/*      $NetBSD: expand.c,v 1.8 2025/05/02 23:04:56 riastradh Exp $     */

/*-
 * Copyright (c) 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: expand.c,v 1.8 2025/05/02 23:04:56 riastradh Exp $");
#endif /* not lint */

#include <ctype.h>
#include <string.h>
#include <sys/sysctl.h>

#ifdef DEBUG_EXPAND
#include <stdio.h>
#include <err.h>
#define xwarn warn
#define xerr err
size_t _rtld_expand_path(char *, size_t, const char *, const char *,
    const char *);
#else
#include <sys/stat.h>
#include "rtld.h"
#endif

#include "../../lib/libc/include/__sysctl.h" /* __sysctl syscall stub */

static const struct {
        const char *name;
        size_t namelen;
} bltn[] = {
#define ADD(a)  { #a, sizeof(#a) - 1 },
        ADD(HWCAP)      /* SSE, MMX, etc */
        ADD(ISALIST)    /* XXX */
        ADD(ORIGIN)     /* dirname argv[0] */
        ADD(OSNAME)     /* uname -s */
        ADD(OSREL)      /* uname -r */
        ADD(PLATFORM)   /* uname -p */
};

static int mib[3][2] = {
        { CTL_KERN, KERN_OSTYPE },
        { CTL_KERN, KERN_OSRELEASE },
        { CTL_HW, HW_MACHINE_ARCH },
};

static size_t
expand(char *buf, const char *execname, size_t what, size_t bl)
{
        const char *p, *ep;
        char *bp = buf;
        size_t len;
        char name[32];

        switch (what) {
        case 0: /* HWCAP XXX: Not yet */
        case 1: /* ISALIST XXX: Not yet */
                return 0;

        case 2: /* ORIGIN */
                if (execname == NULL)
                        xerr(1, "execname not specified in AUX vector");
                if ((ep = strrchr(p = execname, '/')) == NULL)
                        xerr(1, "bad execname `%s' in AUX vector", execname);
                break;

        case 3: /* OSNAME */
        case 4: /* OSREL */
        case 5: /* PLATFORM */
                len = sizeof(name);
                if (__sysctl(mib[what - 3], 2, name, &len, NULL, 0) == -1) {
                        xwarn("sysctl");
                        return 0;
                }
                ep = (p = name) + len - 1;
                break;
        default:
                return 0;
        }

        while (p != ep && bl)
                *bp++ = *p++, bl--;

        return bp - buf;
}


size_t
_rtld_expand_path(char *buf, size_t bufsize, const char *execname,
    const char *bp, const char *ep)
{
        size_t i, ds = bufsize;
        char *dp = buf;
        const char *p;
        int br;

        for (p = bp; p < ep;) {
                if (*p == '$') {
                        br = *++p == '{';

                        if (br)
                                p++;

                        for (i = 0; i < sizeof(bltn) / sizeof(bltn[0]); i++) {
                                size_t s = bltn[i].namelen;
                                const char *es = p + s;

                                if ((br && *es != '}') ||
                                    (!br && (es != ep &&
                                        isalpha((unsigned char)*es))))
                                        continue;

                                if (strncmp(bltn[i].name, p, s) == 0) {
                                        size_t ls = expand(dp, execname, i, ds);
                                        if (ls >= ds)
                                                return bufsize;
                                        ds -= ls;
                                        dp += ls;
                                        p = es + br;
                                        goto done;
                                }
                        }
                        p -= br + 1;

                }
                *dp++ = *p++;
                ds--;
done:;
        }
        *dp = '\0';
        return dp - buf;
}

#ifdef DEBUG_EXPAND
int
main(int argc, char *argv[])
{
        char buf[1024];
        size_t i;

        for (i = 1; i < argc; i++) {
                char *p = argv[i], *ep = argv[i] + strlen(p);
                size_t n = _rtld_expand_path(buf, sizeof(buf), argv[0], p, ep);
                printf("%s\n", buf);
        }
        return 0;
}
#endif