/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * Copyright 2010 Nexenta Systems, Inc.  All rights reserved.
 */

#include "lint.h"
#include <stdlib.h>
#include <string.h>
#include <wchar.h>

/*
 * This function is apparently referenced by parts of ON.  It is
 * not intended for public API usage -- and it is not documented.
 *
 * The usage appears to be to consume bytes until a character is
 * gathered, using a supplied function.   It reads exactly one
 * character and returns the number of bytes in the multibyte string
 * that were consumed.
 *
 * The string "s" is storage for the multibyte string, the
 * wc will receive the interpreted character, the peek function
 * obtains the next character (as an int so we can get EOF),
 * and errorc is stuffed with the character that is responsible
 * for a parse error, if any.
 */

int
_mbftowc(char *s, wchar_t *wc, int (*peek)(void), int *errorc)
{
        int             c;
        mbstate_t       mbs;
        char            *start = s;
        size_t          cons = 0;

        for (;;) {
                c = peek();
                if (c < 0) {
                        /* No bytes returned? */
                        return (s - start);
                }

                *s = (char)c;
                s++;

                (void) memset(&mbs, 0, sizeof (mbs));
                cons = mbrtowc(wc, start, s - start, &mbs);
                if ((int)cons >= 0) {
                        /* fully translated character */
                        return (cons);
                }
                if (cons == (size_t)-2) {
                        /* incomplete, recycle */
                        continue;
                }

                /*
                 * Parse error, don't consider the first character part
                 * of the error.
                 */
                s--;
                cons = (s - start);
                *errorc = c >= 0 ?  c : 0;
                break;
        }

        return (cons);
}