imgact_shell.c revision 27845 
1/*
2 * Copyright (c) 1993, David Greenman
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 *	$Id: imgact_shell.c,v 1.15 1997/04/23 22:07:04 ache Exp $
27 */
28
29#include <sys/param.h>
30#include <sys/sysproto.h>
31#include <sys/exec.h>
32#include <sys/imgact.h>
33#include <sys/kernel.h>
34
35#if BYTE_ORDER == LITTLE_ENDIAN
36#define SHELLMAGIC	0x2123 /* #! */
37#else
38#define SHELLMAGIC	0x2321
39#endif
40
41#define MAXSHELLCMDLEN	64
42
43static int	exec_shell_imgact __P((struct image_params *imgp));
44
45/*
46 * Shell interpreter image activator. A interpreter name beginning
47 *	at imgp->stringbase is the minimal successful exit requirement.
48 */
49static int
50exec_shell_imgact(imgp)
51	struct image_params *imgp;
52{
53	const char *image_header = imgp->image_header;
54	const char *ihp, *line_endp;
55	char *interp;
56
57	/* a shell script? */
58	if (((const short *) image_header)[0] != SHELLMAGIC)
59		return(-1);
60
61	/*
62	 * Don't allow a shell script to be the shell for a shell
63	 *	script. :-)
64	 */
65	if (imgp->interpreted)
66		return(ENOEXEC);
67
68	imgp->interpreted = 1;
69
70	/*
71	 * Copy shell name and arguments from image_header into string
72	 *	buffer.
73	 */
74
75	/*
76	 * Find end of line; return if the line > MAXSHELLCMDLEN long.
77	 */
78	for (ihp = &image_header[2]; *ihp != '\n'; ++ihp) {
79		if (ihp >= &image_header[MAXSHELLCMDLEN])
80			return(ENOEXEC);
81	}
82	line_endp = ihp;
83
84	/* reset for another pass */
85	ihp = &image_header[2];
86
87	/* Skip over leading spaces - until the interpreter name */
88	while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
89
90	/* copy the interpreter name */
91	interp = imgp->interpreter_name;
92	while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
93		*interp++ = *ihp++;
94	*interp = '\0';
95
96	/* Disallow a null interpreter filename */
97	if (*imgp->interpreter_name == '\0')
98		return(ENOEXEC);
99
100	/* reset for another pass */
101	ihp = &image_header[2];
102
103	/* copy the interpreter name and arguments */
104	while (ihp < line_endp) {
105		/* Skip over leading spaces */
106		while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
107
108		if (ihp < line_endp) {
109			/*
110			 * Copy to end of token. No need to watch stringspace
111			 *	because this is at the front of the string buffer
112			 *	and the maximum shell command length is tiny.
113			 */
114			while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
115				*imgp->stringp++ = *ihp++;
116				imgp->stringspace--;
117			}
118
119			*imgp->stringp++ = 0;
120			imgp->stringspace--;
121
122			imgp->argc++;
123		}
124	}
125
126	imgp->argv0 = imgp->uap->fname;
127
128	return(0);
129}
130
131/*
132 * Tell kern_execve.c about it, with a little help from the linker.
133 * Since `const' objects end up in the text segment, TEXT_SET is the
134 * correct directive to use.
135 */
136static const struct execsw shell_execsw = { exec_shell_imgact, "#!" };
137TEXT_SET(execsw_set, shell_execsw);
138