Adding upstream version 3:4.8.29.upstream/3%4.8.29upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1870 insertions, 0 deletions

diff --git a/src/subshell/common.c b/src/subshell/common.c
new file mode 100644
index 0000000..61bf527
--- /dev/null
+++ b/src/subshell/common.c
@@ -0,0 +1,1870 @@
+/*
+   Concurrent shell support for the Midnight Commander
+
+   Copyright (C) 1994-2022
+   Free Software Foundation, Inc.
+
+   Written by:
+   Alexander Kriegisch <Alexander@Kriegisch.name>
+   Aliaksey Kandratsenka <alk@tut.by>
+   Andreas Mohr <and@gmx.li>
+   Andrew Borodin <aborodin@vmail.ru>
+   Andrew V. Samoilov <sav@bcs.zp.ua>
+   Chris Owen <chris@candu.co.uk>
+   Claes Nästén <me@pekdon.net>
+   Egmont Koblinger <egmont@gmail.com>
+   Enrico Weigelt, metux IT service <weigelt@metux.de>
+   Eric Roberts <ericmrobertsdeveloper@gmail.com>
+   Igor Urazov <z0rc3r@gmail.com>
+   Ilia Maslakov <il.smind@gmail.com>
+   Leonard den Ottolander <leonard@den.ottolander.nl>
+   Miguel de Icaza <miguel@novell.com>
+   Mikhail S. Pobolovets <styx.mp@gmail.com>
+   Norbert Warmuth <nwarmuth@privat.circular.de>
+   Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
+   Patrick Winnertz <winnie@debian.org>
+   Pavel Machek <pavel@suse.cz>
+   Pavel Roskin <proski@gnu.org>
+   Pavel Tsekov <ptsekov@gmx.net>
+   Roland Illig <roland.illig@gmx.de>
+   Sergei Trofimovich <slyfox@inbox.ru>
+   Slava Zanko <slavazanko@gmail.com>
+   Timur Bakeyev <mc@bat.ru>
+   Vit Rosin <vit_r@list.ru>
+
+   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 <http://www.gnu.org/licenses/>.
+ */
+
+/** \file subshell.c
+ *  \brief Source: concurrent shell support
+ */
+
+#include <config.h>
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#endif
+
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <signal.h>
+#ifdef HAVE_SYS_SELECT_H
+#include <sys/select.h>
+#else
+#include <sys/time.h>
+#include <unistd.h>
+#endif
+#include <sys/types.h>
+#include <sys/wait.h>
+#ifdef HAVE_SYS_IOCTL_H
+#include <sys/ioctl.h>
+#endif
+#include <termios.h>
+
+#ifdef HAVE_STROPTS_H
+#include <stropts.h>            /* For I_PUSH */
+#endif /* HAVE_STROPTS_H */
+
+#ifdef HAVE_OPENPTY
+/* includes for openpty() */
+#ifdef HAVE_PTY_H
+#include <pty.h>
+#endif
+#ifdef HAVE_UTIL_H
+#include <util.h>
+#endif
+/* <sys/types.h> is a prerequisite of <libutil.h> on FreeBSD 8.0.  */
+#ifdef HAVE_LIBUTIL_H
+#include <libutil.h>
+#endif
+#endif /* HAVE_OPENPTY */
+
+#include "lib/global.h"
+
+#include "lib/fileloc.h"
+#include "lib/unixcompat.h"
+#include "lib/tty/tty.h"        /* LINES */
+#include "lib/tty/key.h"        /* XCTRL */
+#include "lib/vfs/vfs.h"
+#include "lib/strutil.h"
+#include "lib/mcconfig.h"
+#include "lib/util.h"
+#include "lib/widget.h"
+
+#include "src/filemanager/layout.h"     /* setup_cmdline() */
+#include "src/filemanager/command.h"    /* cmdline */
+
+#include "subshell.h"
+#include "internal.h"
+
+/*** global variables ****************************************************************************/
+
+/* State of the subshell:
+ * INACTIVE: the default state; awaiting a command
+ * ACTIVE: remain in the shell until the user hits 'subshell_switch_key'
+ * RUNNING_COMMAND: return to MC when the current command finishes */
+enum subshell_state_enum subshell_state;
+
+/* Holds the latest prompt captured from the subshell */
+GString *subshell_prompt = NULL;
+
+/* Subshell: if set, then the prompt was not saved on CONSOLE_SAVE */
+/* We need to paint it after CONSOLE_RESTORE, see: load_prompt */
+gboolean update_subshell_prompt = FALSE;
+
+/* If set, then a command has just finished executing, and we need */
+/* to be on the lookout for a new prompt string from the subshell. */
+gboolean should_read_new_subshell_prompt;
+
+/*** file scope macro definitions ****************************************************************/
+
+#ifndef WEXITSTATUS
+#define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
+#endif
+
+#ifndef WIFEXITED
+#define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
+#endif
+
+/* Initial length of the buffer for the subshell's prompt */
+#define INITIAL_PROMPT_SIZE 10
+
+/* Used by the child process to indicate failure to start the subshell */
+#define FORK_FAILURE 69         /* Arbitrary */
+
+/* Length of the buffer for all I/O with the subshell */
+#define PTY_BUFFER_SIZE BUF_MEDIUM      /* Arbitrary; but keep it >= 80 */
+
+/*** file scope type declarations ****************************************************************/
+
+/* For pipes */
+enum
+{
+    READ = 0,
+    WRITE = 1
+};
+
+/* This is the keybinding that is sent to the shell, to make the shell send us the contents of
+ * the current command buffer. */
+#define SHELL_BUFFER_KEYBINDING "_"
+
+/* This is the keybinding that is sent to the shell, to make the shell send us the location of
+ * the cursor. */
+#define SHELL_CURSOR_KEYBINDING "+"
+
+/*** file scope variables ************************************************************************/
+
+/* tcsh closes all non-standard file descriptors, so we have to use a pipe */
+static char tcsh_fifo[128];
+
+static int subshell_pty_slave = -1;
+
+/* The key for switching back to MC from the subshell */
+/* *INDENT-OFF* */
+static const char subshell_switch_key = XCTRL ('o') & 255;
+/* *INDENT-ON* */
+
+/* For reading/writing on the subshell's pty */
+static char pty_buffer[PTY_BUFFER_SIZE] = "\0";
+
+/* To pass CWD info from the subshell to MC */
+static int subshell_pipe[2];
+
+/* To pass command buffer info from the subshell to MC */
+static int command_buffer_pipe[2];
+
+/* The subshell's process ID */
+static pid_t subshell_pid = 1;
+
+/* One extra char for final '\n' */
+static char subshell_cwd[MC_MAXPATHLEN + 1];
+
+/* Flag to indicate whether the subshell is ready for next command */
+static int subshell_ready;
+
+/* Flag to indicate if the subshell supports the persistent buffer feature. */
+static gboolean use_persistent_buffer = FALSE;
+
+/* This is the local variable where the subshell prompt is stored while we are working on it. */
+static GString *subshell_prompt_temp_buffer = NULL;
+
+/* The following two flags can be changed by the SIGCHLD handler. This is */
+/* OK, because the 'int' type is updated atomically on all known machines */
+static volatile int subshell_alive, subshell_stopped;
+
+/* We store the terminal's initial mode here so that we can configure
+   the pty similarly, and also so we can restore the real terminal to
+   sanity if we have to exit abruptly */
+static struct termios shell_mode;
+
+/* This is a transparent mode for the terminal where MC is running on */
+/* It is used when the shell is active, so that the control signals */
+/* are delivered to the shell pty */
+static struct termios raw_mode;
+
+/* --------------------------------------------------------------------------------------------- */
+/*** file scope functions ************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+/**
+ *  Write all data, even if the write() call is interrupted.
+ */
+
+static ssize_t
+write_all (int fd, const void *buf, size_t count)
+{
+    ssize_t written = 0;
+
+    while (count > 0)
+    {
+        ssize_t ret;
+
+        ret = write (fd, (const unsigned char *) buf + written, count);
+        if (ret < 0)
+        {
+            if (errno == EINTR)
+            {
+                if (tty_got_winch ())
+                    tty_change_screen_size ();
+
+                continue;
+            }
+
+            return written > 0 ? written : ret;
+        }
+        count -= ret;
+        written += ret;
+    }
+    return written;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ *  Prepare child process to running the shell and run it.
