lib/shell.c

lib/shell.c
/* */
This source file includes following definitions.
mc_shell_get_installed_in_system
mc_shell_get_name_env
mc_shell_get_from_env
mc_shell_recognize_real_path
mc_shell_recognize_path
mc_shell_init
mc_shell_deinit
   1 /*
   2    Provides a functions for working with shell.
   3 
   4    Copyright (C) 2006-2025
   5    Free Software Foundation, Inc.
   6 
   7    Written by:
   8    Slava Zanko <slavazanko@gmail.com>, 2015.
   9 
  10    This file is part of the Midnight Commander.
  11 
  12    The Midnight Commander is free software: you can redistribute it
  13    and/or modify it under the terms of the GNU General Public License as
  14    published by the Free Software Foundation, either version 3 of the License,
  15    or (at your option) any later version.
  16 
  17    The Midnight Commander is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20    GNU General Public License for more details.
  21 
  22    You should have received a copy of the GNU General Public License
  23    along with this program.  If not, see <https://www.gnu.org/licenses/>.
  24  */
  25 
  26 /** \file shell.c
  27  *  \brief Source: provides a functions for working with shell.
  28  */
  29 
  30 #include <config.h>
  31 
  32 #include <pwd.h>  // for username in xterm title
  33 #include <stdarg.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 
  37 #include "global.h"
  38 #include "util.h"
  39 
  40 /*** global variables ****************************************************************************/
  41 
  42 /*** file scope macro definitions ****************************************************************/
  43 
  44 /*** file scope type declarations ****************************************************************/
  45 
  46 /*** forward declarations (file scope functions) *************************************************/
  47 
  48 /*** file scope variables ************************************************************************/
  49 
  50 static char rp_shell[PATH_MAX];
  51 
  52 /* --------------------------------------------------------------------------------------------- */
  53 /*** file scope functions ************************************************************************/
  54 /* --------------------------------------------------------------------------------------------- */
  55 /**
  56  * Get a system shell.
  57  *
  58  * @return newly allocated mc_shell_t object with shell name
  59  */
  60 
  61 static mc_shell_t *
  62 mc_shell_get_installed_in_system (void)
     /*   */
  63 {
  64     mc_shell_t *mc_shell;
  65 
  66     mc_shell = g_new0 (mc_shell_t, 1);
  67 
  68     // 3rd choice: look for existing shells supported as MC subshells.
  69     if (access ("/bin/bash", X_OK) == 0)
  70         mc_shell->path = g_strdup ("/bin/bash");
  71     else if (access ("/bin/zsh", X_OK) == 0)
  72         mc_shell->path = g_strdup ("/bin/zsh");
  73     else if (access ("/bin/oksh", X_OK) == 0)
  74         mc_shell->path = g_strdup ("/bin/oksh");
  75     else if (access ("/bin/ksh", X_OK) == 0)
  76         mc_shell->path = g_strdup ("/bin/ksh");
  77     else if (access ("/bin/ksh93", X_OK) == 0)
  78         mc_shell->path = g_strdup ("/bin/ksh93");
  79     else if (access ("/bin/ash", X_OK) == 0)
  80         mc_shell->path = g_strdup ("/bin/ash");
  81     else if (access ("/bin/dash", X_OK) == 0)
  82         mc_shell->path = g_strdup ("/bin/dash");
  83     else if (access ("/bin/busybox", X_OK) == 0)
  84         mc_shell->path = g_strdup ("/bin/busybox");
  85     else if (access ("/bin/tcsh", X_OK) == 0)
  86         mc_shell->path = g_strdup ("/bin/tcsh");
  87     else if (access ("/bin/csh", X_OK) == 0)
  88         mc_shell->path = g_strdup ("/bin/csh");
  89     else if (access ("/bin/mksh", X_OK) == 0)
  90         mc_shell->path = g_strdup ("/bin/mksh");
  91     /* No fish as fallback because it is so much different from other shells and
  92      * in a way exotic (even though user-friendly by name) that we should not
  93      * present it as a subshell without the user's explicit intention. We rather
  94      * will not use a subshell but just a command line.
