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mc/lib/shell.c

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/*
Provides a functions for working with shell.
Copyright (C) 2006-2023
Free Software Foundation, Inc.
Written by:
Slava Zanko <slavazanko@gmail.com>, 2015.
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 shell.c
* \brief Source: provides a functions for working with shell.
*/
#include <config.h>
#include <pwd.h> /* for username in xterm title */
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include "global.h"
#include "util.h"
/*** global variables ****************************************************************************/
/*** file scope macro definitions ****************************************************************/
/*** file scope type declarations ****************************************************************/
/*** forward declarations (file scope functions) *************************************************/
/*** file scope variables ************************************************************************/
static char rp_shell[PATH_MAX];
/* --------------------------------------------------------------------------------------------- */
/*** file scope functions ************************************************************************/
/* --------------------------------------------------------------------------------------------- */
/**
* Get a system shell.
*
* @return newly allocated mc_shell_t object with shell name
*/
static mc_shell_t *
mc_shell_get_installed_in_system (void)
{
mc_shell_t *mc_shell;
mc_shell = g_new0 (mc_shell_t, 1);
/* 3rd choice: look for existing shells supported as MC subshells. */
if (access ("/bin/bash", X_OK) == 0)
mc_shell->path = g_strdup ("/bin/bash");
else if (access ("/bin/ash", X_OK) == 0)
mc_shell->path = g_strdup ("/bin/ash");
else if (access ("/bin/dash", X_OK) == 0)
mc_shell->path = g_strdup ("/bin/dash");
else if (access ("/bin/busybox", X_OK) == 0)
mc_shell->path = g_strdup ("/bin/busybox");
else if (access ("/bin/zsh", X_OK) == 0)
mc_shell->path = g_strdup ("/bin/zsh");
else if (access ("/bin/tcsh", X_OK) == 0)
mc_shell->path = g_strdup ("/bin/tcsh");
else if (access ("/bin/csh", X_OK) == 0)
mc_shell->path = g_strdup ("/bin/csh");
/* 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 */
mc_shell->path = g_strdup ("/bin/sh");
return mc_shell;
}
/* --------------------------------------------------------------------------------------------- */
static char *
mc_shell_get_name_env (void)
{
const char *shell_env;
char *shell_name = NULL;
shell_env = g_getenv ("SHELL");
if ((shell_env == NULL) || (shell_env[0] == '\0'))
{
/* 2nd choice: user login shell */
struct passwd *pwd;
pwd = getpwuid (geteuid ());
if (pwd != NULL)
shell_name = g_strdup (pwd->pw_shell);
}
else
/* 1st choice: SHELL environment variable */
shell_name = g_strdup (shell_env);
return shell_name;
}
/* --------------------------------------------------------------------------------------------- */
static mc_shell_t *
mc_shell_get_from_env (void)
{
mc_shell_t *mc_shell = NULL;
char *shell_name;
shell_name = mc_shell_get_name_env ();
if (shell_name != NULL)
{
mc_shell = g_new0 (mc_shell_t, 1);
mc_shell->path = shell_name;
}
return mc_shell;
}
/* --------------------------------------------------------------------------------------------- */
static void
mc_shell_recognize_real_path (mc_shell_t * mc_shell)
{
if (strstr (mc_shell->path, "/zsh") != NULL || strstr (mc_shell->real_path, "/zsh") != NULL
|| getenv ("ZSH_VERSION") != NULL)
{
/* Also detects ksh symlinked to zsh */
mc_shell->type = SHELL_ZSH;
mc_shell->name = "zsh";
}
else if (strstr (mc_shell->path, "/tcsh") != NULL
|| strstr (mc_shell->real_path, "/tcsh") != NULL)
{
/* Also detects csh symlinked to tcsh */
mc_shell->type = SHELL_TCSH;
mc_shell->name = "tcsh";
}
else if (strstr (mc_shell->path, "/csh") != NULL
|| strstr (mc_shell->real_path, "/csh") != NULL)
{
mc_shell->type = SHELL_TCSH;
mc_shell->name = "csh";
}
else if (strstr (mc_shell->path, "/fish") != NULL
|| strstr (mc_shell->real_path, "/fish") != NULL)
{
mc_shell->type = SHELL_FISH;
mc_shell->name = "fish";
}
else if (strstr (mc_shell->path, "/dash") != NULL
|| strstr (mc_shell->real_path, "/dash") != NULL)
{
/* Debian ash (also found if symlinked to by ash/sh) */
mc_shell->type = SHELL_DASH;
mc_shell->name = "dash";
}
else if (strstr (mc_shell->real_path, "/busybox") != NULL)
{
/* 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. */
mc_shell->type = SHELL_ASH_BUSYBOX;
mc_shell->name = mc_shell->path;
}
else
mc_shell->type = SHELL_NONE;
}
/* --------------------------------------------------------------------------------------------- */
static void
mc_shell_recognize_path (mc_shell_t * mc_shell)
{
/* If shell is not symlinked to busybox, it is safe to assume it is a real shell */
if (strstr (mc_shell->path, "/bash") != NULL || getenv ("BASH") != NULL)
{
mc_shell->type = SHELL_BASH;
mc_shell->name = "bash";
}
else if (strstr (mc_shell->path, "/sh") != NULL || getenv ("SH") != NULL)
{
mc_shell->type = SHELL_SH;
mc_shell->name = "sh";
}
else if (strstr (mc_shell->path, "/ash") != NULL || getenv ("ASH") != NULL)
{
mc_shell->type = SHELL_ASH_BUSYBOX;
mc_shell->name = "ash";
}
else
mc_shell->type = SHELL_NONE;
}
/* --------------------------------------------------------------------------------------------- */
/*** public functions ****************************************************************************/
/* --------------------------------------------------------------------------------------------- */
void
mc_shell_init (void)
{
mc_shell_t *mc_shell;
mc_shell = mc_shell_get_from_env ();
if (mc_shell == NULL)
mc_shell = mc_shell_get_installed_in_system ();
mc_shell->real_path = mc_realpath (mc_shell->path, rp_shell);
/* 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 (mc_shell->real_path != NULL)
mc_shell_recognize_real_path (mc_shell);
if (mc_shell->type == SHELL_NONE)
mc_shell_recognize_path (mc_shell);
if (mc_shell->type == SHELL_NONE)
mc_global.tty.use_subshell = FALSE;
mc_global.shell = mc_shell;
}
/* --------------------------------------------------------------------------------------------- */
void
mc_shell_deinit (void)
{
if (mc_global.shell != NULL)
{
g_free (mc_global.shell->path);
MC_PTR_FREE (mc_global.shell);
}
}
/* --------------------------------------------------------------------------------------------- */
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