         break;
  217 
  218                 case '[':
  219                         fmt = __sccl(ccltab, fmt);
  220                         flags |= NOSKIP;
  221                         c = CT_CCL;
  222                         break;
  223 
  224                 case 'c':
  225                         flags |= NOSKIP;
  226                         c = CT_CHAR;
  227                         break;
  228 
  229                 case 'p':       /* pointer format is like hex */
  230                         flags |= POINTER | PFXOK;
  231                         c = CT_INT;
  232                         ccfn = strtouq;
  233                         base = 16;
  234                         break;
  235 
  236                 case 'n':
  237                         nconversions++;
  238                         if (flags & SUPPRESS)   /* ??? */
  239                                 continue;
  240                         if (flags & SHORT)
  241                                 *va_arg(ap, short *) = nread;
  242                         else if (flags & LONG)
  243                                 *va_arg(ap, long *) = nread;
  244                         else if (flags & QUAD)
  245                                 *va_arg(ap, quad_t *) = nread;
  246                         else
  247                                 *va_arg(ap, int *) = nread;
  248                         continue;
  249                 }
  250 
  251                 /*
  252                  * We have a conversion that requires input.
  253                  */
  254                 if (inr <= 0)
  255                         goto input_failure;
  256 
  257                 /*
  258                  * Consume leading white space, except for formats
  259                  * that suppress this.
  260                  */
  261                 if ((flags & NOSKIP) == 0) {
  262                         while (isspace(*inp)) {
  263                                 nread++;
  264                                 if (--inr > 0)
  265                                         inp++;
  266                                 else 
  267                                         goto input_failure;
  268                         }
  269                         /*
  270                          * Note that there is at least one character in
  271                          * the buffer, so conversions that do not set NOSKIP
  272                          * can no longer result in an input failure.
  273                          */
  274                 }
  275 
  276                 /*
  277                  * Do the conversion.
  278                  */
  279                 switch (c) {
  280 
  281                 case CT_CHAR:
  282                         /* scan arbitrary characters (sets NOSKIP) */
  283                         if (width == 0)
  284                                 width = 1;
  285                         if (flags & SUPPRESS) {
  286                                 size_t sum = 0;
  287                                 for (;;) {
  288                                         if ((n = inr) < width) {
  289                                                 sum += n;
  290                                                 width -= n;
  291                                                 inp += n;
  292                                                 if (sum == 0)
  293                                                         goto input_failure;
  294                                                 break;
  295                                         } else {
  296                                                 sum += width;
  297                                                 inr -= width;
  298                                                 inp += width;
  299                                                 break;
  300                                         }
  301                                 }
  302                                 nread += sum;
  303                         } else {
  304                                 bcopy(inp, va_arg(ap, char *), width);
  305                                 inr -= width;
  306                                 inp += width;
  307                                 nread += width;
  308                                 nassigned++;
  309                         }
  310                         nconversions++;
  311                         break;
  312 
  313                 case CT_CCL:
  314                         /* scan a (nonempty) character class (sets NOSKIP) */
  315                         if (width == 0)
  316                                 width = (size_t)~0;     /* `infinity' */
  317                         /* take only those things in the class */
  318                         if (flags & SUPPRESS) {
  319                                 n = 0;
  320                                 while (ccltab[(unsigned char)*inp]) {
  321                                         n++, inr--, inp++;
  322                                         if (--width == 0)
  323                                                 break;
  324                                         if (inr <= 0) {
  325                                                 if (n == 0)
  326                                                         goto input_failure;
  327                                                 break;
  328                                         }
  329                                 }
  330                                 if (n == 0)
  331                                         goto match_failure;
  332                         } else {
  333                                 p0 = p = va_arg(ap, char *);
  334                                 while (ccltab[(unsigned char)*inp]) {
  335                                         inr--;
  336                                         *p++ = *inp++;
  337                                         if (--width == 0)
  338                                                 break;
  339                                         if (inr <= 0) {
  340                                                 if (p == p0)
  341                                                         goto input_failure;
  342                                                 break;
  343                                         }
  344                                 }
  345                                 n = p - p0;
  346                                 if (n == 0)
  347                                         goto match_failure;
  348                                 *p = 0;
  349                                 nassigned++;
  350                         }
  351                         nread += n;
  352                         nconversions++;
  353                         break;
  354 
  355                 case CT_STRING:
  356                         /* like CCL, but zero-length string OK, & no NOSKIP */
  357                         if (width == 0)
  358                                 width = (size_t)~0;
  359                         if (flags & SUPPRESS) {
  360                                 n = 0;
  361                                 while (!isspace(*inp)) {
  362                                         n++, inr--, inp++;
  363                                         if (--width == 0)
  364                                                 break;
  365                                         if (inr <= 0)
  366                                                 break;
  367                                 }
  368                                 nread += n;
  369                         } else {
  370                                 p0 = p = va_arg(ap, char *);
  371                                 while (!isspace(*inp)) {
  372                                         inr--;
  373                                         *p++ = *inp++;
  374                                         if (--width == 0)
  375                                                 break;
  376                                         if (inr <= 0)
  377                                                 break;
  378                                 }
  379                                 *p = 0;
  380                                 nread += p - p0;
  381                                 nassigned++;
  382                         }
  383                         nconversions++;
  384                         continue;
  385 
  386                 case CT_INT:
  387                         /* scan an integer as if by strtoq/strtouq */
  388 #ifdef hardway
  389                         if (width == 0 || width > sizeof(buf) - 1)
  390                                 width = sizeof(buf) - 1;
  391 #else
  392                         /* size_t is unsigned, hence this optimisation */
  393                         if (--width > sizeof(buf) - 2)
  394                                 width = sizeof(buf) - 2;
  395                         width++;
  396 #endif
  397                         flags |= SIGNOK | NDIGITS | NZDIGITS;
  398                         for (p = buf; width; width--) {
  399                                 c = *inp;
  400                                 /*
  401                                  * Switch on the character; `goto ok'
  402                                  * if we accept it as a part of number.
