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expand.c revision 1.8 
      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
     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
    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
    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