+ *
+ *  Modifies the global variables (in the child process only):
+ *      shell_mode
+ *
+ *  Returns: never.
+ */
+
+static void
+init_subshell_child (const char *pty_name)
+{
+    char *init_file = NULL;
+    pid_t mc_sid;
+
+    (void) pty_name;
+    setsid ();                  /* Get a fresh terminal session */
+
+    /* Make sure that it has become our controlling terminal */
+
+    /* Redundant on Linux and probably most systems, but just in case: */
+
+#ifdef TIOCSCTTY
+    ioctl (subshell_pty_slave, TIOCSCTTY, 0);
+#endif
+
+    /* Configure its terminal modes and window size */
+
+    /* Set up the pty with the same termios flags as our own tty */
+    if (tcsetattr (subshell_pty_slave, TCSANOW, &shell_mode))
+    {
+        fprintf (stderr, "Cannot set pty terminal modes: %s\r\n", unix_error_string (errno));
+        my_exit (FORK_FAILURE);
+    }
+
+    /* Set the pty's size (80x25 by default on Linux) according to the */
+    /* size of the real terminal as calculated by ncurses, if possible */
+    tty_resize (subshell_pty_slave);
+
+    /* Set up the subshell's environment and init file name */
+
+    /* It simplifies things to change to our home directory here, */
+    /* and the user's startup file may do a 'cd' command anyway   */
+    {
+        int ret;
+
+        ret = chdir (mc_config_get_home_dir ());        /* FIXME? What about when we re-run the subshell? */
+        (void) ret;
+    }
+
+    /* Set MC_SID to prevent running one mc from another */
+    mc_sid = getsid (0);
+    if (mc_sid != -1)
+    {
+        char sid_str[BUF_SMALL];
+
+        g_snprintf (sid_str, sizeof (sid_str), "MC_SID=%ld", (long) mc_sid);
+        putenv (g_strdup (sid_str));
+    }
+
+    switch (mc_global.shell->type)
+    {
+    case SHELL_BASH:
+        /* Do we have a custom init file ~/.local/share/mc/bashrc? */
+        init_file = mc_config_get_full_path (MC_BASHRC_FILE);
+
+        /* Otherwise use ~/.bashrc */
+        if (!exist_file (init_file))
+        {
+            g_free (init_file);
+            init_file = g_strdup (".bashrc");
+        }
+
+        /* Make MC's special commands not show up in bash's history and also suppress
+         * consecutive identical commands*/
+        putenv ((char *) "HISTCONTROL=ignoreboth");
+
+        /* Allow alternative readline settings for MC */
+        {
+            char *input_file;
+
+            input_file = mc_config_get_full_path (MC_INPUTRC_FILE);
+            if (exist_file (input_file))
+                g_setenv ("INPUTRC", input_file, TRUE);
+            g_free (input_file);
+        }
+
+        break;
+
+    case SHELL_ASH_BUSYBOX:
+    case SHELL_DASH:
+        /* Do we have a custom init file ~/.local/share/mc/ashrc? */
+        init_file = mc_config_get_full_path (MC_ASHRC_FILE);
+
+        /* Otherwise use ~/.profile */
+        if (!exist_file (init_file))
+        {
+            g_free (init_file);
+            init_file = g_strdup (".profile");
+        }
+
+        /* Put init file to ENV variable used by ash */
+        g_setenv ("ENV", init_file, TRUE);
+
+        break;
+
+    case SHELL_ZSH:
+        /* ZDOTDIR environment variable is the only way to point zsh
+         * to an other rc file than the default. */
+
+        /* Don't overwrite $ZDOTDIR */
+        if (g_getenv ("ZDOTDIR") != NULL)
+        {
+            /* Do we have a custom init file ~/.local/share/mc/.zshrc?
+             * Otherwise use standard ~/.zshrc */
+            init_file = mc_config_get_full_path (MC_ZSHRC_FILE);
+            if (exist_file (init_file))
+            {
+                /* Set ZDOTDIR to ~/.local/share/mc */
+                g_setenv ("ZDOTDIR", mc_config_get_data_path (), TRUE);
+            }
+        }
+        break;
+
+        /* TODO: Find a way to pass initfile to TCSH and FISH */
+    case SHELL_TCSH:
+    case SHELL_FISH:
+        break;
+
+    default:
+        fprintf (stderr, __FILE__ ": unimplemented subshell type %u\r\n", mc_global.shell->type);
+        my_exit (FORK_FAILURE);
+    }
+
+    /* Attach all our standard file descriptors to the pty */
+
+    /* This is done just before the exec, because stderr must still      */
+    /* be connected to the real tty during the above error messages; */
+    /* otherwise the user will never see them.                   */
+
+    dup2 (subshell_pty_slave, STDIN_FILENO);
+    dup2 (subshell_pty_slave, STDOUT_FILENO);
+    dup2 (subshell_pty_slave, STDERR_FILENO);
+
+    close (subshell_pipe[READ]);
+
+    if (use_persistent_buffer)
+        close (command_buffer_pipe[READ]);
+
+    close (subshell_pty_slave); /* These may be FD_CLOEXEC, but just in case... */
+    /* Close master side of pty.  This is important; apart from */
+    /* freeing up the descriptor for use in the subshell, it also       */
+    /* means that when MC exits, the subshell will get a SIGHUP and     */
+    /* exit too, because there will be no more descriptors pointing     */
+    /* at the master side of the pty and so it will disappear.  */
+    close (mc_global.tty.subshell_pty);
+
+    /* Execute the subshell at last */
+
+    switch (mc_global.shell->type)
+    {
+    case SHELL_BASH:
+        execl (mc_global.shell->path, "bash", "-rcfile", init_file, (char *) NULL);
+        break;
+
+    case SHELL_ZSH:
+        /* Use -g to exclude cmds beginning with space from history
+         * and -Z to use the line editor on non-interactive term */
+        execl (mc_global.shell->path, "zsh", "-Z", "-g", (char *) NULL);
+        break;
+
+    case SHELL_ASH_BUSYBOX:
+    case SHELL_DASH:
+    case SHELL_TCSH:
+    case SHELL_FISH:
+        execl (mc_global.shell->path, mc_global.shell->path, (char *) NULL);
+        break;
+
+    default:
+        break;
+    }
+
+    /* If we get this far, everything failed miserably */
+    g_free (init_file);
+    my_exit (FORK_FAILURE);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+init_raw_mode (void)
+{
+    static gboolean initialized = FALSE;
+
+    /* MC calls tty_reset_shell_mode() in pre_exec() to set the real tty to its */
+    /* original settings.  However, here we need to make this tty very raw,     */
+    /* so that all keyboard signals, XON/XOFF, etc. will get through to the     */
+    /* pty.  So, instead of changing the code for execute(), pre_exec(),        */
+    /* etc, we just set up the modes we need here, before each command.         */
+
+    if (!initialized)           /* First time: initialise 'raw_mode' */
+    {
+        tcgetattr (STDOUT_FILENO, &raw_mode);
+        raw_mode.c_lflag &= ~ICANON;    /* Disable line-editing chars, etc.   */
+        raw_mode.c_lflag &= ~ISIG;      /* Disable intr, quit & suspend chars */
+        raw_mode.c_lflag &= ~ECHO;      /* Disable input echoing              */
+        raw_mode.c_iflag &= ~IXON;      /* Pass ^S/^Q to subshell undisturbed */
+        raw_mode.c_iflag &= ~ICRNL;     /* Don't translate CRs into LFs       */
+        raw_mode.c_oflag &= ~OPOST;     /* Don't postprocess output           */
+        raw_mode.c_cc[VTIME] = 0;       /* IE: wait forever, and return as    */
+        raw_mode.c_cc[VMIN] = 1;        /* soon as a character is available   */
+        initialized = TRUE;
+    }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Wait until the subshell dies or stops.  If it stops, make it resume.
+ * Possibly modifies the globals 'subshell_alive' and 'subshell_stopped'
+ */
+
+static void
+synchronize (void)
+{
+    sigset_t sigchld_mask, old_mask;
+
+    sigemptyset (&sigchld_mask);
+    sigaddset (&sigchld_mask, SIGCHLD);
+    sigprocmask (SIG_BLOCK, &sigchld_mask, &old_mask);
+
+    /*
+     * SIGCHLD should not be blocked, but we unblock it just in case.
