lib/shell.c

   1 /*
   2    Provides a functions for working with shell.
   3
   4    Copyright (C) 2006-2016
   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 <http://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
  41 /*** global variables ****************************************************************************/
  42
  43 /*** file scope macro definitions ****************************************************************/
  44
  45 /*** file scope type declarations ****************************************************************/
  46
  47 /*** file scope variables ************************************************************************/
  48
  49 static char rp_shell[PATH_MAX];
  50
  51 /*** file scope functions ************************************************************************/
  52 /* --------------------------------------------------------------------------------------------- */
  53 /**
  54  * Get a system shell.
  55  *
  56  * @return newly allocated string with shell name
  57  */
  58
  59 static mc_shell_t *
  60 mc_shell_get_installed_in_system (void)
  61 {
  62     mc_shell_t *mc_shell;
  63
  64     mc_shell = g_new0 (mc_shell_t, 1);
  65
  66     /* 3rd choice: look for existing shells supported as MC subshells.  */
  67     if (access ("/bin/bash", X_OK) == 0)
  68         mc_shell->path = g_strdup ("/bin/bash");
  69     else if (access ("/bin/ash", X_OK) == 0)
  70         mc_shell->path = g_strdup ("/bin/ash");
  71     else if (access ("/bin/dash", X_OK) == 0)
  72         mc_shell->path = g_strdup ("/bin/dash");
  73     else if (access ("/bin/busybox", X_OK) == 0)
  74         mc_shell->path = g_strdup ("/bin/busybox");
  75     else if (access ("/bin/zsh", X_OK) == 0)
  76         mc_shell->path = g_strdup ("/bin/zsh");
  77     else if (access ("/bin/tcsh", X_OK) == 0)
  78         mc_shell->path = g_strdup ("/bin/tcsh");
  79     /* No fish as fallback because it is so much different from other shells and
  80      * in a way exotic (even though user-friendly by name) that we should not
  81      * present it as a subshell without the user's explicit intention. We rather
  82      * will not use a subshell but just a command line.
  83      * else if (access("/bin/fish", X_OK) == 0)
  84      *     mc_global.tty.shell = g_strdup ("/bin/fish");
  85      */
  86     else
  87         /* Fallback and last resort: system default shell */
  88         mc_shell->path = g_strdup ("/bin/sh");
  89
  90     return mc_shell;
  91 }
  92
  93 /* --------------------------------------------------------------------------------------------- */
  94
  95 static char *
  96 mc_shell_get_name_env (void)
  97 {
  98     const char *shell_env;
  99     char *shell_name = NULL;
 100
 101     shell_env = g_getenv ("SHELL");
 102     if ((shell_env == NULL) || (shell_env[0] == '\0'))
 103     {
 104         /* 2nd choice: user login shell */
 105         struct passwd *pwd;
 106
 107         pwd = getpwuid (geteuid ());
 108         if (pwd != NULL)
 109             shell_name = g_strdup (pwd->pw_shell);
 110     }
 111     else
 112         /* 1st choice: SHELL environment variable */
 113         shell_name = g_strdup (shell_env);
 114
 115     return shell_name;
 116 }
 117
 118 /* --------------------------------------------------------------------------------------------- */
 119
 120 static mc_shell_t *
 121 mc_shell_get_from_env (void)
 122 {
 123     mc_shell_t *mc_shell = NULL;
 124
 125     char *shell_name;
 126
 127     shell_name = mc_shell_get_name_env ();
 128
 129     if (shell_name != NULL)
 130     {
 131         mc_shell = g_new0 (mc_shell_t, 1);
 132         mc_shell->path = shell_name;
 133     }
 134
 135     return mc_shell;
 136 }
 137
 138 /* --------------------------------------------------------------------------------------------- */
 139 /**
 140  * Get a shell type and store in mc_shell->type variable
 141  */
 142
 143 static gboolean
 144 mc_shell_recognize_and_fill_type (mc_shell_t * mc_shell)
 145 {
 146     gboolean result = TRUE;
 147
 148     /* Find out what type of shell we have. Also consider real paths (resolved symlinks)