  95      * else if (access("/bin/fish", X_OK) == 0)
  96      *     mc_global.tty.shell = g_strdup ("/bin/fish");
  97      */
  98     else
  99         // Fallback and last resort: system default shell
 100         mc_shell->path = g_strdup ("/bin/sh");
 101 
 102     return mc_shell;
 103 }
 104 
 105 /* --------------------------------------------------------------------------------------------- */
 106 
 107 static char *
 108 mc_shell_get_name_env (void)
     /*   */
 109 {
 110     char *shell_name = NULL;
 111 
 112     const char *shell_env = g_getenv ("SHELL");
 113     if ((shell_env == NULL) || (shell_env[0] == '\0'))
 114     {
 115         // 2nd choice: user login shell
 116         const struct passwd *pwd = getpwuid (geteuid ());
 117         if (pwd != NULL)
 118             shell_name = g_strdup (pwd->pw_shell);
 119     }
 120     else
 121         // 1st choice: SHELL environment variable
 122         shell_name = g_strdup (shell_env);
 123 
 124     return shell_name;
 125 }
 126 
 127 /* --------------------------------------------------------------------------------------------- */
 128 
 129 static mc_shell_t *
 130 mc_shell_get_from_env (void)
     /*   */
 131 {
 132     char *shell_name = mc_shell_get_name_env ();
 133 
 134     if (shell_name != NULL)
 135     {
 136         mc_shell_t *mc_shell = NULL;
 137         mc_shell = g_new0 (mc_shell_t, 1);
 138         mc_shell->path = shell_name;
 139         return mc_shell;
 140     }
 141 
 142     return NULL;
 143 }
 144 
 145 /* --------------------------------------------------------------------------------------------- */
 146 
 147 static void
 148 mc_shell_recognize_real_path (mc_shell_t *mc_shell)
     /*   */
 149 {
 150     if (strstr (mc_shell->path, "/zsh") != NULL || strstr (mc_shell->real_path, "/zsh") != NULL
 151         || getenv ("ZSH_VERSION") != NULL)
 152     {
 153         // Also detects ksh symlinked to zsh
 154         mc_shell->type = SHELL_ZSH;
 155         mc_shell->name = "zsh";
 156     }
 157     else if (strstr (mc_shell->path, "/tcsh") != NULL
 158              || strstr (mc_shell->real_path, "/tcsh") != NULL)
 159     {
 160         // Also detects csh symlinked to tcsh
 161         mc_shell->type = SHELL_TCSH;
 162         mc_shell->name = "tcsh";
 163     }
 164     else if (strstr (mc_shell->path, "/csh") != NULL
 165              || strstr (mc_shell->real_path, "/csh") != NULL)
 166     {
 167         mc_shell->type = SHELL_TCSH;
 168         mc_shell->name = "csh";
 169     }
 170     else if (strstr (mc_shell->path, "/fish") != NULL
 171              || strstr (mc_shell->real_path, "/fish") != NULL)
 172     {
 173         mc_shell->type = SHELL_FISH;
 174         mc_shell->name = "fish";
 175     }
 176     else if (strstr (mc_shell->path, "/dash") != NULL
 177              || strstr (mc_shell->real_path, "/dash") != NULL)
 178     {
 179         // Debian ash (also found if symlinked to by ash/sh)
 180         mc_shell->type = SHELL_DASH;
 181         mc_shell->name = "dash";
 182     }
 183     else if (strstr (mc_shell->real_path, "/busybox") != NULL)
 184     {
 185         /* If shell is symlinked to busybox, assume it is an ash, even though theoretically
 186          * it could also be a hush (a mini shell for non-MMU systems deactivated by default).
 187          * For simplicity's sake we assume that busybox always contains an ash, not a hush.
 188          * On embedded platforms or on server systems, /bin/sh often points to busybox.
