cons.handler.c

/*
   Client interface for General purpose Linux console save/restore server

   Copyright (C) 1994-2025
   Free Software Foundation, Inc.

   This file is part of the Midnight Commander.

   The Midnight Commander is free software: you can redistribute it
   and/or modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation, either version 3 of the License,
   or (at your option) any later version.

   The Midnight Commander 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

/** \file cons.handler.c
 *  \brief Source: client %interface for General purpose Linux console save/restore server
 */

#include <config.h>

#include <stdlib.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdio.h>
#include <sys/types.h>
#ifdef __FreeBSD__
#    include <sys/consio.h>
#    ifdef HAVE_SYS_IOCTL_H
#        include <sys/ioctl.h>
#    endif
#endif

#include "lib/global.h"

#include "lib/unixcompat.h"
#include "lib/tty/tty.h"
#include "lib/tty/color.h"  // tty_set_normal_attrs
#include "lib/tty/win.h"
#include "lib/util.h"  // mc_build_filename()

#include "consaver/cons.saver.h"

/*** global variables ****************************************************************************/

#ifdef __linux__
int cons_saver_pid = 1;
#endif

/*** file scope macro definitions ****************************************************************/

#if defined(__FreeBSD__)
#    define FD_OUT 1
#    define cursor_to(x, y)                                                                        \
        do                                                                                         \
        {                                                                                          \
            printf ("\x1B[%d;%df", (y) + 1, (x) + 1);                                              \
            fflush (stdout);                                                                       \
        }                                                                                          \
        while (0)
#endif

/*** file scope type declarations ****************************************************************/

/*** forward declarations (file scope functions) *************************************************/

/*** file scope variables ************************************************************************/

#ifdef __linux__
/* The cons saver can't have a pid of 1, used to prevent bunches of
 * #ifdef linux */
static int pipefd1[2] = { -1, -1 };
static int pipefd2[2] = { -1, -1 };
#elif defined(__FreeBSD__)
static struct scrshot screen_shot;
static struct vid_info screen_info;
#endif

/* --------------------------------------------------------------------------------------------- */
/*** file scope functions ************************************************************************/
/* --------------------------------------------------------------------------------------------- */

#ifdef __linux__
static void
show_console_contents_linux (int starty, unsigned char begin_line, unsigned char end_line)
{
    unsigned char message = 0;
    unsigned short bytes = 0;
    int i;
    ssize_t ret;

    // Is tty console?
    if (mc_global.tty.console_flag == '\0')
        return;
    // Paranoid: Is the cons.saver still running?
    if (cons_saver_pid < 1 || kill (cons_saver_pid, SIGCONT))
    {
        cons_saver_pid = 0;
        mc_global.tty.console_flag = '\0';
        return;
    }

    // Send command to the console handler
    message = CONSOLE_CONTENTS;
    ret = write (pipefd1[1], &message, 1);
    // Check for outdated cons.saver
    ret = read (pipefd2[0], &message, 1);
    if (message != CONSOLE_CONTENTS)
        return;

    // Send the range of lines that we want
    ret = write (pipefd1[1], &begin_line, 1);
    ret = write (pipefd1[1], &end_line, 1);
    // Read the corresponding number of bytes
    ret = read (pipefd2[0], &bytes, 2);

    // Read the bytes and output them
    for (i = 0; i < bytes; i++)
    {
        if ((i % COLS) == 0)
            tty_gotoyx (starty + (i / COLS), 0);
        ret = read (pipefd2[0], &message, 1);
        tty_print_char (message);
    }

    // Read the value of the mc_global.tty.console_flag
    ret = read (pipefd2[0], &message, 1);
    (void) ret;
}

/* --------------------------------------------------------------------------------------------- */

static void
handle_console_linux (console_action_t action)
{
    int status;

    switch (action)
    {
    case CONSOLE_INIT:
        // Close old pipe ends in case it is the 2nd time we run cons.saver
        status = close (pipefd1[1]);
        status = close (pipefd2[0]);
        // Create two pipes for communication
        if (!((pipe (pipefd1) == 0) && ((pipe (pipefd2)) == 0)))
        {
            mc_global.tty.console_flag = '\0';
            break;
        }
        // Get the console saver running
        cons_saver_pid = my_fork ();
        if (cons_saver_pid < 0)
        {
            // Cannot fork
            // Delete pipes
            status = close (pipefd1[1]);
            status = close (pipefd1[0]);
            status = close (pipefd2[1]);
            status = close (pipefd2[0]);
            mc_global.tty.console_flag = '\0';
        }
        else if (cons_saver_pid > 0)
        {
            // Parent
            // Close the extra pipe ends
            status = close (pipefd1[0]);
            status = close (pipefd2[1]);
            // Was the child successful?
            status = read (pipefd2[0], &mc_global.tty.console_flag, 1);
            if (mc_global.tty.console_flag == '\0')
            {
                pid_t ret;
                status = close (pipefd1[1]);
                status = close (pipefd2[0]);
                ret = waitpid (cons_saver_pid, &status, 0);
                (void) ret;
            }
        }
        else
        {
            // Child
            char *tty_name;

