subr_scanf.c

Go to the documentation of this file.

/*-
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * From: Id: vfscanf.c,v 1.13 1998/09/25 12:20:27 obrien Exp 
 * From: static char sccsid[] = "@(#)strtol.c   8.1 (Berkeley) 6/4/93";
 * From: static char sccsid[] = "@(#)strtoul.c  8.1 (Berkeley) 6/4/93";
 */

#include <sys/cdefs.h>
__FBSDID("$BSDSUniX$");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ctype.h>
#include <sys/limits.h>

/*
 * Note that stdarg.h and the ANSI style va_start macro is used for both
 * ANSI and traditional C compilers.
 */
#include <machine/stdarg.h>

#define BUF             32      /* Maximum length of numeric string. */

/*
 * Flags used during conversion.
 */
#define LONG            0x01    /* l: long or double */
#define SHORT           0x04    /* h: short */
#define SUPPRESS        0x08    /* suppress assignment */
#define POINTER         0x10    /* weird %p pointer (`fake hex') */
#define NOSKIP          0x20    /* do not skip blanks */
#define QUAD            0x400
#define SHORTSHORT      0x4000  
/*
 * The following are used in numeric conversions only:
 * SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
 * SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
 */
#define SIGNOK          0x40    /* +/- is (still) legal */
#define NDIGITS         0x80    /* no digits detected */

#define DPTOK           0x100   /* (float) decimal point is still legal */
#define EXPOK           0x200   /* (float) exponent (e+3, etc) still legal */

#define PFXOK           0x100   /* 0x prefix is (still) legal */
#define NZDIGITS        0x200   /* no zero digits detected */

/*
 * Conversion types.
 */
#define CT_CHAR         0       /* %c conversion */
#define CT_CCL          1       /* %[...] conversion */
#define CT_STRING       2       /* %s conversion */
#define CT_INT          3       /* integer, i.e., strtoq or strtouq */
typedef u_quad_t (*ccfntype)(const char *, char **, int);

static const u_char *__sccl(char *, const u_char *);

int
sscanf(const char *ibuf, const char *fmt, ...)
{
        va_list ap;
        int ret;
        
        va_start(ap, fmt);
        ret = vsscanf(ibuf, fmt, ap);
        va_end(ap);
        return(ret);
}

int
vsscanf(const char *inp, char const *fmt0, va_list ap)
{
        int inr;
        const u_char *fmt = (const u_char *)fmt0;
        int c;                  /* character from format, or conversion */
        size_t width;           /* field width, or 0 */
        char *p;                /* points into all kinds of strings */
        int n;                  /* handy integer */
        int flags;              /* flags as defined above */
        char *p0;               /* saves original value of p when necessary */
        int nassigned;          /* number of fields assigned */
        int nconversions;       /* number of conversions */
        int nread;              /* number of characters consumed from fp */
        int base;               /* base argument to strtoq/strtouq */
        ccfntype ccfn;          /* conversion function (strtoq/strtouq) */
        char ccltab[256];       /* character class table for %[...] */
        char buf[BUF];          /* buffer for numeric conversions */

        /* `basefix' is used to avoid `if' tests in the integer scanner */
        static short basefix[17] =
                { 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };

        inr = strlen(inp);
        
        nassigned = 0;
        nconversions = 0;
        nread = 0;
        base = 0;               /* XXX just to keep gcc happy */
        ccfn = NULL;            /* XXX just to keep gcc happy */
        for (;;) {
                c = *fmt++;
                if (c == 0)
                        return (nassigned);
                if (isspace(c)) {
                        while (inr > 0 && isspace(*inp))
                                nread++, inr--, inp++;
                        continue;
                }
                if (c != '%')
                        goto literal;
                width = 0;
                flags = 0;
                /*
                 * switch on the format.  continue if done;
                 * break once format type is derived.
                 */
again:          c = *fmt++;
                switch (c) {
                case '%':
literal:
                        if (inr <= 0)
                                goto input_failure;
                        if (*inp != c)
                                goto match_failure;
                        inr--, inp++;
                        nread++;
                        continue;

                case '*':
                        flags |= SUPPRESS;
                        goto again;
                case 'l':
                        if (flags & LONG){
                                flags &= ~LONG;
                                flags |= QUAD;
                        } else {
                                flags |= LONG;
                        }
                        goto again;
                case 'q':
                        flags |= QUAD;
                        goto again;
                case 'h':
                        if (flags & SHORT){
                                flags &= ~SHORT;
                                flags |= SHORTSHORT;
                        } else {
                                flags |= SHORT;
                        }
                        goto again;

                case '0': case '1': case '2': case '3': case '4':
                case '5': case '6': case '7': case '8': case '9':
                        width = width * 10 + c - '0';
                        goto again;