 189          * Sometimes even bash is symlinked to busybox (CONFIG_FEATURE_BASH_IS_ASH option),
 190          * so we need to check busybox symlinks *before* checking for the name "bash"
 191          * in order to avoid that case. */
 192         mc_shell->type = SHELL_ASH_BUSYBOX;
 193         mc_shell->name = mc_shell->path;
 194     }
 195     else if (strstr (mc_shell->path, "/ksh") != NULL || strstr (mc_shell->real_path, "/ksh") != NULL
 196              || strstr (mc_shell->path, "/ksh93") != NULL
 197              || strstr (mc_shell->real_path, "/ksh93") != NULL
 198              || strstr (mc_shell->path, "/oksh") != NULL
 199              || strstr (mc_shell->real_path, "/oksh") != NULL)
 200     {
 201         mc_shell->type = SHELL_KSH;
 202         mc_shell->name = "ksh";
 203     }
 204     else if (strstr (mc_shell->path, "/mksh") != NULL
 205              || strstr (mc_shell->real_path, "/mksh") != NULL)
 206     {
 207         mc_shell->type = SHELL_MKSH;
 208         mc_shell->name = "mksh";
 209     }
 210     else
 211         mc_shell->type = SHELL_NONE;
 212 }
 213 
 214 /* --------------------------------------------------------------------------------------------- */
 215 
 216 static void
 217 mc_shell_recognize_path (mc_shell_t *mc_shell)
     /*   */
 218 {
 219     // If shell is not symlinked to busybox, it is safe to assume it is a real shell
 220     if (strstr (mc_shell->path, "/bash") != NULL || getenv ("BASH_VERSION") != NULL)
 221     {
 222         mc_shell->type = SHELL_BASH;
 223         mc_shell->name = "bash";
 224     }
 225     else if (strstr (mc_shell->path, "/sh") != NULL)
 226     {
 227         mc_shell->type = SHELL_SH;
 228         mc_shell->name = "sh";
 229     }
 230     else if (strstr (mc_shell->path, "/ash") != NULL || getenv ("BB_ASH_VERSION") != NULL)
 231     {
 232         mc_shell->type = SHELL_ASH_BUSYBOX;
 233         mc_shell->name = "ash";
 234     }
 235     else if (strstr (mc_shell->path, "/ksh") != NULL || strstr (mc_shell->path, "/ksh93") != NULL
 236              || strstr (mc_shell->path, "/oksh") != NULL
 237              || (getenv ("KSH_VERSION") != NULL
 238                  && strstr (getenv ("KSH_VERSION"), "PD KSH") != NULL))
 239     {
 240         mc_shell->type = SHELL_KSH;
 241         mc_shell->name = "ksh";
 242     }
 243     else if (strstr (mc_shell->path, "/mksh") != NULL
 244              || (getenv ("KSH_VERSION") != NULL
 245                  && strstr (getenv ("KSH_VERSION"), "MIRBSD KSH") != NULL))
 246     {
 247         mc_shell->type = SHELL_MKSH;
 248         mc_shell->name = "mksh";
 249     }
 250     else
 251         mc_shell->type = SHELL_NONE;
 252 }
 253 
 254 /* --------------------------------------------------------------------------------------------- */
 255 /*** public functions ****************************************************************************/
 256 /* --------------------------------------------------------------------------------------------- */
 257 
 258 void
 259 mc_shell_init (void)
     /*   */
 260 {
 261     mc_shell_t *mc_shell = mc_shell_get_from_env ();
 262 
 263     if (mc_shell == NULL)
 264         mc_shell = mc_shell_get_installed_in_system ();
 265 
 266     mc_shell->real_path = mc_realpath (mc_shell->path, rp_shell);
 267 
 268     /* Find out what type of shell we have. Also consider real paths (resolved symlinks)
 269      * because e.g. csh might point to tcsh, ash to dash or busybox, sh to anything. */
 270     if (mc_shell->real_path != NULL)
 271         mc_shell_recognize_real_path (mc_shell);
 272 
 273     if (mc_shell->type == SHELL_NONE)
 274         mc_shell_recognize_path (mc_shell);
 275 
 276     if (mc_shell->type == SHELL_NONE)
 277         mc_global.tty.use_subshell = FALSE;
 278 
 279     mc_global.shell = mc_shell;
 280 }
 281 
 282 /* --------------------------------------------------------------------------------------------- */
 283 
 284 void
 285 mc_shell_deinit (void)
     /*   */
 286 {
 287     if (mc_global.shell != NULL)
 288     {
 289         g_free (mc_global.shell->path);
 290         MC_PTR_FREE (mc_global.shell);
 291     }
 292 }
 293 
 294 /* --------------------------------------------------------------------------------------------- */
/* */
root/lib/shell.c

DEFINITIONS
