/* $OpenBSD: cmd-pipe-pane.c,v 1.65 2026/10/09 13:12:14 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 <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",

  .description = "Pipe pane input or output to a command.",

  .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);

}