  403                                  */
  404                                 switch (c) {
  405 
  406                                 /*
  407                                  * The digit 0 is always legal, but is
  408                                  * special.  For %i conversions, if no
  409                                  * digits (zero or nonzero) have been
  410                                  * scanned (only signs), we will have
  411                                  * base==0.  In that case, we should set
  412                                  * it to 8 and enable 0x prefixing.
  413                                  * Also, if we have not scanned zero digits
  414                                  * before this, do not turn off prefixing
  415                                  * (someone else will turn it off if we
  416                                  * have scanned any nonzero digits).
  417                                  */
  418                                 case '':
  419                                         if (base == 0) {
  420                                                 base = 8;
  421                                                 flags |= PFXOK;
  422                                         }
  423                                         if (flags & NZDIGITS)
  424                                             flags &= ~(SIGNOK|NZDIGITS|NDIGITS);
  425                                         else
  426                                             flags &= ~(SIGNOK|PFXOK|NDIGITS);
  427                                         goto ok;
  428 
  429                                 /* 1 through 7 always legal */
  430                                 case '1': case '2': case '3':
  431                                 case '4': case '5': case '6': case '7':
  432                                         base = basefix[base];
  433                                         flags &= ~(SIGNOK | PFXOK | NDIGITS);
  434                                         goto ok;
  435 
  436                                 /* digits 8 and 9 ok iff decimal or hex */
  437                                 case '8': case '9':
  438                                         base = basefix[base];
  439                                         if (base <= 8)
  440                                                 break;  /* not legal here */
  441                                         flags &= ~(SIGNOK | PFXOK | NDIGITS);
  442                                         goto ok;
  443 
  444                                 /* letters ok iff hex */
  445                                 case 'A': case 'B': case 'C':
  446                                 case 'D': case 'E': case 'F':
  447                                 case 'a': case 'b': case 'c':
  448                                 case 'd': case 'e': case 'f':
  449                                         /* no need to fix base here */
  450                                         if (base <= 10)
  451                                                 break;  /* not legal here */
  452                                         flags &= ~(SIGNOK | PFXOK | NDIGITS);
  453                                         goto ok;
  454 
  455                                 /* sign ok only as first character */
  456                                 case '+': case '-':
  457                                         if (flags & SIGNOK) {
  458                                                 flags &= ~SIGNOK;
  459                                                 goto ok;
  460                                         }
  461                                         break;
  462 
  463                                 /* x ok iff flag still set & 2nd char */
  464                                 case 'x': case 'X':
  465                                         if (flags & PFXOK && p == buf + 1) {
  466                                                 base = 16;      /* if %i */
  467                                                 flags &= ~PFXOK;
  468                                                 goto ok;
  469                                         }
  470                                         break;
  471                                 }
  472 
  473                                 /*
  474                                  * If we got here, c is not a legal character
  475                                  * for a number.  Stop accumulating digits.
  476                                  */
  477                                 break;
  478                 ok:
  479                                 /*
  480                                  * c is legal: store it and look at the next.
  481                                  */
  482                                 *p++ = c;
  483                                 if (--inr > 0)
  484                                         inp++;
  485                                 else 
  486                                         break;          /* end of input */
  487                         }
  488                         /*
  489                          * If we had only a sign, it is no good; push
  490                          * back the sign.  If the number ends in `x',
  491                          * it was [sign] '' 'x', so push back the x
  492                          * and treat it as [sign] ''.
