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: src/sys/kern/imgact_shell.c,v 1.12.2.2 1999/09/05 08:14:46 peter Exp $
27 */
28
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/sysproto.h>
32 #include <sys/resourcevar.h>
33 #include <sys/exec.h>
34 #include <sys/imgact.h>
35 #include <sys/kernel.h>
36 #include <machine/endian.h>
37
38 #if BYTE_ORDER == LITTLE_ENDIAN
39 #define SHELLMAGIC 0x2123 /* #! */
40 #else
41 #define SHELLMAGIC 0x2321
42 #endif
43
44 #define MAXSHELLCMDLEN 64
45
46 static int exec_shell_imgact __P((struct image_params *imgp));
47
48 /*
49 * Shell interpreter image activator. A interpreter name beginning
50 * at imgp->stringbase is the minimal successful exit requirement.
51 */
52 static int
53 exec_shell_imgact(imgp)
54 struct image_params *imgp;
55 {
56 const char *image_header = imgp->image_header;
57 const char *ihp, *line_endp;
58 char *interp;
59
60 /* a shell script? */
61 if (((const short *) image_header)[0] != SHELLMAGIC)
62 return(-1);
63
64 /*
65 * Don't allow a shell script to be the shell for a shell
66 * script. :-)
67 */
68 if (imgp->interpreted)
69 return(ENOEXEC);
70
71 imgp->interpreted = 1;
72
73 /*
74 * Copy shell name and arguments from image_header into string
75 * buffer.
76 */
77
78 /*
79 * Find end of line; return if the line > MAXSHELLCMDLEN long.
80 */
81 for (ihp = &image_header[2]; *ihp != '\n'; ++ihp) {
82 if (ihp >= &image_header[MAXSHELLCMDLEN])
83 return(ENOEXEC);
84 }
85 line_endp = ihp;
86
87 /* reset for another pass */
88 ihp = &image_header[2];
89
90 /* Skip over leading spaces - until the interpreter name */
91 while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
92
93 /* copy the interpreter name */
94 interp = imgp->interpreter_name;
95 while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
96 *interp++ = *ihp++;
97 *interp = '\0';
98
99 /* Disallow a null interpreter filename */
100 if (*imgp->interpreter_name == '\0')
101 return(ENOEXEC);
102
103 /* reset for another pass */
104 ihp = &image_header[2];
105
106 /* copy the interpreter name and arguments */
107 while (ihp < line_endp) {
108 /* Skip over leading spaces */
109 while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
110
111 if (ihp < line_endp) {
112 /*
113 * Copy to end of token. No need to watch stringspace
114 * because this is at the front of the string buffer
115 * and the maximum shell command length is tiny.
116 */
117 while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
118 *imgp->stringp++ = *ihp++;
119 imgp->stringspace--;
120 }
121
122 *imgp->stringp++ = 0;
123 imgp->stringspace--;
124
125 imgp->argc++;
126 }
127 }
128
129 imgp->argv0 = imgp->uap->fname;
130
131 return(0);
132 }
133
134 /*
135 * Tell kern_execve.c about it, with a little help from the linker.
136 * Since `const' objects end up in the text segment, TEXT_SET is the
137 * correct directive to use.
138 */
139 static const struct execsw shell_execsw = { exec_shell_imgact, "#!" };
140 TEXT_SET(execsw_set, shell_execsw);
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