1/*	$NetBSD: expand.c,v 1.7 2023/01/04 01:37:00 christos 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 1.7 2023/01/04 01:37:00 christos Exp $");
34#endif /* not lint */
35
36#include <ctype.h>
37#include <string.h>
38#include <sys/sysctl.h>
39
40#ifdef DEBUG_EXPAND
41#include <stdio.h>
42#include <err.h>
43#define xwarn warn
44#define xerr err
45size_t _rtld_expand_path(char *, size_t, const char *, const char *,
46    const char *);
47#else
48#include <sys/stat.h>
49#include "rtld.h"
50#endif
51
52static const struct {
53	const char *name;
54	size_t namelen;
55} bltn[] = {
56#define ADD(a)	{ #a, sizeof(#a) - 1 },
57	ADD(HWCAP)	/* SSE, MMX, etc */
58	ADD(ISALIST)	/* XXX */
59	ADD(ORIGIN) 	/* dirname argv[0] */
60	ADD(OSNAME)	/* uname -s */
61	ADD(OSREL)	/* uname -r */
62	ADD(PLATFORM)	/* uname -p */
63};
64
65static int mib[3][2] = {
66	{ CTL_KERN, KERN_OSTYPE },
67	{ CTL_KERN, KERN_OSRELEASE },
68	{ CTL_HW, HW_MACHINE_ARCH },
69};
70
71static size_t
72expand(char *buf, const char *execname, size_t what, size_t bl)
73{
74	const char *p, *ep;
75	char *bp = buf;
76	size_t len;
77	char name[32];
78
79	switch (what) {
80	case 0:	/* HWCAP XXX: Not yet */
81	case 1:	/* ISALIST XXX: Not yet */
82		return 0;
83
84	case 2:	/* ORIGIN */
85		if (execname == NULL)
86			xerr(1, "execname not specified in AUX vector");
87		if ((ep = strrchr(p = execname, '/')) == NULL)
88			xerr(1, "bad execname `%s' in AUX vector", execname);
89		break;
90
91	case 3:	/* OSNAME */
92	case 4:	/* OSREL */
93	case 5:	/* PLATFORM */
94		len = sizeof(name);
95		if (sysctl(mib[what - 3], 2, name, &len, NULL, 0) == -1) {
96			xwarn("sysctl");
97			return 0;
98		}
99		ep = (p = name) + len - 1;
100		break;
101	default:
102		return 0;
103	}
104
105	while (p != ep && bl)
106		*bp++ = *p++, bl--;
107
108	return bp - buf;
109}
110
111
112size_t
113_rtld_expand_path(char *buf, size_t bufsize, const char *execname,
114    const char *bp, const char *ep)
115{
116	size_t i, ds = bufsize;
117	char *dp = buf;
118	const char *p;
119	int br;
120
121	for (p = bp; p < ep;) {
122		if (*p == '$') {
123			br = *++p == '{';
124
125			if (br)
126				p++;
127
128			for (i = 0; i < sizeof(bltn) / sizeof(bltn[0]); i++) {
129				size_t s = bltn[i].namelen;
130				const char *es = p + s;
131
132				if ((br && *es != '}') ||
133				    (!br && (es != ep &&
134					isalpha((unsigned char)*es))))
135					continue;
136
137				if (strncmp(bltn[i].name, p, s) == 0) {
138					size_t ls = expand(dp, execname, i, ds);
139					if (ls >= ds)
140						return bufsize;
141					ds -= ls;
142					dp += ls;
143					p = es + br;
144					goto done;
145				}
146			}
147			p -= br + 1;
148
149		}
150		*dp++ = *p++;
151		ds--;
152done:;
153	}
154	*dp = '\0';
155	return dp - buf;
156}
157
158#ifdef DEBUG_EXPAND
159int
160main(int argc, char *argv[])
161{
162	char buf[1024];
163	size_t i;
164
165	for (i = 1; i < argc; i++) {
166		char *p = argv[i], *ep = argv[i] + strlen(p);
167		size_t n = _rtld_expand_path(buf, sizeof(buf), argv[0], p, ep);
168		printf("%s\n", buf);
169	}
170	return 0;
171}
172#endif
173