libexplain/ungetc_on_error.c

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/*
 * libexplain - Explain errno values returned by libc functions
 * Copyright (C) 2010, 2012, 2013 Peter Miller
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
 * General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <libexplain/ac/errno.h>
#include <libexplain/ac/stdio.h>

#include <libexplain/ungetc.h>
#include <libexplain/output.h>


int
explain_ungetc_on_error(int c, FILE *fp)
{
    int             hold_errno;
    int             result;

    hold_errno = errno;
    errno = 0;
    result = ungetc(c, fp);
    if (result == EOF)
    {
        hold_errno = errno;
        if (hold_errno == 0)
            hold_errno = EINVAL;
        explain_output_error("%s", explain_errno_ungetc(hold_errno, c, fp));
    }
    errno = hold_errno;
    return result;
}


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