/*-
 * Copyright (c) 2017 Baptiste Daroussin <bapt@FreeBSD.org>
 * 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
 *    in this position and unchanged.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``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 AUTHOR(S) 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/procdesc.h>
#include <sys/wait.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <signal.h>
#include <spawn.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "pr.h"
#include "diff.h"
#include "xmalloc.h"

#define _PATH_PR "/usr/bin/pr"

extern char **environ;

struct pr *
start_pr(char *file1, char *file2)
{
        int pfd[2];
        pid_t pid;
        char *header;
        struct pr *pr;
        posix_spawn_file_actions_t fa;
        posix_spawnattr_t sa;
        int error;

        pr = xcalloc(1, sizeof(*pr));

        xasprintf(&header, "%s %s %s", diffargs, file1, file2);
        signal(SIGPIPE, SIG_IGN);
        fflush(stdout);
        if (pipe2(pfd, O_CLOEXEC) == -1)
                err(2, "pipe");

        if ((error = posix_spawnattr_init(&sa)) != 0)
                errc(2, error, "posix_spawnattr_init");
        if ((error = posix_spawn_file_actions_init(&fa)) != 0)
                errc(2, error, "posix_spawn_file_actions_init");

        posix_spawnattr_setprocdescp_np(&sa, &pr->procd, 0);

        if (pfd[0] != STDIN_FILENO)
                posix_spawn_file_actions_adddup2(&fa, pfd[0], STDIN_FILENO);

        char *argv[] = { __DECONST(char *, _PATH_PR),
            __DECONST(char *, "-h"), header, NULL };
        error = posix_spawn(&pid, _PATH_PR, &fa, &sa, argv, environ);
        if (error != 0)
                errc(2, error, "could not spawn pr");

        posix_spawn_file_actions_destroy(&fa);
        posix_spawnattr_destroy(&sa);

        /* parent */
        if (pfd[1] == STDOUT_FILENO) {
                pr->ostdout = STDOUT_FILENO;
        } else {
                if ((pr->ostdout = dup(STDOUT_FILENO)) < 0 ||
                    dup2(pfd[1], STDOUT_FILENO) < 0) {
                        err(2, "stdout");
                }
                close(pfd[1]);
        }
        close(pfd[0]);
        free(header);
        return (pr);
}

/* close the pipe to pr and restore stdout */
void
stop_pr(struct pr *pr)
{
        int wstatus;

        if (pr == NULL)
                return;

        fflush(stdout);
        if (pr->ostdout != STDOUT_FILENO) {
                dup2(pr->ostdout, STDOUT_FILENO);
                close(pr->ostdout);
        }
        while (pdwait(pr->procd, &wstatus, WEXITED, NULL, NULL) == -1) {
                if (errno != EINTR)
                        err(2, "pdwait");
        }
        close(pr->procd);
        free(pr);
        if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) != 0)
                errx(2, "pr exited abnormally");
        else if (WIFSIGNALED(wstatus))
                errx(2, "pr killed by signal %d",
                    WTERMSIG(wstatus));
}