+     * This is known to be useful for cygwin 1.3.12 and older.
+     */
+    sigdelset (&old_mask, SIGCHLD);
+
+    /* Wait until the subshell has stopped */
+    while (subshell_alive && !subshell_stopped)
+        sigsuspend (&old_mask);
+
+    if (subshell_state != ACTIVE)
+    {
+        /* Discard all remaining data from stdin to the subshell */
+        tcflush (subshell_pty_slave, TCIFLUSH);
+    }
+
+    subshell_stopped = FALSE;
+    kill (subshell_pid, SIGCONT);
+
+    sigprocmask (SIG_SETMASK, &old_mask, NULL);
+    /* We can't do any better without modifying the shell(s) */
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/* Get the contents of the current subshell command line buffer, and */
+/* transfer the contents to the panel command prompt. */
+
+static gboolean
+read_command_line_buffer (gboolean test_mode)
+{
+    char subshell_command_buffer[BUF_LARGE];
+    char subshell_cursor_buffer[BUF_SMALL];
+
+    fd_set read_set;
+    int i;
+    ssize_t bytes;
+    struct timeval subshell_prompt_timer = { 0, 0 };
+    int command_buffer_length;
+    int command_buffer_char_length;
+    int bash_version;
+    int cursor_position;
+    int maxfdp;
+    int rc;
+
+    if (!use_persistent_buffer)
+        return TRUE;
+
+    FD_ZERO (&read_set);
+    FD_SET (command_buffer_pipe[READ], &read_set);
+    maxfdp = command_buffer_pipe[READ];
+
+    /* First, flush the command buffer pipe. This pipe shouldn't be written
+     * to under normal circumstances, but if it somehow does get written
+     * to, we need to make sure to discard whatever data is there before
+     * we try to use it. */
+    while ((rc = select (maxfdp + 1, &read_set, NULL, NULL, &subshell_prompt_timer)) != 0)
+    {
+        if (rc == -1)
+        {
+            if (errno == EINTR)
+                continue;
+
+            return FALSE;
+        }
+
+        if (rc == 1)
+        {
+            bytes = read (command_buffer_pipe[READ], subshell_command_buffer,
+                          sizeof (subshell_command_buffer));
+            (void) bytes;
+        }
+    }
+
+    /* get contents of command line buffer */
+    write_all (mc_global.tty.subshell_pty, ESC_STR SHELL_BUFFER_KEYBINDING,
+               sizeof (ESC_STR SHELL_CURSOR_KEYBINDING) - 1);
+
+    subshell_prompt_timer.tv_sec = 1;
+    FD_ZERO (&read_set);
+    FD_SET (command_buffer_pipe[READ], &read_set);
+
+    while ((rc = select (maxfdp + 1, &read_set, NULL, NULL, &subshell_prompt_timer)) != 1)
+    {
+        if (rc == -1)
+        {
+            if (errno == EINTR)
+                continue;
+
+            return FALSE;
+        }
+
+        if (rc == 0)
+            return FALSE;
+    }
+
+    bytes =
+        read (command_buffer_pipe[READ], subshell_command_buffer, sizeof (subshell_command_buffer));
+    if (bytes == 0 || bytes == sizeof (subshell_command_buffer))
+        return FALSE;
+
+    command_buffer_char_length = bytes - 1;
+    subshell_command_buffer[command_buffer_char_length] = '\0';
+    command_buffer_length = str_length (subshell_command_buffer);
+
+    /* get cursor position */
+    write_all (mc_global.tty.subshell_pty, ESC_STR SHELL_CURSOR_KEYBINDING,
+               sizeof (ESC_STR SHELL_CURSOR_KEYBINDING) - 1);
+
+    subshell_prompt_timer.tv_sec = 1;
+    subshell_prompt_timer.tv_usec = 0;
+    FD_ZERO (&read_set);
+    FD_SET (command_buffer_pipe[READ], &read_set);
+
+    while ((rc = select (maxfdp + 1, &read_set, NULL, NULL, &subshell_prompt_timer)) != 1)
+    {
+        if (rc == -1)
+        {
+            if (errno == EINTR)
+                continue;
+
+            return FALSE;
+        }
+
+        if (rc == 0)
+            return FALSE;
+    }
+
+    bytes =
+        read (command_buffer_pipe[READ], subshell_cursor_buffer, sizeof (subshell_cursor_buffer));
+    if (bytes == 0)
+        return FALSE;
+
+    subshell_cursor_buffer[bytes - 1] = '\0';
+    if (mc_global.shell->type == SHELL_BASH)
+    {
+        if (sscanf (subshell_cursor_buffer, "%d:%d", &bash_version, &cursor_position) != 2)
+            return FALSE;
+    }
+    else
+    {
+        if (sscanf (subshell_cursor_buffer, "%d", &cursor_position) != 1)
+            return FALSE;
+        bash_version = 1000;
+    }
+
+    if (test_mode)
+        return TRUE;
+
+    /* Substitute non-text characters in the command buffer, such as tab, or newline, as this
+     * could cause problems. */
+    for (i = 0; i < command_buffer_char_length; i++)
+        if ((unsigned char) subshell_command_buffer[i] < 32
+            || (unsigned char) subshell_command_buffer[i] == 127)
+            subshell_command_buffer[i] = ' ';
+
+    input_assign_text (cmdline, "");
+    input_insert (cmdline, subshell_command_buffer, FALSE);
+
+    if (bash_version < 5)       /* implies SHELL_BASH */
+    {
+        /* We need to do this because bash < v5 gives the cursor position in a utf-8 string based
+         * on the location in bytes, not in unicode characters. */
+        char *curr, *stop;
+
+        curr = subshell_command_buffer;
+        stop = curr + cursor_position;
+
+        for (cursor_position = 0; curr < stop; cursor_position++)
+            str_next_char_safe (&curr);
+    }
+    if (cursor_position > command_buffer_length)
+        cursor_position = command_buffer_length;
+    cmdline->point = cursor_position;
+    /* We send any remaining data to STDOUT before we finish. */
+    flush_subshell (0, VISIBLY);
+
+    /* Now we erase the current contents of the command line buffer */
+    if (mc_global.shell->type != SHELL_ZSH)
+    {
+        /* In zsh, we can just press c-u to clear the line, without needing to go to the end of
+         * the line first first. In all other shells, we must go to the end of the line first. */
+
+        /* If we are not at the end of the line, we go to the end. */
+        if (cursor_position != command_buffer_length)
+        {
+            write_all (mc_global.tty.subshell_pty, "\005", 1);
+            if (flush_subshell (1, VISIBLY) != 1)
+                return FALSE;
+        }
+    }
+
+    if (command_buffer_length > 0)
+    {
+        /* Now we clear the line. */
+        write_all (mc_global.tty.subshell_pty, "\025", 1);
+        if (flush_subshell (1, VISIBLY) != 1)
+            return FALSE;
+    }
+
+    return TRUE;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+clear_subshell_prompt_string (void)
+{
+    if (subshell_prompt_temp_buffer != NULL)
+        g_string_set_size (subshell_prompt_temp_buffer, 0);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+parse_subshell_prompt_string (const char *buffer, int bytes)
+{
+    int i;
+
+    if (mc_global.mc_run_mode != MC_RUN_FULL)
+        return;
+
+    /* First time through */
+    if (subshell_prompt == NULL)
+        subshell_prompt = g_string_sized_new (INITIAL_PROMPT_SIZE);
+    if (subshell_prompt_temp_buffer == NULL)
+        subshell_prompt_temp_buffer = g_string_sized_new (INITIAL_PROMPT_SIZE);
+
+    /* Extract the prompt from the shell output */
+    for (i = 0; i < bytes; i++)
+        if (buffer[i] == '\n' || buffer[i] == '\r')
+            g_string_set_size (subshell_prompt_temp_buffer, 0);
+        else if (buffer[i] != '\0')
+            g_string_append_c (subshell_prompt_temp_buffer, buffer[i]);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+set_prompt_string (void)
+{
+    if (mc_global.mc_run_mode != MC_RUN_FULL)
+        return;
+
+    if (subshell_prompt_temp_buffer->len != 0)
+        mc_g_string_copy (subshell_prompt, subshell_prompt_temp_buffer);
+
+    setup_cmdline ();
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/** Feed the subshell our keyboard input until it says it's finished */
+
+static gboolean
+feed_subshell (int how, gboolean fail_on_error)
+{
+    fd_set read_set;            /* For 'select' */
+    int bytes;                  /* For the return value from 'read' */
+    int i;                      /* Loop counter */
+
+    struct timeval wtime;       /* Maximum time we wait for the subshell */
+    struct timeval *wptr;
+
+    should_read_new_subshell_prompt = FALSE;
+
+    /* have more than enough time to run subshell:
+       wait up to 10 second if fail_on_error, forever otherwise */
+    wtime.tv_sec = 10;
+    wtime.tv_usec = 0;
