imgact_shell.c revision 12130 
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 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by David Greenman
16 * 4. The name of the developer may be used to endorse or promote products
17 *    derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 *	$Id: imgact_shell.c,v 1.8 1995/10/08 00:05:58 swallace Exp $
32 */
33
34#include <sys/param.h>
35#include <sys/systm.h>
36#include <sys/sysproto.h>
37#include <sys/resourcevar.h>
38#include <sys/exec.h>
39#include <sys/imgact.h>
40#include <sys/kernel.h>
41#include <machine/endian.h>
42
43#if BYTE_ORDER == LITTLE_ENDIAN
44#define SHELLMAGIC	0x2123 /* #! */
45#else
46#define SHELLMAGIC	0x2321
47#endif
48
49#define MAXSHELLCMDLEN	64
50
51/*
52 * Shell interpreter image activator. A interpreter name beginning
53 *	at imgp->stringbase is the minimal successful exit requirement.
54 */
55int
56exec_shell_imgact(imgp)
57	struct image_params *imgp;
58{
59	const char *image_header = imgp->image_header;
60	const char *ihp, *line_endp;
61	char *interp;
62
63	/* a shell script? */
64	if (((short *) image_header)[0] != SHELLMAGIC)
65		return(-1);
66
67	/*
68	 * Don't allow a shell script to be the shell for a shell
69	 *	script. :-)
70	 */
71	if (imgp->interpreted)
72		return(ENOEXEC);
73
74	imgp->interpreted = 1;
75
76	/*
77	 * Copy shell name and arguments from image_header into string
78	 *	buffer.
79	 */
80
81	/*
82	 * Find end of line; return if the line > MAXSHELLCMDLEN long.
83	 */
84	for (ihp = &image_header[2]; *ihp != '\n'; ++ihp) {
85		if (ihp >= &image_header[MAXSHELLCMDLEN])
86			return(ENOEXEC);
87	}
88	line_endp = ihp;
89
90	/* reset for another pass */
91	ihp = &image_header[2];
92
93	/* Skip over leading spaces - until the interpreter name */
94	while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
95
96	/* copy the interpreter name */
97	interp = imgp->interpreter_name;
98	while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
99		*interp++ = *ihp++;
100	*interp = '\0';
101
102	/* Disallow a null interpreter filename */
103	if (*imgp->interpreter_name == '\0')
104		return(ENOEXEC);
105
106	/* reset for another pass */
107	ihp = &image_header[2];
108
109	/* copy the interpreter name and arguments */
110	while (ihp < line_endp) {
111		/* Skip over leading spaces */
112		while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
113
114		if (ihp < line_endp) {
115			/*
116			 * Copy to end of token. No need to watch stringspace
117			 *	because this is at the front of the string buffer
118			 *	and the maximum shell command length is tiny.
119			 */
120			while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
121				*imgp->stringp++ = *ihp++;
122				imgp->stringspace--;
123			}
124
125			*imgp->stringp++ = 0;
126			imgp->stringspace--;
127
128			imgp->argc++;
129		}
130	}
131
132	/* set argv[0] to point to original file name */
133	suword(imgp->uap->argv, (int)imgp->uap->fname);
134
135	return(0);
136}
137
138/*
139 * Tell kern_execve.c about it, with a little help from the linker.
140 * Since `const' objects end up in the text segment, TEXT_SET is the
141 * correct directive to use.
142 */
143static const struct execsw shell_execsw = { exec_shell_imgact, "#!" };
144TEXT_SET(execsw_set, shell_execsw);
145