            // Close the extra pipe ends
            status = close (pipefd1[1]);
            status = close (pipefd2[0]);
            tty_name = ttyname (0);
            // Bind the pipe 0 to the standard input
            do
            {
                gboolean ok;

                if (dup2 (pipefd1[0], STDIN_FILENO) == -1)
                    break;
                status = close (pipefd1[0]);
                // Bind the pipe 1 to the standard output
                if (dup2 (pipefd2[1], STDOUT_FILENO) == -1)
                    break;

                status = close (pipefd2[1]);
                // Bind standard error to /dev/null
                status = open ("/dev/null", O_WRONLY);
                if (status == -1)
                    break;
                ok = dup2 (status, STDERR_FILENO) != -1;
                status = close (status);
                if (!ok)
                    break;

                if (tty_name != NULL)
                {
                    char *mc_conssaver;

                    // Exec the console save/restore handler
                    mc_conssaver = mc_build_filename (SAVERDIR, "cons.saver", (char *) NULL);
                    execl (mc_conssaver, "cons.saver", tty_name, (char *) NULL);
                }
                // Console is not a tty or execl() failed
            }
            while (0);
            mc_global.tty.console_flag = '\0';
            status = write (1, &mc_global.tty.console_flag, 1);
            my_exit (3);
        }  // if (cons_saver_pid ...)
        break;

    case CONSOLE_DONE:
    case CONSOLE_SAVE:
    case CONSOLE_RESTORE:
        // Is tty console?
        if (mc_global.tty.console_flag == '\0')
            return;
        // Paranoid: Is the cons.saver still running?
        if (cons_saver_pid < 1 || kill (cons_saver_pid, SIGCONT))
        {
            cons_saver_pid = 0;
            mc_global.tty.console_flag = '\0';
            return;
        }
        // Send command to the console handler
        {
            /* Convert enum (i.e. int) to char to write the correct value
             * (the least byte) regardless of machine endianness. */
            char act = (char) action;

            status = write (pipefd1[1], &act, 1);
        }
        if (action != CONSOLE_DONE)
        {
            // Wait the console handler to do its job
            status = read (pipefd2[0], &mc_global.tty.console_flag, 1);
        }
        if (action == CONSOLE_DONE || mc_global.tty.console_flag == '\0')
        {
            // We are done -> Let's clean up
            pid_t ret;
            close (pipefd1[1]);
            close (pipefd2[0]);
            ret = waitpid (cons_saver_pid, &status, 0);
            (void) ret;
            mc_global.tty.console_flag = '\0';
        }
        break;
    default:
        break;
    }
}

#elif defined(__FreeBSD__)

/* --------------------------------------------------------------------------------------------- */
/**
 * FreeBSD support copyright (C) 2003 Alexander Serkov <serkov@ukrpost.net>.
 * Support for screenmaps by Max Khon <fjoe@FreeBSD.org>
 */

static void
console_init (void)
{
    if (mc_global.tty.console_flag != '\0')
        return;

    screen_info.size = sizeof (screen_info);
    if (ioctl (FD_OUT, CONS_GETINFO, &screen_info) == -1)
        return;

    memset (&screen_shot, 0, sizeof (screen_shot));
    screen_shot.xsize = screen_info.mv_csz;
    screen_shot.ysize = screen_info.mv_rsz;
    screen_shot.buf = g_try_malloc (screen_info.mv_csz * screen_info.mv_rsz * 2);
    if (screen_shot.buf != NULL)
        mc_global.tty.console_flag = '\001';
}

/* --------------------------------------------------------------------------------------------- */

static void
set_attr (unsigned attr)
{
    /*
     * Convert color indices returned by SCRSHOT (red=4, green=2, blue=1)
     * to indices for ANSI sequences (red=1, green=2, blue=4).
     */
    static const int color_map[8] = { 0, 4, 2, 6, 1, 5, 3, 7 };
    int bc, tc;

    tc = attr & 0xF;
    bc = (attr >> 4) & 0xF;

    printf ("\x1B[%d;%d;3%d;4%dm", (bc & 8) ? 5 : 25, (tc & 8) ? 1 : 22, color_map[tc & 7],
            color_map[bc & 7]);
}

