/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * 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. 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/types.h>

#include <capsicum_helpers.h>
#include <err.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>

#include "extern.h"

int
c_special(int fd1, const char *file1, off_t skip1,
    int fd2, const char *file2, off_t skip2, off_t limit)
{
        int ch1, ch2;
        off_t byte, line;
        FILE *fp1, *fp2;
        int dfound;

        if (caph_limit_stream(fd1, CAPH_READ) < 0)
                err(ERR_EXIT, "caph_limit_stream(%s)", file1);
        if (caph_limit_stream(fd2, CAPH_READ) < 0)
                err(ERR_EXIT, "caph_limit_stream(%s)", file2);
        if (caph_enter() < 0)
                err(ERR_EXIT, "unable to enter capability mode");

        if ((fp1 = fdopen(fd1, "r")) == NULL)
                err(ERR_EXIT, "%s", file1);
        (void)setvbuf(fp1, NULL, _IOFBF, 65536);
        if ((fp2 = fdopen(fd2, "r")) == NULL)
                err(ERR_EXIT, "%s", file2);
        (void)setvbuf(fp2, NULL, _IOFBF, 65536);

        dfound = 0;
        while (skip1--)
                if (getc(fp1) == EOF)
                        goto eof;
        while (skip2--)
                if (getc(fp2) == EOF)
                        goto eof;

        for (byte = line = 1; limit == 0 || byte <= limit; ++byte) {
#ifdef SIGINFO
                if (info) {
                        (void)fprintf(stderr, "%s %s char %zu line %zu\n",
                            file1, file2, (size_t)byte, (size_t)line);
                        info = 0;
                }
#endif
                ch1 = getc(fp1);
                ch2 = getc(fp2);
                if (ch1 == EOF || ch2 == EOF)
                        break;
                if (ch1 != ch2) {
                        if (xflag) {
                                dfound = 1;
                                (void)printf("%08llx %02x %02x\n",
                                    (long long)byte - 1, ch1, ch2);
                        } else if (lflag) {
                                dfound = 1;
                                if (bflag)
                                        (void)printf("%6lld %3o %c %3o %c\n",
                                            (long long)byte, ch1, ch1, ch2,
                                            ch2);
                                else
                                        (void)printf("%6lld %3o %3o\n",
                                            (long long)byte, ch1, ch2);
                        } else {
                                diffmsg(file1, file2, byte, line, ch1, ch2);
                                return (DIFF_EXIT);
                        }
                }
                if (ch1 == '\n')
                        ++line;
        }

eof:    if (ferror(fp1))
                err(ERR_EXIT, "%s", file1);
        if (ferror(fp2))
                err(ERR_EXIT, "%s", file2);
        if (feof(fp1)) {
                if (!feof(fp2)) {
                        eofmsg(file1);
                        return (DIFF_EXIT);
                }
        } else {
                if (feof(fp2)) {
                        eofmsg(file2);
                        return (DIFF_EXIT);
                }
        }
        fclose(fp2);
        fclose(fp1);
        return (dfound ? DIFF_EXIT : 0);
}