+    wptr = fail_on_error ? &wtime : NULL;
+
+    while (TRUE)
+    {
+        int maxfdp;
+
+        if (!subshell_alive)
+            return FALSE;
+
+        /* Prepare the file-descriptor set and call 'select' */
+
+        FD_ZERO (&read_set);
+        FD_SET (mc_global.tty.subshell_pty, &read_set);
+        FD_SET (subshell_pipe[READ], &read_set);
+        maxfdp = MAX (mc_global.tty.subshell_pty, subshell_pipe[READ]);
+        if (how == VISIBLY)
+        {
+            FD_SET (STDIN_FILENO, &read_set);
+            maxfdp = MAX (maxfdp, STDIN_FILENO);
+        }
+
+        if (select (maxfdp + 1, &read_set, NULL, NULL, wptr) == -1)
+        {
+            /* Despite using SA_RESTART, we still have to check for this */
+            if (errno == EINTR)
+            {
+                if (tty_got_winch ())
+                    tty_change_screen_size ();
+
+                continue;       /* try all over again */
+            }
+            tcsetattr (STDOUT_FILENO, TCSANOW, &shell_mode);
+            fprintf (stderr, "select (FD_SETSIZE, &read_set...): %s\r\n",
+                     unix_error_string (errno));
+            exit (EXIT_FAILURE);
+        }
+
+        if (FD_ISSET (mc_global.tty.subshell_pty, &read_set))
+            /* Read from the subshell, write to stdout */
+
+            /* This loop improves performance by reducing context switches
+               by a factor of 20 or so... unfortunately, it also hangs MC
+               randomly, because of an apparent Linux bug.  Investigate. */
+            /* for (i=0; i<5; ++i)  * FIXME -- experimental */
+        {
+            bytes = read (mc_global.tty.subshell_pty, pty_buffer, sizeof (pty_buffer));
+
+            /* The subshell has died */
+            if (bytes == -1 && errno == EIO && !subshell_alive)
+                return FALSE;
+
+            if (bytes <= 0)
+            {
+#ifdef PTY_ZEROREAD
+                /* On IBM i, read(1) can return 0 for a non-closed fd */
+                continue;
+#else
+                tcsetattr (STDOUT_FILENO, TCSANOW, &shell_mode);
+                fprintf (stderr, "read (subshell_pty...): %s\r\n", unix_error_string (errno));
+                exit (EXIT_FAILURE);
+#endif
+            }
+
+            if (how == VISIBLY)
+                write_all (STDOUT_FILENO, pty_buffer, bytes);
+
+            if (should_read_new_subshell_prompt)
+                parse_subshell_prompt_string (pty_buffer, bytes);
+        }
+
+        else if (FD_ISSET (subshell_pipe[READ], &read_set))
+            /* Read the subshell's CWD and capture its prompt */
+        {
+            bytes = read (subshell_pipe[READ], subshell_cwd, sizeof (subshell_cwd));
+            if (bytes <= 0)
+            {
+                tcsetattr (STDOUT_FILENO, TCSANOW, &shell_mode);
+                fprintf (stderr, "read (subshell_pipe[READ]...): %s\r\n",
+                         unix_error_string (errno));
+                exit (EXIT_FAILURE);
+            }
+
+            subshell_cwd[bytes - 1] = '\0';     /* Squash the final '\n' */
+
+            synchronize ();
+
+            clear_subshell_prompt_string ();
+            should_read_new_subshell_prompt = TRUE;
+            subshell_ready = TRUE;
+            if (subshell_state == RUNNING_COMMAND)
+            {
+                subshell_state = INACTIVE;
+                return TRUE;
+            }
+        }
+
+        else if (FD_ISSET (STDIN_FILENO, &read_set))
+            /* Read from stdin, write to the subshell */
+        {
+            should_read_new_subshell_prompt = FALSE;
+            bytes = read (STDIN_FILENO, pty_buffer, sizeof (pty_buffer));
+            if (bytes <= 0)
+            {
+                tcsetattr (STDOUT_FILENO, TCSANOW, &shell_mode);
+                fprintf (stderr,
+                         "read (STDIN_FILENO, pty_buffer...): %s\r\n", unix_error_string (errno));
+                exit (EXIT_FAILURE);
+            }
+
+            for (i = 0; i < bytes; ++i)
+                if (pty_buffer[i] == subshell_switch_key)
+                {
+                    write_all (mc_global.tty.subshell_pty, pty_buffer, i);
+
+                    if (subshell_ready)
+                    {
+                        subshell_state = INACTIVE;
+                        set_prompt_string ();
+                        if (subshell_ready && !read_command_line_buffer (FALSE))
+                        {
+                            /* If we got here, some unforseen error must have occurred. */
+                            if (mc_global.shell->type != SHELL_FISH)
+                            {
+                                write_all (mc_global.tty.subshell_pty, "\003", 1);
+                                subshell_state = RUNNING_COMMAND;
+                                if (feed_subshell (QUIETLY, TRUE))
+                                    if (read_command_line_buffer (FALSE))
+                                        return TRUE;
+                            }
+                            subshell_state = ACTIVE;
+                            flush_subshell (0, VISIBLY);
+                            input_assign_text (cmdline, "");
+                        }
+                    }
+
+                    return TRUE;
+                }
+
+            write_all (mc_global.tty.subshell_pty, pty_buffer, bytes);
+
+            if (pty_buffer[bytes - 1] == '\n' || pty_buffer[bytes - 1] == '\r')
+            {
+                /* We should only clear the command line if we are using a shell that works
+                 * with persistent command buffer, otherwise we get awkward results. */
+                if (use_persistent_buffer)
+                    input_assign_text (cmdline, "");
+                subshell_ready = FALSE;
+            }
+        }
+        else
+            return FALSE;
+    }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/* pty opening functions */
+
+#ifndef HAVE_OPENPTY
+
+#ifdef HAVE_GRANTPT
+
+/* System V version of pty_open_master */
+
+static int
+pty_open_master (char *pty_name)
+{
+    char *slave_name;
+    int pty_master;
+
+#ifdef HAVE_POSIX_OPENPT
+    pty_master = posix_openpt (O_RDWR);
+#elif defined HAVE_GETPT
+    /* getpt () is a GNU extension (glibc 2.1.x) */
+    pty_master = getpt ();
+#elif defined IS_AIX
+    strcpy (pty_name, "/dev/ptc");
+    pty_master = open (pty_name, O_RDWR);
+#else
+    strcpy (pty_name, "/dev/ptmx");
+    pty_master = open (pty_name, O_RDWR);
+#endif
+
+    if (pty_master == -1)
+        return -1;
+
+    if (grantpt (pty_master) == -1      /* Grant access to slave */
+        || unlockpt (pty_master) == -1  /* Clear slave's lock flag */
+        || !(slave_name = ptsname (pty_master)))        /* Get slave's name */
+    {
+        close (pty_master);
+        return -1;
+    }
+    strcpy (pty_name, slave_name);
+    return pty_master;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/** System V version of pty_open_slave */
+
+static int
+pty_open_slave (const char *pty_name)
+{
+    int pty_slave;
+
+    pty_slave = open (pty_name, O_RDWR);
+    if (pty_slave == -1)
+    {
+        fprintf (stderr, "open (%s, O_RDWR): %s\r\n", pty_name, unix_error_string (errno));
+        return -1;
+    }
+#if !defined(__osf__) && !defined(__linux__)
+#if defined (I_FIND) && defined (I_PUSH)
+    if (ioctl (pty_slave, I_FIND, "ptem") == 0)
+        if (ioctl (pty_slave, I_PUSH, "ptem") == -1)
+        {
+            fprintf (stderr, "ioctl (%d, I_PUSH, \"ptem\") failed: %s\r\n",
+                     pty_slave, unix_error_string (errno));
+            close (pty_slave);
+            return -1;
+        }
+
+    if (ioctl (pty_slave, I_FIND, "ldterm") == 0)
+        if (ioctl (pty_slave, I_PUSH, "ldterm") == -1)
+        {
+            fprintf (stderr,
+                     "ioctl (%d, I_PUSH, \"ldterm\") failed: %s\r\n",
+                     pty_slave, unix_error_string (errno));
+            close (pty_slave);
+            return -1;
+        }
+#if !defined(sgi) && !defined(__sgi)
+    if (ioctl (pty_slave, I_FIND, "ttcompat") == 0)
+        if (ioctl (pty_slave, I_PUSH, "ttcompat") == -1)
+        {
+            fprintf (stderr,
+                     "ioctl (%d, I_PUSH, \"ttcompat\") failed: %s\r\n",
+                     pty_slave, unix_error_string (errno));