/* --------------------------------------------------------------------------------------------- */

static void
console_restore (void)
{
    int i, last;

    if (mc_global.tty.console_flag == '\0')
        return;

    cursor_to (0, 0);

    // restoring all content up to cursor position
    last = screen_info.mv_row * screen_info.mv_csz + screen_info.mv_col;
    for (i = 0; i < last; ++i)
    {
        set_attr ((screen_shot.buf[i] >> 8) & 0xFF);
        putc (screen_shot.buf[i] & 0xFF, stdout);
    }

    // restoring cursor color
    set_attr ((screen_shot.buf[last] >> 8) & 0xFF);

    fflush (stdout);
}

/* --------------------------------------------------------------------------------------------- */

static void
console_shutdown (void)
{
    if (mc_global.tty.console_flag == '\0')
        return;

    g_free (screen_shot.buf);

    mc_global.tty.console_flag = '\0';
}

/* --------------------------------------------------------------------------------------------- */

static void
console_save (void)
{
    int i;
    scrmap_t map;
    scrmap_t revmap;

    if (mc_global.tty.console_flag == '\0')
        return;

    // screen_info.size is already set in console_init()
    if (ioctl (FD_OUT, CONS_GETINFO, &screen_info) == -1)
    {
        console_shutdown ();
        return;
    }

    // handle console resize
    if (screen_info.mv_csz != screen_shot.xsize || screen_info.mv_rsz != screen_shot.ysize)
    {
        console_shutdown ();
        console_init ();
    }

    if (ioctl (FD_OUT, CONS_SCRSHOT, &screen_shot) == -1)
    {
        console_shutdown ();
        return;
    }

    if (ioctl (FD_OUT, GIO_SCRNMAP, &map) == -1)
    {
        console_shutdown ();
        return;
    }

    for (i = 0; i < 256; i++)
    {
        char *p = memchr (map.scrmap, i, 256);
        revmap.scrmap[i] = p ? p - map.scrmap : i;
    }

    for (i = 0; i < screen_shot.xsize * screen_shot.ysize; i++)
    {
        screen_shot.buf[i] = (screen_shot.buf[i] & 0xff00)
            | (unsigned char) revmap.scrmap[screen_shot.buf[i] & 0xff];
    }
}

/* --------------------------------------------------------------------------------------------- */

static void
show_console_contents_freebsd (int starty, unsigned char begin_line, unsigned char end_line)
{
    int col, line;
    char c;

    if (mc_global.tty.console_flag == '\0')
        return;

    for (line = begin_line; line <= end_line; line++)
    {
        tty_gotoyx (starty + line - begin_line, 0);
        for (col = 0; col < MIN (COLS, screen_info.mv_csz); col++)
        {
            c = screen_shot.buf[line * screen_info.mv_csz + col] & 0xFF;
            tty_print_char (c);
        }
    }
}

/* --------------------------------------------------------------------------------------------- */

static void
handle_console_freebsd (console_action_t action)
{
    switch (action)
    {
    case CONSOLE_INIT:
        console_init ();
        break;

    case CONSOLE_DONE:
        console_shutdown ();
        break;

    case CONSOLE_SAVE:
        console_save ();
        break;

    case CONSOLE_RESTORE:
        console_restore ();
        break;
    default:
        break;
    }
}
#endif

/* --------------------------------------------------------------------------------------------- */
/*** public functions ****************************************************************************/
/* --------------------------------------------------------------------------------------------- */

void
show_console_contents (int starty, unsigned char begin_line, unsigned char end_line)
{
    tty_set_normal_attrs ();

    if (look_for_rxvt_extensions ())
    {
        show_rxvt_contents (starty, begin_line, end_line);
        return;
    }
#ifdef __linux__
    show_console_contents_linux (starty, begin_line, end_line);
#elif defined(__FreeBSD__)
    show_console_contents_freebsd (starty, begin_line, end_line);
#else
    mc_global.tty.console_flag = '\0';
#endif
}

/* --------------------------------------------------------------------------------------------- */

void
handle_console (console_action_t action)
{
    (void) action;

    if (look_for_rxvt_extensions ())
        return;

#ifdef __linux__
    handle_console_linux (action);
#elif defined(__FreeBSD__)
    handle_console_freebsd (action);
#endif
}

/* --------------------------------------------------------------------------------------------- */