/*
 * $FreeBSD: src/usr.sbin/zic/scheck.c,v 1.4 1999/08/28 01:21:19 peter Exp $
 */
/*LINTLIBRARY*/

#include "private.h"

const char *
scheck(const char * const string, const char * const format)
{
        char *fbuf;
        const char *fp;
        char *tp;
        int c;
        const char *result;
        char dummy;

        result = "";
        if (string == NULL || format == NULL)
                return result;
        fbuf = malloc(2 * strlen(format) + 4);
        if (fbuf == NULL)
                return result;
        fp = format;
        tp = fbuf;

        /*
        ** Copy directives, suppressing each conversion that is not
        ** already suppressed.  Scansets containing '%' are not
        ** supported; e.g., the conversion specification "%[%]" is not
        ** supported.  Also, multibyte characters containing a
        ** non-leading '%' byte are not supported.
        */
        while ((*tp++ = c = *fp++) != '\0') {
                if (c != '%')
                        continue;
                if (is_digit(*fp)) {
                        char const *f = fp;
                        char *t = tp;
                        do {
                                *t++ = c = *f++;
                        } while (is_digit(c));
                        if (c == '$') {
                                fp = f;
                                tp = t;
                        }
                }
                *tp++ = '*';
                if (*fp == '*')
                        ++fp;
                if ((*tp++ = *fp++) == '\0')
                        break;
        }

        *(tp - 1) = '%';
        *tp++ = 'c';
        *tp = '\0';
        if (sscanf(string, fbuf, &dummy) != 1)
                result = format;
        free(fbuf);
        return result;
}