/*
 * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_LICENSE_HEADER_END@
 */
/*-
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 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.
 */

#include <sys/cdefs.h>
#include <stdio.h>
#include <stdlib.h>

#if 0 /* XXX coming soon */
#include <ctype.h>
#else
static inline int
isspace(char c)
{
    return (c == ' ' || c == '\t' || c == '\n' || c == '\12');
}
#endif
#include <stdarg.h>
#include <string.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    /* p: void * (as hex) */
#define    NOSKIP        0x20    /* [ or c: do not skip blanks */
#define    LONGLONG    0x400    /* ll: long long (+ deprecated q: quad) */
#define    SHORTSHORT    0x4000    /* hh: char */
#define    UNSIGNED    0x8000    /* %[oupxX] conversions */

/*
 * 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    /* %[dioupxX] conversion */

static const unsigned char *__sccl(char *, const unsigned 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 unsigned char *fmt = (const unsigned 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 conversion function */
    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 */
    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 |= LONGLONG;
            } else
                flags |= LONG;
            goto again;
        case 'q':
            flags |= LONGLONG;    /* not quite */
            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;
            base = 10;
            break;

        case 'i':
            c = CT_INT;
            base = 0;
            break;

        case 'o':
            c = CT_INT;
            flags |= UNSIGNED;
            base = 8;
            break;

        case 'u':
            c = CT_INT;
            flags |= UNSIGNED;
            base = 10;
            break;

        case 'X':
        case 'x':
            flags |= PFXOK;    /* enable 0x prefixing */
            c = CT_INT;
            flags |= UNSIGNED;
            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;
            flags |= UNSIGNED;
            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 & LONGLONG)
                *va_arg(ap, long long *) = 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) < (int)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);
                memcpy(va_arg(ap, char *), inp, 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 the conversion function */
#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 = ((unsigned char *)p)[-1];
            if (c == 'x' || c == 'X') {
                --p;
                inp--;
                inr++;
            }
            if ((flags & SUPPRESS) == 0) {
                long long res;

                *p = 0;
                if ((flags & UNSIGNED) == 0)
                    res = strtoll(buf, (char **)NULL, base);
                else
                    res = strtoull(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 & LONGLONG)
                    *va_arg(ap, long long *) = 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 unsigned char *
__sccl(char *tab, const unsigned 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) */
    (void) 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 */
}