                /*
                 * Conversions.
                 *
                 */
                case 'd':
                        c = CT_INT;
                        ccfn = (ccfntype)strtoq;
                        base = 10;
                        break;

                case 'i':
                        c = CT_INT;
                        ccfn = (ccfntype)strtoq;
                        base = 0;
                        break;

                case 'o':
                        c = CT_INT;
                        ccfn = strtouq;
                        base = 8;
                        break;

                case 'u':
                        c = CT_INT;
                        ccfn = strtouq;
                        base = 10;
                        break;

                case 'x':
                        flags |= PFXOK; /* enable 0x prefixing */
                        c = CT_INT;
                        ccfn = strtouq;
                        base = 16;
                        break;

                case 's':
                        c = CT_STRING;
                        break;

                case '[':
                        fmt = __sccl(ccltab, fmt);
                        flags |= NOSKIP;
                        c = CT_CCL;
                        break;

                case 'c':
                        flags |= NOSKIP;
                        c = CT_CHAR;
                        break;

                case 'p':       /* pointer format is like hex */
                        flags |= POINTER | PFXOK;
                        c = CT_INT;
                        ccfn = strtouq;
                        base = 16;
                        break;

                case 'n':
                        nconversions++;
                        if (flags & SUPPRESS)   /* ??? */
                                continue;
                        if (flags & SHORTSHORT)
                                *va_arg(ap, char *) = nread;
                        else if (flags & SHORT)
                                *va_arg(ap, short *) = nread;
                        else if (flags & LONG)
                                *va_arg(ap, long *) = nread;
                        else if (flags & QUAD)
                                *va_arg(ap, quad_t *) = nread;
                        else
                                *va_arg(ap, int *) = nread;
                        continue;
                }

                /*
                 * We have a conversion that requires input.
                 */
                if (inr <= 0)
                        goto input_failure;

                /*
                 * Consume leading white space, except for formats
                 * that suppress this.
                 */
                if ((flags & NOSKIP) == 0) {
                        while (isspace(*inp)) {
                                nread++;
                                if (--inr > 0)
                                        inp++;
                                else 
                                        goto input_failure;
                        }
                        /*
                         * Note that there is at least one character in
                         * the buffer, so conversions that do not set NOSKIP
                         * can no longer result in an input failure.
                         */
                }

                /*
                 * Do the conversion.
                 */
                switch (c) {

                case CT_CHAR:
                        /* scan arbitrary characters (sets NOSKIP) */
                        if (width == 0)
                                width = 1;
                        if (flags & SUPPRESS) {
                                size_t sum = 0;
                                for (;;) {
                                        if ((n = inr) < width) {
                                                sum += n;
                                                width -= n;
                                                inp += n;
                                                if (sum == 0)
                                                        goto input_failure;
                                                break;
                                        } else {
                                                sum += width;
                                                inr -= width;
                                                inp += width;
                                                break;
                                        }
                                }
                                nread += sum;
                        } else {
                                bcopy(inp, va_arg(ap, char *), width);
                                inr -= width;
                                inp += width;
                                nread += width;
                                nassigned++;
                        }
                        nconversions++;
                        break;

                case CT_CCL:
                        /* scan a (nonempty) character class (sets NOSKIP) */
                        if (width == 0)
                                width = (size_t)~0;     /* `infinity' */
                        /* take only those things in the class */
                        if (flags & SUPPRESS) {
                                n = 0;
                                while (ccltab[(unsigned char)*inp]) {
                                        n++, inr--, inp++;
                                        if (--width == 0)
                                                break;
                                        if (inr <= 0) {
                                                if (n == 0)
                                                        goto input_failure;
                                                break;
                                        }
                                }
                                if (n == 0)
                                        goto match_failure;
                        } else {
                                p0 = p = va_arg(ap, char *);
                                while (ccltab[(unsigned char)*inp]) {
                                        inr--;
                                        *p++ = *inp++;
                                        if (--width == 0)
                                                break;
                                        if (inr <= 0) {
                                                if (p == p0)
                                                        goto input_failure;
                                                break;
                                        }
                                }
                                n = p - p0;
                                if (n == 0)
                                        goto match_failure;
                                *p = 0;
                                nassigned++;
                        }
                        nread += n;
                        nconversions++;
                        break;