+            close (pty_slave);
+            return -1;
+        }
+#endif /* sgi || __sgi */
+#endif /* I_FIND && I_PUSH */
+#endif /* __osf__ || __linux__ */
+
+    fcntl (pty_slave, F_SETFD, FD_CLOEXEC);
+    return pty_slave;
+}
+
+#else /* !HAVE_GRANTPT */
+
+/* --------------------------------------------------------------------------------------------- */
+/** BSD version of pty_open_master */
+static int
+pty_open_master (char *pty_name)
+{
+    int pty_master;
+    const char *ptr1, *ptr2;
+
+    strcpy (pty_name, "/dev/ptyXX");
+    for (ptr1 = "pqrstuvwxyzPQRST"; *ptr1; ++ptr1)
+    {
+        pty_name[8] = *ptr1;
+        for (ptr2 = "0123456789abcdef"; *ptr2 != '\0'; ++ptr2)
+        {
+            pty_name[9] = *ptr2;
+
+            /* Try to open master */
+            pty_master = open (pty_name, O_RDWR);
+            if (pty_master == -1)
+            {
+                if (errno == ENOENT)    /* Different from EIO */
+                    return -1;  /* Out of pty devices */
+                continue;       /* Try next pty device */
+            }
+            pty_name[5] = 't';  /* Change "pty" to "tty" */
+            if (access (pty_name, 6) != 0)
+            {
+                close (pty_master);
+                pty_name[5] = 'p';
+                continue;
+            }
+            return pty_master;
+        }
+    }
+    return -1;                  /* Ran out of pty devices */
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/** BSD version of pty_open_slave */
+
+static int
+pty_open_slave (const char *pty_name)
+{
+    int pty_slave;
+    struct group *group_info;
+
+    group_info = getgrnam ("tty");
+    if (group_info != NULL)
+    {
+        /* The following two calls will only succeed if we are root */
+        /* [Commented out while permissions problem is investigated] */
+        /* chown (pty_name, getuid (), group_info->gr_gid);  FIXME */
+        /* chmod (pty_name, S_IRUSR | S_IWUSR | S_IWGRP);   FIXME */
+    }
+    pty_slave = open (pty_name, O_RDWR);
+    if (pty_slave == -1)
+        fprintf (stderr, "open (pty_name, O_RDWR): %s\r\n", pty_name);
+    fcntl (pty_slave, F_SETFD, FD_CLOEXEC);
+    return pty_slave;
+}
+#endif /* !HAVE_GRANTPT */
+
+#endif /* !HAVE_OPENPTY */
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Set up `precmd' or equivalent for reading the subshell's CWD.
+ *
+ * Attention! Never forget that these are *one-liners* even though the concatenated
+ * substrings contain line breaks and indentation for better understanding of the
+ * shell code. It is vital that each one-liner ends with a line feed character ("\n" ).
+ *
+ * @return initialized pre-command string
+ */
+
+static void
+init_subshell_precmd (char *precmd, size_t buff_size)
+{
+    switch (mc_global.shell->type)
+    {
+    case SHELL_BASH:
+        g_snprintf (precmd, buff_size,
+                    " mc_print_command_buffer () { printf \"%%s\\\\n\" \"$READLINE_LINE\" >&%d; }\n"
+                    " bind -x '\"\\e" SHELL_BUFFER_KEYBINDING "\":\"mc_print_command_buffer\"'\n"
+                    " bind -x '\"\\e" SHELL_CURSOR_KEYBINDING
+                    "\":\"echo $BASH_VERSINFO:$READLINE_POINT >&%d\"'\n"
+                    " PROMPT_COMMAND=${PROMPT_COMMAND:+$PROMPT_COMMAND\n}'pwd>&%d;kill -STOP $$'\n"
+                    "PS1='\\u@\\h:\\w\\$ '\n", command_buffer_pipe[WRITE],
+                    command_buffer_pipe[WRITE], subshell_pipe[WRITE]);
+        break;
+
+    case SHELL_ASH_BUSYBOX:
+        /* BusyBox ash needs a somewhat complicated precmd emulation via PS1, and it is vital
+         * that BB be built with active CONFIG_ASH_EXPAND_PRMT, but this is the default anyway.
+         *
+         * A: This leads to a stopped subshell (=frozen mc) if user calls "ash" command
+         *    "PS1='$(pwd>&%d; kill -STOP $$)\\u@\\h:\\w\\$ '\n",
+         *
+         * B: This leads to "sh: precmd: not found" in sub-subshell if user calls "ash" command
+         *    "precmd() { pwd>&%d; kill -STOP $$; }; "
+         *    "PS1='$(precmd)\\u@\\h:\\w\\$ '\n",
+         *
+         * C: This works if user calls "ash" command because in sub-subshell
+         *    PRECMD is undefined, thus evaluated to empty string - no damage done.
+         *    Attention: BusyBox must be built with FEATURE_EDITING_FANCY_PROMPT to
+         *    permit \u, \w, \h, \$ escape sequences. Unfortunately this cannot be guaranteed,
+         *    especially on embedded systems where people try to save space, so let's use
+         *    the dash version below. It should work on virtually all systems.
+         *    "precmd() { pwd>&%d; kill -STOP $$; }; "
+         *    "PRECMD=precmd; "
+         *    "PS1='$(eval $PRECMD)\\u@\\h:\\w\\$ '\n",
+         */
+    case SHELL_DASH:
+        /* Debian ash needs a precmd emulation via PS1, similar to BusyBox ash,
+         * but does not support escape sequences for user, host and cwd in prompt.
+         * Attention! Make sure that the buffer for precmd is big enough.
+         *
+         * We want to have a fancy dynamic prompt with user@host:cwd just like in the BusyBox
+         * examples above, but because replacing the home directory part of the path by "~" is
+         * complicated, it bloats the precmd to a size > BUF_SMALL (128).
+         *
+         * The following example is a little less fancy (home directory not replaced)
+         * and shows the basic workings of our prompt for easier understanding:
+         *
+         * "precmd() { "
+         *     "echo \"$USER@$(hostname -s):$PWD\"; "
+         *     "pwd>&%d; "
+         *     "kill -STOP $$; "
+         * "}; "
+         * "PRECMD=precmd; "
+         * "PS1='$($PRECMD)$ '\n",
+         */
+        g_snprintf (precmd, buff_size,
+                    "precmd() { "
+                    "if [ ! \"${PWD##$HOME}\" ]; then "
+                    "MC_PWD=\"~\"; "
+                    "else "
+                    "[ \"${PWD##$HOME/}\" = \"$PWD\" ] && MC_PWD=\"$PWD\" || MC_PWD=\"~/${PWD##$HOME/}\"; "
+                    "fi; "
+                    "echo \"$USER@$(hostname -s):$MC_PWD\"; "
+                    "pwd>&%d; "
+                    "kill -STOP $$; "
+                    "}; " "PRECMD=precmd; " "PS1='$($PRECMD)$ '\n", subshell_pipe[WRITE]);
+        break;
+
+    case SHELL_ZSH:
+        g_snprintf (precmd, buff_size,
+                    " mc_print_command_buffer () { printf \"%%s\\\\n\" \"$BUFFER\" >&%d; }\n"
+                    " zle -N mc_print_command_buffer\n"
+                    " bindkey '^[" SHELL_BUFFER_KEYBINDING "' mc_print_command_buffer\n"
+                    " mc_print_cursor_position () { echo $CURSOR >&%d}\n"
+                    " zle -N mc_print_cursor_position\n"
+                    " bindkey '^[" SHELL_CURSOR_KEYBINDING "' mc_print_cursor_position\n"
+                    " _mc_precmd(){ pwd>&%d;kill -STOP $$ }; precmd_functions+=(_mc_precmd)\n"
+                    "PS1='%%n@%%m:%%~%%# '\n",
+                    command_buffer_pipe[WRITE], command_buffer_pipe[WRITE], subshell_pipe[WRITE]);
+        break;
+
+    case SHELL_TCSH:
+        g_snprintf (precmd, buff_size,
+                    "set echo_style=both; "
+                    "set prompt='%%n@%%m:%%~%%# '; "
+                    "alias precmd 'echo -n;echo $cwd:q >>%s; kill -STOP $$'\n", tcsh_fifo);
+        break;
+    case SHELL_FISH:
+        g_snprintf (precmd, buff_size,
+                    " bind \\e" SHELL_BUFFER_KEYBINDING " 'commandline >&%d';"
+                    "bind \\e" SHELL_CURSOR_KEYBINDING " 'commandline -C >&%d';"
+                    "if not functions -q fish_prompt_mc;"
+                    "functions -e fish_right_prompt;"
+                    "functions -c fish_prompt fish_prompt_mc; end;"
+                    "function fish_prompt;"
+                    "echo \"$PWD\">&%d; fish_prompt_mc; kill -STOP %%self; end\n",
+                    command_buffer_pipe[WRITE], command_buffer_pipe[WRITE], subshell_pipe[WRITE]);
+        break;
+
+    default:
+        break;
+    }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Carefully quote directory name to allow entering any directory safely,
+ * no matter what weird characters it may contain in its name.
