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load.c revision 1.1 
      1 /*	$NetBSD: load.c,v 1.1 1996/12/16 20:37:59 cgd Exp $	*/
      2 
      3 /*
      4  * Copyright 1996 John D. Polstra.
      5  * Copyright 1996 Matt Thomas <matt (at) 3am-software.com>
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *      This product includes software developed by John Polstra.
     19  * 4. The name of the author may not be used to endorse or promote products
     20  *    derived from this software without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     32  */
     33 
     34 /*
     35  * Dynamic linker for ELF.
     36  *
     37  * John Polstra <jdp (at) polstra.com>.
     38  */
     39 
     40 #include <err.h>
     41 #include <errno.h>
     42 #include <fcntl.h>
     43 #include <stdarg.h>
     44 #include <stdio.h>
     45 #include <stdlib.h>
     46 #include <string.h>
     47 #include <unistd.h>
     48 #include <sys/types.h>
     49 #include <sys/mman.h>
     50 #include <dirent.h>
     51 
     52 #include "debug.h"
     53 #include "rtld.h"
     54 
     55 /*
     56  * Load a shared object into memory, if it is not already loaded.  The
     57  * argument must be a string allocated on the heap.  This function assumes
     58  * responsibility for freeing it when necessary.
     59  *
     60  * Returns a pointer to the Obj_Entry for the object.  Returns NULL
     61  * on failure.
     62  */
     63 Obj_Entry *
     64 _rtld_load_object(
     65     char *filepath)
     66 {
     67     Obj_Entry *obj;
     68 
     69     for (obj = _rtld_objlist->next;  obj != NULL;  obj = obj->next)
     70 	if (strcmp(obj->path, filepath) == 0)
     71 	    break;
     72 
     73     if (obj == NULL) {	/* First use of this object, so we must map it in */
     74 	int fd;
     75 
     76 	if ((fd = open(filepath, O_RDONLY)) == -1) {
     77 	    _rtld_error("Cannot open \"%s\"", filepath);
     78 	    return NULL;
     79 	}
     80 	obj = _rtld_map_object(filepath, fd);
     81 	close(fd);
     82 	if (obj == NULL) {
     83 	    free(filepath);
     84 	    return NULL;
     85 	}
     86 
     87 	obj->path = filepath;
     88 	_rtld_digest_dynamic(obj);
     89 
     90 	*_rtld_objtail = obj;
     91 	_rtld_objtail = &obj->next;
     92 #ifdef RTLD_LOADER
     93 	_rtld_linkmap_add(obj);		/* for GDB */
     94 #endif
     95 
     96 	dbg("  %p .. %p: %s", obj->mapbase,
     97 	    obj->mapbase + obj->mapsize - 1, obj->path);
     98 	if (obj->textrel)
     99 	    dbg("  WARNING: %s has impure text", obj->path);
    100     } else
    101 	free(filepath);
    102 
    103     ++obj->refcount;
    104     return obj;
    105 }
    106 
    107 /*
    108  * Given a shared object, traverse its list of needed objects, and load
    109  * each of them.  Returns 0 on success.  Generates an error message and
    110  * returns -1 on failure.
    111  */
    112 int
    113 _rtld_load_needed_objects(
    114     Obj_Entry *first)
    115 {
    116     Obj_Entry *obj;
    117     int status = 0;
    118 
    119     for (obj = first;  obj != NULL;  obj = obj->next) {
    120 	Needed_Entry *needed;
    121 
    122 	for (needed = obj->needed;  needed != NULL;  needed = needed->next) {
    123 	    const char *name = obj->strtab + needed->name;
    124 	    char *libpath = _rtld_find_library(name, obj);
    125 
    126 	    if (libpath == NULL) {
    127 		status = -1;
    128 	    } else {
    129 		needed->obj = _rtld_load_object(libpath);
    130 		if (needed->obj == NULL)
    131 		    status = -1;		/* FIXME - cleanup */
    132 	    }
    133 #ifdef RTLD_LOADER
    134 	    if (status == -1)
    135 		return status;
    136 #endif
    137 	}
    138     }
    139 
    140     return status;
    141 }
    142