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/* wrapper.c -- C code booting Guile
Copyright © 2003, 2014 Dale Mellor <dale_mellor@users.sourceforge.net>
Copyright © 2015, 2016, 2017 Mathieu Lirzin <mthl@gnu.org>
This file is part of GNU Mcron.
GNU Mcron 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.
GNU Mcron 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 GNU Mcron. If not, see <http://www.gnu.org/licenses/>. */
/* This C code represents a thin wrapper around the Guile code of Mcron. It
is needed because the crontab personality requires SUID which is not
permitted for executable scripts. */
#include <libguile.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Forward declarations. */
static void wrap_env_path (const char *envar, const char *dir);
static void inner_main (void *closure, int argc, char **argv);
static void react_to_terminal_signal (int sig);
static SCM set_cron_signals (void);
int
main (int argc, char **argv)
{
/* Set Guile load paths to ensure that Mcron modules will be found after
installation. In a build environment let the 'pre-inst-env' script set
the correct paths. */
if (getenv ("MCRON_UNINSTALLED") == NULL)
{
wrap_env_path ("GUILE_LOAD_PATH", PACKAGE_LOAD_PATH);
wrap_env_path ("GUILE_LOAD_COMPILED_PATH", PACKAGE_LOAD_PATH);
}
scm_boot_guile (argc, argv, inner_main, 0);
return EXIT_SUCCESS;
}
/* Append DIR in front of ENVAR environment variable value. If ENVAR is not
defined, then define it with DIR. Bail out if something went wrong. */
static void
wrap_env_path (const char *envar, const char *dir)
{
const char *path = getenv (envar);
if (path == NULL)
setenv (envar, dir, true);
else
{
char *new_path;
int ret = asprintf (&new_path, "%s:%s", dir, path);
if (ret >= 0)
setenv (envar, new_path, true);
else
{
perror (envar);
exit (EXIT_FAILURE);
}
free (new_path);
}
}
/* Launch the Mcron Guile main program. */
static void
inner_main (void *closure, int argc, char **argv)
{
scm_set_current_module (scm_c_resolve_module ("mcron scripts " PROGRAM));
/* Register the procedures to be called from Guile. */
scm_c_define_gsubr ("c-set-cron-signals", 0, 0, 0, set_cron_signals);
/* Call main procedure. */
scm_call_0 (scm_variable_ref (scm_c_lookup ("main")));
}
/* Set up all the signal handlers as required by the cron personality. This
is necessary to perform the signal processing in C because the sigaction
function won't work when called from Guile. */
static SCM
set_cron_signals ()
{
static struct sigaction sa;
memset (&sa, 0, sizeof (sa));
sa.sa_handler = react_to_terminal_signal;
sigaction (SIGTERM, &sa, 0);
sigaction (SIGINT, &sa, 0);
sigaction (SIGQUIT, &sa, 0);
sigaction (SIGHUP, &sa, 0);
return SCM_BOOL_T;
}
/* Handle signal SIG and exit. All signals that mcron handles will produce
the same behavior so we don't need to use SIG in the implementation. */
static void
react_to_terminal_signal (int sig)
{
scm_c_eval_string ("(delete-run-file)");
exit (EXIT_FAILURE);
}
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