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: releng/5.2/sys/kern/imgact_shell.c 116182 2003-06-11 00:56:59Z obrien $");
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 */
47 int
48 exec_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 != '#'; ++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 */
132 static struct execsw shell_execsw = { exec_shell_imgact, "#!" };
133 EXEC_SET(shell, shell_execsw);
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