xref: /src/libexec/ld.elf_so/search.c

/*	$NetBSD: search.c,v 1.9.6.1 2001/12/09 17:22:04 he Exp $	 */

/*
 * Copyright 1996 Matt Thomas <matt (at) 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 (at) polstra.com>.
 */

#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 bool _rtld_check_library __P((const char *));
static char *_rtld_search_library_path __P((const char *, size_t, const char *,
    size_t));

static bool
_rtld_check_library(pathname)
	const char *pathname;
{
	struct stat mystat;
	Elf_Ehdr ehdr;
	int fd;

	if (stat(pathname, &mystat) == -1 || !S_ISREG(mystat.st_mode))
		return false;

	if ((fd = open(pathname, O_RDONLY)) == -1)
		return false;

	if (read(fd, &ehdr, sizeof(ehdr)) != sizeof(ehdr))
		goto lose;

	/* ELF_Ehdr.e_ident includes class */
	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
	    ehdr.e_ident[EI_CLASS] != ELFCLASS)
		goto lose;

	switch (ehdr.e_machine) {
		ELFDEFNNAME(MACHDEP_ID_CASES)
	default:
		goto lose;
	}

	if (ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
	    ehdr.e_version != EV_CURRENT ||
	    ehdr.e_ident[EI_DATA] != ELFDEFNNAME(MACHDEP_ENDIANNESS) ||
	    ehdr.e_type != ET_DYN)
		goto lose;

	close(fd);
	return true;

lose:
	close(fd);
	return false;
}


static char *
_rtld_search_library_path(name, namelen, dir, dirlen)
	const char *name;
	size_t namelen;
	const char *dir;
	size_t dirlen;
{
	char *pathname;

	pathname = xmalloc(dirlen + 1 + namelen + 1);
	(void)strncpy(pathname, dir, dirlen);
	pathname[dirlen] = '/';
	strcpy(pathname + dirlen + 1, name);

	dbg(("  Trying \"%s\"", pathname));
	if (_rtld_check_library(pathname))	/* We found it */
		return pathname;

	free(pathname);
	return NULL;
}

/*
 * 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.
 */
char *
_rtld_find_library(name, refobj)
	const char *name;
	const Obj_Entry *refobj;
{
	Search_Path *sp;
	char *pathname;
	int namelen;

	if (strchr(name, '/') != NULL) {	/* Hard coded pathname */
		if (name[0] != '/' && !_rtld_trust) {
			_rtld_error(
			"Absolute pathname required for shared object \"%s\"",
			    name);
			return NULL;
		}
#ifdef SVR4_LIBDIR
		if (strncmp(name, SVR4_LIBDIR, SVR4_LIBDIRLEN) == 0
		    && name[SVR4_LIBDIRLEN] == '/') {	/* In "/usr/lib" */
			/*
			 * Map hard-coded "/usr/lib" onto our ELF library
			 * directory.
			 */
			pathname = xmalloc(strlen(name) + LIBDIRLEN -
			    SVR4_LIBDIRLEN + 1);
			(void)strcpy(pathname, LIBDIR);
			(void)strcpy(pathname + LIBDIRLEN, name +
			    SVR4_LIBDIRLEN);
			return pathname;
		}
#endif /* SVR4_LIBDIR */
		return xstrdup(name);
	}
	dbg((" Searching for \"%s\" (%p)", name, refobj));

	namelen = strlen(name);

	for (sp = _rtld_paths; sp != NULL; sp = sp->sp_next)
		if ((pathname = _rtld_search_library_path(name, namelen,
		    sp->sp_path, sp->sp_pathlen)) != NULL)
			return (pathname);

	if (refobj != NULL)
		for (sp = refobj->rpaths; sp != NULL; sp = sp->sp_next)
			if ((pathname = _rtld_search_library_path(name,
			    namelen, sp->sp_path, sp->sp_pathlen)) != NULL)
				return (pathname);

	for (sp = _rtld_default_paths; sp != NULL; sp = sp->sp_next)
		if ((pathname = _rtld_search_library_path(name, namelen,
		    sp->sp_path, sp->sp_pathlen)) != NULL)
			return (pathname);

#if 0
	if ((refobj != NULL &&
	    (pathname = _rtld_search_library_path(name,
	    refobj->rpath)) != NULL) ||
	    (pathname = _rtld_search_library_path(name,
	    ld_library_path)) != NULL
#ifdef SVR4_LIBDIR
	    LOSE !
	    ||(pathname = _rtld_search_library_path(name, SVR4_LIBDIR)) != NULL
#endif
	    )
		return pathname;
#endif

	_rtld_error("Shared object \"%s\" not found", name);
	return NULL;
}