imgact_shell.c revision 25115 
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 1.14 1997/02/22 09:38:57 peter Exp $
27 */
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/sysproto.h>
32#include <sys/resourcevar.h>
33#include <sys/exec.h>
34#include <sys/imgact.h>
35#include <sys/kernel.h>
36#include <machine/endian.h>
37
38#if BYTE_ORDER == LITTLE_ENDIAN
39#define SHELLMAGIC	0x2123 /* #! */
40#else
41#define SHELLMAGIC	0x2321
42#endif
43
44#define MAXSHELLCMDLEN	64
45
46static int	exec_shell_imgact __P((struct image_params *imgp));
47
48/*
49 * Shell interpreter image activator. A interpreter name beginning
50 *	at imgp->stringbase is the minimal successful exit requirement.
51 */
52static int
53exec_shell_imgact(imgp)
54	struct image_params *imgp;
55{
56	const char *image_header = imgp->image_header;
57	const char *ihp, *line_endp;
58	char *interp;
59
60	/* a shell script? */
61	if (((const short *) image_header)[0] != SHELLMAGIC)
62		return(-1);
63
64	/*
65	 * Don't allow a shell script to be the shell for a shell
66	 *	script. :-)
67	 */
68	if (imgp->interpreted)
69		return(ENOEXEC);
70
71	imgp->interpreted = 1;
72
73	/*
74	 * Copy shell name and arguments from image_header into string
75	 *	buffer.
76	 */
77
78	/*
79	 * Find end of line; return if the line > MAXSHELLCMDLEN long.
80	 */
81	for (ihp = &image_header[2]; *ihp != '\n'; ++ihp) {
82		if (ihp >= &image_header[MAXSHELLCMDLEN])
83			return(ENOEXEC);
84	}
85	line_endp = ihp;
86
87	/* reset for another pass */
88	ihp = &image_header[2];
89
90	/* Skip over leading spaces - until the interpreter name */
91	while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
92
93	/* copy the interpreter name */
94	interp = imgp->interpreter_name;
95	while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
96		*interp++ = *ihp++;
97	*interp = '\0';
98
99	/* Disallow a null interpreter filename */
100	if (*imgp->interpreter_name == '\0')
101		return(ENOEXEC);
102
103	/* reset for another pass */
104	ihp = &image_header[2];
105
106	/* copy the interpreter name and arguments */
107	while (ihp < line_endp) {
108		/* Skip over leading spaces */
109		while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
110
111		if (ihp < line_endp) {
112			/*
113			 * Copy to end of token. No need to watch stringspace
114			 *	because this is at the front of the string buffer
115			 *	and the maximum shell command length is tiny.
116			 */
117			while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
118				*imgp->stringp++ = *ihp++;
119				imgp->stringspace--;
120			}
121
122			*imgp->stringp++ = 0;
123			imgp->stringspace--;
124
125			imgp->argc++;
126		}
127	}
128
129	imgp->argv0 = imgp->uap->fname;
130
131	return(0);
132}
133
134/*
135 * Tell kern_execve.c about it, with a little help from the linker.
136 * Since `const' objects end up in the text segment, TEXT_SET is the
137 * correct directive to use.
138 */
139static const struct execsw shell_execsw = { exec_shell_imgact, "#!" };
140TEXT_SET(execsw_set, shell_execsw);
141