1 /* $NetBSD: expand.c,v 1.8 2025/05/02 23:04:56 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2007 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31 #include <sys/cdefs.h>
32 #ifndef lint
33 __RCSID("$NetBSD: expand.c,v 1.8 2025/05/02 23:04:56 riastradh Exp $");
34 #endif /* not lint */
35
36 #include <ctype.h>
37 #include <string.h>
38 #include <sys/sysctl.h>
39
40 #ifdef DEBUG_EXPAND
41 #include <stdio.h>
42 #include <err.h>
43 #define xwarn warn
44 #define xerr err
45 size_t _rtld_expand_path(char *, size_t, const char *, const char *,
46 const char *);
47 #else
48 #include <sys/stat.h>
49 #include "rtld.h"
50 #endif
51
52 #include "../../lib/libc/include/__sysctl.h" /* __sysctl syscall stub */
53
54 static const struct {
55 const char *name;
56 size_t namelen;
57 } bltn[] = {
58 #define ADD(a) { #a, sizeof(#a) - 1 },
59 ADD(HWCAP) /* SSE, MMX, etc */
60 ADD(ISALIST) /* XXX */
61 ADD(ORIGIN) /* dirname argv[0] */
62 ADD(OSNAME) /* uname -s */
63 ADD(OSREL) /* uname -r */
64 ADD(PLATFORM) /* uname -p */
65 };
66
67 static int mib[3][2] = {
68 { CTL_KERN, KERN_OSTYPE },
69 { CTL_KERN, KERN_OSRELEASE },
70 { CTL_HW, HW_MACHINE_ARCH },
71 };
72
73 static size_t
expand(char * buf,const char * execname,size_t what,size_t bl)74 expand(char *buf, const char *execname, size_t what, size_t bl)
75 {
76 const char *p, *ep;
77 char *bp = buf;
78 size_t len;
79 char name[32];
80
81 switch (what) {
82 case 0: /* HWCAP XXX: Not yet */
83 case 1: /* ISALIST XXX: Not yet */
84 return 0;
85
86 case 2: /* ORIGIN */
87 if (execname == NULL)
88 xerr(1, "execname not specified in AUX vector");
89 if ((ep = strrchr(p = execname, '/')) == NULL)
90 xerr(1, "bad execname `%s' in AUX vector", execname);
91 break;
92
93 case 3: /* OSNAME */
94 case 4: /* OSREL */
95 case 5: /* PLATFORM */
96 len = sizeof(name);
97 if (__sysctl(mib[what - 3], 2, name, &len, NULL, 0) == -1) {
98 xwarn("sysctl");
99 return 0;
100 }
101 ep = (p = name) + len - 1;
102 break;
103 default:
104 return 0;
105 }
106
107 while (p != ep && bl)
108 *bp++ = *p++, bl--;
109
110 return bp - buf;
111 }
112
113
114 size_t
_rtld_expand_path(char * buf,size_t bufsize,const char * execname,const char * bp,const char * ep)115 _rtld_expand_path(char *buf, size_t bufsize, const char *execname,
116 const char *bp, const char *ep)
117 {
118 size_t i, ds = bufsize;
119 char *dp = buf;
120 const char *p;
121 int br;
122
123 for (p = bp; p < ep;) {
124 if (*p == '$') {
125 br = *++p == '{';
126
127 if (br)
128 p++;
129
130 for (i = 0; i < sizeof(bltn) / sizeof(bltn[0]); i++) {
131 size_t s = bltn[i].namelen;
132 const char *es = p + s;
133
134 if ((br && *es != '}') ||
135 (!br && (es != ep &&
136 isalpha((unsigned char)*es))))
137 continue;
138
139 if (strncmp(bltn[i].name, p, s) == 0) {
140 size_t ls = expand(dp, execname, i, ds);
141 if (ls >= ds)
142 return bufsize;
143 ds -= ls;
144 dp += ls;
145 p = es + br;
146 goto done;
147 }
148 }
149 p -= br + 1;
150
151 }
152 *dp++ = *p++;
153 ds--;
154 done:;
155 }
156 *dp = '\0';
157 return dp - buf;
158 }
159
160 #ifdef DEBUG_EXPAND
161 int
main(int argc,char * argv[])162 main(int argc, char *argv[])
163 {
164 char buf[1024];
165 size_t i;
166
167 for (i = 1; i < argc; i++) {
168 char *p = argv[i], *ep = argv[i] + strlen(p);
169 size_t n = _rtld_expand_path(buf, sizeof(buf), argv[0], p, ep);
170 printf("%s\n", buf);
171 }
172 return 0;
173 }
174 #endif
175