mc: add ash subshell support

* backport a slightly modified subshell patch to stable 4.8.15
  (see ticket: https://www.midnight-commander.org/ticket/2742)
* enable subshell support by default

Signed-off-by: Dirk Brenken <dirk@brenken.org>

utils/mc/Config.in

@@ -17,10 +17,10 @@ config MC_EDITOR
 
 config MC_SUBSHELL
 	bool "Enable concurrent subshell"
-	default n
+	default y
 	help
            This option enables concurrent subshell support.
-           Disabled by default.
+           Enabled by default.
 
 config MC_LARGEFILE
 	bool "Enable largefile support"

utils/mc/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=mc
 PKG_VERSION:=4.8.15
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 PKG_MAINTAINER:=Dirk Brenken <dirk@brenken.org>
 PKG_LICENSE:=GPL-3.0+
 

utils/mc/patches/010-subshell.patch

@@ -0,0 +1,579 @@
+--- a/lib/global.c
++++ b/lib/global.c
+@@ -97,6 +97,7 @@ mc_global_t mc_global = {
+ #endif /* !ENABLE_SUBSHELL */
+ 
+         .shell = NULL,
++        .shell_realpath = NULL,
+ 
+         .xterm_flag = FALSE,
+         .disable_x11 = FALSE,
+--- a/lib/global.h
++++ b/lib/global.h
+@@ -255,6 +255,7 @@ typedef struct
+ 
+         /* The user's shell */
+         char *shell;
++        char *shell_realpath;
+ 
+         /* This flag is set by xterm detection routine in function main() */
+         /* It is used by function view_other_cmd() */
+--- a/lib/mcconfig/paths.c
++++ b/lib/mcconfig/paths.c
+@@ -84,6 +84,7 @@ static const struct
+     /* data */
+     { "skins",                                 &mc_data_str, MC_SKINS_SUBDIR},
+     { "fish",                                  &mc_data_str, FISH_PREFIX},
++    { "ashrc",                                 &mc_data_str, "ashrc"},
+     { "bashrc",                                &mc_data_str, "bashrc"},
+     { "inputrc",                               &mc_data_str, "inputrc"},
+     { "extfs.d",                               &mc_data_str, MC_EXTFS_DIR},
+--- a/src/main.c
++++ b/src/main.c
+@@ -87,6 +87,9 @@
+ /*** file scope variables ************************************************************************/
+ 
+ /*** file scope functions ************************************************************************/
++
++static char rp_shell[PATH_MAX];
++
+ /* --------------------------------------------------------------------------------------------- */
+ 
+ static void
+@@ -118,6 +121,44 @@ check_codeset (void)
+ }
+ 
+ /* --------------------------------------------------------------------------------------------- */
++/**
++ * Get a system shell.
++ *
++ * @return newly allocated string with shell name
++ */
++
++static char *
++mc_get_system_shell (void)
++{
++    char *sh_str;
++    /* 3rd choice: look for existing shells supported as MC subshells.  */
++    if (access ("/bin/bash", X_OK) == 0)
++        sh_str = g_strdup ("/bin/bash");
++    else if (access ("/bin/ash", X_OK) == 0)
++        sh_str = g_strdup ("/bin/ash");
++    else if (access ("/bin/dash", X_OK) == 0)
++        sh_str = g_strdup ("/bin/dash");
++    else if (access ("/bin/busybox", X_OK) == 0)
++        sh_str = g_strdup ("/bin/busybox");
++    else if (access ("/bin/zsh", X_OK) == 0)
++        sh_str = g_strdup ("/bin/zsh");
++    else if (access ("/bin/tcsh", X_OK) == 0)
++        sh_str = g_strdup ("/bin/tcsh");
++    /* No fish as fallback because it is so much different from other shells and
++     * in a way exotic (even though user-friendly by name) that we should not
++     * present it as a subshell without the user's explicit intention. We rather
++     * will not use a subshell but just a command line.
++     * else if (access("/bin/fish", X_OK) == 0)
++     *     mc_global.tty.shell = g_strdup ("/bin/fish");
++     */
++    else
++        /* Fallback and last resort: system default shell */
++        sh_str = g_strdup ("/bin/sh");
++
++    return sh_str;
++}
++
++/* --------------------------------------------------------------------------------------------- */
+ 
+ /** POSIX version.  The only version we support.  */
+ static void
+@@ -126,9 +167,11 @@ OS_Setup (void)
+     const char *shell_env;
+     const char *datadir_env;
+ 
++
+     shell_env = getenv ("SHELL");
+     if ((shell_env == NULL) || (shell_env[0] == '\0'))
