xref: /freebsd/sys/kern/imgact_shell.c (revision 6e8394b8baa7d5d9153ab90de6824bcd19b3b4e1)
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 1.18 1999/01/29 22:59:43 dillon Exp $
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 
44 static 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  */
50 static int
51 exec_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  */
135 static struct execsw shell_execsw = { exec_shell_imgact, "#!" };
136 EXEC_SET(shell, shell_execsw);
137