/* $OpenBSD: vsscanf.c,v 1.3 2023/10/17 09:52:09 nicm Exp $ */

/****************************************************************************
 * Copyright 2020 Thomas E. Dickey                                          *
 * Copyright 1998-2004,2012 Free Software Foundation, Inc.                  *
 *                                                                          *
 * Permission is hereby granted, free of charge, to any person obtaining a  *
 * copy of this software and associated documentation files (the            *
 * "Software"), to deal in the Software without restriction, including      *
 * without limitation the rights to use, copy, modify, merge, publish,      *
 * distribute, distribute with modifications, sublicense, and/or sell       *
 * copies of the Software, and to permit persons to whom the Software is    *
 * furnished to do so, subject to the following conditions:                 *
 *                                                                          *
 * The above copyright notice and this permission notice shall be included  *
 * in all copies or substantial portions of the Software.                   *
 *                                                                          *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
 *                                                                          *
 * Except as contained in this notice, the name(s) of the above copyright   *
 * holders shall not be used in advertising or otherwise to promote the     *
 * sale, use or other dealings in this Software without prior written       *
 * authorization.                                                           *
 ****************************************************************************/

/****************************************************************************
 *  State-machine fallback written by Thomas E. Dickey 2002                 *
 ****************************************************************************/

/*
 * This function is needed to support vwscanw
 */

#include <curses.priv.h>

#if !HAVE_VSSCANF

MODULE_ID("$Id: vsscanf.c,v 1.3 2023/10/17 09:52:09 nicm Exp $")

#if !(HAVE_VFSCANF || HAVE__DOSCAN)

#include <ctype.h>

#define L_SQUARE '['
#define R_SQUARE ']'

typedef enum {
    cUnknown
    ,cError			/* anything that isn't ANSI */
    ,cAssigned
    ,cChar
    ,cInt
    ,cFloat
    ,cDouble
    ,cPointer
    ,cLong
    ,cShort
    ,cRange
    ,cString
} ChunkType;

typedef enum {
    oUnknown
    ,oShort
    ,oLong
} OtherType;

typedef enum {
    sUnknown
    ,sPercent			/* last was '%' beginning a format */
    ,sNormal			/* ...somewhere in the middle */
    ,sLeft			/* last was left square bracket beginning a range */
    ,sRange			/* ...somewhere in the middle */
    ,sFinal			/* last finished a format */
} ScanState;

static ChunkType
final_ch(int ch, OtherType other)
{
    ChunkType result = cUnknown;

    switch (ch) {
    case 'c':
	if (other == oUnknown)
	    result = cChar;
	else
	    result = cError;
	break;
    case 'd':
    case 'i':
    case 'X':
    case 'x':
	switch (other) {
	case oUnknown:
	    result = cInt;
	    break;
	case oShort:
	    result = cShort;
	    break;
	case oLong:
	    result = cLong;
	    break;
	}
	break;
    case 'E':
    case 'e':
    case 'f':
    case 'g':
	switch (other) {
	case oUnknown:
	    result = cFloat;
	    break;
	case oShort:
	    result = cError;
	    break;
	case oLong:
	    result = cDouble;
	    break;
	}
	break;
    case 'n':
	if (other == oUnknown)
	    result = cAssigned;
	else
	    result = cError;
	break;
    case 'p':
	if (other == oUnknown)
	    result = cPointer;
	else
	    result = cError;
	break;
    case 's':
	if (other == oUnknown)
	    result = cString;
	else
	    result = cError;
	break;
    }
    return result;
}

static OtherType
other_ch(int ch)
{
    OtherType result = oUnknown;
    switch (ch) {
    case 'h':
	result = oShort;
	break;
    case 'l':
	result = oLong;
	break;
    }
    return result;
}
#endif

/*VARARGS2*/
NCURSES_EXPORT(int)
vsscanf(const char *str, const char *format, va_list ap)
{
#if HAVE_VFSCANF || HAVE__DOSCAN
    /*
     * This code should work on anything descended from AT&T SVr1.
     */
    FILE strbuf;

    strbuf._flag = _IOREAD;
    strbuf._ptr = strbuf._base = (unsigned char *) str;
    strbuf._cnt = strlen(str);
    strbuf._file = _NFILE;

#if HAVE_VFSCANF
    return (vfscanf(&strbuf, format, ap));
#else
    return (_doscan(&strbuf, format, ap));
#endif
#else
    static int can_convert = -1;

    int assigned = 0;
    int consumed = 0;

