imgact_shell.c revision 50477 
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 * $FreeBSD: head/sys/kern/imgact_shell.c 50477 1999-08-28 01:08:13Z peter $
27 */
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/sysproto.h>
32#include <sys/exec.h>
33#include <sys/imgact.h>
34#include <sys/kernel.h>
35
36#if BYTE_ORDER == LITTLE_ENDIAN
37#define SHELLMAGIC	0x2123 /* #! */
38#else
39#define SHELLMAGIC	0x2321
40#endif
41
42#define MAXSHELLCMDLEN	64
43
44static int	exec_shell_imgact __P((struct image_params *imgp));
45
46/*
47 * Shell interpreter image activator. A interpreter name beginning
48 *	at imgp->stringbase is the minimal successful exit requirement.
49 */
50static int
51exec_shell_imgact(imgp)
52	struct image_params *imgp;
53{
54	const char *image_header = imgp->image_header;
55	const char *ihp, *line_endp;
56	char *interp;
57
58	/* a shell script? */
59	if (((const short *) image_header)[0] != SHELLMAGIC)
60		return(-1);
61
62	/*
63	 * Don't allow a shell script to be the shell for a shell
64	 *	script. :-)
65	 */
66	if (imgp->interpreted)
67		return(ENOEXEC);
68
69	imgp->interpreted = 1;
70
71	/*
72	 * Copy shell name and arguments from image_header into string
73	 *	buffer.
74	 */
75
76	/*
77	 * Find end of line; return if the line > MAXSHELLCMDLEN long.
78	 */
79	for (ihp = &image_header[2]; *ihp != '\n'; ++ihp) {
80		if (ihp >= &image_header[MAXSHELLCMDLEN])
81			return(ENOEXEC);
82	}
83	line_endp = ihp;
84
85	/* reset for another pass */
86	ihp = &image_header[2];
87
88	/* Skip over leading spaces - until the interpreter name */
89	while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
90
91	/* copy the interpreter name */
92	interp = imgp->interpreter_name;
93	while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
94		*interp++ = *ihp++;
95	*interp = '\0';
96
97	/* Disallow a null interpreter filename */
98	if (*imgp->interpreter_name == '\0')
99		return(ENOEXEC);
100
101	/* reset for another pass */
102	ihp = &image_header[2];
103
104	/* copy the interpreter name and arguments */
105	while (ihp < line_endp) {
106		/* Skip over leading spaces */
107		while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
108
109		if (ihp < line_endp) {
110			/*
111			 * Copy to end of token. No need to watch stringspace
112			 *	because this is at the front of the string buffer
113			 *	and the maximum shell command length is tiny.
114			 */
115			while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
116				*imgp->stringp++ = *ihp++;
117				imgp->stringspace--;
118			}
119
120			*imgp->stringp++ = 0;
121			imgp->stringspace--;
122
123			imgp->argc++;
124		}
125	}
126
127	imgp->argv0 = imgp->uap->fname;
128
129	return(0);
130}
131
132/*
133 * Tell kern_execve.c about it, with a little help from the linker.
134 */
135static struct execsw shell_execsw = { exec_shell_imgact, "#!" };
136EXEC_SET(shell, shell_execsw);
137