/* $OpenBSD: cmd-pipe-pane.c,v 1.64 2026/07/27 14:25:46 nicm Exp $ */

/*
 * Copyright (c) 2009 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>

#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "tmux.h"

/*
 * Open pipe to redirect pane output. If already open, close first.
 */

static enum cmd_retval  cmd_pipe_pane_exec(struct cmd *, struct cmdq_item *);

static void cmd_pipe_pane_read_callback(struct bufferevent *, void *);
static void cmd_pipe_pane_write_callback(struct bufferevent *, void *);
static void cmd_pipe_pane_error_callback(struct bufferevent *, short, void *);

const struct cmd_entry cmd_pipe_pane_entry = {
        .name = "pipe-pane",
        .alias = "pipep",

        .args = { "IOot:", 0, 1, NULL },
        .usage = "[-IOo] " CMD_TARGET_PANE_USAGE " [shell-command]",

        .target = { 't', CMD_FIND_PANE, 0 },

        .flags = CMD_AFTERHOOK,
        .exec = cmd_pipe_pane_exec
};

static enum cmd_retval
cmd_pipe_pane_exec(struct cmd *self, struct cmdq_item *item)
{
        struct args                     *args = cmd_get_args(self);
        struct cmd_find_state           *target = cmdq_get_target(item);
        struct client                   *tc = cmdq_get_target_client(item);
        struct window_pane              *wp = target->wp;
        struct session                  *s = target->s;
        struct winlink                  *wl = target->wl;
        struct window_pane_offset       *wpo = &wp->pipe_offset;
        char                            *cmd;
        int                              old_fd, pipe_fd[2], null_fd, in, out;
        struct format_tree              *ft;
        sigset_t                         set, oldset;

        /* Do nothing if pane is dead. */
        if (window_pane_exited(wp)) {
                cmdq_error(item, "target pane has exited");
                return (CMD_RETURN_ERROR);
        }

        /* Destroy the old pipe. */
        old_fd = wp->pipe_fd;
        if (wp->pipe_fd != -1) {
                bufferevent_free(wp->pipe_event);
                close(wp->pipe_fd);
                wp->pipe_fd = -1;

                if (window_pane_destroy_ready(wp)) {
                        server_destroy_pane(wp, 1);
                        return (CMD_RETURN_NORMAL);
                }
        }

        /* If no pipe command, that is enough. */
        if (args_count(args) == 0 || *args_string(args, 0) == '\0')
                return (CMD_RETURN_NORMAL);

        /*
         * With -o, only open the new pipe if there was no previous one. This
         * allows a pipe to be toggled with a single key, for example:
         *
         *      bind ^p pipep -o 'cat >>~/output'
         */
        if (args_has(args, 'o') && old_fd != -1)
                return (CMD_RETURN_NORMAL);

        /* What do we want to do? Neither -I or -O is -O. */
        if (args_has(args, 'I')) {
                in = 1;
                out = args_has(args, 'O');
        } else {
                in = 0;
                out = 1;
        }

        /* Open the new pipe. */
        if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe_fd) != 0) {
                cmdq_error(item, "socketpair error: %s", strerror(errno));
                return (CMD_RETURN_ERROR);
        }

        /* Expand the command. */
        ft = format_create(cmdq_get_client(item), item, FORMAT_NONE, 0);
        format_defaults(ft, tc, s, wl, wp);
        cmd = format_expand_time(ft, args_string(args, 0));
        format_free(ft);

        /* Fork the child. */
        sigfillset(&set);
        sigprocmask(SIG_BLOCK, &set, &oldset);
        switch ((wp->pipe_pid = fork())) {
        case -1:
                sigprocmask(SIG_SETMASK, &oldset, NULL);
                cmdq_error(item, "fork error: %s", strerror(errno));

                close(pipe_fd[0]);
                close(pipe_fd[1]);
                free(cmd);
                return (CMD_RETURN_ERROR);
        case 0:
                /* Child process. */
                proc_clear_signals(server_proc, 1);
                sigprocmask(SIG_SETMASK, &oldset, NULL);
                close(pipe_fd[0]);

                if (setpgid(0, 0) == -1)
                        _exit(1);

                null_fd = open(_PATH_DEVNULL, O_WRONLY);
                if (out) {
                        if (dup2(pipe_fd[1], STDIN_FILENO) == -1)
                                _exit(1);
                } else {
                        if (dup2(null_fd, STDIN_FILENO) == -1)
                                _exit(1);
                }
                if (in) {
                        if (dup2(pipe_fd[1], STDOUT_FILENO) == -1)
                                _exit(1);
                        if (pipe_fd[1] != STDOUT_FILENO)
                                close(pipe_fd[1]);
                } else {
                        if (dup2(null_fd, STDOUT_FILENO) == -1)
                                _exit(1);
                }
                if (dup2(null_fd, STDERR_FILENO) == -1)
                        _exit(1);
                closefrom(STDERR_FILENO + 1);

                execl(_PATH_BSHELL, "sh", "-c", cmd, (char *) NULL);
                _exit(1);
        default:
                /* Parent process. */
                sigprocmask(SIG_SETMASK, &oldset, NULL);
                close(pipe_fd[1]);

                wp->pipe_fd = pipe_fd[0];
                memcpy(wpo, &wp->offset, sizeof *wpo);

                setblocking(wp->pipe_fd, 0);
                wp->pipe_event = bufferevent_new(wp->pipe_fd,
                    cmd_pipe_pane_read_callback,
                    cmd_pipe_pane_write_callback,
                    cmd_pipe_pane_error_callback,
                    wp);
                if (wp->pipe_event == NULL)
                        fatalx("out of memory");
                if (out)
                        bufferevent_enable(wp->pipe_event, EV_WRITE);
                if (in)
                        bufferevent_enable(wp->pipe_event, EV_READ);

                free(cmd);
                return (CMD_RETURN_NORMAL);
        }
}

static void
cmd_pipe_pane_read_callback(__unused struct bufferevent *bufev, void *data)
{
        struct window_pane      *wp = data;
        struct evbuffer         *evb;
        size_t                   available;

        if (wp->pipe_event == NULL)
                return;
        evb = wp->pipe_event->input;

        available = EVBUFFER_LENGTH(evb);
        log_debug("%%%u pipe read %zu", wp->id, available);

        bufferevent_write(wp->event, EVBUFFER_DATA(evb), available);
        evbuffer_drain(evb, available);

        if (window_pane_destroy_ready(wp))
                server_destroy_pane(wp, 1);
}

static void
cmd_pipe_pane_write_callback(__unused struct bufferevent *bufev, void *data)
{
        struct window_pane      *wp = data;

        log_debug("%%%u pipe empty", wp->id);

        if (window_pane_destroy_ready(wp))
                server_destroy_pane(wp, 1);
}

static void
cmd_pipe_pane_error_callback(__unused struct bufferevent *bufev,
    __unused short what, void *data)
{
        struct window_pane      *wp = data;

        log_debug("%%%u pipe error", wp->id);

        bufferevent_free(wp->pipe_event);
        close(wp->pipe_fd);
        wp->pipe_fd = -1;

        if (window_pane_destroy_ready(wp))
                server_destroy_pane(wp, 1);
}