+ * NOTE: Treat directory name an untrusted data, don't allow it to cause
+ * executing any commands in the shell.  Escape all control characters.
+ * Use following technique:
+ *
+ * printf(1) with format string containing a single conversion specifier,
+ * "b", and an argument which contains a copy of the string passed to 
+ * subshell_name_quote() with all characters, except digits and letters,
+ * replaced by the backslash-escape sequence \0nnn, where "nnn" is the
+ * numeric value of the character converted to octal number.
+ * 
+ *   cd "`printf '%b' 'ABC\0nnnDEF\0nnnXYZ'`"
+ *
+ * N.B.: Use single quotes for conversion specifier to work around
+ *       tcsh 6.20+ parser breakage, see ticket #3852 for the details.
+ */
+
+static GString *
+subshell_name_quote (const char *s)
+{
+    GString *ret;
+    const char *su, *n;
+    const char *quote_cmd_start, *quote_cmd_end;
+
+    if (mc_global.shell->type == SHELL_FISH)
+    {
+        quote_cmd_start = "(printf '%b' '";
+        quote_cmd_end = "')";
+    }
+    /* TODO: When BusyBox printf is fixed, get rid of this "else if", see
+       http://lists.busybox.net/pipermail/busybox/2012-March/077460.html */
+    /* else if (subshell_type == ASH_BUSYBOX)
+       {
+       quote_cmd_start = "\"`echo -en '";
+       quote_cmd_end = "'`\"";
+       } */
+    else
+    {
+        quote_cmd_start = "\"`printf '%b' '";
+        quote_cmd_end = "'`\"";
+    }
+
+    ret = g_string_sized_new (64);
+
+    /* Prevent interpreting leading '-' as a switch for 'cd' */
+    if (s[0] == '-')
+        g_string_append (ret, "./");
+
+    /* Copy the beginning of the command to the buffer */
+    g_string_append (ret, quote_cmd_start);
+
+    /*
+     * Print every character except digits and letters as a backslash-escape
+     * sequence of the form \0nnn, where "nnn" is the numeric value of the
+     * character converted to octal number.
+     */
+    for (su = s; su[0] != '\0'; su = n)
+    {
+        n = str_cget_next_char_safe (su);
+
+        if (str_isalnum (su))
+            g_string_append_len (ret, su, n - su);
+        else
+        {
+            int c;
+
+            for (c = 0; c < n - su; c++)
+                g_string_append_printf (ret, "\\0%03o", (unsigned char) su[c]);
+        }
+    }
+
+    g_string_append (ret, quote_cmd_end);
+
+    return ret;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * This function checks the pipe from which we receive data about the current working directory.
+ * If there is any data waiting, we clear it.
+ */
+
+static void
+clear_cwd_pipe (void)
+{
+    fd_set read_set;
+    struct timeval wtime = { 0, 0 };
+    int maxfdp;
+
+    FD_ZERO (&read_set);
+    FD_SET (subshell_pipe[READ], &read_set);
+    maxfdp = subshell_pipe[READ];
+
+    if (select (maxfdp + 1, &read_set, NULL, NULL, &wtime) > 0
+        && FD_ISSET (subshell_pipe[READ], &read_set))
+    {
+        if (read (subshell_pipe[READ], subshell_cwd, sizeof (subshell_cwd)) <= 0)
+        {
+            tcsetattr (STDOUT_FILENO, TCSANOW, &shell_mode);
+            fprintf (stderr, "read (subshell_pipe[READ]...): %s\r\n", unix_error_string (errno));
+            exit (EXIT_FAILURE);
+        }
+
+        synchronize ();
+    }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/*** public functions ****************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ *  Fork the subshell, and set up many, many things.
+ *
+ *  Possibly modifies the global variables:
+ *      subshell_type, subshell_alive, subshell_stopped, subshell_pid
+ *      mc_global.tty.use_subshell - Is set to FALSE if we can't run the subshell
+ *      quit - Can be set to SUBSHELL_EXIT by the SIGCHLD handler
+ */
+
+void
+init_subshell (void)
+{
+    /* This must be remembered across calls to init_subshell() */
+    static char pty_name[BUF_SMALL];
+    /* Must be considerably longer than BUF_SMALL (128) to support fancy shell prompts */
+    char precmd[BUF_MEDIUM];
+
+    /* Take the current (hopefully pristine) tty mode and make */
+    /* a raw mode based on it now, before we do anything else with it */
+    init_raw_mode ();
+
+    if (mc_global.tty.subshell_pty == 0)
+    {                           /* First time through */
+        if (mc_global.shell->type == SHELL_NONE)
+            return;
+
+        /* Open a pty for talking to the subshell */
+
+        /* FIXME: We may need to open a fresh pty each time on SVR4 */
+
+#ifdef HAVE_OPENPTY
+        if (openpty (&mc_global.tty.subshell_pty, &subshell_pty_slave, NULL, NULL, NULL))
+        {
+            fprintf (stderr, "Cannot open master and slave sides of pty: %s\n",
+                     unix_error_string (errno));
+            mc_global.tty.use_subshell = FALSE;
+            return;
+        }
+#else
+        mc_global.tty.subshell_pty = pty_open_master (pty_name);
+        if (mc_global.tty.subshell_pty == -1)
+        {
+            fprintf (stderr, "Cannot open master side of pty: %s\r\n", unix_error_string (errno));
+            mc_global.tty.use_subshell = FALSE;
+            return;
+        }
+        subshell_pty_slave = pty_open_slave (pty_name);
+        if (subshell_pty_slave == -1)
+        {
+            fprintf (stderr, "Cannot open slave side of pty %s: %s\r\n",
+                     pty_name, unix_error_string (errno));
+            mc_global.tty.use_subshell = FALSE;
+            return;
+        }
+#endif /* HAVE_OPENPTY */
+
+        /* Create a pipe for receiving the subshell's CWD */
+
+        if (mc_global.shell->type == SHELL_TCSH)
+        {
+            g_snprintf (tcsh_fifo, sizeof (tcsh_fifo), "%s/mc.pipe.%d",
+                        mc_tmpdir (), (int) getpid ());
+            if (mkfifo (tcsh_fifo, 0600) == -1)
+            {
+                fprintf (stderr, "mkfifo(%s) failed: %s\r\n", tcsh_fifo, unix_error_string (errno));
+                mc_global.tty.use_subshell = FALSE;
+                return;
+            }
+
+            /* Opening the FIFO as O_RDONLY or O_WRONLY causes deadlock */
+
+            if ((subshell_pipe[READ] = open (tcsh_fifo, O_RDWR)) == -1
+                || (subshell_pipe[WRITE] = open (tcsh_fifo, O_RDWR)) == -1)
+            {
+                fprintf (stderr, _("Cannot open named pipe %s\n"), tcsh_fifo);
+                perror (__FILE__ ": open");
+                mc_global.tty.use_subshell = FALSE;
+                return;
+            }
+        }
+        else if (pipe (subshell_pipe) != 0)     /* subshell_type is BASH, ASH_BUSYBOX, DASH or ZSH */
+        {
+            perror (__FILE__ ": couldn't create pipe");
+            mc_global.tty.use_subshell = FALSE;
+            return;
+        }
+
+        if (mc_global.mc_run_mode == MC_RUN_FULL &&
+            (mc_global.shell->type == SHELL_BASH || mc_global.shell->type == SHELL_ZSH
+             || mc_global.shell->type == SHELL_FISH))
+            use_persistent_buffer = TRUE;
+        if (use_persistent_buffer && pipe (command_buffer_pipe) != 0)
+        {
+            perror (__FILE__ ": couldn't create pipe");
+            mc_global.tty.use_subshell = FALSE;
+            return;
+        }
+    }
+
+    /* Fork the subshell */
+
+    subshell_alive = TRUE;
+    subshell_stopped = FALSE;
+    subshell_pid = fork ();
+
+    if (subshell_pid == -1)
+    {
+        fprintf (stderr, "Cannot spawn the subshell process: %s\r\n", unix_error_string (errno));