                case CT_STRING:
                        /* like CCL, but zero-length string OK, & no NOSKIP */
                        if (width == 0)
                                width = (size_t)~0;
                        if (flags & SUPPRESS) {
                                n = 0;
                                while (!isspace(*inp)) {
                                        n++, inr--, inp++;
                                        if (--width == 0)
                                                break;
                                        if (inr <= 0)
                                                break;
                                }
                                nread += n;
                        } else {
                                p0 = p = va_arg(ap, char *);
                                while (!isspace(*inp)) {
                                        inr--;
                                        *p++ = *inp++;
                                        if (--width == 0)
                                                break;
                                        if (inr <= 0)
                                                break;
                                }
                                *p = 0;
                                nread += p - p0;
                                nassigned++;
                        }
                        nconversions++;
                        continue;

                case CT_INT:
                        /* scan an integer as if by strtoq/strtouq */
#ifdef hardway
                        if (width == 0 || width > sizeof(buf) - 1)
                                width = sizeof(buf) - 1;
#else
                        /* size_t is unsigned, hence this optimisation */
                        if (--width > sizeof(buf) - 2)
                                width = sizeof(buf) - 2;
                        width++;
#endif
                        flags |= SIGNOK | NDIGITS | NZDIGITS;
                        for (p = buf; width; width--) {
                                c = *inp;
                                /*
                                 * Switch on the character; `goto ok'
                                 * if we accept it as a part of number.
                                 */
                                switch (c) {

                                /*
                                 * The digit 0 is always legal, but is
                                 * special.  For %i conversions, if no
                                 * digits (zero or nonzero) have been
                                 * scanned (only signs), we will have
                                 * base==0.  In that case, we should set
                                 * it to 8 and enable 0x prefixing.
                                 * Also, if we have not scanned zero digits
                                 * before this, do not turn off prefixing
                                 * (someone else will turn it off if we
                                 * have scanned any nonzero digits).
                                 */
                                case '0':
                                        if (base == 0) {
                                                base = 8;
                                                flags |= PFXOK;
                                        }
                                        if (flags & NZDIGITS)
                                            flags &= ~(SIGNOK|NZDIGITS|NDIGITS);
                                        else
                                            flags &= ~(SIGNOK|PFXOK|NDIGITS);
                                        goto ok;

                                /* 1 through 7 always legal */
                                case '1': case '2': case '3':
                                case '4': case '5': case '6': case '7':
                                        base = basefix[base];
                                        flags &= ~(SIGNOK | PFXOK | NDIGITS);
                                        goto ok;

                                /* digits 8 and 9 ok iff decimal or hex */
                                case '8': case '9':
                                        base = basefix[base];
                                        if (base <= 8)
                                                break;  /* not legal here */
                                        flags &= ~(SIGNOK | PFXOK | NDIGITS);
                                        goto ok;

                                /* letters ok iff hex */
                                case 'A': case 'B': case 'C':
                                case 'D': case 'E': case 'F':
                                case 'a': case 'b': case 'c':
                                case 'd': case 'e': case 'f':
                                        /* no need to fix base here */
                                        if (base <= 10)
                                                break;  /* not legal here */
                                        flags &= ~(SIGNOK | PFXOK | NDIGITS);
                                        goto ok;

                                /* sign ok only as first character */
                                case '+': case '-':
                                        if (flags & SIGNOK) {
                                                flags &= ~SIGNOK;
                                                goto ok;
                                        }
                                        break;

                                /* x ok iff flag still set & 2nd char */
                                case 'x': case 'X':
                                        if (flags & PFXOK && p == buf + 1) {
                                                base = 16;      /* if %i */
                                                flags &= ~PFXOK;
                                                goto ok;
                                        }
                                        break;
                                }

