lib/libc/gen/dlfcn.c

   1 /*-
   2  * Copyright (c) 1998 John D. Polstra
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/lib/libc/gen/dlfcn.c 217154 2011-01-08 17:13:43Z kib $
  27  */
  28
  29 #include <sys/mman.h>
  30 #include <dlfcn.h>
  31 #include <link.h>
  32 #include <stddef.h>
  33 #include <string.h>
  34
  35 extern char **environ;
  36
  37 static char sorry[] = "Service unavailable";
  38
  39 /*
  40  * For ELF, the dynamic linker directly resolves references to its
  41  * services to functions inside the dynamic linker itself.  These
  42  * weak-symbol stubs are necessary so that "ld" won't complain about
  43  * undefined symbols.  The stubs are executed only when the program is
  44  * linked statically, or when a given service isn't implemented in the
  45  * dynamic linker.  They must return an error if called, and they must
  46  * be weak symbols so that the dynamic linker can override them.
  47  */
  48
  49 #pragma weak _rtld_error
  50 void
  51 _rtld_error(const char *fmt __unused, ...)
  52 {
  53 }
  54
  55 #pragma weak dladdr
  56 int
  57 dladdr(const void *addr __unused, Dl_info *dlip __unused)
  58 {
  59         _rtld_error(sorry);
  60         return 0;
  61 }
  62
  63 #pragma weak dlclose
  64 int
  65 dlclose(void *handle __unused)
  66 {
  67         _rtld_error(sorry);
  68         return -1;
  69 }
  70
  71 #pragma weak dlerror
  72 char *
  73 dlerror(void)
  74 {
  75         return sorry;
  76 }
  77
  78 #pragma weak dlopen
  79 void *
  80 dlopen(const char *name __unused, int mode __unused)
  81 {
  82         _rtld_error(sorry);
  83         return NULL;
  84 }
  85
  86 #pragma weak dlsym
  87 void *
  88 dlsym(void *handle __unused, const char *name __unused)
  89 {
  90         _rtld_error(sorry);
  91         return NULL;
  92 }
  93
  94 #pragma weak dlfunc
  95 dlfunc_t
  96 dlfunc(void * handle __unused, const char * name __unused)
  97 {
  98         _rtld_error(sorry);
  99         return NULL;
 100 }
 101
 102 #pragma weak dlvsym
 103 void *
 104 dlvsym(void *handle __unused,const char *name __unused,
 105     const char *version __unused)
 106 {
 107         _rtld_error(sorry);
 108         return NULL;
 109 }
 110
 111 #pragma weak _rtld_thread_init
 112 void
 113 _rtld_thread_init(void * li)
 114 {
 115         _rtld_error(sorry);
 116 }
 117
 118 #pragma weak dlinfo
 119 int
 120 dlinfo(void *handle __unused, int request __unused, void *p __unused)
 121 {
 122         _rtld_error(sorry);
 123         return 0;
 124 }
 125
 126 __dso_hidden struct dl_phdr_info
 127 build_phdr_info(void)
 128 {
 129         struct dl_phdr_info phdr_info;
 130         Elf_Addr *sp;
 131         Elf_Auxinfo *aux, *auxp;
 132         unsigned int i;
 133
 134         sp = (Elf_Addr *) environ;
 135         while (*sp++ != 0)
 136                 ;
 137         aux = (Elf_Auxinfo *) sp;
 138         memset (&phdr_info, 0, sizeof(phdr_info));
 139         for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
 140                 switch (auxp->a_type) {
 141                 case AT_BASE:
 142                         phdr_info.dlpi_addr = (Elf_Addr) auxp->a_un.a_ptr;
 143                         break;
 144                 case AT_EXECPATH:
 145                         phdr_info.dlpi_name = (const char *) auxp->a_un.a_ptr;
 146                         break;
 147                 case AT_PHDR:
 148                         phdr_info.dlpi_phdr = (const Elf_Phdr *) auxp->a_un.a_ptr;
 149                         break;
 150                 case AT_PHNUM:
 151                         phdr_info.dlpi_phnum = (Elf_Half) auxp->a_un.a_val;
 152                         break;
 153                 }
 154         }
 155
 156         for (i = 0; i < phdr_info.dlpi_phnum; i++)
 157             if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) {
 158                 phdr_info.dlpi_tls_modid = 1;
 159                 phdr_info.dlpi_tls_data =
 160                   (void*)phdr_info.dlpi_phdr[i].p_vaddr;
 161             }
 162
 163         return (phdr_info);
 164 }
 165
 166 #pragma weak dl_iterate_phdr
 167 int
 168 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *),
 169     void *data)
 170 {
 171         static int seen = 0;
 172         static struct dl_phdr_info phdr_info;
 173         if (!seen) {
 174                 seen = 1;
 175                 phdr_info = build_phdr_info();
 176         }
 177
 178         return callback(&phdr_info, sizeof(phdr_info), data);
 179 }
 180
 181 #pragma weak fdlopen
 182 void *
 183 fdlopen(int fd __unused, int mode __unused)
 184 {
 185         _rtld_error(sorry);
 186         return NULL;
 187 }
 188
 189 #pragma weak _rtld_addr_phdr
 190 int
 191 _rtld_addr_phdr(const void *addr __unused,
 192                 struct dl_phdr_info *phdr_info __unused)
 193 {
 194
 195         return (0);
 196 }
 197
 198 #pragma weak _rtld_get_stack_prot
 199 int
 200 _rtld_get_stack_prot(void)
 201 {
 202         return (PROT_EXEC | PROT_READ | PROT_WRITE);
 203 }