118 lines
3.8 KiB
C
118 lines
3.8 KiB
C
/*
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* Copyright 1989 - 1991, Julianne Frances Haugh
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of Julianne F. Haugh nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JULIE HAUGH AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL JULIE HAUGH OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <config.h>
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#ident "$Id$"
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#include <stdio.h>
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#include <errno.h>
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#include "prototypes.h"
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#include "defines.h"
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extern char **newenvp;
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extern size_t newenvc;
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/*
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* shell - execute the named program
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*
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* shell begins by trying to figure out what argv[0] is going to
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* be for the named process. The user may pass in that argument,
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* or it will be the last pathname component of the file with a
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* '-' prepended. The first attempt is to just execute the named
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* file. If the errno comes back "ENOEXEC", the file is assumed
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* at first glance to be a shell script. The first two characters
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* must be "#!", in which case "/bin/sh" is executed to process
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* the file. If all that fails, give up in disgust ...
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*/
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int shell (const char *file, const char *arg, char *const envp[])
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{
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char arg0[1024];
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int err;
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if (file == (char *) 0) {
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errno = EINVAL;
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return errno;
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}
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/*
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* The argv[0]'th entry is usually the path name, but
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* for various reasons the invoker may want to override
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* that. So, we determine the 0'th entry only if they
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* don't want to tell us what it is themselves.
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*/
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if (arg == (char *) 0) {
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snprintf (arg0, sizeof arg0, "-%s", Basename ((char *) file));
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arg = arg0;
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}
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/*
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* First we try the direct approach. The system should be
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* able to figure out what we are up to without too much
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* grief.
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*/
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execle (file, arg, (char *) 0, envp);
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err = errno;
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/* Linux handles #! in the kernel, and bash doesn't make
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sense of "#!" so it wouldn't work anyway... --marekm */
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#ifndef __linux__
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/*
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* It is perfectly OK to have a shell script for a login
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* shell, and this code attempts to support that. It
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* relies on the standard shell being able to make sense
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* of the "#!" magic number.
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*/
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if (err == ENOEXEC) {
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FILE *fp;
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if ((fp = fopen (file, "r"))) {
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if (getc (fp) == '#' && getc (fp) == '!') {
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fclose (fp);
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execle ("/bin/sh", "sh",
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file, (char *) 0, envp);
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err = errno;
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} else {
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fclose (fp);
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}
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}
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}
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#endif
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/*
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* Obviously something is really wrong - I can't figure out
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* how to execute this stupid shell, so I might as well give
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* up in disgust ...
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*/
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snprintf (arg0, sizeof arg0, _("Cannot execute %s"), file);
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errno = err;
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perror (arg0);
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return err;
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}
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