/*      $NetBSD: search.c,v 1.28 2026/07/01 19:29:57 riastradh Exp $     */

/*
 * Copyright 1996 Matt Thomas <matt@3am-software.com>
 * All rights reserved.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by John Polstra.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/*
 * Dynamic linker for ELF.
 *
 * John Polstra <jdp@polstra.com>.
 */

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: search.c,v 1.28 2026/07/01 19:29:57 riastradh Exp $");
#endif /* not lint */

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <dirent.h>

#include "debug.h"
#include "rtld.h"

/*
 * Data declarations.
 */
static Search_Path    *_rtld_invalid_paths;

static Obj_Entry *_rtld_search_library_path(const char *, size_t,
    const char *, size_t, int, sigset_t *);

static Obj_Entry *
_rtld_search_library_path(const char *name, size_t namelen,
    const char *dir, size_t dirlen, int flags, sigset_t *mask)
{
        char pathname[MAXPATHLEN];
        size_t pathnamelen;
        Obj_Entry *obj;
        Search_Path *sp;

        pathnamelen = dirlen + 1 + namelen;
        if (pathnamelen >= sizeof(pathname))
                return NULL;

        for (sp = _rtld_invalid_paths; sp != NULL; sp = sp->sp_next) {
                if (sp->sp_pathlen == pathnamelen &&
                    sp->sp_path[dirlen] == '/' &&
                    !memcmp(name, sp->sp_path + dirlen + 1, namelen) &&
                    !memcmp(dir, sp->sp_path, dirlen)) {
                        return NULL;
                }
        }

        memcpy(pathname, dir, dirlen);
        pathname[dirlen] = '/';
        memcpy(pathname + dirlen + 1, name, namelen);
        pathname[pathnamelen] = '\0';

        dbg(("  Trying \"%s\"", pathname));
        obj = _rtld_load_object(pathname, flags, mask);
        if (obj == NULL) {
                Search_Path *path;

                path = NEW(Search_Path);
                path->sp_pathlen = pathnamelen;
                path->sp_path = xstrdup(pathname);
                path->sp_next = _rtld_invalid_paths;
                _rtld_invalid_paths = path;
        } else {
                assert(obj->refcount > 0);
        }
        return obj;
}

/*
 * Find the library with the given name, and return its full pathname.
 * The returned string is dynamically allocated.  Generates an error
 * message and returns NULL if the library cannot be found.
 *
 * If the second argument is non-NULL, then it refers to an already-
 * loaded shared object, whose library search path will be searched.
 */
Obj_Entry *
_rtld_load_library(const char *name, const Obj_Entry *refobj, int flags,
    sigset_t *mask)
{
        extern char *__progname;
        char tmperror[512], *tmperrorp;
        Search_Path *sp;
        const char *pathname;
        int namelen;
        Obj_Entry *obj;

        if (strchr(name, '/') != NULL) {        /* Hard coded pathname */
                if (name[0] != '/' && !_rtld_trust) {
                        _rtld_error(
                        "absolute pathname required for shared object \"%s\"",
                            name);
                        return NULL;
                }
                pathname = name;
                goto found;
        }
        dbg((" Searching for \"%s\" (%p)", name, refobj));

        tmperrorp = dlerror();
        if (tmperrorp != NULL) {
                strlcpy(tmperror, tmperrorp, sizeof(tmperror));
                tmperrorp = tmperror;
        }

        namelen = strlen(name);

        for (sp = _rtld_paths; sp != NULL; sp = sp->sp_next)
                if ((obj = _rtld_search_library_path(name, namelen,
                    sp->sp_path, sp->sp_pathlen, flags, mask)) != NULL)
                        goto pathfound;

        if (refobj != NULL)
                for (sp = refobj->rpaths; sp != NULL; sp = sp->sp_next)
                        if ((obj = _rtld_search_library_path(name,
                            namelen, sp->sp_path, sp->sp_pathlen, flags, mask))
                            != NULL)
                                goto pathfound;

        for (sp = _rtld_default_paths; sp != NULL; sp = sp->sp_next)
                if ((obj = _rtld_search_library_path(name, namelen,
                    sp->sp_path, sp->sp_pathlen, flags, mask)) != NULL)
                        goto pathfound;

        _rtld_error("%s: Shared object \"%s\" not found",
            refobj ? refobj->path : __progname, name);
        return NULL;

pathfound:
        /*
         * The library has been found, but it couldn't be loaded for some
         * reason.
         */
        if (obj == OBJ_ERR)
                return NULL;
        /*
         * Successfully found a library; restore the dlerror state as it was
         * before _rtld_load_library() was called (any failed call to
         * _rtld_search_library_path() will set the dlerror state, but if the
         * library was eventually found, then the error state should not
         * change.
         */
        if (tmperrorp)
                _rtld_error("%s", tmperror);
        else
                (void)dlerror();
        assert(obj->refcount > 0);
        return obj;

found:
        obj = _rtld_load_object(pathname, flags, mask);
        if (obj == OBJ_ERR)
                return NULL;

        assert(obj->refcount > 0);
        return obj;
}