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

/*	$NetBSD: search.c,v 1.3 1997/02/17 19:32:05 cgd 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"

#define CONCAT(x,y)     __CONCAT(x,y)
#define ELFNAME(x)      CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x)))
#define ELFNAME2(x,y)   CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y))))
#define ELFNAMEEND(x)   CONCAT(x,CONCAT(_elf,ELFSIZE))
#define ELFDEFNNAME(x)  CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x)))

/*
 * Data declarations.
 */

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

    if (stat(pathname, &mystat) >= 0 && S_ISREG(mystat.st_mode)) {
	if ((fd = open(pathname, O_RDONLY)) >= 0) {
	    if (read(fd, &ehdr, sizeof(ehdr)) != sizeof(ehdr))
		goto lose;

	    /* Elf_e_ident includes class */
	    if (memcmp(Elf_e_ident, ehdr.e_ident, Elf_e_siz) != 0)
		goto lose;

	    switch (ehdr.e_machine) {
	    ELFDEFNNAME(MACHDEP_ID_CASES)

	    default:
		goto lose;
	    }

	    if (ehdr.e_ident[Elf_ei_version] != Elf_ev_current ||
	      ehdr.e_version != Elf_ev_current ||
	      ehdr.e_ident[Elf_ei_data] != ELFDEFNNAME(MACHDEP_ENDIANNESS) ||
	      ehdr.e_type != Elf_et_dyn)
		goto lose;

	    close(fd);
	    return true;

lose:
	    close(fd);
	}
    }

    return false;
}


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

	pathname = xmalloc(dirlen + 1 + namelen + 1);
	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(
    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);
	    strcpy(pathname, LIBDIR);
	    strcpy(pathname + LIBDIRLEN, name + SVR4_LIBDIRLEN);
	    return pathname;
	}
#endif /* SVR4_LIBDIR */
	return xstrdup(name);
    }

    dbg(" Searching for \"%s\" (%p)", name, refobj);

	namelen = strlen(name);

    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_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;
}