+        /* We exit here because, if the process table is full, the */
+        /* other method of running user commands won't work either */
+        exit (EXIT_FAILURE);
+    }
+
+    if (subshell_pid == 0)
+    {
+        /* We are in the child process */
+        init_subshell_child (pty_name);
+    }
+
+    init_subshell_precmd (precmd, BUF_MEDIUM);
+
+    write_all (mc_global.tty.subshell_pty, precmd, strlen (precmd));
+
+    /* Wait until the subshell has started up and processed the command */
+
+    subshell_state = RUNNING_COMMAND;
+    tty_enable_interrupt_key ();
+    if (!feed_subshell (QUIETLY, TRUE))
+        mc_global.tty.use_subshell = FALSE;
+    tty_disable_interrupt_key ();
+    if (!subshell_alive)
+        mc_global.tty.use_subshell = FALSE;     /* Subshell died instantly, so don't use it */
+
+    /* Try out the persistent command buffer feature. If it doesn't work the first time, we
+     * assume there must be something wrong with the shell, and we turn persistent buffer off
+     * for good. This will save the user the trouble of having to wait for the persistent
+     * buffer function to time out every time they try to close the subshell. */
+    if (use_persistent_buffer && !read_command_line_buffer (TRUE))
+        use_persistent_buffer = FALSE;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+int
+invoke_subshell (const char *command, int how, vfs_path_t ** new_dir_vpath)
+{
+    /* Make the MC terminal transparent */
+    tcsetattr (STDOUT_FILENO, TCSANOW, &raw_mode);
+
+    /* Make the subshell change to MC's working directory */
+    if (new_dir_vpath != NULL)
+        do_subshell_chdir (subshell_get_cwd (), TRUE);
+
+    if (command == NULL)        /* The user has done "C-o" from MC */
+    {
+        if (subshell_state == INACTIVE)
+        {
+            subshell_state = ACTIVE;
+
+            /* FIXME: possibly take out this hack; the user can re-play it by hitting C-hyphen a few times! */
+            if (subshell_ready && mc_global.mc_run_mode == MC_RUN_FULL)
+                write_all (mc_global.tty.subshell_pty, " \b", 2);       /* Hack to make prompt reappear */
+
+            if (use_persistent_buffer)
+            {
+                const char *s;
+                size_t i;
+                int pos;
+
+                s = input_get_ctext (cmdline);
+
+                /* Check to make sure there are no non text characters in the command buffer,
+                 * such as tab, or newline, as this could cause problems. */
+                for (i = 0; i < cmdline->buffer->len; i++)
+                    if ((unsigned char) s[i] < 32 || (unsigned char) s[i] == 127)
+                        g_string_overwrite_len (cmdline->buffer, i, " ", 1);
+
+                /* Write the command buffer to the subshell. */
+                write_all (mc_global.tty.subshell_pty, s, cmdline->buffer->len);
+
+                /* Put the cursor in the correct place in the subshell. */
+                pos = str_length (s) - cmdline->point;
+                for (i = 0; i < (size_t) pos; i++)
+                    write_all (mc_global.tty.subshell_pty, ESC_STR "[D", 3);
+            }
+        }
+    }
+    else                        /* MC has passed us a user command */
+    {
+        /* Before we write to the command prompt, we need to clear whatever */
+        /* data is there, but only if we are using one of the shells that */
+        /* doesn't support keeping command buffer contents, OR if there was */
+        /* some sort of error. */
+        if (use_persistent_buffer)
+            clear_cwd_pipe ();
+        else
+        {
+            /* We don't need to call feed_subshell here if we are using fish, because of a
+             * quirk in the behavior of that particular shell. */
+            if (mc_global.shell->type != SHELL_FISH)
+            {
+                write_all (mc_global.tty.subshell_pty, "\003", 1);
+                subshell_state = RUNNING_COMMAND;
+                feed_subshell (QUIETLY, FALSE);
+            }
+        }
+
+        if (how == QUIETLY)
+            write_all (mc_global.tty.subshell_pty, " ", 1);
+        /* FIXME: if command is long (>8KB ?) we go comma */
+        write_all (mc_global.tty.subshell_pty, command, strlen (command));
+        write_all (mc_global.tty.subshell_pty, "\n", 1);
+        subshell_state = RUNNING_COMMAND;
+        subshell_ready = FALSE;
+    }
+
+    feed_subshell (how, FALSE);
+
+    if (new_dir_vpath != NULL && subshell_alive)
+    {
+        const char *pcwd;
+
+        pcwd = vfs_translate_path (vfs_path_as_str (subshell_get_cwd ()));
+        if (strcmp (subshell_cwd, pcwd) != 0)
+            *new_dir_vpath = vfs_path_from_str (subshell_cwd);  /* Make MC change to the subshell's CWD */
+    }
+
+    /* Restart the subshell if it has died by SIGHUP, SIGQUIT, etc. */
+    while (!subshell_alive && subshell_get_mainloop_quit () == 0 && mc_global.tty.use_subshell)
+        init_subshell ();
+
+    return subshell_get_mainloop_quit ();
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+gboolean
+flush_subshell (int max_wait_length, int how)
+{
+    int rc = 0;
+    ssize_t bytes = 0;
+    struct timeval timeleft = { 0, 0 };
+    gboolean return_value = FALSE;
+    fd_set tmp;
+
+    timeleft.tv_sec = max_wait_length;
+    FD_ZERO (&tmp);
+    FD_SET (mc_global.tty.subshell_pty, &tmp);
+
+    while (subshell_alive
+           && (rc = select (mc_global.tty.subshell_pty + 1, &tmp, NULL, NULL, &timeleft)) != 0)
+    {
+        /* Check for 'select' errors */
+        if (rc == -1)
+        {
+            if (errno == EINTR)
+            {
+                if (tty_got_winch ())
+                    tty_change_screen_size ();
+
+                continue;
+            }
+
+            fprintf (stderr, "select (FD_SETSIZE, &tmp...): %s\r\n", unix_error_string (errno));
+            exit (EXIT_FAILURE);
+        }
+
+        return_value = TRUE;
+        timeleft.tv_sec = 0;
+        timeleft.tv_usec = 0;
+
+        bytes = read (mc_global.tty.subshell_pty, pty_buffer, sizeof (pty_buffer));
+        if (how == VISIBLY)
+            write_all (STDOUT_FILENO, pty_buffer, bytes);
+    }
+
+    return return_value;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+gboolean
+read_subshell_prompt (void)
+{
+    int rc = 0;
+    ssize_t bytes = 0;
+    struct timeval timeleft = { 0, 0 };
+    gboolean should_reset_prompt = TRUE;
+    gboolean got_new_prompt = FALSE;
+
+    fd_set tmp;
+    FD_ZERO (&tmp);
+    FD_SET (mc_global.tty.subshell_pty, &tmp);
+
+    while (subshell_alive
+           && (rc = select (mc_global.tty.subshell_pty + 1, &tmp, NULL, NULL, &timeleft)) != 0)
+    {
+        /* Check for 'select' errors */
+        if (rc == -1)
+        {
+            if (errno == EINTR)
+            {
+                if (tty_got_winch ())
+                    tty_change_screen_size ();
+
+                continue;
+            }
+
+            fprintf (stderr, "select (FD_SETSIZE, &tmp...): %s\r\n", unix_error_string (errno));
+            exit (EXIT_FAILURE);
+        }
+
+        bytes = read (mc_global.tty.subshell_pty, pty_buffer, sizeof (pty_buffer));
+        if (should_reset_prompt)
+        {
+            should_reset_prompt = FALSE;
+            clear_subshell_prompt_string ();
+        }
+
+        parse_subshell_prompt_string (pty_buffer, bytes);
+        got_new_prompt = TRUE;
