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deb-mbse/unix/shell.c

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2002-01-02 22:17:58 +00:00
/*****************************************************************************
*
* $Id$
* Purpose ...............: MBSE BBS Shadow Password Suite
* Original Source .......: Shadow Password Suite
2002-01-04 21:10:21 +00:00
* Original Copyright ....: Julianne Frances Haugh and others.
2002-01-02 22:17:58 +00:00
*
*****************************************************************************
* Copyright (C) 1997-2001
*
* Michiel Broek FIDO: 2:280/2802
* Beekmansbos 10
* 1971 BV IJmuiden
* the Netherlands
*
* This file is part of MBSE BBS.
*
* This BBS 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 2, or (at your option) any
* later version.
*
* MBSE BBS 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 MBSE BBS; see the file COPYING. If not, write to the Free
* Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*****************************************************************************/
#include "../config.h"
#include <stdio.h>
#include <errno.h>
#include "mblogin.h"
#include "basename.h"
#include "shell.h"
extern char **newenvp;
extern size_t newenvc;
/*
* shell - execute the named program
*
* shell begins by trying to figure out what argv[0] is going to
* be for the named process. The user may pass in that argument,
* or it will be the last pathname component of the file with a
* '-' prepended. The first attempt is to just execute the named
* file. If the errno comes back "ENOEXEC", the file is assumed
* at first glance to be a shell script. The first two characters
* must be "#!", in which case "/bin/sh" is executed to process
* the file. If all that fails, give up in disgust ...
*/
void shell(const char *file, const char *arg)
{
char arg0[1024];
int err;
if (file == (char *) 0)
exit (1);
/*
* The argv[0]'th entry is usually the path name, but
* for various reasons the invoker may want to override
* that. So, we determine the 0'th entry only if they
* don't want to tell us what it is themselves.
*/
if (arg == (char *) 0) {
snprintf(arg0, sizeof arg0, "-%s", Basename((char *) file));
arg = arg0;
}
#ifdef DEBUG
printf (_("Executing shell %s\n"), file);
#endif
/*
* First we try the direct approach. The system should be
* able to figure out what we are up to without too much
* grief.
*/
execle (file, arg, (char *) 0, newenvp);
err = errno;
/* Linux handles #! in the kernel, and bash doesn't make
sense of "#!" so it wouldn't work anyway... --marekm */
#ifndef __linux__
/*
* It is perfectly OK to have a shell script for a login
* shell, and this code attempts to support that. It
* relies on the standard shell being able to make sense
* of the "#!" magic number.
*/
if (err == ENOEXEC) {
FILE *fp;
if ((fp = fopen (file, "r"))) {
if (getc (fp) == '#' && getc (fp) == '!') {
fclose (fp);
execle ("/bin/sh", "sh",
file, (char *) 0, newenvp);
err = errno;
} else {
fclose (fp);
}
}
}
#endif
/*
* Obviously something is really wrong - I can't figure out
* how to execute this stupid shell, so I might as well give
* up in disgust ...
*/
snprintf(arg0, sizeof arg0, "Cannot execute %s", file);
errno = err;
perror(arg0);
exit(1);
}