 149      * because e.g. csh might point to tcsh, ash to dash or busybox, sh to anything. */
 150
 151     if (strstr (mc_shell->path, "/zsh") != NULL || strstr (mc_shell->real_path, "/zsh") != NULL
 152         || getenv ("ZSH_VERSION") != NULL)
 153     {
 154         /* Also detects ksh symlinked to zsh */
 155         mc_shell->type = SHELL_ZSH;
 156         mc_shell->name = "zsh";
 157     }
 158     else if (strstr (mc_shell->path, "/tcsh") != NULL
 159              || strstr (mc_shell->real_path, "/tcsh") != NULL)
 160     {
 161         /* Also detects csh symlinked to tcsh */
 162         mc_shell->type = SHELL_TCSH;
 163         mc_shell->name = "tcsh";
 164     }
 165     else if (strstr (mc_shell->path, "/fish") != NULL
 166              || strstr (mc_shell->real_path, "/fish") != NULL)
 167     {
 168         mc_shell->type = SHELL_FISH;
 169         mc_shell->name = "fish";
 170     }
 171     else if (strstr (mc_shell->path, "/dash") != NULL
 172              || strstr (mc_shell->real_path, "/dash") != NULL)
 173     {
 174         /* Debian ash (also found if symlinked to by ash/sh) */
 175         mc_shell->type = SHELL_DASH;
 176         mc_shell->name = "dash";
 177     }
 178     else if (strstr (mc_shell->real_path, "/busybox") != NULL)
 179     {
 180         /* If shell is symlinked to busybox, assume it is an ash, even though theoretically
 181          * it could also be a hush (a mini shell for non-MMU systems deactivated by default).
 182          * For simplicity's sake we assume that busybox always contains an ash, not a hush.
 183          * On embedded platforms or on server systems, /bin/sh often points to busybox.
 184          * Sometimes even bash is symlinked to busybox (CONFIG_FEATURE_BASH_IS_ASH option),
 185          * so we need to check busybox symlinks *before* checking for the name "bash"
 186          * in order to avoid that case. */
 187         mc_shell->type = SHELL_ASH_BUSYBOX;
 188         mc_shell->name = mc_shell->path;
 189     }
 190     else if (strstr (mc_shell->path, "/bash") != NULL || getenv ("BASH") != NULL)
 191     {
 192         /* If bash is not symlinked to busybox, it is safe to assume it is a real bash */
 193         mc_shell->type = SHELL_BASH;
 194         mc_shell->name = "bash";
 195     }
 196     else if (strstr (mc_shell->path, "/sh") != NULL || getenv ("SH") != NULL)
 197     {
 198         /* If bash is not symlinked to busybox, it is safe to assume it is a real bash */
 199         mc_shell->type = SHELL_SH;
 200         mc_shell->name = "sh";
 201     }
 202     else if (strstr (mc_shell->path, "/ash") != NULL || getenv ("ASH") != NULL)
 203     {
 204         /* If bash is not symlinked to busybox, it is safe to assume it is a real bash */
 205         mc_shell->type = SHELL_ASH_BUSYBOX;
 206         mc_shell->name = "ash";
 207     }
 208     else
 209     {
 210         mc_shell->type = SHELL_NONE;
 211         mc_global.tty.use_subshell = FALSE;
 212         result = FALSE;
 213     }
 214     return result;
 215 }
 216
 217 /* --------------------------------------------------------------------------------------------- */
 218 /*** public functions ****************************************************************************/
 219 /* --------------------------------------------------------------------------------------------- */
 220
 221 void
 222 mc_shell_init (void)
 223 {
 224     mc_shell_t *mc_shell;
 225
 226     mc_shell = mc_shell_get_from_env ();
 227
 228     if (mc_shell == NULL)
 229         mc_shell = mc_shell_get_installed_in_system ();
 230
 231     mc_shell->real_path = mc_realpath (mc_shell->path, rp_shell);
 232
 233     if (!mc_shell_recognize_and_fill_type (mc_shell))
 234         mc_global.tty.use_subshell = FALSE;
 235
 236     mc_global.shell = mc_shell;
 237 }
 238
 239 /* --------------------------------------------------------------------------------------------- */
 240
 241 void
 242 mc_shell_deinit (void)
 243 {
 244     if (mc_global.shell != NULL)
 245     {
 246         g_free (mc_global.shell->path);
 247         MC_PTR_FREE (mc_global.shell);
 248     }
 249 }
 250
 251 /* --------------------------------------------------------------------------------------------- */