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- lib/shell.c
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*/
1 /*
2 Provides a functions for working with shell.
3
4 Copyright (C) 2006-2020
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 mc_shell_t object with shell name
57 */
58
59 static mc_shell_t *
60 mc_shell_get_installed_in_system (void)
/* ![[next]](../icons/right.png)
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*/
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 else if (access ("/bin/csh", X_OK) == 0)
80 mc_shell->path = g_strdup ("/bin/csh");
81 /* No fish as fallback because it is so much different from other shells and
82 * in a way exotic (even though user-friendly by name) that we should not
83 * present it as a subshell without the user's explicit intention. We rather
84 * will not use a subshell but just a command line.
85 * else if (access("/bin/fish", X_OK) == 0)
86 * mc_global.tty.shell = g_strdup ("/bin/fish");
87 */
88 else
89 /* Fallback and last resort: system default shell */
90 mc_shell->path = g_strdup ("/bin/sh");
91
92 return mc_shell;
93 }
94
95 /* --------------------------------------------------------------------------------------------- */
96
97 static char *
98 mc_shell_get_name_env (void)
/* ![[previous]](../icons/left.png)
*/
99 {
100 const char *shell_env;
101 char *shell_name = NULL;
102
103 shell_env = g_getenv ("SHELL");
104 if ((shell_env == NULL) || (shell_env[0] == '\0'))
105 {
106 /* 2nd choice: user login shell */
107 struct passwd *pwd;
108
109 pwd = getpwuid (geteuid ());
110 if (pwd != NULL)
111 shell_name = g_strdup (pwd->pw_shell);
112 }
113 else
114 /* 1st choice: SHELL environment variable */
115 shell_name = g_strdup (shell_env);
116
117 return shell_name;
118 }
119
120 /* --------------------------------------------------------------------------------------------- */
121
122 static mc_shell_t *
123 mc_shell_get_from_env (void)
/* */
124 {
125 mc_shell_t *mc_shell = NULL;
126
127 char *shell_name;
128
129 shell_name = mc_shell_get_name_env ();
130
131 if (shell_name != NULL)
132 {
133 mc_shell = g_new0 (mc_shell_t, 1);
134 mc_shell->path = shell_name;
135 }
136
137 return mc_shell;
138 }
139
140 /* --------------------------------------------------------------------------------------------- */
141
142 static void
143 mc_shell_recognize_real_path (mc_shell_t * mc_shell)
/* */
144 {
145 if (strstr (mc_shell->path, "/zsh") != NULL || strstr (mc_shell->real_path, "/zsh") != NULL
146 || getenv ("ZSH_VERSION") != NULL)
147 {
148 /* Also detects ksh symlinked to zsh */
149 mc_shell->type = SHELL_ZSH;
150 mc_shell->name = "zsh";
151 }
152 else if (strstr (mc_shell->path, "/tcsh") != NULL
153 || strstr (mc_shell->real_path, "/tcsh") != NULL)
154 {
155 /* Also detects csh symlinked to tcsh */
156 mc_shell->type = SHELL_TCSH;
157 mc_shell->name = "tcsh";
158 }
159 else if (strstr (mc_shell->path, "/csh") != NULL
160 || strstr (mc_shell->real_path, "/csh") != NULL)
161 {
162 mc_shell->type = SHELL_TCSH;
163 mc_shell->name = "csh";
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
191 mc_shell->type = SHELL_NONE;
192 }
193
194 /* --------------------------------------------------------------------------------------------- */
195
196 static void
197 mc_shell_recognize_path (mc_shell_t * mc_shell)
/* */
198 {
199 /* If shell is not symlinked to busybox, it is safe to assume it is a real shell */
200 if (strstr (mc_shell->path, "/bash") != NULL || getenv ("BASH") != NULL)
201 {
202 mc_shell->type = SHELL_BASH;
203 mc_shell->name = "bash";
204 }
205 else if (strstr (mc_shell->path, "/sh") != NULL || getenv ("SH") != NULL)
206 {
207 mc_shell->type = SHELL_SH;
208 mc_shell->name = "sh";
209 }
210 else if (strstr (mc_shell->path, "/ash") != NULL || getenv ("ASH") != NULL)
211 {
212 mc_shell->type = SHELL_ASH_BUSYBOX;
213 mc_shell->name = "ash";
214 }
215 else
216 mc_shell->type = SHELL_NONE;
217 }
218
219 /* --------------------------------------------------------------------------------------------- */
220 /*** public functions ****************************************************************************/
221 /* --------------------------------------------------------------------------------------------- */
222
223 void
224 mc_shell_init (void)
/* */
225 {
226 mc_shell_t *mc_shell;
227
228 mc_shell = mc_shell_get_from_env ();
229
230 if (mc_shell == NULL)
231 mc_shell = mc_shell_get_installed_in_system ();
232
233 mc_shell->real_path = mc_realpath (mc_shell->path, rp_shell);
234
235 /* Find out what type of shell we have. Also consider real paths (resolved symlinks)
236 * because e.g. csh might point to tcsh, ash to dash or busybox, sh to anything. */
237
238 if (mc_shell->real_path != NULL)
239 mc_shell_recognize_real_path (mc_shell);
240
241 if (mc_shell->type == SHELL_NONE)
242 mc_shell_recognize_path (mc_shell);
243
244 if (mc_shell->type == SHELL_NONE)
245 mc_global.tty.use_subshell = FALSE;
246
247 mc_global.shell = mc_shell;
248 }
249
250 /* --------------------------------------------------------------------------------------------- */
251
252 void
253 mc_shell_deinit (void)
/* ![[last]](../icons/n_last.png)
*/
254 {
255 if (mc_global.shell != NULL)
256 {
257 g_free (mc_global.shell->path);
258 MC_PTR_FREE (mc_global.shell);
259 }
260 }
261
262 /* --------------------------------------------------------------------------------------------- */
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*/