shadow/libmisc/shell.c
Alejandro Colomar 62172f6fb5 Call NULL by its name
In variadic functions we still do the cast.  In POSIX, it's not
necessary, since NULL is required to be of type 'void *', and 'void *'
is guaranteed to have the same alignment and representation as 'char *'.
However, since ISO C still doesn't mandate that, and moreover they're
doing dubious stuff by adding nullptr, let's be on the cautious side.
Also, C++ requires that NULL is _not_ 'void *', but either plain 0 or
some magic stuff.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-02 13:08:30 -06:00

81 lines
1.9 KiB
C

/*
* SPDX-FileCopyrightText: 1989 - 1991, Julianne Frances Haugh
* SPDX-FileCopyrightText: 1996 - 1998, Marek Michałkiewicz
* SPDX-FileCopyrightText: 2003 - 2006, Tomasz Kłoczko
* SPDX-FileCopyrightText: 2009 , Nicolas François
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <config.h>
#ident "$Id$"
#include <stdio.h>
#include <errno.h>
#include "prototypes.h"
#include "defines.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.
* Then, it executes the named file.
*/
int shell (const char *file, /*@null@*/const char *arg, char *const envp[])
{
char arg0[1024];
int err;
if (file == NULL) {
errno = EINVAL;
return errno;
}
/*
* 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 == NULL) {
(void) snprintf (arg0, sizeof arg0, "-%s", Basename (file));
arg0[sizeof arg0 - 1] = '\0';
arg = arg0;
}
/*
* First we try the direct approach. The system should be
* able to figure out what we are up to without too much
* grief.
*/
(void) execle (file, arg, (char *) NULL, envp);
err = errno;
if (access (file, R_OK|X_OK) == 0) {
/*
* Assume this is a shell script (with no shebang).
* Interpret it with /bin/sh
*/
(void) execle (SHELL, "sh", "-", file, (char *) NULL, envp);
err = errno;
}
/*
* 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 ...
*/
(void) snprintf (arg0, sizeof arg0, _("Cannot execute %s"), file);
errno = err;
perror (arg0);
return err;
}