imgact_shell.c revision 106437 
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 106437 2002-11-05 01:59:56Z rwatson $
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/*
43 * Shell interpreter image activator. A interpreter name beginning
44 *	at imgp->stringbase is the minimal successful exit requirement.
45 */
46int
47exec_shell_imgact(imgp)
48	struct image_params *imgp;
49{
50	const char *image_header = imgp->image_header;
51	const char *ihp, *line_endp;
52	char *interp;
53
54	/* a shell script? */
55	if (((const short *) image_header)[0] != SHELLMAGIC)
56		return(-1);
57
58	/*
59	 * Don't allow a shell script to be the shell for a shell
60	 *	script. :-)
61	 */
62	if (imgp->interpreted)
63		return(ENOEXEC);
64
65	imgp->interpreted = 1;
66
67	/*
68	 * Copy shell name and arguments from image_header into string
69	 *	buffer.
70	 */
71
72	/*
73	 * Find end of line; return if the line > MAXSHELLCMDLEN long.
74	 */
75	for (ihp = &image_header[2]; *ihp != '\n' && *ihp != '#'; ++ihp) {
76		if (ihp >= &image_header[MAXSHELLCMDLEN])
77			return(ENAMETOOLONG);
78	}
79	line_endp = ihp;
80
81	/* reset for another pass */
82	ihp = &image_header[2];
83
84	/* Skip over leading spaces - until the interpreter name */
85	while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
86
87	/* copy the interpreter name */
88	interp = imgp->interpreter_name;
89	while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
90		*interp++ = *ihp++;
91	*interp = '\0';
92
93	/* Disallow a null interpreter filename */
94	if (*imgp->interpreter_name == '\0')
95		return(ENOEXEC);
96
97	/* reset for another pass */
98	ihp = &image_header[2];
99
100	/* copy the interpreter name and arguments */
101	while (ihp < line_endp) {
102		/* Skip over leading spaces */
103		while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
104
105		if (ihp < line_endp) {
106			/*
107			 * Copy to end of token. No need to watch stringspace
108			 *	because this is at the front of the string buffer
109			 *	and the maximum shell command length is tiny.
110			 */
111			while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
112				*imgp->stringp++ = *ihp++;
113				imgp->stringspace--;
114			}
115
116			*imgp->stringp++ = 0;
117			imgp->stringspace--;
118
119			imgp->argc++;
120		}
121	}
122
123	imgp->argv0 = imgp->fname;
124
125	return(0);
126}
127
128/*
129 * Tell kern_execve.c about it, with a little help from the linker.
130 */
131static struct execsw shell_execsw = { exec_shell_imgact, "#!" };
132EXEC_SET(shell, shell_execsw);
133