+     {
++        /* 2nd choice: user login shell */
+         struct passwd *pwd;
+ 
+         pwd = getpwuid (geteuid ());
+@@ -136,13 +179,15 @@ OS_Setup (void)
+             mc_global.tty.shell = g_strdup (pwd->pw_shell);
+     }
+     else
++        /* 1st choice: SHELL environment variable */
+         mc_global.tty.shell = g_strdup (shell_env);
+ 
+     if ((mc_global.tty.shell == NULL) || (mc_global.tty.shell[0] == '\0'))
+     {
+         g_free (mc_global.tty.shell);
+-        mc_global.tty.shell = g_strdup ("/bin/sh");
++        mc_global.tty.shell = mc_get_system_shell ();
+     }
++    mc_global.tty.shell_realpath = mc_realpath (mc_global.tty.shell, rp_shell);
+ 
+     /* This is the directory, where MC was installed, on Unix this is DATADIR */
+     /* and can be overriden by the MC_DATADIR environment variable */
+--- a/src/subshell.c
++++ b/src/subshell.c
+@@ -114,6 +114,8 @@ enum
+ static enum
+ {
+     BASH,
++    ASH_BUSYBOX,                /* BusyBox default shell (ash) */
++    DASH,                       /* Debian variant of ash */
+     TCSH,
+     ZSH,
+     FISH
+@@ -209,6 +211,7 @@ static void
+ init_subshell_child (const char *pty_name)
+ {
+     char *init_file = NULL;
++    char *putenv_str = NULL;
+     pid_t mc_sid;
+ 
+     (void) pty_name;
+@@ -257,32 +260,53 @@ init_subshell_child (const char *pty_nam
+     switch (subshell_type)
+     {
+     case BASH:
++        /* Do we have a custom init file ~/.local/share/mc/bashrc? */
+         init_file = mc_config_get_full_path ("bashrc");
+ 
++        /* Otherwise use ~/.bashrc */
+         if (access (init_file, R_OK) == -1)
+         {
+             g_free (init_file);
+             init_file = g_strdup (".bashrc");
+         }
+ 
+-        /* Make MC's special commands not show up in bash's history */
+-        putenv ((char *) "HISTCONTROL=ignorespace");
++        /* 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 = mc_config_get_full_path ("inputrc");
+             if (access (input_file, R_OK) == 0)
+             {
+-                char *putenv_str = g_strconcat ("INPUTRC=", input_file, NULL);
++                putenv_str = g_strconcat ("INPUTRC=", input_file, NULL);
+                 putenv (putenv_str);
+-                g_free (putenv_str);
+             }
+             g_free (input_file);
+         }
+ 
+         break;
+ 
+-        /* TODO: Find a way to pass initfile to TCSH and ZSH */
++    case ASH_BUSYBOX:
++    case DASH:
++        /* Do we have a custom init file ~/.local/share/mc/ashrc? */
++        init_file = mc_config_get_full_path ("ashrc");
++
++        /* Otherwise use ~/.profile */
++        if (access (init_file, R_OK) == -1)
++        {
++            g_free (init_file);
++            init_file = g_strdup (".profile");
++        }
++
++        /* Put init file to ENV variable used by ash */
++        putenv_str = g_strconcat ("ENV=", init_file, NULL);
++        putenv (putenv_str);
++        /* Do not use "g_free (putenv_str)" here, otherwise ENV will be undefined! */
++
++        break;
++
++        /* TODO: Find a way to pass initfile to TCSH, ZSH and FISH */
+     case TCSH:
+     case ZSH:
+     case FISH:
+@@ -320,10 +344,6 @@ init_subshell_child (const char *pty_nam
+         execl (mc_global.tty.shell, "bash", "-rcfile", init_file, (char *) NULL);
+         break;
+ 
+-    case TCSH:
+-        execl (mc_global.tty.shell, "tcsh", (char *) NULL);
+-        break;
+-
+     case ZSH:
+         /* Use -g to exclude cmds beginning with space from history
+          * and -Z to use the line editor on non-interactive term */
+@@ -331,8 +351,11 @@ init_subshell_child (const char *pty_nam
+ 
+         break;
+ 
++    case ASH_BUSYBOX:
++    case DASH:
++    case TCSH:
+     case FISH:
+-        execl (mc_global.tty.shell, "fish", (char *) NULL);
++        execl (mc_global.tty.shell, mc_global.tty.shell, (char *) NULL);
+         break;
+ 
+     default:
+@@ -341,6 +364,7 @@ init_subshell_child (const char *pty_nam
+ 
+     /* If we get this far, everything failed miserably */
+     g_free (init_file);
++    g_free (putenv_str);
+     my_exit (FORK_FAILURE);
+ }
+ 
+@@ -742,6 +766,171 @@ pty_open_slave (const char *pty_name)
+ }
+ #endif /* !HAVE_GRANTPT */