+    }
+
+    if (got_new_prompt)
+        set_prompt_string ();
+
+    return (rc != 0 || bytes != 0);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+void
+do_update_prompt (void)
+{
+    if (update_subshell_prompt)
+    {
+        if (subshell_prompt != NULL)
+        {
+            printf ("\r\n%s", subshell_prompt->str);
+            fflush (stdout);
+        }
+        update_subshell_prompt = FALSE;
+    }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+gboolean
+exit_subshell (void)
+{
+    gboolean subshell_quit = TRUE;
+
+    if (subshell_state != INACTIVE && subshell_alive)
+        subshell_quit =
+            query_dialog (_("Warning"),
+                          _("The shell is still active. Quit anyway?"),
+                          D_NORMAL, 2, _("&Yes"), _("&No")) == 0;
+
+    if (subshell_quit)
+    {
+        if (mc_global.shell->type == SHELL_TCSH)
+        {
+            if (unlink (tcsh_fifo) == -1)
+                fprintf (stderr, "Cannot remove named pipe %s: %s\r\n",
+                         tcsh_fifo, unix_error_string (errno));
+        }
+
+        if (subshell_prompt != NULL)
+        {
+            g_string_free (subshell_prompt, TRUE);
+            subshell_prompt = NULL;
+        }
+
+        if (subshell_prompt_temp_buffer != NULL)
+        {
+            g_string_free (subshell_prompt_temp_buffer, TRUE);
+            subshell_prompt_temp_buffer = NULL;
+        }
+
+        pty_buffer[0] = '\0';
+    }
+
+    return subshell_quit;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+/** If it actually changed the directory it returns true */
+void
+do_subshell_chdir (const vfs_path_t * vpath, gboolean update_prompt)
+{
+    char *pcwd;
+
+    pcwd = vfs_path_to_str_flags (subshell_get_cwd (), 0, VPF_RECODE);
+
+    if (!(subshell_state == INACTIVE && strcmp (subshell_cwd, pcwd) != 0))
+    {
+        /* We have to repaint the subshell prompt if we read it from
+         * the main program.  Please note that in the code after this
+         * if, the cd command that is sent will make the subshell
+         * repaint the prompt, so we don't have to paint it. */
+        if (update_prompt)
+            do_update_prompt ();
+        g_free (pcwd);
+        return;
+    }
+
+    /* If we are using a shell that doesn't support persistent command buffer, we need to clear
+     * the command prompt before we send the cd command. */
+    if (!use_persistent_buffer)
+    {
+        write_all (mc_global.tty.subshell_pty, "\003", 1);
+        subshell_state = RUNNING_COMMAND;
+        if (mc_global.shell->type != SHELL_FISH)
+            if (!feed_subshell (QUIETLY, TRUE))
+            {
+                subshell_state = ACTIVE;
+                return;
+            }
+    }
+    /* The initial space keeps this out of the command history (in bash
+       because we set "HISTCONTROL=ignorespace") */
+    write_all (mc_global.tty.subshell_pty, " cd ", 4);
+
+    if (vpath != NULL)
+    {
+        const char *translate;
+
+        translate = vfs_translate_path (vfs_path_as_str (vpath));
+        if (translate != NULL)
+        {
+            GString *temp;
+
+            temp = subshell_name_quote (translate);
+            write_all (mc_global.tty.subshell_pty, temp->str, temp->len);
+            g_string_free (temp, TRUE);
+        }
+        else
+        {
+            write_all (mc_global.tty.subshell_pty, ".", 1);
+        }
+    }
+    else
+    {
+        write_all (mc_global.tty.subshell_pty, "/", 1);
+    }
+    write_all (mc_global.tty.subshell_pty, "\n", 1);
+
+    subshell_state = RUNNING_COMMAND;
+    if (!feed_subshell (QUIETLY, TRUE))
+    {
+        subshell_state = ACTIVE;
+        return;
+    }
+
+    if (subshell_alive)
+    {
+        gboolean bPathNotEq;
+
+        bPathNotEq = strcmp (subshell_cwd, pcwd) != 0;
+
+        if (bPathNotEq && mc_global.shell->type == SHELL_TCSH)
+        {
+            char rp_subshell_cwd[PATH_MAX];
+            char rp_current_panel_cwd[PATH_MAX];
+            char *p_subshell_cwd, *p_current_panel_cwd;
+
+            p_subshell_cwd = mc_realpath (subshell_cwd, rp_subshell_cwd);
+            p_current_panel_cwd = mc_realpath (pcwd, rp_current_panel_cwd);
+
+            if (p_subshell_cwd == NULL)
+                p_subshell_cwd = subshell_cwd;
+            if (p_current_panel_cwd == NULL)
+                p_current_panel_cwd = pcwd;
+            bPathNotEq = strcmp (p_subshell_cwd, p_current_panel_cwd) != 0;
+        }
+
+        if (bPathNotEq && !DIR_IS_DOT (pcwd))
+        {
+            char *cwd;
+
+            cwd = vfs_path_to_str_flags (subshell_get_cwd (), 0, VPF_STRIP_PASSWORD);
+            vfs_print_message (_("Warning: Cannot change to %s.\n"), cwd);
+            g_free (cwd);
+        }
+    }
+
+    /* Really escape Zsh history */
+    if (mc_global.shell->type == SHELL_ZSH)
+    {
+        /* Per Zsh documentation last command prefixed with space lingers in the internal history
+         * until the next command is entered before it vanishes. To make it vanish right away,
+         * type a space and press return. */
+        write_all (mc_global.tty.subshell_pty, " \n", 2);
+        subshell_state = RUNNING_COMMAND;
+        feed_subshell (QUIETLY, TRUE);
+    }
+
+    update_subshell_prompt = FALSE;
+
+    g_free (pcwd);
+    /* Make sure that MC never stores the CWD in a silly format */
+    /* like /usr////lib/../bin, or the strcmp() above will fail */
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+void
+subshell_get_console_attributes (void)
+{
+    /* Get our current terminal modes */
+
+    if (tcgetattr (STDOUT_FILENO, &shell_mode))
+    {
+        fprintf (stderr, "Cannot get terminal settings: %s\r\n", unix_error_string (errno));
+        mc_global.tty.use_subshell = FALSE;
+    }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Figure out whether the subshell has stopped, exited or been killed
+ * Possibly modifies: 'subshell_alive', 'subshell_stopped' and 'quit' */
+
+void
+sigchld_handler (int sig)
+{
+    int status;
+    pid_t pid;
+
+    (void) sig;
+
+    pid = waitpid (subshell_pid, &status, WUNTRACED | WNOHANG);
+
+    if (pid == subshell_pid)
+    {
+        /* Figure out what has happened to the subshell */
+
+        if (WIFSTOPPED (status))
+        {
+            if (WSTOPSIG (status) == SIGSTOP)
+            {
+                /* The subshell has received a SIGSTOP signal */
+                subshell_stopped = TRUE;
+            }
+            else
+            {
+                /* The user has suspended the subshell.  Revive it */
+                kill (subshell_pid, SIGCONT);
+            }
+        }
+        else
+        {
+            /* The subshell has either exited normally or been killed */
+            subshell_alive = FALSE;
+            delete_select_channel (mc_global.tty.subshell_pty);
+            if (WIFEXITED (status) && WEXITSTATUS (status) != FORK_FAILURE)
+            {
+                int subshell_quit;
+                subshell_quit = subshell_get_mainloop_quit () | SUBSHELL_EXIT;  /* Exited normally */
+                subshell_set_mainloop_quit (subshell_quit);
+            }
+        }
+    }
+    subshell_handle_cons_saver ();
+
+    /* If we got here, some other child exited; ignore it */
+}
+
+/* --------------------------------------------------------------------------------------------- */