+/* PSPP - a program for statistical analysis.
+ Copyright (C) 1997-9, 2000, 2009, 2010 Free Software Foundation, Inc.
+
+ This program 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.
+
+ This program 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/>. */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <errno.h>
+#include <unistd.h>
+#if HAVE_SYS_WAIT_H
+#include <sys/wait.h>
+#endif
+
+#include "data/settings.h"
+#include "language/command.h"
+#include "language/lexer/lexer.h"
+#include "libpspp/assertion.h"
+#include "libpspp/compiler.h"
+#include "libpspp/message.h"
+#include "libpspp/str.h"
+
+#include "gl/xalloc.h"
+#include "gl/xmalloca.h"
+
+#include "gettext.h"
+#define _(msgid) gettext (msgid)
+#define N_(msgid) msgid
+\f
+#if HAVE_FORK && HAVE_EXECL
+/* Spawn an interactive shell process. */
+static bool
+shell (void)
+{
+ int pid;
+
+ pid = fork ();
+ switch (pid)
+ {
+ case 0:
+ {
+ const char *shell_fn;
+ char *shell_process;
+
+ {
+ int i;
+
+ for (i = 3; i < 20; i++)
+ close (i);
+ }
+
+ shell_fn = getenv ("SHELL");
+ if (shell_fn == NULL)
+ shell_fn = "/bin/sh";
+
+ {
+ const char *cp = strrchr (shell_fn, '/');
+ cp = cp ? &cp[1] : shell_fn;
+ shell_process = xmalloca (strlen (cp) + 8);
+ strcpy (shell_process, "-");
+ strcat (shell_process, cp);
+ if (strcmp (cp, "sh"))
+ shell_process[0] = '+';
+ }
+
+ execl (shell_fn, shell_process, NULL);
+
+ _exit (1);
+ }
+
+ case -1:
+ msg (SE, _("Couldn't fork: %s."), strerror (errno));
+ return false;
+
+ default:
+ assert (pid > 0);
+ while (wait (NULL) != pid)
+ ;
+ return true;
+ }
+}
+#else /* !(HAVE_FORK && HAVE_EXECL) */
+/* Don't know how to spawn an interactive shell. */
+static bool
+shell (void)
+{
+ msg (SE, _("Interactive shell not supported on this platform."));
+ return false;
+}
+#endif
+
+/* Executes the specified COMMAND in a subshell. Returns true if
+ successful, false otherwise. */
+static bool
+run_command (const char *command)
+{
+ if (system (NULL) == 0)
+ {
+ msg (SE, _("Command shell not supported on this platform."));
+ return false;
+ }
+
+ /* Execute the command. */
+ if (system (command) == -1)
+ msg (SE, _("Error executing command: %s."), strerror (errno));
+
+ return true;
+}
+
+int
+cmd_host (struct lexer *lexer, struct dataset *ds UNUSED)
+{
+ if (settings_get_safer_mode ())
+ {
+ msg (SE, _("This command not allowed when the SAFER option is set."));
+ return CMD_FAILURE;
+ }
+
+ if (lex_token (lexer) == '.')
+ return shell () ? CMD_SUCCESS : CMD_FAILURE;
+ else if (lex_match_id (lexer, "COMMAND"))
+ {
+ struct string command;
+ bool ok;
+
+ lex_match (lexer, '=');
+ if (!lex_force_match (lexer, '['))
+ return CMD_FAILURE;
+
+ ds_init_empty (&command);
+ while (lex_token (lexer) == T_STRING)
+ {
+ if (!ds_is_empty (&command))
+ ds_put_char (&command, '\n');
+ ds_put_substring (&command, ds_ss (lex_tokstr (lexer)));
+ lex_get (lexer);
+ }
+ if (!lex_force_match (lexer, ']'))
+ {
+ ds_destroy (&command);
+ return CMD_FAILURE;
+ }
+
+ ok = run_command (ds_cstr (&command));
+ ds_destroy (&command);
+
+ return ok ? lex_end_of_command (lexer) : CMD_FAILURE;
+ }
+ else
+ {
+ lex_error (lexer, NULL);
+ return CMD_FAILURE;
+ }
+}