                                /*
                                 * If we got here, c is not a legal character
                                 * for a number.  Stop accumulating digits.
                                 */
                                break;
                ok:
                                /*
                                 * c is legal: store it and look at the next.
                                 */
                                *p++ = c;
                                if (--inr > 0)
                                        inp++;
                                else 
                                        break;          /* end of input */
                        }
                        /*
                         * If we had only a sign, it is no good; push
                         * back the sign.  If the number ends in `x',
                         * it was [sign] '0' 'x', so push back the x
                         * and treat it as [sign] '0'.
                         */
                        if (flags & NDIGITS) {
                                if (p > buf) {
                                        inp--;
                                        inr++;
                                }
                                goto match_failure;
                        }
                        c = ((u_char *)p)[-1];
                        if (c == 'x' || c == 'X') {
                                --p;
                                inp--;
                                inr++;
                        }
                        if ((flags & SUPPRESS) == 0) {
                                u_quad_t res;

                                *p = 0;
                                res = (*ccfn)(buf, (char **)NULL, base);
                                if (flags & POINTER)
                                        *va_arg(ap, void **) =
                                                (void *)(uintptr_t)res;
                                else if (flags & SHORTSHORT)
                                        *va_arg(ap, char *) = res;
                                else if (flags & SHORT)
                                        *va_arg(ap, short *) = res;
                                else if (flags & LONG)
                                        *va_arg(ap, long *) = res;
                                else if (flags & QUAD)
                                        *va_arg(ap, quad_t *) = res;
                                else
                                        *va_arg(ap, int *) = res;
                                nassigned++;
                        }
                        nread += p - buf;
                        nconversions++;
                        break;

                }
        }
input_failure:
        return (nconversions != 0 ? nassigned : -1);
match_failure:
        return (nassigned);
}

/*
 * Fill in the given table from the scanset at the given format
 * (just after `[').  Return a pointer to the character past the
 * closing `]'.  The table has a 1 wherever characters should be
 * considered part of the scanset.
 */
static const u_char *
__sccl(char *tab, const u_char *fmt)
{
        int c, n, v;

        /* first `clear' the whole table */
        c = *fmt++;             /* first char hat => negated scanset */
        if (c == '^') {
                v = 1;          /* default => accept */
                c = *fmt++;     /* get new first char */
        } else
                v = 0;          /* default => reject */

        /* XXX: Will not work if sizeof(tab*) > sizeof(char) */
        for (n = 0; n < 256; n++)
                     tab[n] = v;        /* memset(tab, v, 256) */

        if (c == 0)
                return (fmt - 1);/* format ended before closing ] */

        /*
         * Now set the entries corresponding to the actual scanset
         * to the opposite of the above.
         *
         * The first character may be ']' (or '-') without being special;
         * the last character may be '-'.
         */
        v = 1 - v;
        for (;;) {
                tab[c] = v;             /* take character c */
doswitch:
                n = *fmt++;             /* and examine the next */
                switch (n) {

                case 0:                 /* format ended too soon */
                        return (fmt - 1);

                case '-':
                        /*
                         * A scanset of the form
                         *      [01+-]
                         * is defined as `the digit 0, the digit 1,
                         * the character +, the character -', but
                         * the effect of a scanset such as
                         *      [a-zA-Z0-9]
                         * is implementation defined.  The V7 Unix
                         * scanf treats `a-z' as `the letters a through
                         * z', but treats `a-a' as `the letter a, the
                         * character -, and the letter a'.
                         *
                         * For compatibility, the `-' is not considerd
                         * to define a range if the character following
                         * it is either a close bracket (required by ANSI)
                         * or is not numerically greater than the character
                         * we just stored in the table (c).
                         */
                        n = *fmt;
                        if (n == ']' || n < c) {
                                c = '-';
                                break;  /* resume the for(;;) */
                        }
                        fmt++;
                        /* fill in the range */
                        do {
                            tab[++c] = v;
                        } while (c < n);
                        c = n;
                        /*
                         * Alas, the V7 Unix scanf also treats formats
                         * such as [a-c-e] as `the letters a through e'.
                         * This too is permitted by the standard....
                         */
                        goto doswitch;
                        break;

                case ']':               /* end of scanset */
                        return (fmt);

                default:                /* just another character */
                        c = n;
                        break;
                }
        }
        /* NOTREACHED */
}