    T((T_CALLED("vsscanf(%s,%s,...)"),
       _nc_visbuf2(1, str),
       _nc_visbuf2(2, format)));

    /*
     * This relies on having a working "%n" format conversion.  Check if it
     * works.  Only very old C libraries do not support it.
     *
     * FIXME: move this check into the configure script.
     */
    if (can_convert < 0) {
	int check1;
	int check2;
	if (sscanf("123", "%d%n", &check1, &check2) > 0
	    && check1 == 123
	    && check2 == 3) {
	    can_convert = 1;
	} else {
	    can_convert = 0;
	}
    }

    if (can_convert) {
	size_t len_fmt = strlen(format) + 32;
	char *my_fmt = malloc(len_fmt);
	ChunkType chunk, ctest;
	OtherType other, otest;
	ScanState state;
	unsigned n;
	int eaten;
	void *pointer;

	if (my_fmt != 0) {
	    /*
	     * Split the original format into chunks, adding a "%n" to the end
	     * of each (except of course if it used %n), and use that
	     * information to decide where to start scanning the next chunk.
	     *
	     * FIXME:  does %n count bytes or characters?  If the latter, this
	     * will require further work for multibyte strings.
	     */
	    while (*format != '\0') {
		/* find a chunk */
		state = sUnknown;
		chunk = cUnknown;
		other = oUnknown;
		pointer = 0;
		for (n = 0; format[n] != 0 && state != sFinal; ++n) {
		    my_fmt[n] = format[n];
		    switch (state) {
		    case sUnknown:
			if (format[n] == '%')
			    state = sPercent;
			break;
		    case sPercent:
			if (format[n] == '%') {
			    state = sUnknown;
			} else if (format[n] == L_SQUARE) {
			    state = sLeft;
			} else {
			    state = sNormal;
			    --n;
			}
			break;
		    case sLeft:
			state = sRange;
			if (format[n] == '^') {
			    ++n;
			    my_fmt[n] = format[n];
			}
			break;
		    case sRange:
			if (format[n] == R_SQUARE) {
			    state = sFinal;
			    chunk = cRange;
			}
			break;
		    case sNormal:
			if (format[n] == '*') {
			    state = sUnknown;
			} else {
			    if ((ctest = final_ch(format[n], other)) != cUnknown) {
				state = sFinal;
				chunk = ctest;
			    } else if ((otest = other_ch(format[n])) != oUnknown) {
				other = otest;
			    } else if (isalpha(UChar(format[n]))) {
				state = sFinal;
				chunk = cError;
			    }
			}
			break;
		    case sFinal:
			break;
		    }
		}
		my_fmt[n] = '\0';
		format += n;

		if (chunk == cUnknown
		    || chunk == cError) {
		    if (assigned == 0)
			assigned = EOF;
		    break;
		}

		/* add %n, if the format was not that */
		if (chunk != cAssigned) {
		    _nc_STRCAT(my_fmt, "%n", len_fmt);
		}

		switch (chunk) {
		case cAssigned:
		    _nc_STRCAT(my_fmt, "%n", len_fmt);
		    pointer = &eaten;
		    break;
		case cInt:
		    pointer = va_arg(ap, int *);
		    break;
		case cShort:
		    pointer = va_arg(ap, short *);
		    break;
		case cFloat:
		    pointer = va_arg(ap, float *);
		    break;
		case cDouble:
		    pointer = va_arg(ap, double *);
		    break;
		case cLong:
		    pointer = va_arg(ap, long *);
		    break;
		case cPointer:
		    pointer = va_arg(ap, void *);
		    break;
		case cChar:
		case cRange:
		case cString:
		    pointer = va_arg(ap, char *);
		    break;
		case cError:
		case cUnknown:
		    break;
		}
		/* do the conversion */
		T(("...converting chunk #%d type %d(%s,%s)",
		   assigned + 1, chunk,
		   _nc_visbuf2(1, str + consumed),
		   _nc_visbuf2(2, my_fmt)));
		if (sscanf(str + consumed, my_fmt, pointer, &eaten) > 0)
		    consumed += eaten;
		else
		    break;
		++assigned;
	    }
	    free(my_fmt);
	}
    }
    returnCode(assigned);
#endif
}
#else
extern
NCURSES_EXPORT(void)
_nc_vsscanf(void);		/* quiet's gcc warning */
NCURSES_EXPORT(void)
_nc_vsscanf(void)
{
}				/* nonempty for strict ANSI compilers */
#endif /* !HAVE_VSSCANF */