imgact_shell.c revision 137097 
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
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/kern/imgact_shell.c 137097 2004-10-31 11:12:59Z pjd $");
29
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/sysproto.h>
33#include <sys/exec.h>
34#include <sys/imgact.h>
35#include <sys/kernel.h>
36
37#if BYTE_ORDER == LITTLE_ENDIAN
38#define SHELLMAGIC	0x2123 /* #! */
39#else
40#define SHELLMAGIC	0x2321
41#endif
42
43/*
44 * Shell interpreter image activator. An interpreter name beginning
45 *	at imgp->stringbase is the minimal successful exit requirement.
46 */
47int
48exec_shell_imgact(imgp)
49	struct image_params *imgp;
50{
51	const char *image_header = imgp->image_header;
52	const char *ihp, *line_endp;
53	char *interp;
54
55	/* a shell script? */
56	if (((const short *) image_header)[0] != SHELLMAGIC)
57		return(-1);
58
59	/*
60	 * Don't allow a shell script to be the shell for a shell
61	 *	script. :-)
62	 */
63	if (imgp->interpreted)
64		return(ENOEXEC);
65
66	imgp->interpreted = 1;
67
68	/*
69	 * Copy shell name and arguments from image_header into string
70	 *	buffer.
71	 */
72
73	/*
74	 * Find end of line; return if the line > MAXSHELLCMDLEN long.
75	 */
76	for (ihp = &image_header[2]; *ihp != '\n'; ++ihp) {
77		if (ihp >= &image_header[MAXSHELLCMDLEN])
78			return(ENAMETOOLONG);
79	}
80	line_endp = ihp;
81
82	/* reset for another pass */
83	ihp = &image_header[2];
84
85	/* Skip over leading spaces - until the interpreter name */
86	while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
87
88	/* copy the interpreter name */
89	interp = imgp->interpreter_name;
90	while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
91		*interp++ = *ihp++;
92	*interp = '\0';
93
94	/* Disallow a null interpreter filename */
95	if (*imgp->interpreter_name == '\0')
96		return(ENOEXEC);
97
98	/* reset for another pass */
99	ihp = &image_header[2];
100
101	/* copy the interpreter name and arguments */
102	while (ihp < line_endp) {
103		/* Skip over leading spaces */
104		while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
105
106		if (ihp < line_endp) {
107			/*
108			 * Copy to end of token. No need to watch stringspace
109			 *	because this is at the front of the string buffer
110			 *	and the maximum shell command length is tiny.
111			 */
112			while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
113				*imgp->stringp++ = *ihp++;
114				imgp->stringspace--;
115			}
116
117			*imgp->stringp++ = 0;
118			imgp->stringspace--;
119
120			imgp->argc++;
121		}
122	}
123
124	imgp->argv0 = imgp->fname;
125
126	return(0);
127}
128
129/*
130 * Tell kern_execve.c about it, with a little help from the linker.
131 */
132static struct execsw shell_execsw = { exec_shell_imgact, "#!" };
133EXEC_SET(shell, shell_execsw);
134