1 files changed, 264 insertions, 0 deletions
diff --git a/lib/shell.c b/lib/shell.c
new file mode 100644
index 0000000..0646171
--- /dev/null
+++ b/lib/shell.c
@@ -0,0 +1,264 @@
+/*
+   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);
+    }
+}
+
+/* --------------------------------------------------------------------------------------------- */