  493                          */
  494                         if (flags & NDIGITS) {
  495                                 if (p > buf) {
  496                                         inp--;
  497                                         inr++;
  498                                 }
  499                                 goto match_failure;
  500                         }
  501                         c = ((u_char *)p)[-1];
  502                         if (c == 'x' || c == 'X') {
  503                                 --p;
  504                                 inp--;
  505                                 inr++;
  506                         }
  507                         if ((flags & SUPPRESS) == 0) {
  508                                 u_quad_t res;
  509 
  510                                 *p = 0;
  511                                 res = (*ccfn)(buf, (char **)NULL, base);
  512                                 if (flags & POINTER)
  513                                         *va_arg(ap, void **) =
  514                                                 (void *)(uintptr_t)res;
  515                                 else if (flags & SHORT)
  516                                         *va_arg(ap, short *) = res;
  517                                 else if (flags & LONG)
  518                                         *va_arg(ap, long *) = res;
  519                                 else if (flags & QUAD)
  520                                         *va_arg(ap, quad_t *) = res;
  521                                 else
  522                                         *va_arg(ap, int *) = res;
  523                                 nassigned++;
  524                         }
  525                         nread += p - buf;
  526                         nconversions++;
  527                         break;
  528 
  529                 }
  530         }
  531 input_failure:
  532         return (nconversions != 0 ? nassigned : -1);
  533 match_failure:
  534         return (nassigned);
  535 }
  536 
  537 /*
  538  * Fill in the given table from the scanset at the given format
  539  * (just after `[').  Return a pointer to the character past the
  540  * closing `]'.  The table has a 1 wherever characters should be
  541  * considered part of the scanset.
  542  */
  543 static const u_char *
  544 __sccl(char *tab, const u_char *fmt)
  545 {
  546         int c, n, v;
  547 
  548         /* first `clear' the whole table */
  549         c = *fmt++;             /* first char hat => negated scanset */
  550         if (c == '^') {
  551                 v = 1;          /* default => accept */
  552                 c = *fmt++;     /* get new first char */
  553         } else
  554                 v = 0;          /* default => reject */
  555 
  556         /* XXX: Will not work if sizeof(tab*) > sizeof(char) */
  557         for (n = 0; n < 256; n++)
  558                      tab[n] = v;        /* memset(tab, v, 256) */
  559 
  560         if (c == 0)
  561                 return (fmt - 1);/* format ended before closing ] */
  562 
  563         /*
  564          * Now set the entries corresponding to the actual scanset
  565          * to the opposite of the above.
  566          *
  567          * The first character may be ']' (or '-') without being special;
  568          * the last character may be '-'.
  569          */
  570         v = 1 - v;
  571         for (;;) {
  572                 tab[c] = v;             /* take character c */
  573 doswitch:
  574                 n = *fmt++;             /* and examine the next */
  575                 switch (n) {
  576 
  577                 case 0:                 /* format ended too soon */
  578                         return (fmt - 1);
  579 
  580                 case '-':
  581                         /*
  582                          * A scanset of the form
  583                          *      [01+-]
  584                          * is defined as `the digit 0, the digit 1,
  585                          * the character +, the character -', but
  586                          * the effect of a scanset such as
  587                          *      [a-zA-Z0-9]
  588                          * is implementation defined.  The V7 Unix
  589                          * scanf treats `a-z' as `the letters a through
  590                          * z', but treats `a-a' as `the letter a, the
  591                          * character -, and the letter a'.
  592                          *
  593                          * For compatibility, the `-' is not considerd
  594                          * to define a range if the character following
  595                          * it is either a close bracket (required by ANSI)
  596                          * or is not numerically greater than the character
  597                          * we just stored in the table (c).
  598                          */
  599                         n = *fmt;
  600                         if (n == ']' || n < c) {
  601                                 c = '-';
  602                                 break;  /* resume the for(;;) */
  603                         }
  604                         fmt++;
  605                         /* fill in the range */
  606                         do {
  607                             tab[++c] = v;
  608                         } while (c < n);
  609                         c = n;
  610                         /*
  611                          * Alas, the V7 Unix scanf also treats formats
  612                          * such as [a-c-e] as `the letters a through e'.
  613                          * This too is permitted by the standard....
  614                          */
  615                         goto doswitch;
  616                         break;
  617 
  618                 case ']':               /* end of scanset */
  619                         return (fmt);
  620 
  621                 default:                /* just another character */
  622                         c = n;
  623                         break;
  624                 }
  625         }
  626         /* NOTREACHED */
  627 }
  628 

Cache object: b0ab3ef5584ded191b48b2992c2e8842


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