+ 
++
++/* --------------------------------------------------------------------------------------------- */
++/**
++ * Get a subshell type and store in subshell_type variable
++ *
++ * @return TRUE if subtype was gotten, FALSE otherwise
++ */
++
++static gboolean
++init_subshell_type (void)
++{
++    gboolean result = TRUE;
++
++    /* Find out what type of shell we have. Also consider real paths (resolved symlinks)
++     * because e.g. csh might point to tcsh, ash to dash or busybox, sh to anything. */
++
++    if (strstr (mc_global.tty.shell, "/zsh") || strstr (mc_global.tty.shell_realpath, "/zsh")
++        || getenv ("ZSH_VERSION"))
++        /* Also detects ksh symlinked to zsh */
++        subshell_type = ZSH;
++    else if (strstr (mc_global.tty.shell, "/tcsh")
++             || strstr (mc_global.tty.shell_realpath, "/tcsh"))
++        /* Also detects csh symlinked to tcsh */
++        subshell_type = TCSH;
++    else if (strstr (mc_global.tty.shell, "/fish")
++             || strstr (mc_global.tty.shell_realpath, "/fish"))
++        subshell_type = FISH;
++    else if (strstr (mc_global.tty.shell, "/dash")
++             || strstr (mc_global.tty.shell_realpath, "/dash"))
++        /* Debian ash (also found if symlinked to by ash/sh) */
++        subshell_type = DASH;
++    else if (strstr (mc_global.tty.shell_realpath, "/busybox"))
++    {
++        /* If shell is symlinked to busybox, assume it is an ash, even though theoretically
++         * it could also be a hush (a mini shell for non-MMU systems deactivated by default).
++         * For simplicity's sake we assume that busybox always contains an ash, not a hush.
++         * On embedded platforms or on server systems, /bin/sh often points to busybox.
++         * Sometimes even bash is symlinked to busybox (CONFIG_FEATURE_BASH_IS_ASH option),
++         * so we need to check busybox symlinks *before* checking for the name "bash"
++         * in order to avoid that case. */
++        subshell_type = ASH_BUSYBOX;
++    }
++    else if (strstr (mc_global.tty.shell, "/bash") || getenv ("BASH"))
++        /* If bash is not symlinked to busybox, it is safe to assume it is a real bash */
++        subshell_type = BASH;
++    else
++    {
++        mc_global.tty.use_subshell = FALSE;
++        result = FALSE;
++    }
++    return result;
++}
++
++/* --------------------------------------------------------------------------------------------- */
++/**
++ * 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 (subshell_type)
++    {
++    case BASH:
++        g_snprintf (precmd, buff_size,
++                    " PROMPT_COMMAND='pwd>&%d; kill -STOP $$';\n", subshell_pipe[WRITE]);
++        break;
++
++    case ASH_BUSYBOX:
++        /* BusyBox ash needs a somewhat complicated precmd emulation via PS1, and it is vital
++         * that BB be built with active CONFIG_ASH_EXPAND_PRMT, but this is the default anyway.
++         *
++         * A: This leads to a stopped subshell (=frozen mc) if user calls "ash" command
++         *    "PS1='$(pwd>&%d; kill -STOP $$)\\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 $$; }; "
++         *    "PS1='$(precmd)\\u@\\h:\\w\\$ '\n",
++         *
++         * C: This works if user calls "ash" command because in sub-subshell
++         *    PRECMD is unfedined, thus evaluated to empty string - no damage done.
++         *    Attention: BusyBox must be built with FEATURE_EDITING_FANCY_PROMPT to
++         *    permit \u, \w, \h, \$ escape sequences. Unfortunately this cannot be guaranteed,
++         *    especially on embedded systems where people try to save space, so let's use
++         *    the dash version below. It should work on virtually all systems.
++         *    "precmd() { pwd>&%d; kill -STOP $$; }; "
++         *    "PRECMD=precmd; "
++         *    "PS1='$(eval $PRECMD)\\u@\\h:\\w\\$ '\n",
++         */
++    case 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 $$; "
++         * "}; "
++         * "PRECMD=precmd; "
++         * "PS1='$($PRECMD)$ '\n",
++         */
++        g_snprintf (precmd, buff_size,
++                    "precmd() { "
++                    "if [ ! \"${PWD##$HOME}\" ]; then "
++                    "MC_PWD=\"~\"; "
