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: src/sys/kern/imgact_shell.c,v 1.26.4.3 2005/03/02 00:00:13 gad Exp $");
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 #define REL4_SCRIPT_OPTIONS 1
77 #if REL4_SCRIPT_OPTIONS
78 /*
79 * XXX - This behavior is not correct, but it matches what FreeBSD
80 * has being doing since March 2000 (3.5-release, and all of the
81 * 4.x releases), so we will continue to go with it for 5.4-release.
82 * This behavior will certainly be changed before 6.0-release, and
83 * might change for 5.5-release.
84 */
85 for (ihp = &image_header[2]; *ihp != '\n' && *ihp != '#'; ++ihp) {
86 #else
87 /*
88 * XXX - This behavior is closer to correct, but it requires a
89 * change to /bin/sh which is not ready yet, and which will also
90 * require making another incompatible change here. We will
91 * not have all that tested in time for 5.4-release. But this
92 * is left here as a compile-time option, because attempting to
93 * parse-out the comments causes a problem for some users.
94 */
95 for (ihp = &image_header[2]; *ihp != '\n'; ++ihp) {
96 #endif
97 if (ihp >= &image_header[MAXSHELLCMDLEN])
98 return(ENAMETOOLONG);
99 }
100 line_endp = ihp;
101
102 /* reset for another pass */
103 ihp = &image_header[2];
104
105 /* Skip over leading spaces - until the interpreter name */
106 while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
107
108 /* copy the interpreter name */
109 interp = imgp->interpreter_name;
110 while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
111 *interp++ = *ihp++;
112 *interp = '\0';
113
114 /* Disallow a null interpreter filename */
115 if (*imgp->interpreter_name == '\0')
116 return(ENOEXEC);
117
118 /* reset for another pass */
119 ihp = &image_header[2];
120
121 /* copy the interpreter name and arguments */
122 while (ihp < line_endp) {
123 /* Skip over leading spaces */
124 while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
125
126 if (ihp < line_endp) {
127 /*
128 * Copy to end of token. No need to watch stringspace
129 * because this is at the front of the string buffer
130 * and the maximum shell command length is tiny.
131 */
132 while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
133 *imgp->stringp++ = *ihp++;
134 imgp->stringspace--;
135 }
136
137 *imgp->stringp++ = 0;
138 imgp->stringspace--;
139
140 imgp->argc++;
141 }
142 }
143
144 imgp->argv0 = imgp->fname;
145
146 return(0);
147 }
148
149 /*
150 * Tell kern_execve.c about it, with a little help from the linker.
151 */
152 static struct execsw shell_execsw = { exec_shell_imgact, "#!" };
153 EXEC_SET(shell, shell_execsw);
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