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dlfcn_elf.c revision 1.8 
      1 /*	$NetBSD: dlfcn_elf.c,v 1.8 2011/03/07 05:09:11 joerg Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2000 Takuya SHIOZAKI
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #include <sys/cdefs.h>
     29 #if defined(LIBC_SCCS) && !defined(lint)
     30 __RCSID("$NetBSD: dlfcn_elf.c,v 1.8 2011/03/07 05:09:11 joerg Exp $");
     31 #endif /* LIBC_SCCS and not lint */
     32 
     33 #include "reentrant.h"
     34 #include "namespace.h"
     35 #include <elf.h>
     36 #include <errno.h>
     37 #include <string.h>
     38 
     39 #undef dlopen
     40 #undef dlclose
     41 #undef dlsym
     42 #undef dlerror
     43 #undef dladdr
     44 #undef dfinfo
     45 
     46 #define	dlopen		___dlopen
     47 #define	dlclose		___dlclose
     48 #define	dlsym		___dlsym
     49 #define	dlerror		___dlerror
     50 #define	dladdr		___dladdr
     51 #define	dlinfo		___dlinfo
     52 #define	dl_iterate_phdr		___dl_iterate_phdr
     53 
     54 #define ELFSIZE ARCH_ELFSIZE
     55 #include "rtld.h"
     56 
     57 #ifdef __weak_alias
     58 __weak_alias(dlopen,___dlopen)
     59 __weak_alias(dlclose,___dlclose)
     60 __weak_alias(dlsym,___dlsym)
     61 __weak_alias(dlerror,___dlerror)
     62 __weak_alias(dladdr,___dladdr)
     63 __weak_alias(dlinfo,___dlinfo)
     64 __weak_alias(dl_iterate_phdr,___dl_iterate_phdr)
     65 
     66 __weak_alias(__dlopen,___dlopen)
     67 __weak_alias(__dlclose,___dlclose)
     68 __weak_alias(__dlsym,___dlsym)
     69 __weak_alias(__dlerror,___dlerror)
     70 __weak_alias(__dladdr,___dladdr)
     71 __weak_alias(__dlinfo,___dlinfo)
     72 __weak_alias(__dl_iterate_phdr,___dl_iterate_phdr)
     73 #endif
     74 
     75 /*
     76  * For ELF, the dynamic linker directly resolves references to its
     77  * services to functions inside the dynamic linker itself.  These
     78  * weak-symbol stubs are necessary so that "ld" won't complain about
     79  * undefined symbols.  The stubs are executed only when the program is
     80  * linked statically, or when a given service isn't implemented in the
     81  * dynamic linker.  They must return an error if called, and they must
     82  * be weak symbols so that the dynamic linker can override them.
     83  */
     84 
     85 static char dlfcn_error[] = "Service unavailable";
     86 
     87 /*ARGSUSED*/
     88 void *
     89 dlopen(const char *name, int mode)
     90 {
     91 
     92 	return NULL;
     93 }
     94 
     95 /*ARGSUSED*/
     96 int
     97 dlclose(void *fd)
     98 {
     99 
    100 	return -1;
    101 }
    102 
    103 /*ARGSUSED*/
    104 void *
    105 dlsym(void *handle, const char *name)
    106 {
    107 
    108 	return NULL;
    109 }
    110 
    111 /*ARGSUSED*/
    112 __aconst char *
    113 dlerror()
    114 {
    115 
    116 	return dlfcn_error;
    117 }
    118 
    119 /*ARGSUSED*/
    120 int
    121 dladdr(const void *addr, Dl_info *dli)
    122 {
    123 
    124 	return 0;
    125 }
    126 
    127 /*ARGSUSED*/
    128 int
    129 dlinfo(void *handle, int req, void *v)
    130 {
    131 
    132 	return -1;
    133 }
    134 
    135 static once_t dl_iterate_phdr_once = ONCE_INITIALIZER;
    136 static const char *dlpi_name;
    137 static Elf_Addr dlpi_addr;
    138 static const Elf_Phdr *dlpi_phdr;
    139 static Elf_Half dlpi_phnum;
    140 
    141 /*
    142  * Declare as common symbol to allow new libc with older binaries to
    143  * not trigger an undefined reference.
    144  */
    145 extern __dso_hidden void *__auxinfo;
    146 
    147 static void
    148 dl_iterate_phdr_setup(void)
    149 {
    150 	const AuxInfo *aux;
    151 
    152 	if (__auxinfo == NULL)
    153 		return;
    154 
    155 	for (aux = __auxinfo; aux->a_type != AT_NULL; ++aux) {
    156 		switch (aux->a_type) {
    157 		case AT_BASE:
    158 			dlpi_addr = aux->a_v;
    159 			break;
    160 		case AT_PHDR:
    161 			dlpi_phdr = (void *)aux->a_v;
    162 			break;
    163 		case AT_PHNUM:
    164 			dlpi_phnum = aux->a_v;
    165 			break;
    166 		case AT_SUN_EXECNAME:
    167 			dlpi_name = (void *)aux->a_v;
    168 			break;
    169 		}
    170 	}
    171 }
    172 
    173 /*ARGSUSED*/
    174 int
    175 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *),
    176     void *data)
    177 {
    178 	struct dl_phdr_info phdr_info;
    179 
    180 	if (__auxinfo == NULL)
    181 		return EOPNOTSUPP;
    182 
    183 	thr_once(&dl_iterate_phdr_once, dl_iterate_phdr_setup);
    184 
    185 	memset(&phdr_info, 0, sizeof(phdr_info));
    186 	phdr_info.dlpi_addr = dlpi_addr;
    187 	phdr_info.dlpi_phdr = dlpi_phdr;
    188 	phdr_info.dlpi_phnum = dlpi_phnum;
    189 	phdr_info.dlpi_name = dlpi_name;
    190 
    191 	return callback(&phdr_info, sizeof(phdr_info), data);
    192 }
    193