++                    "else "
++                    "[ \"${PWD##$HOME/}\" = \"$PWD\" ] && MC_PWD=\"$PWD\" || MC_PWD=\"~/${PWD##$HOME/}\"; "
++                    "fi; "
++                    "echo \"$USER@openwrt:$MC_PWD\"; "
++                    "pwd>&%d; "
++                    "kill -STOP $$; "
++                    "}; " "PRECMD=precmd; " "PS1='$($PRECMD)$ '\n", subshell_pipe[WRITE]);
++        break;
++
++    case ZSH:
++        g_snprintf (precmd, buff_size,
++                    " precmd() { pwd>&%d; kill -STOP $$; }; "
++                    "PS1='%%n@%%m:%%~%%# '\n", subshell_pipe[WRITE]);
++        break;
++
++    case TCSH:
++        g_snprintf (precmd, buff_size,
++                    "set echo_style=both; "
++                    "set prompt='%%n@%%m:%%~%%# '; "
++                    "alias precmd 'echo $cwd:q >>%s; kill -STOP $$'\n", tcsh_fifo);
++        break;
++
++    case FISH:
++        /* We also want a fancy user@host:cwd prompt here, but fish makes it very easy to also
++         * use colours, which is what we will do. But first here is a simpler, uncoloured version:
++         * "function fish_prompt; "
++         *     "echo (whoami)@(hostname -s):(pwd)\\$\\ ; "
++         *     "echo \"$PWD\">&%d; "
++         *     "kill -STOP %%self; "
++         * "end\n",
++         *
++         * TODO: fish prompt is shown when panel is hidden (Ctrl-O), but not when it is visible.
++         * Find out how to fix this.
++         */
++        g_snprintf (precmd, buff_size,
++                    "function fish_prompt; "
++                    "echo (whoami)@(hostname -s):(set_color $fish_color_cwd)(pwd)(set_color normal)\\$\\ ; "
++                    "echo \"$PWD\">&%d; " "kill -STOP %%self; " "end\n", subshell_pipe[WRITE]);
++        break;
++
++    default:
++        break;
++    }
++}
++
+ /* --------------------------------------------------------------------------------------------- */
+ /*** public functions ****************************************************************************/
+ /* --------------------------------------------------------------------------------------------- */
+@@ -761,6 +950,7 @@ 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];
+ 
+     switch (check_sid ())
+@@ -782,23 +972,8 @@ init_subshell (void)
+ 
+     if (mc_global.tty.subshell_pty == 0)
+     {                           /* First time through */
+-        /* Find out what type of shell we have */
+-
+-        if (strstr (mc_global.tty.shell, "/zsh") || getenv ("ZSH_VERSION"))
+-            subshell_type = ZSH;
+-        else if (strstr (mc_global.tty.shell, "/tcsh"))
+-            subshell_type = TCSH;
+-        else if (strstr (mc_global.tty.shell, "/csh"))
+-            subshell_type = TCSH;
+-        else if (strstr (mc_global.tty.shell, "/bash") || getenv ("BASH"))
+-            subshell_type = BASH;
+-        else if (strstr (mc_global.tty.shell, "/fish"))
+-            subshell_type = FISH;
+-        else
+-        {
+-            mc_global.tty.use_subshell = FALSE;
++        if (!init_subshell_type ())
+             return;
+-        }
+ 
+         /* Open a pty for talking to the subshell */
+ 
+@@ -844,7 +1019,7 @@ init_subshell (void)
+                 return;
+             }
+         }
+-        else /* subshell_type is BASH or ZSH */ if (pipe (subshell_pipe))
++        else if (pipe (subshell_pipe))  /* subshell_type is BASH, ASH_BUSYBOX, DASH or ZSH */
+         {
+             perror (__FILE__ ": couldn't create pipe");
+             mc_global.tty.use_subshell = FALSE;
+@@ -872,39 +1047,116 @@ init_subshell (void)
+         init_subshell_child (pty_name);
+     }
+ 
+-    /* Set up 'precmd' or equivalent for reading the subshell's CWD */
++    init_subshell_precmd (precmd, BUF_MEDIUM);
++
++    /* 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" ).
++     */
+ 
+     switch (subshell_type)
+     {
+     case BASH:
+         g_snprintf (precmd, sizeof (precmd),
+-                    " PROMPT_COMMAND=${PROMPT_COMMAND:+$PROMPT_COMMAND\n}'pwd>&%d;kill -STOP $$'\n",
+-                    subshell_pipe[WRITE]);
++                    " PROMPT_COMMAND=${PROMPT_COMMAND:+$PROMPT_COMMAND\n}'pwd>&%d;kill -STOP $$'\n"
++                    "PS1='\\u@\\h:\\w\\$ '\n", subshell_pipe[WRITE]);
++        break;
++
++    case 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 unfedined, 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 $$; }; "
++         *    "PRECMD=precmd; "
++         *    "PS1='$(eval $PRECMD)\\u@\\h:\\w\\$ '\n",
++         */
++    case DASH:
++        /* Debian ash needs a precmd emulation via PS1, similar to BusyBox ash,
++         * but does not support escape sequences for user, host and cwd in prompt.
++         * Attention! Make sure that the buffer for precmd is big enough.
++         *
++         * We want to have a fancy dynamic prompt with user@host:cwd just like in the BusyBox
++         * examples above, but because replacing the home directory part of the path by "~" is
++         * complicated, it bloats the precmd to a size > BUF_SMALL (128).
++         *
++         * The following example is a little less fancy (home directory not replaced)
++         * and shows the basic workings of our prompt for easier understanding:
++         *
++         * "precmd() { "
++         *     "echo \"$USER@$(hostname -s):$PWD\"; "
++         *     "pwd>&%d; "
++         *     "kill -STOP $$; "
++         * "}; "
++         * "PRECMD=precmd; "
++         * "PS1='$($PRECMD)$ '\n",
++         */
++        g_snprintf (precmd, sizeof (precmd),
++                    "precmd() { "
++                    "if [ ! \"${PWD##$HOME}\" ]; then "
++                    "MC_PWD=\"~\"; "
++                    "else "
++                    "[ \"${PWD##$HOME/}\" = \"$PWD\" ] && MC_PWD=\"$PWD\" || MC_PWD=\"~/${PWD##$HOME/}\"; "
++                    "fi; "
++                    "echo \"$USER@openwrt:$MC_PWD\"; "
++                    "pwd>&%d; "
++                    "kill -STOP $$; "
++                    "}; " "PRECMD=precmd; " "PS1='$($PRECMD)$ '\n", subshell_pipe[WRITE]);
+         break;
+ 
+     case ZSH:
+         g_snprintf (precmd, sizeof (precmd),
+-                    " _mc_precmd(){ pwd>&%d;kill -STOP $$ }; precmd_functions+=(_mc_precmd)\n",
+-                    subshell_pipe[WRITE]);
++                    " _mc_precmd(){ pwd>&%d;kill -STOP $$ }; precmd_functions+=(_mc_precmd)\n"
++                    "PS1='%%n@%%m:%%~%%# '\n", subshell_pipe[WRITE]);
+         break;
+ 
+     case TCSH:
+         g_snprintf (precmd, sizeof (precmd),
+-                    "set echo_style=both;"
+-                    "alias precmd 'echo $cwd:q >>%s;kill -STOP $$'\n", tcsh_fifo);
++                    "set echo_style=both; "
++                    "set prompt='%%n@%%m:%%~%%# '; "
++                    "alias precmd 'echo $cwd:q >>%s; kill -STOP $$'\n", tcsh_fifo);
+         break;
++
+     case FISH:
+         /* Use fish_prompt_mc function for prompt, if not present then copy fish_prompt to it. */
++        /* We also want a fancy user@host:cwd prompt here, but fish makes it very easy to also
++         * use colours, which is what we will do. But first here is a simpler, uncoloured version:
++         * "function fish_prompt; "
++         *     "echo (whoami)@(hostname -s):(pwd)\\$\\ ; "
++         *     "echo \"$PWD\">&%d; "
++         *     "kill -STOP %%self; "
++         * "end\n",
++         *
++         * TODO: fish prompt is shown when panel is hidden (Ctrl-O), but not when it is visible.
++         * Find out how to fix this.
++         */
+         g_snprintf (precmd, sizeof (precmd),
+                     "if not functions -q fish_prompt_mc;"
+                     "functions -c fish_prompt fish_prompt_mc; end;"
+-                    "function fish_prompt; echo $PWD>&%d; fish_prompt_mc; kill -STOP %%self; end\n",
++                    "function fish_prompt;"
++                    "echo (whoami)@(hostname -s):(set_color $fish_color_cwd)(pwd)(set_color normal)\\$\\ ; "
++                    "echo \"$PWD\">&%d; fish_prompt_mc; kill -STOP %%self; end\n",
+                     subshell_pipe[WRITE]);
+         break;
+ 
+     default:
+         break;
+     }
++
+     write_all (mc_global.tty.subshell_pty, precmd, strlen (precmd));
+ 
+     /* Wait until the subshell has started up and processed the command */
+@@ -1108,6 +1360,13 @@ subshell_name_quote (const char *s)
+         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\" '";